Congenital LVOT Obstruction Seoul National University Hospital Department of Thoracic & Cardiovascular Surgery

Congenital LVOT Obstruction

Seoul National University Hospital

Department of Thoracic & Cardiovascular Surgery

Congenital LVOT Obstruction

Types of obstruction1. Supravalvular aortic stenosis

2. Valvular aortic stenosis

3. Subvalvular aortic stenosis

4. Intraventricular obstruction

5. Hypoplastic left heart syndrome

Left Ventricular Outflow Tract

Congenital malformations• Obstruction * Supravalvular * Valvular * Subvalvular * Intraventricular obstruction - Occurs in combination with other cardiac lesions ( Interruption, COA, MV apparatus anomalies, left ventricular hypoplasia )

• Regurgitation * Annular aortic root dilatation * Prolapse of valve leaflets * Degenerative abnormality * Rupture of aneurysm of sinus of Valsalva

LVOT Obstruction

Pathophysiology Left ventricular outflow tract obstruction(LVOTO ) leads to left ventricular hypertrophy, ischemia, and ventricular dysfunction. The obstruction is at the valvar , subvavar, or supravalvar level.

Congenital Aortic Valve Diseases

Manifestation1 Incidence * 2 - 6% of CHD ( about 5%) * AS : common, M : F = 4 : 1 * AR : less common, no sex predilection

2 Etiology 1) AS : not known or no evidence # probably genetic aberration in IHS, and supravalvular stenosis # fetal aortic valve endocarditis 2) AR : caused by any one of several disease (rheumatic fever, endocarditis, Marfan syndrome, Ehlers - Danlos syndrome, connective tissue disorders)

Congenital Aortic Valve Diseases

Reparative procedures 1 Aortic stenosis * Not curative, but palliative * High mortality in neonate * Reasonable mortality in infant and children * Residual stenosis & induced aortic regurgitation * Overall 10-year survival : 80 - 90% * 10-year reoperation-free survival : 50 - 60%

2 Aortic regurgitation * Medical treatment if possible * Valvoplasty for prolapsing cusp * Aortic valve replacement

Congenital Aortic Stenosis

Definition• A cardiac anomaly in which narrowing at valvar, s

ubvalvar, supravalvar, or combined levels results in a systolic pressure gradient between the inflow portion of left ventricle & aorta beyond obstruction.

• Classification refers to the predominant area of obstruction in the left ventricular outflow tract, inevitably, these groups sometimes overlap because of the complexity of pathologic changes

LV Outflow Tract Structures

Aortic Stenosis Types

Aortic Outflow Obstruction

Clinical features1 Infantile 1) Usually appears within the 1st. month of life 2) Presentation in later infancy according to the severity and growth 3) Untreated mortality ; 23% in the 1st. year

2 Childhood 1) Progressive with growth, rare in early childhood 2) If left ventricular failure develops, rapidly deteriorate 3) Sudden death : 1-19%, but rare in low pressure gradient * Consequence of low aortic pressure (coronary insufficiency) * Arrhythmia * Frequent when resting pressure gradient more than 50mmHg

4) Untreated mortality * 60% at 40 years * Mean age of death : 35 years

Aortic Outflow Obstruction

Operation1 Indications 1) Critical AS in neonate ; urgent 2) Infant and children * Pressure gradient over 70mmHg

* Sx. of angina, syncope, exercise intolerance, LVH, with pr. gradient over 50mmHg and valve area less than 0.5 square cm/BSA

* Pressure gradient over 40mmHg in subvalvular lesion

2 Methods 1) Valvotomy * Open & closed technique (hypothermia) * Balloon valvotomy

2) Resection of subvalvular tissue & myocardium 3) Aortoplasty of supravalvular stenosis 4) Aortoventriculoplasty in tunnel stenosis 5) Valve replacement

