Chapter 7 Pericardium, Heart, And Great Vessels in the Thorax

5/24/2014 Print: Chapter 7. Pericardium, Heart, and Great Vessels in the Thorax

http://web.uni-plovdiv.bg/stu1104541018/docs/res/skandalakis'%20surgical%20anatomy%20-%202004/Chapter%2007_%20Pericardium,%20Heart,%20and%20 1/62

Print | Close Window

Note: Large images and tables on this page may necessitate printing in landscape mode.

Skandalakis' Surgical Anatomy > Chapter 7. Pericardium, Heart, and Great Vessels in the Thorax >

HISTORY

The anatomic and surgical history of the heart is shown in Table 7-1.

Table 7-1. Anatomic and Surgical History of the Pericardium, Heart, and Great Vessels in the Thorax

Unknown (Imhotep of

Egypt?)

3000

BC

Heart described as center of a system of blood vessels; pulse and heart were directly correlated

Hippocrates (460-377

BC)

Described the valves and chambers of the heart. Described the pericardium as "a smooth tunic which envelops the heart

and contains a small amount of fluid resembling urine."

Demonstrated that fluid could flow in only one direction through the aortic valve.

Herophilus (335-280

BC)

Described the pulmonary artery

Galen (130-ca.200) Observed that the heart can beat independent of central nervous system control

Mondino de Luzzi

(1270-1326)

Accurately described the anatomy of the heart; challenged Galen's view of the existence of pores in the interventricular

septum

Leonardo Da Vinci

(1452-1519)

Performed dissections and carefully illustrated heart anatomy; observed that air does not pass through the heart

Malpighi 1661 Discovered capillaries. Discovered the linkage between arteries and veins.

Scarpa (1747-1832) Accurately illustrated the nerves of the heart

Romero 1819 Successfully opened pericardium

Schuch 1840 Performed pericardiocentesis without incision

Fick 1870 Reported a calculation of the cardiac output

Matas 1888 Reported effective occlusion of arterial aneurysm

DelVecchio 1895 Suture of wound in dog heart

Rehn 1896 Successful suture of stab wound in human right ventricle

Einthoven 1903 Performed first electrocardiograph yielding good tracings

Korotkoff 1905 Described his method of blood pressure measurement, now standard practice

Carrel and Guthrie 1905 Performed the first successful biterminal transplantation of a vein in a dog

Rehn, Sauerbruch 1913 Each independently introduced pericardiectomy

Berberich & Hirsch 1923 Published reproductions of living human angiograms

Cutler, Levine, and

Beck

1924 Operated on stenosed mitral valves

Abbott & Dawson 1924 Published a paper on classification of cardiac malformations

Abbott 1936 Published Atlas of Congenital Cardiac Disease

Forssman 1929 Performed a right-sided heart catheterization on himself

Dos Santos 1929 Reported the development of translumbar aortography

Claude Beck 1930s Provided important clinical and experimental descriptions that greatly enhanced the understanding of constrictive

pericarditis: "Beck's triad" (small, quiet heart with elevated venous pressure)

Hyman 1932 Reported the development of the artificial cardiac pacemaker

Gross 1939 First successful closure of ductus arteriosus

Cournand 1941 Reported on cardiac catheterization and its clinical significance

Blalock and Taussig 1944 Performed the subclavian-pulmonary shunt in tetralogy of Fallot to increase pulmonary blood flow

Crafoord and Cross 1945 Aortic resection for coarctation

Harken 1946 Report of removal of foreign bodies from the heart

Sellors 1947 Performed first pulmonic valvotomy

Harken et al. 1948 Report of mitral valvuloplasty for mitral stenosis

Murray 1948 Closure of atrial septal defect

Bailey 1948 Performed a successful mitral valvulotomy

Gross 1949 Demonstrated that preserved arterial homographs could be used in the major arteries

Bigelow 1949 Demonstrated the use of deep hypothermia and cardiac arrest in cardiac surgery on a dog

Hufnagel 1951 Demonstrated that aortic insufficiency could be partially controlled with a caged plastic ball device in the descending aorta



Zoll 1952 Developed a cardiac pacemaker for clinical use

Gibbon 1953 Successfully closed an atrial septal defect; used cardiopulmonary bypass (heart-lung machine)

Voorhees 1953 Successfully used a synthetic arterial graft in a human

DeBakey & Cooley 1953 Resected abdominal aortic aneurysms and bridged with homografts

Lillehei 1955 Corrected cardiac congenital anomalies with cross-circulation

Lewis and Varco 1956 Corrected total anomalous pulmonary venous return

Mustard 1957

Akutsu & Kolff 1958 Implanted an artificial heart in a dog

Senning 1959 Correction of transposition of great arteries

Lower and Shumway 1960 First successful canine orthotopic cardiac transplants

Sones and Shirey 1962 Published landmark paper on selective coronary arteriography

Kolesov 1964 Performed first coronary artery bypass with internal mammary artery

Rashkind 1966 Introduced balloon atrial septostomy for correction of transposition of great arteries

Barnard 1967 Performed the first heart transplant in human

Stinson, Dong,

Schroeder, Shumway

1969 Report of 13 heart transplants in humans

Favaloro 1969 Performed coronary artery bypass using saphenous vein

Cooley 1969 First to implant an artificial heart in human

DeVries 1982 First attempt at the permanent implantation of an artificial heart in a human

Bolman et al. 1985 Reported results of immunosuppressive cocktail of cyclosporine, prednisone, and azathioprine

Ochsner and Eiswirth

Jr.

1988 Reported 91% one-year survival after heart transplantation in humans (the Louisiana experience)

Battista et al. 1997 Performed the first partial left ventriculectomy

History table compiled by David A. McClusky III and John E. Skandalakis.

History Table References:

Acierno LJ. The history of cardiology. New York: Parthenon, 1994.

Barnard MS. Heart transplantation: an experimental review and preliminary research. S Afr Med J 1967;41:1260.

Battista RJ, Verde J, Nery P, Bocchino L, Takeshita N, Bhayana JN, Bergsland J, Graham S, Houck JP, Salerno TA. Partial left ventriculectomy to treat end-stage

heart disease. Ann Thorac Surg 1997;64:634-38.

Bolman RM, Elick B, Olivari MT, Ring WS, Arentsen CE. Improved immunosuppression for heart transplantation. J Heart Transplant 1985;4:315

Beck CS, Moore RL. Significance of pericardium in relation to surgery of the heart. Arch Surg 11:689-821, 1925

Beck CS, Grisvold RA. Pericardiectomy in the treatment of the Pick syndrome: experimental and clinical observations. Arch Surg 21:1064-1113, 1930

Carrel A, Guthrie CC. The transplantation of veins and organs. Am Med 1905;10:1101.

DeBakey ME, Cooley DA. Surgical treatment of aneurysm of abdominal aorta by resection and restoration of continuity with homograft. Surg Gynecol Obstet

1953;97:157.

Ebert PA, Najafi H. The pericardium. In Sabiston DC Jr, Spencer FC (eds). Surgery of the Chest, 5th Ed. Philadelphia: WB Saunders, 1990, p. 1230.

Gray SW, Skandalakis JE, Rowe JS, Symbas PN. Status of cardiac surgery: surgical embryology of the heart. In: Bourne GH (ed). Hearts and Heart-like

Organs. New York: Academic Press, 1980.

Harken DE, Ellis LB, Ware PF, Norman LR. The surgical treatment of mitral stenosis. I. Valvuloplasty. N Engl J Med 1948;239:804

Lower RR, Shumway NE. Studies on orthotopic transplantation of the canine heart. Surg Forum 1960;11:18.

Ochsner JL, Eiswirth CC Jr. Heart transplantation: the Louisiana experience. J La State Med Soc 1988;140:34.

Sones FM Jr, Shirey EK. Cine coronary arteriography. Mod Concepts Cardiovasc Dis 1962;31:735-38.

Stinson EB, Dong E, Schroeder JS, Shumway NE. Cardiac transplantation in man. Ann Surg 1969;170:588.

Weisse AB. Medical Odysseys. New Brunswick NJ: Rutgers University Press, 1991.

EMBRYOGENESIS

Normal Development of Heart, Pericardium, and Great Vessels

During the first 20 days, the human embryo survives by diffusion. At that time, the genesis of the heart takes place by proliferation of mesenchymal

cells. These cells, which are located in the splanchnic mesoderm, are known as the angiogenic clusters. The cells form a network of small blood

vessels. The anterior central part of this network is the cardiogenic area, which is responsible for the formation of the heart and the dorsal aortas.

At the end of the third week, the primitive heart is formed by two endocardial heart tubes. These tubes unite to form a single heart tube. At the

time of the union, cardiac jelly appears, surrounding the tubes. The myoepicardial mantle, which is of mesenchymal origin, surrounds the cardiac

jelly.

