Formation of the Heart Formation of the Heart and Heart Defectsand Heart Defects

Michele KondrackiMichele Kondracki

MSII MSII

mkondracki@hmc.psu.edumkondracki@hmc.psu.edu

Learning ObjectivesLearning Objectives

Review anatomy of the heartReview anatomy of the heart

Formation of the HeartFormation of the Heart

Congenital heart defectsCongenital heart defects

Development stages for infants and childrenDevelopment stages for infants and children

Review of AnatomyReview of Anatomy

How does the Heart How does the Heart Form?Form?

Formation of the HeartFormation of the Heart Mesoderm divides into two layersMesoderm divides into two layers

Mesoderm = one of the primary germ cell Mesoderm = one of the primary germ cell layers in the early embryolayers in the early embryo

Heart precursor cells come from one of Heart precursor cells come from one of those two mesoderm layers (cardiogenic those two mesoderm layers (cardiogenic mesoderm)mesoderm)

Heart precursor cells form a single Heart precursor cells form a single heart tube by day 22 of heart tube by day 22 of embryogenesis embryogenesis

Formation of the HeartFormation of the Heart

These cells differentiate into the These cells differentiate into the endocardium and myocardiumendocardium and myocardium Endocardium = innermost layer that lines the Endocardium = innermost layer that lines the

heart chambers and valves valvesheart chambers and valves valves Myocardium = the muscular layer of the atria Myocardium = the muscular layer of the atria

and ventriclesand ventricles

The heart tube grows and elongatesThe heart tube grows and elongates

Primitive heart begins to form around day Primitive heart begins to form around day 22-2322-23

Formation of the HeartFormation of the Heart

The heart tube begins to bulge into The heart tube begins to bulge into primitive heart chambers and undergoes primitive heart chambers and undergoes right ward loopingright ward looping

Followed by proper valve positioning and Followed by proper valve positioning and chamber formationchamber formation

Congenital Heart Congenital Heart DefectsDefects

Abnormalities in heart present at birthAbnormalities in heart present at birth

Affects 8:1000 live birthsAffects 8:1000 live births

Examples:Examples: Ventricular Septal DefectVentricular Septal Defect Atrial Septal DefectAtrial Septal Defect Coarctation of the AortaCoarctation of the Aorta Tetralogy of FallotTetralogy of Fallot Transposition of the Great ArteriesTransposition of the Great Arteries

Ventricular Septal Defect Ventricular Septal Defect (VSD)(VSD)

Most common congenital cardiac anomalyMost common congenital cardiac anomaly

There is a hole between the two ventriclesThere is a hole between the two ventricles

Hole can vary in size and locationHole can vary in size and location

Oxygenated blood forced through hole from left Oxygenated blood forced through hole from left ventricle to right ventricle then returns to the ventricle to right ventricle then returns to the lungs even though it already carries oxygenlungs even though it already carries oxygen

ConsequencesConsequences Volume load causes enlargement of both Volume load causes enlargement of both

ventricles and the pulmonary artery and ventricles and the pulmonary artery and exposes right ventricle and pulmonary exposes right ventricle and pulmonary arteries to high pressuresarteries to high pressures

RememberRemember

VSDVSD

VSD Signs and VSD Signs and SymptomsSymptoms

Heart murmur Heart murmur

Difficulty maintaining weightDifficulty maintaining weight

Increased breathing rateIncreased breathing rate

Lower energy and easy tiringLower energy and easy tiring

Atrial Septal DefectAtrial Septal Defect

Hole in the septum between the atriaHole in the septum between the atria

Blood flows through the hole primarily from Blood flows through the hole primarily from left to right atria left to right atria

Causes increased blood volume in right Causes increased blood volume in right atrium so more blood goes to the lungs than atrium so more blood goes to the lungs than normal normal

ASD: Signs and ASD: Signs and SymptomsSymptoms

Usually no symptoms in childrenUsually no symptoms in children

If very large can cause fatigue, poor growthIf very large can cause fatigue, poor growth

In adulthood can lead to pulmonary In adulthood can lead to pulmonary hypertension, atrial arrhythmias or hypertension, atrial arrhythmias or congestive heart failurecongestive heart failure

Usually a split S2 (second heart sound) Usually a split S2 (second heart sound)

Murmur heard as large amount of blood Murmur heard as large amount of blood forced through normal size pulmonary valveforced through normal size pulmonary valve

Coarctation of the Coarctation of the AortaAorta

Common in patients with some Common in patients with some chromosomal anomalies (Turner’s chromosomal anomalies (Turner’s syndrome)syndrome)

