Congenital Heart Disease

AVSD Blood Flow

Blood flows from Left side of the heart to the Right side of the heart. Pulmonary arterioles clamp down; start to thicken, irreversible pulmonary artery disease. Must operate within the first year. If have trisomy 21 must have operation within the first few months of life. They have poorly developed airways and already have increased acid levels; baseline already clamped down arterioles.

Define Plexiform Lesions

Characteristic vascular change of pulmonary arteries in pulmonary hypertension

Define the following terms: Atresia

Congenital absence or closure of a normal body tubular structure or orifice.

Common terms and their meanings

- Valvular atresia = Imperforate valvular orifice - Hypoplasia (vs atrophy) = Underdeveloped chamber or vessel - Cyanosis = Dusky blueness of skin or mucosa

Ebstein Anomaly

1) Tricuspid valve malformation, wherein the septal and posterior leaflets are adherent to the wall of the RV and the anterior leaflet is redundant, causing apical displacement of the functional annulus, annular dilatation, and torrential tricuspid regurgitation. 2) Causes massive RV and RA dilatation. 3) Associated with Wolff-Parkinson-White syndrome, a particular type of cardiac arrhythmia syndrome where abnormal accessory conduction pathways exist between the atria and ventricles 4) May be asymptomatic until adulthood.

List the common causes of *right-to-left* shunts, describing their gross morphology and physiologic consequences Truncus Arteriosus

1) Aorta and pulmonary artery arise from a single truncal artery that receives blood from both ventricles. 2) Due to failure of separation of the embryonic truncus arteriosus into the aorta and pulmonary artery. 3) A large VSD is also present in most patients. 4) Severe pulmonary hypertension often occurs. 5) Strongly associated with DiGeorge syndrome (22q11.2 deletion).

List the common causes of *right-to-left* shunts, describing their gross morphology and physiologic consequences Tetralogy of Fallot

1) Presence of 4 simultaneous anomalies: VSD (large and subaortic), subpulmonary ste- nosis, overriding aorta, and right ventricular hypertrophy. 2) Most common form of cyanotic congenital heart disease. 3) Results from anterosuperior displacement of the infundibular septum during cardiac development. 4) Three types, based on severity of pulmonary stenosis: a) "Pink Tetralogy": Mild pulmonary stenosis; NO cyanosis. b) "Classic Tetralogy": Moderate to severe pulmonary stenosis, WITH cyanosis. c) "Pulmonary Atresia-Ventricular Septal Defect (PA-VSD)": Variant of Tetralogy with complete absence of pulmonary valve and main pulmonary artery, WITH cyanosis. 5) Usually patients do NOT develop pulmonary hypertension, despite the presence of a VSD, because lung vessels are protected by subpulmonary stenosis. 6) Often good results with surgical repair.

List the common causes of *left-to-right* shunts, describing their gross morphology and physiologic consequences Atrial Septal Defect (ASD)

10% of congenital heart defects. May be asymptomatic until adulthood (30s) and undetected as no murmurs / unusual heart sounds. Septum Secundum defect more common, and occurs in rim of the fossa ovalis. Primum type rare, and occurs low in atrial septum. Therefore, the blood flows back from the LA to the RA, going back through the entire cardiac cycle. The Right side of the heart grows as a result, because it is receiving excessive blood flow. It often results in atrial dysrythmias due to enlarged right heart as well as RV disfunction. Pulmonary hypertension is an infrequent, late complication because increase VOLUME flow through pulmonary artery. Increased pressure on the pulmonary valve can also result in pulmonary vascular occlusive disease - in which case you will hear a murmur. Plexiform lesions in <10% (unoperated). Needs surgery.

List the common causes of *left-to-right* shunts, describing their gross morphology and physiologic consequences Ventricular Septal Defect (VSD)

2/5 of congenital heart defects. Most located high in the ventricular septum, but some are located in the muscle. Larger size is worse than small (will not spontaneously close if large). Flow goes from LV to RV, then goes through lungs, etc. all over again. LV increases in size as the blood spends very little time in RV; immediately goes to lungs. Pulmonary hypertension occurs due to HIGH PRESSURE flow, which often results in pulmonary vascular occlusive disease. Can eventually shift to cyanotic heart disease (Eisenmenger's syndrome) due to pulmonary hypertension. Causes pulmonary edema, gas exchanges no longer work. Can no longer eat because need oxygen all the time. Plexiform lesions will form in all (100%) with large un-op VSD ; Will form in none (0%) with small un-op VSD. Operate at 4-6mo.