The progressive genesis of specific heart parts takes place at this time:

The endocardium, which is the endothelial lining of the heart, is formed by the endocardial tube.



The endocardium, which is the endothelial lining of the heart, is formed by the endocardial tube.

The muscular wall of the heart (myocardium) is formed by the myocardial mantle.

The visceral pericardium, or epicardium, is also formed by the myoepicardial mantle.

Therefore, the cardiac wall is formed from inside to outside by the endocardium, myocardium, and epicardium.

Around the end of the third week, several embryologic entities appear. From above downward, they are the:

Truncus arteriosus

Bulbus cordis

Ventricle

Atrium

Sinus venosus

The student should not be confused by the use of the term "bulboventricular tube," which includes the aortic sac (from which the aortic arches will

develop) and the primitive ventricle (which develops by expansion of the tube).

Next, a dextral looping takes place. The heart is nearly S-shaped. The atrium is positioned dorsal to the outflow tract (bulbus cordis), which

represents the upper limb of the S. The ventricle is represented by the middle limb of the S, and the atrium by its lower limb.

It is not within the scope of this chapter to present the mechanisms of septation and the formation of the seven septa (atrial septum primum, atrial

septum secundum, ventricular septum, aorticopulmonary septum, septum of the atrioventricular canal, canal septum, and truncal septum) which are

responsible for the partitioning of the heart. Septation starts approximately at the middle of the fourth week and ends at the end of the fifth week.

The "parts of the developing heart should not be simplistically identified with the components of the full-term heart."2 To start with, the heart has

one atrium and one ventricle. These septate around the end of the fifth week. The separation of the atrioventricular canal into right and left

atrioventricular canals is accomplished by fusion of the endocardial cushions which develop at the dorsal and ventral walls of the heart.

The septum primum and septum secundum are responsible for the partitioning of the primitive atrium. The original right atrium, together with the

sinus venosus and its right horn, is responsible for the final formation of the right atrium. The original left atrium, with participation of the terminal

portions of the pulmonary veins, is responsible for the final formation of the left atrium.

At the end of the fourth week, the cardiac ventricles begin to form. The left ventricle arises from the ventricular portion of the primitive heart.

During development, the bulboventricular fold disappears entirely. It is important to be aware of this in order to avoid thinking that it gives rise to

the interventricular septum. As the muscular interventricular septum develops, it actually separates the heart tube ventricle (presumptive left

ventricle) from the bulbus cordis (presumptive right ventricle). Because the primitive atrium and ultimately the definitive right and left atria shift to

the right, the interventricular septum forms such as to fuse with the endocardial cushions, and the right atrium opens into the right ventricle, etc.

Should this shift not occur, the double inlet malformation results. An exaggerated shift to the right results in a double outlet malformation.

The interventricular foramen is bounded by the ventricular muscular ridge, the endocardial cushions, and a neural crest derivative, the

aorticopulmonary septum. The closure of this foramen at the end of the seventh week is effected by the development of the membranous portion of

the interventricular septum by contributions from the three aforementioned structures. Thus the aorticopulmonary septum is involved in the

formation of the left and right ventricular outlets as well as that of the pulmonary trunk and aorta.

The fusion of bulbar and truncal ridges around the fifth week is responsible for the partitioning of the bulbus cordis and truncus arteriosus, and

therefore, for the reciprocally upward-spiraling formation of the ascending aorta and pulmonary trunk. The left pulmonary artery and the distal

segment of the aortic arch communicate by means of the ductus arteriosus, a channel of variable length and diameter. The ductus arteriosus is

derived embryologically from the sixth left aortic arch. At the time of birth, the ductus constricts, quickly becomes atretic, and thereafter remains

as the ligamentum arteriosum.

The right common cardinal vein and the proximal part of the right anterior cardinal (right precardinal) vein are responsible for the development of

both superior and inferior vena cavae. Most likely, the following three embryonic networks form parts of the inferior vena cava (IVC).

The hepatic portion derives from the omphalomesenteric vein (right vitelline vein)

The renal portion comes from the right subcardinal vein

The sacrocardinal (subcardinal) or postrenal part comes from the right sacrocardinal vein

We quote Skandalakis and Gray3 on the development of the inferior and superior vena cavae:

The channels that will form the SVC are all present by the seventh week, and the definitive channel is already larger than the alternative

pathways. By the end of the eighth week, almost all of the changes have been completed although the left supracardinal vein below the

renal collar has not disappeared. It is probably the last of the old channels to vanish since it persists the most frequently as an anomalous

left IVC.



The conducting system of the heart consists of the sinoatrial (SA) and atrioventricular (AV) nodes and the atrioventricular bundle. As reported by

O'Rahilly and Mller,4 the conducting system appears at approximately 5 weeks. It is well developed at about the eighth week.

Congenital Anomalies

Pathogenetic classification of congenital cardiovascular malformations is summarized in Table 7-2. Syndromes featuring congenital heart disease are

presented in Table 7-3.

Table 7-2. Pathogenetic Classification of Congenital Cardiovascular Malformations

I. Ectomesenchymal tissue migration abnormalities

Conotruncal septation defects

Increased mitral aortic separation (a clinically silent, forme fruste)

Subarterial, type I ventricular septal defect

Double outlet right ventricle

Tetralogy of Fallot

Pulmonary atresia with ventricular septal defect

Aorticopulmonary window

Truncus arteriosus communis

Abnormal conotrucal cushion position

Transposition of the great arteries (dextro-)

Branchial arch defects

Interrupted aortic arch type B

Double aortic arch

Right aortic arch with mirror-image branching

II. Abnormal intracardiac blood flow

Perimembranous ventricular septal defect

Left heart defects

Bicuspid aortic valve

Aortic valve stenosis

Coarctation of the aorta

Interrupted aortic arch type A

Hypoplastic left heart, aortic atresia: mitral atresia

Right heart defects

Bicuspid pulmonary valve

Secundum atrial septal defect

Pulmonary valve stenosis

Pulmonary valve atresia with intact ventricular septum

III. Cell death abnormalities

Muscular ventricular septal defect

Ebstein's malformation of the tricuspid valve

IV. Extracellular matrix abnormalities

Endocardial cushion defects

Ostium primum atrial septal defect

Type III, inflow ventricular septal defect

Atrioventricular canal

Dysplastic pulmonary or aortic valve

Source: Clark EB. Growth, morphogenesis and function: the dynamics of cardiovascular development. In: Miller JM, Neal WA, Lock JA (eds). Fetal, Neonatal

and Infant Heart Disease. New York: Appleton-Century-Crofts, 1989, p. 1-14; with permission.

Table 7-3. Syndromes Featuring Congenital Heart Disease

Name of Syndrome Clinical Features Cardiac Lesion Etiological Factors:

Chromosomal

Abnormalities

Asymmetric crying

facies

Asymmetric facies on crying (usually right sided) ? due to agenesis of anguli

oris muscle. There may also be other congenital defects

Septal defect or other

abnormality

Bonnevie-Ullrich More usually applied to Turner's syndrome with special features in the

newborn. Prominence of redundant skin over back of neck; migratory edema

and lymphangiectasia of hands and feet. Deepset nails

See Turner's syndrome See Turner



Cri-du-chat Physical and mental retardation. Cat-like cry. Microcephaly. Hypertelorism.

Epicanthic folds. Downward slant of palpebral fissures. Cleft palate

Variable Partial deletion of

short arm of

chromosome 5

De Lange Physical and mental retardation. Small hands and feet. Bushy eyebrows. Thin

lips with midline break in upper and notch in lower

Variable. Ventricular septal

defect

Sporadic. ?Mutant

gene

DiGeorge 3rd and 4th Aplasia of thymus gland impairs cellular immunity causing susceptibility to

infections. Parathyroid hypoplasia causes hypocalcemia with tetany and

convulsions. Physical and mental retardation. Choanal atresia

Septal defects. Truncus

arteriosus. Anomalies of great

vessels; double aortic arch;

interrupted arch

Sporadic.

Males/females: 2/1.

Failure of 3rd and

4th branchial arch

development

Down Mongoloid facies. Mental retardation. Hypotonia. Short metacarpals and

phalanges

Atrioventricular canal. Septal

defect. Patent ductus.

Tetralogy of Fallot

21 Trisomy (94%).

21 Trisomy/normal

mosaicism (2.4%).

Translocation

(3.3%)

Ebstein Excessive breathlessness, cyanosis, syncope but many are symptom-free.