Congenital Valvar Aortic Stenosis

Definition An obstruction at valve level caused by imperfect cusp development with leaflet thickening and fusio

n• History Marquis, Logan : Surgical treatment by dilator in 1955

Swan, Lewis : Open valvotomy in 1956

Spencer : Valvotomy through OHS in 1958


Manifestation1 Etiology : unknown * Malabsorption of conal element ( leaflet dysplasia as in PS) * Histologic disorganization of aortic media and dysplasia in left ventricular septum (Somerville) & hypoplasia of annulus rarely2 Incidence : 3~6% of all CHD, 60 - 70% of AS

3 Anatomy * Hypoplasia of annulus : rare * Abnormally formed valve leaflets : majority Bicuspid ; 70% (left and right) Unicuspid Thick and dysplastic valve - Commonly associated with COA, MV abnormalities, sub or supravalvar stenosis, hypoplastic ventricle -


Morphology• Aortic valve Bicuspid in 70% Tricuspid in 30% Unicuspid rarely Varying degree of thickened dysplastic leaflets

• Left ventricle Concentric hypertrophied, tiny cavity Endocardial fibroelastosis in extreme case with dilation

• Coexisting cardiac anomalies Fibrous subvalvar, supravalvar stenosis COA, varying degree of HLHS PDA, VSD, PA

Bicuspid aortic valve


Bicuspid aortic valve



Patterns of presentation • Presentation in infancy Almost always severe, rapidly progressive CHF Untreated mortality : 23% in 1st year

• Presentation in childhood Beyond 1 year of age, heart failure is rare. Sudden death varies between 1-19%. Develop progressive ultimately important stenosis Bacterial endocarditis

Bicuspid Aortic Valve

Natural history 1. Incidence approximately 1~2% of population 2. Rarely becomes stenotic or incompetence in early life 3. Sclerosis begins in the second decade of life. 4. Aortic stenosis develops in 72% by the fifth & sixth decades of life. 5. Endocarditis occurs in 10% of these patients. 6. Incompetence independent of endocarditis occurs in 5 - 39% of these patients. 7. Bicuspid aortic valve have been noted in 25-40% with supravalvar & 9-20% with subvalvular aortic stenosis.

Bicuspid Aortic ValveDevelopment• Bicuspid aortic valve, the most common congenital cardiac

malformation, is caused by fusion of valve cushions at the onset of valvulogenesis.

• At the beginning of valvulogenesis, a population of cells called neural crest cells migrate away from the neural fold and spread throughout the embryo.

• These cells seem to play a crucial role in normal development of cardiac outflow tract &semilunar valves

• The basic helix-loop-helix transcription factor dHAND is essential for survival of cells in neural crest–derived ventricular structures and aortic arch arteries


Techniques of operation

• Percutaneous balloon valvotomy

• Valvotomy in neonates & critically ill infants

• Valvotomy in older infants, children & adults

• Aortic valve replacement


Open techniques • Precise commissurotomy• Shaving of thickened leaflets• Excision of obstructive myxomatous nodulariti

es• Mobilization of leaflets • These procedures can be performed with a low surgical risk & 85% freedom from reoperation at 5 years

Bicuspid Valvar Aortic Stenosis

Tricuspidization with cusp extension • Criteria for TCE included an aortic orifice that is equal

to or greater than normal (normalized for body surface area) after commissurotomy and division of the raphe, adequate mobility of all cusps at the hinge point, absence of cusp dysplasia involving the belly of the cusps, commissures that are free of calcification or exuberant fibrosis, and normal location of the coronary ostia.

• When these criteria were met, TCE was the procedure of choice.