Due to narrowing of the aortaDue to narrowing of the aorta

Left ventricle has to work harder to force Left ventricle has to work harder to force blood through narrow aortablood through narrow aorta

Coarctation of the Coarctation of the AortaAorta

Coarctation of the Coarctation of the aorta: Signs aorta: Signs

Depends on degree of narrowingDepends on degree of narrowing Severe – possible heart failure in first days of Severe – possible heart failure in first days of

lifelife Mild – progressive left ventricular hypertrophy Mild – progressive left ventricular hypertrophy

(thickening of the muscle)(thickening of the muscle)

Weak pulses in the legs of the infant Weak pulses in the legs of the infant (femoral artery pulse) and increased (femoral artery pulse) and increased pressure in upper extremitiespressure in upper extremities

Tetralogy of FallotTetralogy of Fallot

Combination of four heart defectsCombination of four heart defects Pulmonary stenosis – narrowing of pulmonic Pulmonary stenosis – narrowing of pulmonic

valve that impedes blood flow from right valve that impedes blood flow from right ventricle to pulmonary arteryventricle to pulmonary artery

VSDVSD Overriding aorta – Aorta is enlarged and Overriding aorta – Aorta is enlarged and

appears to arise from both right and left appears to arise from both right and left ventriclesventricles

Right ventricular hypertrophy – due to Right ventricular hypertrophy – due to pumping at high pressurepumping at high pressure

Tetralogy of FallotTetralogy of Fallot

Overriding aorta

Pulmonary stenosis

RV hypertrophy

VSD

Tetralogy of Fallot: Signs Tetralogy of Fallot: Signs and Symptomsand Symptoms

Usually diagnosed in the first few weeks of Usually diagnosed in the first few weeks of lifelife

Loud murmur Loud murmur

Cyanosis due to pulmonary stenosis Cyanosis due to pulmonary stenosis

Rapid breathing in response to low oxygen Rapid breathing in response to low oxygen

Transposition of the Transposition of the Great ArteriesGreat Arteries

The aorta and pulmonary artery arise from the The aorta and pulmonary artery arise from the wrong ventricle wrong ventricle

Oxygen poor blood from body to the RA and RV Oxygen poor blood from body to the RA and RV is pumped out of the aorta to the bodyis pumped out of the aorta to the body

Oxygen rich blood from the lungs to the LA and Oxygen rich blood from the lungs to the LA and LV is sent back to the lungs through the LV is sent back to the lungs through the pulmonary arterypulmonary artery

VSD is common with Transposition of Great VSD is common with Transposition of Great Arteries and allows for some blood mixing but Arteries and allows for some blood mixing but not enough to give adequate oxygen to all not enough to give adequate oxygen to all organsorgans

Transposition of the Transposition of the Great ArteriesGreat Arteries

Signs and SymptomsSigns and Symptoms

Cyanosis during first hours/days of lifeCyanosis during first hours/days of life

Rapid breathing due to lack of oxygenRapid breathing due to lack of oxygen

If untreated, 50% will die in the first months If untreated, 50% will die in the first months of life, and 90% in the first yearof life, and 90% in the first year

Helpful Information for Helpful Information for CaseCase

General guidelines for a child's growth rates include:General guidelines for a child's growth rates include:

Weight:Weight:

2 weeks - regains birth weight and then gains about 1 1/2 - 2 pounds a 2 weeks - regains birth weight and then gains about 1 1/2 - 2 pounds a monthmonth

3 months - gains about 1 pound a month3 months - gains about 1 pound a month

5 months - doubles birth weight5 months - doubles birth weight

1 year - triples birth weight and then gains about 1/2 pound a month1 year - triples birth weight and then gains about 1/2 pound a month

2 years - quadruples birth weight and then gains about 4-5 pounds a year2 years - quadruples birth weight and then gains about 4-5 pounds a year

9-10 years - increased weight gain as puberty approaches, often about 9-10 years - increased weight gain as puberty approaches, often about 10 pounds a year10 pounds a year

Height:Height:

0-12 months - grows about 10 inches (25 cm)0-12 months - grows about 10 inches (25 cm)

1-2 years - grows about 5 inches (13 cm)1-2 years - grows about 5 inches (13 cm)

2-3 years - grows about 3 1/2 inches a year most children will double 2-3 years - grows about 3 1/2 inches a year most children will double their birth height by 3-4 years of agetheir birth height by 3-4 years of age

3 years to puberty - grows about 2 inches (5cm) a year3 years to puberty - grows about 2 inches (5cm) a year

Questions??Questions??

Thank you!Thank you!