Death sudden or from congestive heart failure

Displacement of tricuspid valve

into right ventricle. Large right

atrium. Arrhythmia. Associated

congenital heart lesions in

one-third

Sporadic

Ehlers-Danlos Hypermobility of joints, hyperelasticity of skin Atrial septal defect,

atrioventricular septal defect,

tetralogy of Fallot

Autosomal

dominant

Ellis-van Creveld

chondroectodermal

Growth retardation. Short extremities. Genuvalgus. Polydactyly, small thorax,

hypoplasia of teeth and nails. Early cardiac or respiratory death in some

Atrial septal defect (50%) Autosomal

recessive

Holt-Oram Hypoplasia of thumb, radius, clavicles with narrow shoulders. Phocomelia may

occur. Scoliosis

Variable. Atrial, ventricular

septal defect. Arrhythmia

(frequent)

Autosomal

dominant

Hurler Characteristic facies with hypertelorism, protruding tongue. Physical and

mental retardation later in first year. Kyphosis. Corneal opacities.

Hepatosplenomegaly

Infiltration of coronary arteries

(narrowing) and valves (mitral

incompetence) causes heart

failure

Autosomal

recessiveGargoylism

Mucopolysaccharidosis

Infantile

hypercalcaemia (see

Williams syndrome)

Mental and physical retardation. Characteristic facies: epicanthic folds,

hypertelorism, snub nose, carp mouth. Vomiting. Diarrhea, hypercalcemia

inconstant (role uncertain)

Supravalvar aortic stenosis.

Pulmonary artery branch

stenoses. Coarctation of aorta.

Systemic hypertension

Sporadic. Dietetic ?

excess maternal

vitamin D intake

Ivemark A syndrome associated with isomerism Anomalies of venous drainage.

Endocardial cushion defects.

Conotruncal abnormalities

Sporadic

Kartagener Situs inversus. Absent frontal sinus in some. Bronchiectasis. Upper and lower

airway infections frequent: pansinusitis, otitis, pneumonia

Anomalies of venous return,

endocardial cushions,

septation, and great vessels.

Dextrocardia

Autosomal

recessive

Laurence-Moon-Biedl-

Bardet

Mental retardation, obesity, hypogenitalism, retinitis pigmentosa Tetralogy of Fallot ?

Leopard, multiple

lentigines

Multiple dark spots on skin present at birth. Physical and mental retardation

(mild). Hypogonadism

Pulmonary stenosis. Prolonged

P-R interval and QRS complex.

Aortic stenosis

Autosomal

dominant

18 Long arm deletion Mental and physical retardation. Narrow or atretic auditory canal. Cleft palate.

Long hands; tapering fingers. Undescended testicles

Variable Long arm deletion

of chromosome 18

Marfan Connective tissue defect resulting in tall stature, thin limbs, hypotonia,

scoliosis, narrow palate, lens subluxation and lung malformation

Dilation or aneurysm of aorta

or pulmonary artery. Aortic

valve and mitral valve

incompetence (50%)

Autosomal

dominant

Noonan, Male Turner's Physical and some mental retardation. Characteristic facies with epicanthic

folds; ptosis of eyelids; low-set ears. Webbed neck. Cubitus valgus. Pectus

excavatum. Small penis. Undescended testicles. Occurs in male and female

Pulmonary stenosis. Septal

defect. Left ventricular

obstruction or non-obstructive

myopathy

Sporadic. No

chromosomal

abnormality

Osteogenesis Fragile bones, blue sclera Weakness of the media of

arteries, aneurisms, valvular

incompetence

Autosomal

dominant

Pseudo-Hurler,

Polydystrophy,

Mucolipidosis III

Physical and mental retardation. Similar to Hurler syndrome but milder Aortic stenosis and

incompetence

Autosomal

recessive

Radial aplasia

thrombocytopenia

Absent or hypoplastic radius and sometimes other limb defects.

Thrombocytopenia. Eosinophiliapenia

Variable; 25% Autosomal

recessive

Rubella Mental and physical retardation. Deafness, cataract, anemia,

thrombocytopenia. Hepatosplenomegaly. Obstructive jaundice. Osteolytic

trabeculation in metaphyses with subperiosteal rarefaction. Interstitial

Patent ductus. Pulmonary

artery branch stenoses. Septal

defect. Carditis. Lesions may

Rubella virus

transmitted from

mother. May persist



pneumonia cause heart failure in excretions of

infant for months

13 Trisomy Gross mental retardation. Microcephaly. Cleft lip and palate. Widespread

skeletal abnormality. Single umbilical artery. Early death

Ventricular and atrial septal

defects. Patent ductus. Other

gross defects 80%

Trisomy for large

part of D group (13

to 15) chromosome

18 Trisomy Mental and physical retardation. Small mouth and palpebral fissures. Short

sternum. Limb abnormalities. Hirsutism. Single umbilical artery. Early death

Ventricular and atrial septal

defects. Patent ductus and

other lesions

Extra 18

chromosome

Turner Female with short stature. Ovarian dysgenesis. Lymphedema of hands and

feet. Prominent ears. Web neck. Broad chest. Widely spaced nipples. Cutibus

valgus. Horseshoe kidney. Buccal smear shows no female sex chromatin (Barr

bodies)

Cardiac defect in over 20% and

of these 70% have coarctation

of the aorta

Sporadic.

Chromosome

pattern 45,XO (or

mosaics XX/XO,

XY/XO or part of X

missing)

Gonadal dysgenesis

VATER VATER describes the main anomalies: Vertebral anomalies; vascular

anomalies including ventricular septal defect and single umbilical artery; anal

atresia; tracheoesophageal fistula and atresia; radial dysplasia; polydactyly;

syndactyly; renal anomaly; single umbilical artery. Physical and mental

retardation (but not in all

Ventricular septal defect and

other lesions

Sporadic

Williams (see Infantile

hypercalcemia

syndrome)

Physical and mental retardation. Coarse hair. Hypoplastic nails. Hypercalcemia

occasionally found

Supravalvar aortic stenosis.

Peripheral pulmonary artery

stenosis. Pulmonary valve

stenosis. Ventricular septal

defect

Sporadic

Wolff-Parkinson-White Paroxysmal tachycardia which may cause heart failure, ECG: short P-R interval

and slurred upstroke of QRS may be found between attacks

Usually heart otherwise normal Accessory

atrioventricular

node and

conducting bundle

of Kent. Sporadic

Source: Arnold R. Heart disease in the neonate. In: Lister J, Irving IM (eds). Neonatal Surgery, 3rd ed. London: Butterworth 1990; with permission.

Clark (personal communication, 1992) correctly stated that it is impossible to classify all cardiac defects because of etiologic heterogeneity and

phenotypic variability. It is not within the scope of this book to present all the congenital anomalies of the pericardium, heart, and great vessels.

We will present a few here, and refer the interested student to Embryology for Surgeons.3

Pericardial Anomalies

Anomalies of the pericardium are shown in Table 7-4.

Table 7-4. Anomalies of the Pericardium

Anomaly Prenatal Age at

Onset

First Appearance (or Other

Diagnostic Clues)

Sex Chiefly

Affected

Relative

Frequency

Remarks

Congenital defects of the

pericardium

5th-6th weeks At any age, if at all Male Rare Usually asymptomatic; more

frequent on left

Pericardial cysts and

diverticula

4th week Adolescence or later Male Rare Rarely symptomatic

Source: Skandalakis JE, Gray SW. Embryology for Surgeons, 2nd Ed. Baltimore: Williams & Wilkins, 1994; with permission.

PERICARDIAL DEFECTS

Pericardial defects are usually asymptomatic. However, sudden death secondary to herniation and strangulation of the heart has been reported.

Pericardiectomy is the treatment of choice in symptomatic patients, especially when cardiac herniation is present.

Isolated congenital absence of the pericardium was studied by Gatzoulis et al.5 Periodic stabbing chest pain was a presenting feature, and

pericardioplasty benefitted the symptomatic patients. Chest x-rays and magnetic resonance imaging are necessary for diagnosis.

We quote Bennett6 on congenital foramen of the left pericardium:

Congenital foramen of the left parietal pericardium is uncommon. The condition has the potential to cause angina pectoris, myocardial

infarction, or even death. [In 43 confirmed cases from the English language literature] the diagnosis, made at a mean age of 20 years (range

2 to 48) was five times more common in men. In 5 fatal cases, the heart had become incarcerated. In the remainder of cases, one-third were

asymptomatic and two-thirds suffered a chest complaint that prompted diagnosis. Chest discomfort, dyspnea, and syncope were the most

common symptoms. The most common finding at surgery... was a foramen at the base of the heart through which the atrial appendage had

herniated. In eight instances, the rim of the defect lay upon and compressed the coronary circulation. Measures to remedy the disorder have

included a variety of operations, some to enlarge the defect, others to close it, amputation of the atrial appendage, and, in two cases,

myocardial revascularization. Surgery is appropriate in the majority of symptomatic patients and in all who are at risk for ventricular

herniation.

PERICARDIAL CYSTS AND DIVERTICULA

Pericardial cysts, which are quite rare, vary in size from 1 cm to 15 cm. They are almost always asymptomatic. Occasionally, they communicate

with the pericardial cavity; the term diverticulum is then more appropriate. Surgery is necessary for diagnostic confirmation.



with the pericardial cavity; the term diverticulum is then more appropriate. Surgery is necessary for diagnostic confirmation.