Bicuspid Aortic Stenosis

Tricuspidization with cusp extension

The height of coapting pericardial patches is increased toward the neocommissure to compensate for the lack of a true interleaflet triangle and to elevate the hinge point of the leaflets. Each new commissure is constructed by suturing the apposing short edges of each patch together and to the aortic wall, creating an elongated vertical axis of the native commissures

http://jtcs.ctsnetjournals.org/cgi/content/full/134/1/90/FIG1

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Critical Aortic Stenosis Optimal management• In fact, if percutaneous balloon valvotomy usually causes rupt

ure along lines of least resistance, either along underdeveloped

commissures or into leaflet tissue.• Surgical valvotomy allows direct inspection of the valve, more

fashioning of commissurotomies, and debridement of any excess tissue on the leaflets.

• When small aortic annulus and depressed ventricular function are associated, surgical or therapeutic options other than surgical commissurotomy could be considered, including balloon dilation as a bridge to surgery, neonatal Ross operation, Norwood operation, or possibly neonatal double switch operation.

Bicuspid Aortic Valve

Operative technique

Aortic valve bypass

• Aortic valve bypass for high-risk patient with aortic stenosis

Aortic Stenosis

Aortic Stenosis

Aortic valve bypass surgery• Ideal candidates for this type of approach could include

patients with ascending aortic calcification, patients who require complex reoperations, and patients with a small annulus

• Potential problems include pseudoaneurysm as described in their article, bleeding due to lack of control of the left ventricular (LV) apex, difficulty with the aortic anastomosis in the descending aorta due to extensive calcification of the descending aorta, kinking of the conduit, and theoretical dislodgement of an LV apical thrombus and nonphysiologic flow from the LV

Results of operation 1. Survival

Early deaths

Time-related survival

2. Modes of death

Acute cardiac failure

Sudden death, residual

stenosis, incompetence

3. Incremental risk factors for

premature death 1) Left-sided cardiac anomalies

2) Preoperative functional class

3) Type of valvar stenosis

4) Young age

4. Functional status

5. EKG changes

6. LV structure and function

7. Residual or restenosis

8. Aortic valve incompetence

9. Bacterial endocarditis

10. Reintervention

Valvar Aortic Stenosis

Valvar Aortic Stenosis

Indications for operation 1. Original valvotomy 1) Neonates and young infants Treatment on emergency basis 2) Older infants and children EKG shows severe hypertrophy Pressure gradient more than 50mmHg Symptoms of angina or syncope

2. Reoperation Symptoms develop with moderate stenosis


Biventricular repairContraindications• Small left ventricle < 20ml / BSA, Inlet length < 25mm

• Narrow aortic valve ring < 5mm • Small mitral valve orifice < 9mm

• Extensive fibroelastosis


Norwood vs aortic valvotomy 1. Mitral valve area less than 4.75 cm 2 /m2 2. LV inflow dimension less than 25 mm 3. Small LV by a ratio between apex-to-base dimension of LV & that of RV of less than 0.8 4. Left ventricular transverse cavity & aortic annular dimension less than 6 mm

Subvalvar Aortic Stenosis

Introduction 1. Definition An obstruction beneath the aortic valve due either to a short, localized fibrous or fibromuscular ridge or a long (diffuse) fibrous tunnel. Subvalvar aortic stenosis may also be a part of other cardiac anomalies.

2. History Chevers : 1st description in 1842 Brock : Transventricular dilation in 1956 Spencer : 1st repair using CPB in 1960 Konno,Rastan : Aortoventriculoplasty in 1975

Subvalvular Aortic StenosisCharcteristics1 Etiology : unknown but congenital and postnatal (turbulence phenomenon to abnormal contractility caused by focal area of dysplastic myocardium)

2 Incidence : 10 -20% of AS (0.25 for every 1000 live births)

3 Anatomy * Discrete ring of fibrous tissue * Persistent conus muscle in subaortic area * Tunnel syndrome( 20% of SubAS)

Subvalvar Aortic Stenosis Morphology• Aortic valve Usually normal Trivial or mild AR in 2/3 due to leaflet thickening, or , effect of eddy current.