Cardiac and Great Vessel Anomalies

The incidence of cardiac and great vessel anomalies is 3 to 5 per 1000 live births. It is beyond the scope of this book to discuss the wide variety of

developmental defects that give rise to the broad spectrum of circulatory pathophysiology. The etiology of most of these defects is enigmatic.

Surgery is the only appropriate treatment.

Several classifications are used for anomalies of the heart and great vessels. It is extremely important that pediatricians, as well as cardiac

surgeons, understand the anatomy of the abnormal along with the pathophysiology of these malformations. We will list the three most common

groups of abnormalities and their associated defects.

Left to right shunts (acyanotic group)

Uncomplicated septal ventricular or atrial defects

Patent ductus arteriosus

Right to left shunts (cyanotic group)

Tetralogy of Fallot

Truncus arteriosus

Transposition of the great arteries

Total anomalous pulmonary venous connection

Tricuspid arteria

Ventricular outflow obstruction

Coarctation of the aorta

Aortic stenosis

Pulmonary valve stenosis

A fourth group of anomalies might include ectopia cordis, dextrocardia, and other rare malformations.

Congenital anomalies of the aorta are found in Table 7-5.

Table 7-5. Anomalies of the Aorta

Anomaly Prenatal Age at Onset First Appearance Sex Chiefly Affected Relative Frequency Remarks

Kinked aorta 7th week? None Equal Rare Asymptomatic

Aortic hypoplasia ? Young adulthood Male Rare

Double aortic arch 7th week Infancy Equal Uncommon

Right aortic arch 7th week Adulthood Male Uncommon

Retroesophageal subclavian artery 7th week Any age Female Common Usually asymptomatic

Persistent third arch 7th week Childhood ? Very rare

Cardioaortic fistula and aneurysm 6th week Adulthood Male Rare Some cases acquired

Coarctation of aorta 8th week or later Childhood Male Common

Interruption of aortic arch Infancy Male Rare

Coarctation of the abdominal aorta ? Adolescence or adulthood Equal Rare

Patent ductus arteriosus At birth Childhood Female Common

Persistent truncus arteriosus 4th to 7th weeks Childhood Male Rare

Source: Skandalakis JE, Gray SW. Embryology for Surgeons, 2nd Ed. Baltimore: Williams & Wilkins, 1994; with permission.

Anomalies of the Superior Vena Cava

The anomalies of the superior vena cava (SVC) are left persistent superior vena cava and left persistent superior vena cava with failure of

development of the coronary sinus. Awareness of an abnormal left superior vena cava is essential in order to avoid ligation during open heart

surgery.

Left persistent superior vena cava is a common defect that originates in the fifth week and affects the sexes equally. Symptoms are related to

associated cardiac defects only. A persistent left superior vena cava is not anomalous in complete situs inversus.



The pathway of left persistent superior vena cava is as follows:

It develops from the union of the left subclavian and left internal jugular veins

It receives the superior intercostal vein and the accessory hemiazygos vein

It travels downward in front of the aortic arch and in front of the left pulmonary artery and left pulmonary vein

After entering the pericardium, it is related to the posterior wall of the left atrium and the posterior atrioventricular groove

It forms the coronary sinus after receiving the great cardiac vein

The anatomic pathway of left superior vena cava with failure of coronary sinus development is similar to that of persistent left superior vena cava.

A left superior vena cava with failure of coronary sinus development empties into the upper part of the left atrium between the left superior

pulmonary vein and the atrial appendage. It bypasses the coronary sinus, which is not developed and not formed (unroofed coronary sinus).

Remember

Anomalous pulmonary veins may enter the superior vena cava. These veins must be recognized and avoided during surgery.

An absent left brachiocephalic vein may indicate a left superior vena cava. This may be detected by palpation of an enlarged coronary sinus or by entrance

of the left superior vena cava into the coronary sinus slightly above the left atrial appendage.

Curtil et al.7 reported 27 cases of left retroaortic brachiocephalic vein as follows.

A retrospective study was made of 5218 congenital [pediatric] cardiopathies. . .. A left retro-aortic brachiocephalic vein was demonstrated in

27 patients, i.e. an incidence of 0.5%. The chief cardiopathy in these patients was a tetralogy of Fallot in 25 cases (93%). Among these 25

cases of Fallot's tetralogy the aortic arch was rightsided in 19 cases (70%). . .. The embryological origin of the left retro-aortic

brachiocephalic vein. . . derives from the inferior (but not superior) transverse plexuses, connecting the two anterior cardinal veins.

Referring to left persistent superior vena cava, Hammon and Bender8 wrote, "Complications are usually related to the magnitude of operation for

associated anomalies and not to the operative therapy for this uncommon situation."

The two operations for persistent superior vena cava are

Simple ligation

'Roofing' of the coronary sinus using pericardium or part of the left atrium. This directs the blood into the right atrium.

Standardized terminology for congenital heart, pericardial, and great vessel disease is still evolving. Mavroudis and Jacobs9 have provided an introduction

to the work of the International Congenital Heart Surgery Nomenclature and Database Project, and we urge the interested student to study the April 2000

issue of Annals of Thoracic Surgery.

SURGICAL ANATOMY

Knowledge of detailed cardiac anatomy is a prerequisite for successful surgery. Nowhere is this more important than in the setting of

congenital cardiac malformations.R.H. Anderson, B.R. Wilcox10

In this chapter, the anatomy of the pericardium, heart, and great vessels is reviewed in some detail. Advances in surgical instrumentation,

techniques, and medication have facilitated the development of cardiac surgical procedures for repair of congenital cardiac defects, correction of

cardiac vascular insufficiency, replacement of diseased cardiac valves, implantation of electronic devices for regulation of pacemaking activity, and

replacement of the heart itself. The reader seeking the particulars of surgical procedures relating to the correction of congenital malformations or of

pathologic processes should consult appropriate texts that treat thoracic or cardiac surgery in detail.

Pericardium

Topographic Relations

The pericardial sac and the heart within reside in the mediastinum, an area between the pleural sacs. It is bounded anteriorly by the sternum and

posteriorly by the thoracic vertebrae.

The mediastinum is divided arbitrarily into superior and inferior portions by a transverse plane passing through the sternal angle of Louis and the T4

intervertebral disk (Fig. 7-1). The inferior mediastinum is further subdivided into anterior, middle and posterior sections. The middle mediastinum is

defined by the pericardium and its contents: the heart (Fig. 7-2) and the roots of the eight great vessels (aorta, pulmonary trunk, superior and

inferior vena cavae, and four pulmonary veins).

Fig 7-1.



Diagrammatic lateral view of thorax indicating divisions of mediastinum. Arbitrary line forming lower boundary of superior mediastinum also marks division

between ascending aorta and aortic arch anteriorly, and division between aortic arch and descending aorta posteriorly. (Modified from Skandalakis JE, Gray

SW, Rowe JS. The anatomy of the human pericardium and heart. In: Bourne GH (ed). Hearts and Heart-like Organs. New York: Academic Press, 1980; with

permission.)

Fig 7-2.



Diagrammatic representation of pericardium and its relation to heart. (Modified from Skandalakis JE, Gray SW, Rowe JS. The anatomy of the human

pericardium and heart. In: Bourne GH (ed). Hearts and Heart-like Organs. New York: Academic Press, 1980; with permission.)

In front of the pericardium are the structures of the anterior mediastinum. These include the first four sternebrae, the lower part of the thymus, and

connective tissues. Behind the pericardium are the principal contents of the posterior mediastinum: the aorta, the esophagus, the azygos system,

and the fifth through the eighth thoracic vertebrae. Above is the superior mediastinum; below, the diaphragm forms a lower limit for the middle

mediastinum.

PERICARDIAL SAC

The pericardial sac, or parietal pericardium, is formed by two layers: an outer fibrous layer and an inner serous layer, responsible for secretion of the

fluid film within the pericardial sac (Fig. 7-3). The simple squamous epithelium (mesothelium) that forms the serous lining of the pericardial cavity is

a portion of the primitive embryonic celom. Therefore, it is similar to the lining of the pleural and peritoneal cavities. At the points of exit of the

vessels from the pericardial sac, the fibrous layer becomes continuous with the adventitia of the vessels and the pretracheal fascia. There the

serous lining is also reflected over the surface of the heart, as the visceral pericardium or epicardium. Deep to this layer is a variably thick lamina of

connective tissue, which can be thought of as representing the fibrous layer of the pericardial sac.

Fig 7-3.



Layers of the pericardium.

PERICARDIAL CAVITY

The parietal and visceral layers of pericardium form a closed sac, the pericardial cavity. Two topographic areas within the sac are of special

importance. One of these is a part of the pericardial cavity called the oblique sinus. It is found behind the heart, and is bounded superiorly and on

either side by the left atrium, pulmonary veins, and inferior vena cava. The esophagus is related posteriorly to this space.

The second space of note within the pericardial sac is the transverse sinus. This is a potential space behind the pulmonary artery and ascending

aorta. It is bounded from behind by the front of the atria and the superior vena cava. The surgeon can place a digit or two, or a ligature, into this

space without dissection, and quickly clamp the great arteries.

The transverse sinus is separated from the oblique sinus by the venous mesocardial reflection. The venous mesocardial reflection runs from the

pericardial sac to the dorsum of the left atrium between the uppermost right and left pulmonary veins. From a clinical standpoint, the pericardium

should be considered a single entity, a closed fibroserous sac (see Fig. 7-3).

In the cadaver, the pericardial cavity contains between 40 and 60 ml of fluid. Much more can be accommodated if the increase in quantity is

gradual.

RELATIONS OF THE PARIETAL PERICARDIUM

The pericardial sac is roughly conical in shape. It is fused at its base to the diaphragm, and fused at its apex to the adventitia of the great vessels

and pretracheal fascia. Two other minor points of fixation are the superior and inferior sternopericardial ligaments.

The relations of the pericardium are as follows:

Anterior: The fibrous pericardium is related to the sternum and the costal cartilages, but is separated from them, for the most part, by the anterior medial

reflections of the left and right pleurae (the costomediastinal reflections). The pericardium is thus covered by the pleurae, except over a small bare area on

the left at the level of the fourth to sixth cartilages. This is known as the "bare area of Edwards," or the "cardiac dull space." The latter term is attributable

to the lack of resonance to percussion at this point.

Posterior: The right and left bronchi, lymph nodes, esophagus and its nerve plexus, descending thoracic aorta, and vertebral reflection of pleura are all

related to the posterior portion of the pericardium (Figs. 7-4, 7-5)

Lateral: Mediastinal pleurae, phrenic nerves, and pericardiacophrenic vessels

Inferior: Diaphragm, peritoneum, and inferior vena cava

Superior: Roots of the great vessels, the left brachiocephalic vein, the left recurrent laryngeal nerve, and the left superior intercostal vein

Fig 7-4.



Diagrammatic representation of superior and posterior relationships of pericardium. (Modified from Skandalakis JE, Gray SW, Rowe JS. The anatomy of the

human pericardium and heart. In: Bourne GH (ed). Hearts and Heart-like Organs. New York: Academic Press, 1980; with permission.)

Fig 7-5.



Anatomy of posterior cardiac bed of pericardium. Major pericardial sinuses are shown with probes lying in them. Upper recess (transverse sinus) is a

palpable interval between the great arteries (aorta, pulmonary) and the atria, by means of which the arteries can be electively clamped. (Modified from

Spodick DH. Macrophysiology, microphysiology and anatomy of the pericardium: a synopsis. Am Heart J 1992;124:1046; with permission.)

William Osler envisioned an "abdominal area of romance where the head of the pancreas lies folded in the arms of the duodenum." We like to think

that within the chest cavity also there is a love affair, with the lungs embracing the pericardial sac and the heart.

Vascular Supply

ARTERIES

About 80 percent of the blood to the pericardium comes from the right and left internal thoracic arteries by way of their pericardiacophrenic

branches (Fig. 7-6). In addition, the lower pericardium is supplied by branches of the superior phrenic arteries. The posterior portion receives

branches from the bronchial and esophageal arteries and mediastinal twigs from the descending thoracic aorta. All of these vessels anastomose

freely.

Fig 7-6.

Blood supply of pericardium seen from right side. (Modified from Skandalakis JE, Gray SW, Rowe JS. The anatomy of the human pericardium and heart. In:

Bourne GH (ed). Hearts and Heart-like Organs. New York: Academic Press, 1980; with permission.)

VEINS

The veins follow the arteries. They empty into the azygos and hemiazygos veins, the internal thoracic veins, and the superior phrenic veins.

LYMPHATICS

The pericardium is drained by three groups of lymph nodes:

Anterior mediastinal nodes

Diaphragmatic nodes

Inferior tracheobronchial nodes

Warren11 reported on pericardial malignancies:

Malignancies rarely arise from the pericardium. Mesothelioma, the most common of these, is usually unresectable and almost always incurable.

Malignancies may secondarily involve the pericardium by direct extension...More frequently, malignancies may involve the pericardium by a

process of retrograde lymphangitic spread or hematogenous dissemination. These patients present with a symptomatic pericardial effusion

and occasionally pericardial tamponade. Subxiphoid pericardiostomy and drainage is a safe procedure that provides effective and durable

symptomatic relief in these terminally ill patients.

Innervation



Innervation

Nerve fibers from the vagus nerves, the phrenic nerves, and the cardiac branches of the recurrent laryngeal nerves supply the parietal pericardium.

Sympathetic fibers arise from the cervical and upper thoracic parts of the sympathetic chains, and from the stellate ganglia. The fibers reach the

pericardium by way of the aortic and cardiac plexuses.

Surgical Applications

PERICARDIOCENTESIS

Aspiration of the fluid contents of the pericardial sac may be necessary for the diagnosis or treatment of pericardial effusion caused by trauma,

secondary manifestations of heart disease, infection, or neoplasms. Cardiac tamponade may also be produced from central venous catheters.

Unexplained hypotension, tightness of the chest, and shortness of breath are the signs and symptoms of cardiac tamponade. Collier et al.12 advised

emergency echocardiogram for diagnosis, but for prevention advised that the tip of the catheter should be outside of the cardiac silhouette on

chest X-rays. It is obvious that the greater the accumulated amount of fluid, the easier the aspiration, but the more desperate the patient's

condition.

Remember Beck's Triad of cardiac tamponade:

Small, quiet heart

Falling atrial pressure

Rising venous pressure

We quote from Schrump and Nguyen13 on malignant pericardial effusion:

Malignant pericardial effusion is frequently an indication of advanced, incurable malignancy. Hence, the goals of intervention include relief of

symptoms and prevention of recurrence...Surgical interventions (subxiphoid pericardiostomy) or medical interventions (ultrasound-guided

percutaneous tube pericardiostomy and sclerotherapy) have acceptable risks and provide excellent results. We favor surgical drainage as the

primary approach for patients with malignant pericardial effusion because of its simplicity and extremely high success rate without the need

for intrapericardial instillation of sclerosing agents and tube manipulations that may be associated with patient discomfort. Recurrent

malignant pericardial effusion can be managed either by repeat pericardiostomy or insertion of a shunt. Patients responding to treatment with

complete control of the effusion should have a meaningful survival with life expectancy (average, 9 months) contingent on the histology of

the underlying malignancy.

Parasternal Approach

The needle is inserted into the fifth or sixth intercostal space 2 cm lateral to the apical impulse, or just medial to the left border of the cardiac

dullness. The needle is then directed to the right shoulder. The parasternal position of the internal thoracic artery and vein must be remembered to

avoid hemothorax from their laceration.

Abdominal (Paraxiphoid) Approach

The needle is inserted 1 cm below and 1 cm to the left of the xiphoid, between it and the left costal arch, pointing in the direction of the left

shoulder. This is the preferable route, because the needle will transgress neither the pleural nor the peritoneal cavities; most importantly, it is less

likely to cause injury to a coronary artery.

Olsen et al.14 recommended pericardial-peritoneal window for patients with malignant and non-infectious benign pericardial effusions, including those

with tamponade.

PERICARDIOTOMY AND PERICARDIECTOMY

Indications include constrictive pericarditis, and malignant or benign constrictive effusion.

Approaches

For the drainage of the pericardial space and/or partial pericardiectomy, two approaches may be used, the subxiphoid and the anterolateral.

For the subxiphoid approach, a midline incision is made from approximately the xiphoid process to approximately halfway above the umbilicus. The

xiphoid process is then resected. With downward traction of the diaphragm, the anterior pericardium is exposed and resected.

For the anterolateral approach, an anterolateral thoracotomy at the left fifth intercostal space is made, and part or all of the left anterolateral

pericardium is removed.

For total pericardiectomy, median sternotomy is the best approach, although the "clamshell" bilateral submammary incision may be used in special

cases. The pericardium is removed from the aorta and pulmonary artery above to the diaphragm below, and from the left to the right pulmonary

veins.

Inflammatory Response to Pericardial Trauma

In some patients, opening of the pericardium may be accompanied by fever, pericardial and pleural effusion, and/or pain. These manifestations have

been termed 'postpericardiotomy syndrome.' Injury to the pericardium and the presence of blood in the pericardial cavity appears to be the cause.

Salicylates and corticosteroids provide relief from the symptoms. The condition is usually self-limiting.