• Left ventricle Usually concentrically hypertrophied Subendocardial ischemia and fibrosis

• Coexisting cardiac anomalies Isolated in 1/2-2/3 VSD, IAA, PDA, COA, PS, TOF, ASD, AP window

• Other type of discrete subvalvar stenosis Mitral valve anomalies : accessory tissue or leaflet malposition Localized muscular obstructions : related to malalignment


Patterns of type 1. Localized type Fibrous or fibromuscular Localized or circular Variable degree of septal hypertrophy 2. Tunnel type 1/5 of subvalvar aortic stenosis Circumferential irregular zone of fibrosis

Varying degree of obstruction

Fibromuscular stenosis


Subaortic tunnel stenosis


Supramitral ring


Clinical features & diagnosis 1. Incidence

10-20% of AS

2. Symptoms and signs 25% requiring operation are asymptomatic.

Systolic murmur, diastolic murmur in 65%

Pulse is slow rising.

3. Chest X-Ray, EKG

4. Echocardiography

5. Cardiac catheterization and cineangiography



Natural history• 10-30% of congenital LVOT obstruction

• Rarely important obstruction in infancy

• Evident and progressive with age

probably more rapidly than valvar stenosis

• Aortic incompetence is a progressive lesion

secondary to leaflet thickening.

Subaortic Stenosis

Development & progression 1. Acquired nature of this lesion 2. Rarely in neonate and young children 3. Rheologic theory Morphologic abnormalities in left ventricular - aorta junction, such as steeper aortoseptal angle results in altered septal shear stress and triggers a genetic predisposition leading to cell proliferation and structure in LVOT.

4. Uncertainty about rapidity of progression

Subaortic Stenosis

Development 1. Subaortic constraint at the entry of the tunnel and the sinus shape of the letter lead to turbulent flow, resulting in muscle hypertrophy, or deposition of fibrous material. 2. Growth of heart without concomitant increase in the size of VSD, and tunnel 3. Excessive decrease of LV diameter and the increase in wall thickness after biventricular repair, causes the diminution of the VSD orifice and the augmentation of the malalignment. 4. Other possible causes are kinking of the baffle, shrinkage of the baffle with time 5. Chronic flow disturbance caused by a somewhat narrowed and elongated LVOT

Discrete Fibrous Ring

Histology In the subaortic region, the progression of discrete fibro

us obstruction results in a gross appearance & histology with similarity to vascular lesions by Rodbard. The typical fibrous ring has distinct five layers.

• Endothelial layer• Mucopolysaccharide-rich subendothelial layer• Fibroelastic layer• Smooth muscle layer• Central fibrous layer

Effect of localized stenosis

A is normal aorta is depicted with the arrow indicating the direction of flow in the longitudinal view.

B, C, and D show the progressive nature of the changes in the aorta.

Subaortic Stenosis

LVOT geometry & shear stress

Role of shear stress in the progression of subaortic stenosis

( Aortoseptal angle )

Subaortic Stenosis

Discrete Subaortic Stenosis

• Morphologic abnormalities & subsequent rheologic effects, an exuberant response to local injury, and further exacerbation of the process through a positive feedback loop

Etiology

Subaortic Stenosis

Anatomic abnormalities• Increased steepness of aortoseptal angle Malalignment of ventricular septum Prominent ventricular band Protrusion of muscular septum• Increased aorto-mitral separation• Small aortic annulus

Subaortic Stenosis

Prior Closure of VSD during Repair of DORV

Extended septoplasty

Subaortic Septal Plane

Relationship between the plane of the outlet septum and the plane of the septal crest

in the normal heart (A), and atrioventricular septal defect (B),

a VSD has been created and a patch applied to augment the diameter of the LVOT.

Anatomy

LVOT & RVOT

The scheme of the left & right ventricular outflow tract showing the normal anatomy (A),

subaortic myectomy (B), a modified Konno procedure (C).