Heart

External Topographic Features



External Topographic Features

PROJECTION OF THE HEART ON THE ANTERIOR CHEST WALL

The projection of the living heart on the chest wall (Fig. 7-7) is highly variable. It depends upon the position of the body and other factors such as

age and obesity. There are four anatomic landmarks, identified in Figure 7-7 by Roman numerals I-IV:

I, Superior vena cava Second right intercostal space or third right costal cartilage, 1.2 cm lateral to the right sternal margin

II, Inferior vena cava Sixth right costal cartilage, 1 cm lateral to the right sternal line

III, Apex Fifth left intercostal space, 6 cm lateral to the left sternal line or 9 cm lateral to the midline

IV, Tip of left auricle Second left costal cartilage, 1.2 cm lateral to the left sternal margin

Fig 7-7.

Projection of heart on anterior thoracic wall. I, Superior vena cava; II, Inferior vena cava; III, Apex; IV, Tip of left auricle. See text for further identification.

If you connect the four Roman numerals as indicated below, the figure so outlined (Fig. 7-7) provides a rough approximation of the projection of the

heart. This projection can never be taken for granted, because the heart is not rigidly fixed in the thorax:

I and II with a convex line (SVC to IVC)

II and III with a straight line (IVC to apex)

III and IV with a convex line (apex to tip of left auricle)



IV and I with a straight line (tip of left auricle to SVC)

The projection of the four cardiac valves (Fig. 7-8) is approximately as follows:

P, Pulmonary valve: Third left sternochondral junction

A, Aortic valve: Left sternal line at third left intercostal space, just below and medial to the pulmonary valve projection

M, Mitral valve: Fourth left sternochondral junction

T, Tricuspid valve: Right sternal line at fourth left intercostal space

Fig 7-8.

Normal heart sounds. Mitral valve (M) closure followed by tricuspid valve (T) closure produces first heart sound (1). Aortic valve (A) closure followed by

pulmonary valve (P) closure produces second heart sound (2). Note that 2 is louder than 1 at second intercostal space adjacent to sternum because of

loudness of A. P is louder in second intercostal space adjacent to sternum than at cardiac apex. In normal subjects, the pulmonary closure is not heard at

the apex, or it is only barely heard. Circles and the rectangle next to the left sternal border indicate the areas where physicians listen for heart sounds and

murmurs. The elliptical circles indicate the approximate location of heart valves.

The location of the points of best auscultation of these valves is different from their actual projections. Valve sounds are best heard at the



The location of the points of best auscultation of these valves is different from their actual projections. Valve sounds are best heard at the

following sites (Fig. 7-8):

P, Pulmonary valve: Second left intercostal space, adjacent to the sternum

A, Aortic valve: Second right intercostal space, adjacent to the sternum

M, Mitral valve: Fourth or fifth left intercostal space, near the midclavicular line (apex beat)

T, Tricuspid valve: Fourth or fifth left sternochondral junction, near the end of the sternum (right lower sternal line)

According to Waller and Schlant,15 the weight and size of the heart vary, depending on such factors as age, sex, body length, epicardial fat, and

general nutrition. Edwards16 stated that the adult human heart averages 325 75 g in men and 275 75 g in women.

Anterior or Sternocostal Surface

The right atrium and auricle, the atrioventricular groove, and the right ventricle and pulmonary outflow tract, or conus arteriosus, form the anterior

surface of the heart. The anterior right ventricle is typically in nearly direct contact with the sternum. Occasionally, a small portion of the left

ventricle participates in the formation of the anterior surface (Figs. 7-9, 7-10).

Fig 7-9.

Sternocostal surface of heart and great veins, constructed on projection lines. (Modified from Basmajian JV, Slonecker CE. Grant's Method of Anatomy (11th

ed). Baltimore: Williams & Wilkins, 1989; with permission.)

Fig 7-10.



Anterior view of intact human heart. (Modified from Skandalakis JE, Gray SW, Rowe JS. The anatomy of the human pericardium and heart. In: Bourne GH

(ed). Hearts and Heart-like Organs. New York: Academic Press, 1980; with permission.)

Remember

With median sternotomy, the atrial appendages in a normal heart are located clasping the arterial pedicle (Fig. 7-11) in most cases.

If the atrial appendages are on the same side of the pedicle, they produce an anomaly known as juxtaposition of the appendages. This anomaly can also

be associated with congenital heart disease.

Fig 7-11.



Median sternotomy. Lower inset, anomalous lateral costal artery. (Modified from Edwards WD. Applied anatomy of the heart. In: Brandenburg RO, Fuster V,

Guiliani ER (eds). Cardiology: Fundamentals and Practice. Chicago: Year Book Medical Publishers, 1987, 47-112; with permission.)

Posterior Surface

The posterior surface of the heart consists of the left ventricle, the atrioventricular and posterior interventricular sulci, the left atrium and its four

(or five) pulmonary veins, and a portion of the right atrium (Figs. 7-12, 7-13).

Fig 7-12.



Posterior aspect of heart. Star is site of contact of left bronchus with left atrium.

Fig 7-13.



Posterior view of intact human heart. (Modified from Skandalakis JE, Gray SW, Rowe JS. The anatomy of the human pericardium and heart. In: Bourne GH

(ed). Hearts and Heart-like Organs. New York: Academic Press, 1980; with permission.)

Diaphragmatic or Inferior Surface

The inferior (or diaphragmatic) surface of the heart is formed by the right one-third of the right ventricle, the posterior interventricular sulcus, the

left two-thirds of the left ventricle, and a small portion of the right atrium at the entrance of the inferior vena cava. In contrast to the rounded,

convex form of the anterior and left sides of the heart, this surface is noticeably flattened from its contact with the diaphragm.

Relations of the Borders of the Heart

Superior: The roots of the great vessels extend obliquely from the third right costal cartilage to the left second costal cartilage, and form the superior

border. A line drawn across the sternum at the level of the second intercostal space is said to approximate the "clinical base" of the heart, indicating the

general level of the cardiac attachment of the great vessels.

Right: The right border is formed by the terminal part of the superior vena cava, right atrium, and suprahepatic inferior vena cava. It extends from the third

right costal cartilage, 1.3 cm from the right sternal border, to the sixth right costal cartilage.

Left (oblique or pulmonary): The left border is formed by the convexity of the pulmonary trunk, the tip of the left auricle, and the left ventricle. It extends

from the second left costal cartilage, 1.3 cm from the left sternal border, to the apex of the heart. This is usually located just inferior to the left nipple and

slightly medial to the midclavicular line in the fifth intercostal space, about 9 cm from the midline.

Inferior: The inferior border is formed by both ventricles. It extends from the sixth right costal cartilage, 1 cm from the right sternal line, to the apex of the

heart.

Apex: The apex of the heart is formed by the junction of the left and inferior borders in the fifth left intercostal space, 6.5 cm from the left sternal border. It

is usually composed of the tip of the left ventricle.

Sulci

As soon as the pericardium is opened, one can see two irregular lines of fat deposits on the external surface of the heart. These lines indicate the

groove or sulcus that separates the atria from the ventricles, and the groove that separates the left and right ventricles.

ATRIOVENTRICULAR (CORONARY) SULCUS

The atrioventricular sulcus almost encircles the heart. It is interrupted only by the conus or infundibulum of the right ventricle (pulmonary trunk)

anteriorly. Beginning to the right of the infundibulum, the sulcus descends to the right side of the diaphragmatic border, passing to the left of the

entrance of the inferior vena cava. It continues deeply under the coronary venous sinus and left atrium, and ascends again to the left side of the

infundibulum.

Anteriorly, the atrioventricular sulcus separates the right atrium from the right ventricle, and contains the right coronary artery and the small

cardiac vein. Posteriorly, it separates the left atrium from the left ventricle, and contains the coronary sinus, the great cardiac vein, and the

circumflex branch of the left coronary artery.

INTERVENTRICULAR SULCUS

The interventricular sulcus indicates the position of the underlying interventricular septum between the right and left ventricles. On the anterior

surface, it leaves the coronary sulcus just to the left of the infundibulum (the pulmonary trunk), and curves gracefully in a reverse sigmoid form to

the diaphragmatic surface, to the right of the apex. It continues on the posterior surface, ascending to join the coronary sulcus at the "crux." The

crux is the small posterior region where all four major chambers are most closely approximated.

The anterior portion of the interventricular sulcus contains the anterior interventricular (left anterior descending) branch of the left coronary artery

and the great cardiac vein of Galen. In the majority of people, the posterior portion contains the posterior interventricular (posterior descending)

branch of the right coronary artery (which can sometimes arise from the left circumflex) and the middle cardiac vein.

INTERATRIAL SULCUS



INTERATRIAL SULCUS

The interatrial sulcus separates the atria. Anteriorly, it is covered by the pulmonary trunk and aorta; posteriorly, it is very faint. The interatrial

sulcus is not a useful landmark.

Fibrous Cardiac Skeleton

The skeleton of the heart is usually described as a framework of fibrous "rings," the valve anuli, encircling the mitral, tricuspid, aortic, and pulmonary

orifices, interconnected by dense aggregates of connective tissue. These fibrous elements provide both sites of origin and insertion for the muscular

bands which form the walls of the chambers, the interventricular septum, and the papillary musculature (Figs. 7-14, 7-15, 7-16).

Fig 7-14.

Primitive muscular spongework of ventricles.

Fig 7-15.



Skeleton of heart.

Fig 7-16.

Relative positions of cardiac valves, fibrous skeleton, atrioventricular conducting bundle (AV), and origins of coronary arteries. L, Left; A, Anterior; R, Right;

P, Posterior. (Modified from Skandalakis JE, Gray SW, Rowe JS. The anatomy of the human pericardium and heart. In: Bourne GH (ed). Hearts and Heart-like

Organs. New York: Academic Press, 1980; with permission.)

The four rings are mutually supported and held together by the right and left fibrous trigones, and by the conus tendon. From the right side of the

aortic ring, the membranous portion of the interventricular septum extends downward to meet the muscular portion of the septum. The right fibrous

trigone, often also referred to as the central fibrous body, joins the aortic, mitral, and tricuspid valve anuli or rings.



trigone, often also referred to as the central fibrous body, joins the aortic, mitral, and tricuspid valve anuli or rings.

The left fibrous trigone, considerably less distinct than the right trigone, joins the mitral anulus to that of the aorta. The aortic and pulmonary valve

rings are joined together by a stout band of fibrous tissue, the tendon of the conus.

The myocardium of the atria and the myocardium of the ventricles are separated, and also electrically insulated from each other, by the mitral and

tricuspid rings and by the right fibrous trigone. Normally, the sole functional interconnection of the myocardia is through the atrioventricular bundle

(of His), which perforates the right fibrous trigone to reach the top of the muscular septum. Thereafter, it divides into the broad left bundle branch

and the narrow right bundle branch.

For a more detailed description of the fibrous skeleton, the reader should consult Zimmerman17 and Zimmerman and Bailey.18

Lal et al19 questioned the presence of the tendon (or ligament) of the infundibulum. We present their summary of their findings.

The fibrous skeleton of the heart has featured prominently in anatomical and surgical descriptions, although all its purported components are

difficult to demonstrate. In descriptions of the skeleton, there have been repeated references to the presence of a tendon (or ligament)

between the aortic and pulmonary roots. Such a tendon is rarely, if ever, discussed in the context of surgical procedures being carried out on

the ventricular outflow tracts. Our study was undertaken, therefore, to investigate the existence and nature of such a tendon or ligament.

Serial transverse sections were made through roots of the aorta and pulmonary trunk in an intact fetal heart. In addition, ten normal adult

hearts were dissected to display the components of the fibrous skeleton of the heart. No discrete fibrous or elastic structure could be

detected in the tissue plane between the aortic sinuses and the subpulmonary muscular infundibulum, although a fascial strand was observed

in one heart. Apart from this specimen, the space between the free-standing muscular subpulmonary infundibulum and the sinuses of aorta

bearing the coronary arteries was occupied only by loose fibroareolar tissue. The initial presence of the ligament was described following

studies of animal and macerated human hearts. Subsequently, it would seem its existence has been passed on through generations of

morphologists and surgeons without its presence being reconfirmed. We have been unable to demonstrate any structure approximating to the

initial illustrations.

So-called "accessory bundles" (of Kent) are atypical muscle fibers which, by bypassing the atrioventricular node and the normally intervening fibrous

skeleton, interconnect atrial and ventricular muscle. Such cardiac muscle fibers can form an alternative conduction pathway which, not being

subject to the normal delay of the stimulating impulse provided by the atrioventricular node, leads to early ventricular excitation, or to Wolff-

Parkinson-White syndrome.

The membranous part of the interventricular septum is composed of a pars interventriculare lying beneath the septal leaflet of the tricuspid valve,

and a pars atrioventriculare just superior to the attachment of the septal leaflet, forming part of the floor of the left atrium. Defects of the

membranous septum usually result in ventricular communication through the pars interventriculare, but can sometimes result in left ventricle/right

atrium communication through the pars atrioventriculare.

Chambers of the Heart

RIGHT ATRIUM

General Relations

The right atrium lies between the openings of the superior and inferior venae cavae. Blood enters the right atrium from the venae cavae, and leaves

it to enter the right ventricle. Together, the right atrium and the right ventricle form the physiologic "right heart."

The relations of the right atrium:

Superior: Superior vena cava

Anterior: Pericardium, right lung, right mediastinal pleura

Posterior: Right pulmonary veins, left atrium

Lateral: Pericardium, right phrenic nerve and pericardiacophrenic vessels, right lung, right mediastinal pleura

Medial: Ascending aorta, left atrium; the right auricle is related to the right and anterior wall of the ascending aorta

Inferior: Inferior vena cava

External Features

The chief external features of the right atrium include the following, from above downward:

Superior vena cava

Right auricle over the root of the aorta

Coronary sulcus separating the right atrium from the right ventricle

Sulcus terminalis

Inferior vena cava



The sulcus terminalis is a shallow groove and is not always obvious. It starts at the right side of the superior vena cava and ends at the right side

of the inferior vena cava. The sulcus corresponds to an internal ridge between the right atrium and the right auricle, the crista terminalis. The

groove and the ridge separate the smooth posterior portion of the atrium, the sinus venarum, from the anterior trabeculated auricle, which is the

right half of the primitive atrium. The sinus venarum is derived from the embryonic right horn of the sinus venosus.

Internal Features

The principal feature of the interior of the right atrium is the crista terminalis, corresponding to the externally-seen sulcus terminalis (see above).

This ridge separates the posterior, smooth area of the atrium (sinus venarum) from the anterior rough area (trabeculated region), the atrium proper,

and its auricle. The trabeculations extend outward to the margin of the auricle (Fig. 7-17). They are also called the musculi pectinati, for their

fancied resemblance to the teeth of a comb.

Fig 7-17.

Interior of right atrium.

The fossa ovalis on the interatrial septal wall is a depression marking the site of the prenatal atrial communication, the foramen ovale. The margin of

the fossa, the limbus fossa ovalis, is formed by the edge of the septum secundum. The floor is formed by the septum primum of the fetal heart. The

limbus is absent inferiorly, and is continuous with the left leaf of the inferior vena cava. In about 15 percent of the population, the floor of the fossa

ovalis is not entirely sealed shut. Usually, this has no physiologic significance, for the higher pressure within the left atrium keeps the floor of the

fossa pressed shut against the limbus.

Taylor and Taylor20 support the hypothesis that the right atrial appendage, the pectinate muscles, and the terminal crest evolved to supply blood

to the conducting myocardium of the sinus part of the right atrium. Like the right ventricle, the right atrium is structured as a single and completely

finished unit. The interpectinate spaces and the thebesian sinusoids offer suggestions to the topography of the conducting pathway and the sinus

node.

Openings

The openings of the right atrium include the following anatomic entities

Orifices of the superior vena cava and inferior vena cava

Coronary sinus

Several minute orifices of small veins

Several small, irregular openings in each of the four chambers of the heart

Atrioventricular orifice

The orifice of the superior vena cava is at the uppermost portion of the sinus venarum. The orifice of the inferior vena cava is at the posteroinferior

portion of the sinus venarum. It is guarded by the proper (eustachian) valve of the inferior vena cava.

The coronary sinus is on the medial wall of the atrium, between the orifice of the inferior vena cava and the attachment of the septal cusp of the

tricuspid valve. It is guarded by the thebesian valve. This opening is said to be large enough to admit the tip of the surgeon's little finger. It may

occasionally be covered by a multi-perforated net of tissue, the network of Chiari.

We quote from Ortale et al.21 on their cadaveric studies of the coronary sinus and its tributaries:



Knowledge of the tributaries and the relationships of the coronary sinus are important in cardiac surgery, especially when dissecting the

coronary arteries, as well as in the area of the arteriovenous trigone...An anastomosis of approximately 1.0 mm in calibre was observed

between the anterior and posterior interventricular veins in 19% of specimens. Myocardial bridges were detected above the anterior

interventricular vein or its tributaries in 8% of specimens. The great cardiac vein formed the base of the arteriovenous trigone of Brocq and

Mouchet with the bifurcating branches of the left coronary artery in 89% of specimens and formed an angle accompanying these arterial

branches in 11%. In the trigone the anterior interventricular and great cardiac veins were superficial to the arteries in 73% of specimens. The

left marginal vein was present in 97% of specimens, emptying into the great cardiac vein in 81% of cases and into the coronary sinus in the

remaining 19%. The small cardiac vein was present in 54% of specimens. In the coronary sulcus the great cardiac vein was adjacent to the

circumflex branch of the left coronary artery in 76% of specimens and to the right coronary artery in 5%; in 19% there was no relationship

with either artery. The coronary sinus maintained a relationship with the right coronary artery in 46% of specimens and with the left coronary

artery in 32%; in 22% it had no relationship with these vessels.