Geometry

Muscular Subaortic Obstruction

Clinical characteristics1 Etiology * Genetic basis

* Secondary hypertrophy

. Idiopathic hypertrophic subaortic stenosis

. Hypertrophic obstructive cardiomyopathy

. Asymmetrical septal hypertrophy

2 Incidence : rare in infant & childhood

3 Pathology * Microscopic finding :

Irregular arrangement of sarcomere and myofibrils

( possibility of hamartoma, and of inappropriate

development of primitive myocardial cell)

Subaortic Stenosis

Techniques of operation 1. Resection of localized subvalvar aortic stenosis

2. Repair of tunnel stenosis by aortoventriculoplasty

3. Aortoventriculoplasty by mini root replacement

Autograft

Homograft

4. Modified Konno operation.

Subaortic Stenosis

Principles of surgical treatment• Surgery must be aimed at the removal of all the str

uctures causing flow turbulence in the LVOT in order to reduce the incidence of these complications

• Aggressive surgical approaches have been proposed other than "simple" excision of the fibrous ring, including early operation before appearance of severe left ventricle hypertrophy, extended and circumferential myectomy, and mobilization of the left & right fibrous trigones.

Subaortic Stenosis

LVOT Anomalies• The association between discrete subaortic stenosis & o

ther left ventricular outflow tract anomalies such as • Anomalous mitral valve insertion • Accessory mitral valve tissue • Abnormal mitral papillary muscle • Anomalous muscular bands within the LVOT • Posterior displacement of infundibular septum without

VSD

Hypertrophic Cardiomyopathy

• Accessory papillary muscle arising from the anterior free wall with chordal attachments to the mitral leaflet and free wall. • Anomalous chordae tendineae arising from a papillary muscle and inserting into the septum.

Morphology

Extended septal myectomy

• Ventricular septal myectomy for hypertrophic obstructive cardiomyopathy

• Extended left ventricular septal myectomy for anomalous papillary muscle

with direct insertion into anterior mitral leaflet and also fusion to septum.

Hypertrophic Cardiomyopathy

Apical Aortic Conduits Subaortic Stenosis

Apical Aortic Conduits

Complications• The reported late complications of AACs are L

V pseudoaneurysm, erosion of the conduit into the esophagus or stomach when placed to the abdominal aorta, systemic emboli, and tissue valve dysfunction

• The major drawback of currently available AACs appears to be the limited durability of the porcine and AH valves in children.

Recurrent Obstruction

Mechanisms• Limited resection at the initial operation

• Midventricular obstruction

• Anomalies of the papillary muscles

• Ventricular remodeling, especially in pediatric patients

• Repeat myectomy can be performed with excellent outcomes and need for reoperation may be reduced with a more extended resection of the midventricular septum, relief of papillary muscle anomalies, and use of TEE

Subvalvular MembraneSurgical resection

Hypertropic Subaortic Stenosis

Transaortic myectomy

Subvalvular Excision

Subvalvular excision

Konno operation

Opening the right ventricular outflow tract before incising the aortic annulus during the Konno procedure is important to protect both the native pulmonary valve and the conduction tissue.

Subaortic Stenosis

Modified Konno procedure

• Subaortic left ventricular outflow tract is augmented by

a patch which closes created ventricular septal defect

Subaortic Stenosis

Ross-Konno procedure

• Widened Interventricular Septum (Ventriculoseptoplasty)

Ventriculoseptoplasty

Subaortic Stenosis

Aortic Valve Sparing Procedure

Enlargement of LVOT, mitral annulus• A; incision in the right lateral aspect of aorta is carried through commissure(Lt & non)• B; incision in the roof of left atrium and atrial septum exposes mitral annulus• C; triangular prosthetic patch enlarges mitral annulus (MVR) and subaortic area

Nicks & Manouguian operation

Aortic Root Enlargement

Subaortic StenosisResults of operation 1. Survival Early death ; very low Time-related survival ; related with residual stenosis or endocarditis 2. Incremental risk factors for premature death Small aortic annulus Extensive operation(tunnel form) Persistent stenosis or restenosis : 10% recur 3. Complications Complete heart block Iatrogenic VSD 4. Functional status, hemodynamic state 5. Recurrence of discrete subvalvar stenosis 6. Aortic incompetence

Subaortic Stenosis

Indications for Operation• Operation is advisable whenever stenosis is mo

derate. (more than 50mmHg pressure gradient)• When obstruction is mild, reevaluation is indic

ated every 6 months as rapid progression can occur.