There are several minute orifices of small veins. These are the anterior cardiac veins. They arise on the anterior surface of the right ventricle, and

cross the right coronary artery to reach the margin of the auricle.

Variably small, irregular openings on the medial wall of the right atrium mark the sites of entry of the venae cordis minimae (thebesian veins), which

drain venous blood from the musculature of the chamber. Such openings are present in all four chambers of the heart. Since their number is

inversely proportional to the pressure within the chamber, they are most numerous in the right atrium and least numerous in the left ventricle.

The atrioventricular orifice, which occupies the entire left anterior wall of the atrium, is surrounded by a fibrous ring. It is guarded by the tricuspid

valve leaflets. In the adult heart, the orifice admits three fingers.

Remember

The sinus node is located beneath the epicardial surface of the terminal sulcus, at the base of the superior vena cava. The terminal sulcus is located

between the triangular appendage and the sinus venarum.

There are four eponymous entities associated with the internal surface of the right atrium.

Waterston's groove: The superior limbus is a fold of the interatrial sulcus, which is named Waterston's groove. It is located between the fossa ovalis and

the opening of the superior vena cava. There is no inferior limbus.

Tendon of Todaro: Todaro's tendon is a fibrous cord under the endocardium, 1 mm in diameter (see Fig. 7-15). It extends from the right fibrous trigone of

the heart (elliptical mass between the aortic, mitral, and tricuspid openings) to the valve of the inferior vena cava. To be more anatomically correct, its

pathway is from the right atrial wall to the medial end of the valve of the inferior vena cava.

Kozlowski et al.22 studied the morphology of the tendon of Todaro in histologic sections of human hearts from fetal stage to older adults, and

reported the following:

The tendon of Todaro, found in the right atrium of the heart, has considerable clinical importance in the fields of both cardiac surgery and

invasive cardiology...In fetal hearts...a very well-developed, white structure was observed, convexed into the lumen of the atrium...In the

group of hearts of young adults, it was also possible to follow the course of the tendon of Todaro macroscopically. However, the older the

heart was, the less the convex was visible, and in older adults it was completely invisible. In the hearts of older adults the tendon of Todaro

formed very small ribbons of connective tissue. In the adult heart, the examined tendon was located the deepest and did not connect to the

endocardium...[T]he tendon of Todaro is a stable structure, occurring in all examined hearts even when it is not macroscopically visible.

Ho and Anderson23 declared the tendon of Todaro or its surrogate (a projected line between the eustachian valve and the central fibrous body) to

be a landmark to locate the atrial components of the AV conduction axis, and a reliable border for the triangle of Koch.

Triangle of Koch: The triangle of Koch is the home of the atrioventricular node. Its inferior border is Todaro's tendon; the superior border is the septal

leaflet of the tricuspid valve. The base is the post-eustachian sinus.

Sinus of Keith: The sinus of Keith is a pouch above the orifice of the coronary sinus. It is related to the tricuspid valve and to the extension of the terminal

crest.

The right atrial surface of the fossa ovalis is located between the triangle of Koch and the opening of the superior vena cava.

An aneurysm of the aortic sinus of Valsalva may rupture into the right atrium because of the proximity.

RIGHT VENTRICLE

General Relations

The right ventricle lies behind the sternum and to the left of the right atrium. It receives blood from the right atrium, and expels it through the

pulmonary artery. The myocardium of the right ventricle is thicker than that of the atria, and thinner than that of the left ventricle.

The relations of the right ventricle are:

Superior: Right auricle and pulmonary trunk

Anterior: Pericardium, left pleura, anterior margin of the left lung, sternum, and costal wall of the thorax



Posterior: Interventricular septum

Inferior: Pericardium, central tendon of diaphragm

External Features

The right ventricle forms most of the sternocostal surface of the heart. The atrioventricular groove on the right margin marks the boundary between

the two chambers, and contains the right coronary artery. Its dextral margin, the acute margin, forms a relatively sharp angle between the

sternocostal surface and the diaphragmatic surface.

Internal Features

The crista supraventricularis divides the ventricle into the inflow tract (an inferior, roughened, and trabeculated region) and the infundibulum (a

superior, smooth, outflow tract) (Fig. 7-18).

Fig 7-18.

Interior of right ventricle showing relative position of orifices.

The trabeculae carneae of the rough inflow tract are muscular ridges or bundles of the myocardium. One bundle forms a muscular bridge from the

interventricular septum and anterior wall of the right ventricle to the base of the anterior papillary muscle. It has been named the septomarginal

trabeculum or, more commonly, the moderator band. In about half of individuals, the moderator band is very clearly identifiable; in others, it is

variably less so. The term 'moderator band' comes from the fact that the right bundle branch of the conducting system passes in a subendocardial

position along the surface of the band, often visible as a narrow, light streak of tissue.

Slender strands of pale tissue, the cardiac pseudotendons, can be seen passing to the walls of the chamber near the base of the anterior papillary

muscle. The pseudotendons can be seen particularly well near the apex of the chamber. They typically contain slender strands of specialized

cardiac muscle for conducting the contractile impulse to the working myocardium.

Arising from the trabeculae carneae are pyramidal or cylindrical muscular projections, the papillary muscles. Although named anterior, posterior, and

septal because of their relative positions in the chamber, the form and number of papillary muscles is quite variable, especially the septal papillary

muscles. Often, the anterior papillary muscle provides anchorage for slender, tendinous chordae tendineae that pass to the anterior and posterior

leaflets of the tricuspid valve. The more posteriorly situated papillary muscle is attached to the posterior and septal cusps.

One little papillary muscle, the papillary muscle of the conus, is of more significance than its diminutive size might indicate. The papillary muscle of

the conus is located at the medial end of the crista supraventricularis, the junction of the smooth and rough portions of the chamber. It is at the

location of this muscle that the right bundle branch commonly attains a subendocardial position in the right ventricle, where it can often be

discerned. The papillary muscle of the conus is, in some instances, represented only by a few chordae tendineae that arise at the margin of the

crista supraventricularis and pass to the septal cusp of the tricuspid valve.

Right Atrioventricular Opening

The right atrioventricular opening is oval, 4 cm in its longest axis, and admits the tips of three fingers. The opening is guarded by three leaflets

(anterior, posterior, and septal [medial]) of the tricuspid valve. The leaflets arise peripherally from the fibrous atrioventricular (tricuspid) anulus of

the cardiac skeleton. Their free margins are attached by several complex tiers of chordae tendineae to the papillary muscles (Fig. 7-19).

Fig 7-19.



Right atrioventricular valve shown spread out.

Pulmonary Orifice

The pulmonary trunk leaves the uppermost part of the smooth-walled outflow tract (the infundibulum) through the fibrous pulmonary ring. It is

guarded by three semilunar cusps (anterior, right, and left). Each cusp consists of a crescentic lunule which has a thickened nodule midway along

its arc. Adjacent cusps are interconnected by the commissures of the valve.

LEFT ATRIUM

General Relations

The left atrium forms two-thirds of the base of the heart. It receives the blood carried by the pulmonary veins, and discharges its blood to the left

ventricle. It is related to other structures as follows:

Superior: Left bronchus and right pulmonary artery

Anterior: Proximal ascending aorta and proximal pulmonary trunk

Posterior: Anterior wall of the oblique sinus of the pericardial cavity, esophagus, right pulmonary veins

Right: Right atrium and interatrial septum

Left: Pericardium and left pulmonary veins

Inferior: Left ventricle

External Features

The most striking features of the left atrium are the four pulmonary veins, two on each side. The veins are enveloped, together with the superior

and inferior venae cavae, in a serous pericardial sleeve.

In some hearts, a small vein (the oblique vein of the left atrium) can be seen on the left extremity of the chamber, near the entrance of the left

inferior pulmonary vein. This normally small vessel drains into the coronary venous sinus. It represents the termination of the embryonic left common

cardinal vein. In a small percentage of individuals, it is much enlarged as a left-sided superior vena cava. In these circumstances, the coronary

venous sinus can be very large in diameter.

Internal Features

Like the right auricle, the left auricular appendage is trabeculated; the left is much smaller, however. But the left auricle does not possess a crista

terminalis as does the right auricle. The pectinate muscles of the right auricle arise from the crista terminalis. The remainder of the interior of the

left atrium is quite smooth and relatively featureless, although a few small openings of venae cordis minimae (thebesian veins) may be seen.

The two right pulmonary veins open, one above the other, on the right wall of the atrium. In some cases, three right pulmonary veins may end

separately there, with the vein from each of the three lobes of the right lung retaining its independence. The two left pulmonary veins, similarly

arranged, open in the posterior wall. In other words, the orifices of the four pulmonary veins are located near the corners

Documents

Chapter 7 Pericardium, Heart, And Great Vessels in the Thorax