• When multiple levels of LVOTO, or associated cardiac anomalies, general indications pertain.

Redo-aortic Valve Replacement

Etiology• Although surgical and catheter-based techniques for pres

erving the aortic valve in children with aortic valve disease have improved, there are a certain number of children in whom successful aortic valve salvage cannot be accomplished and therefore will need aortic valve replacement

• As times goes on, some of these children will require repeat AVR (redo-AVR) due to a variety of reasons such as outgrowth of the valve, deterioration of a bioprosthetic or homograft valve, endocarditis, or pannus formation.

Supravalvar Aortic Stenosis

Introduction 1. Definition An obstruction caused by localized or diffuse narrowing of aortic lumen commencing immediately above the aortic valve.

2. History Mencarelli : 1st description in 1930 Mayo Clinic : 1st operation in 1956 Hara : Excision & anastomosis in 1960


Characteristics1 Etiology : undefined, but genetically determined * Hypercalcemia * Williams’ syndrome2 Incidence : 10 - 20% of AS3 Anatomy * Localized diaphragm * Localized hour-glass narrowing * Diffuse narrowing4 Type * A : SVAS occurring as part of this syndrome * B : SVAS familiar without other abnormalities * C : SVAS occurring as purely isolated case


Morphology 1. Supravalvar stenosis Localized or diffuse Variable intimal thickening Less often diffuse extending 2. Associated aortic stenosis Valve thickening in 1/3 Occasional hypoplastic anulus Subvalvar stenosis is uncommon. 3. Coronary arteries Obstructing coronary flow, more common in left sinus.

Dilation, tortuosity, medial

hypertrophy.

4. Associated anomalies

Multiple peripheral PS

Thickening fibromuscular

dysplasia in both PA

Stenosis of brachiocephalic

branches

COA, VSD rarely

Supravalvular Aortic StenosisAngiography

Supravalvular Aortic StenosisAngiography

Supravalvular Aortic Stenosis

Angiography

Supravalvular Aortic Stenosis

Clinical features & diagnosis 1. Symptoms and signs

Rarely develop in infancy

Appear as late as 2nd or 3rd decade

Murmur and thrill sited higher

Elfin faces, reduced IQ, failure to thrive

Hypercalcemia in less than 5%

2. Echocardiography

3. Cardiac catheterization and angiocardiography


Natural history• Least common type of congenital aortic stenosis• Infants with elfin face, sudden death is common.• Progression of surpravalvar stenosis documented.• Untreated patients die before reaching adult life.• Decrease of peripheral PS occurs as patients age.

Supravalvar Aortic StenosisOperation 1. Technique 1) Classic repair (pericardium is more desirable) 2) Brom repair 3) Repair of diffuse type

2. Results 1) Survival Early death : low Time-related survival : good 2) Functional & hemodynamic status Without symptoms Rare reoperation Residual gradients by coexisting stenosis

Brom’s aortoplasty repair



Operative view

Stenosis of aortic sinuses


Indications for operation• Operation is advisable when pressure gradient more than 50mmHg at whatever age in view of

progressive nature.• Presence of pulmonary artery stenosis should not be a contraindication to surgical relief of supravalvar aortic stenosis.


LV Outflow Tract Obstruction

Root replacement

Documents

Congenital LVOT Obstruction Seoul National University Hospital Department of Thoracic & Cardiovascular Surgery