List the obstructive congenital anomalies, describing their gross appearance and physiologic consequences Coarctation of aorta

5% of congenital heart disease. PDA in children (hear murmur); non-PDA in adults. Ridge-like indentation of distal aortic arch, across from ductus arteriosus Preductal (before ductus arteriosus), with tubular aortic hypoplasia. Postductal is short, ridge-like infolding of the aorta (blood pressure lower in legs than in arms is a classic sign). Aortic valve may be bicuspid. Rib notching apparent on CXR (see extended collateral arteries to bypass the area; become tortuous and spread - a real tangle of lots of arteries, producing notches on ribs). Can surgically treat the hypertension in this case.

List the common causes of *right-to-left* shunts, describing their gross morphology and physiologic consequences Transposition of Great Arteries (TGA)

Aorta and pulmonary artery are both transposed (flipped in anterio-posterior position) and discordant (connected to the wrong ventricle). Cyanotic. Shunt is necessary (otherwise incompatible with life); either ASD, VSD, or PDA.

ASD Location

At fossa ovalis (90%) - (secundum ASD)

VSD Location

At memb septum (90%) (membranous VSD) - usually large

Define the following terms: atrioventricular canal

Develops into the heart septum and mitral/tricuspid valves. Congenital abnormalities result in atrioventricular septal defect.

Why do we close PDAs?

Due to excessive blood flow to the lungs (HIGH PRESSURE flow), it results in pulmonary hypertension. As a result, Pulmonary Vascular Occlusion Disease occurs; high pressure from change in blood flow and can no longer relax. Results in changes - muscularized pulmonary vasculature. Left ventricle increases in size and can no longer stretch properly, resulting in end-diastolic pressure. Risk of infection to the smaller vessels - endarteritis. Give prostaglandin inhibitors to fix it - stimulates PDAs to close. Otherwise, babies need surgery (after a year).

List the common causes of *left-to-right* shunts, describing their gross morphology and physiologic consequences Atrioventricular Septal Defect (AVSD)

Due to the heart's asymmetry, the center of the heart separates the RA from the LV. Here, one large valve in the middle of the heart (instead of AV valves); 1/3 of complete AVSD have trisomy 21. Can be complete [B] (primum ASD, membranous VSD, common AV valve) or partial (primum ASD [A] and cleft mitral leaflet [C]).

Define the following terms: Eisenmenger syndrome

Eisenmenger's syndrome occurs when a left-to-right shunt reverses to a right-to-left shunt. This occurs later in life, and occurs as a result of pulmonary hypertension. - The shunt, which was not cyanotic at birth, is now cyanotic. - Can occur with ASD (rare), VSD, AVSD, or PDA. - Can only be treated with heart transplant (possibly a good surgeon?)

List the obstructive congenital anomalies, describing their gross appearance and physiologic consequences Hypoplastic left heart syndrome

Hypoplasia of the left ventricle, ascending aorta, aortic valve, and mitral valve (smaller than normal at birth)

List the obstructive congenital anomalies, describing their gross appearance and physiologic consequences Hypoplastic left heart syndrome II

Hypoplasia of the left ventricle, ascending aorta, aortic valve, and mitral valve (smaller than normal at birth)

Define the following terms: hypoplastic left heart syndrome

Hypoplastic left heart syndrome refers to an underdevelopment of the left ventricle, aorta, aortic valve, and mitral valve such that they are smaller than normal at birth.

List the incidence and pathogenesis of congenital heart disease in general, and common specific types of congenital heart disease

Incidence: about 1/100 births (.6-.8% of live births) Etiology: - Sporadic genetic abnormalities/unknown (90%) - Chromosomal abnormalities, trisomies 13, 15, 18, 21; Turner's syndrome - Viral infection during pregnancy, i.e. rubella - Drugs (during pregnancy) - Radiation (during pregnancy) Classification: - Left to right shunts (no or late cyanosis) - Right to left shunts (early cyanosis) - Obstructive anomalies (no cyanosis)

Congenital Heart Disease Classification

Late cyanosis - acyanotic at first; becomes blue later on L-->R shunts = ALL HAVE Ds R-->L shunts = ALL START WITH Ts

List the common causes of *left-to-right* shunts, describing their gross morphology and physiologic consequences Patent (Persistent) Ductus Arteriosus (PDA)

Normal structure that usually closes by day 3 after birth; connects the aorta to the pulmonary artery. In these patients, it remains a persistent; isolated defect. It's worse at high altitudes or in premature babies. Plexiform lesions in most (unop, >5 yrs). Babies with AV or PV atresia need to keep the duct open in order to survive. Treated with drugs to keep it open. Initially L-> R shunt because of pressure differences between the two atria. Over time, w/development of plexiform lesions, development of Eisenmenger syndrome.

Fetal Development, Foramen Ovale and Ductus Arteriosus

Oxygenated blood doesn't get oxygenated through lungs, but through umbilical cord. Moves to RA, then LA, then aorta, thanks to: - Foramen ovale: shunt between RA and LA Blue blood goes through: - Ductus Arteriosus: shunt between pulmonary artery and aorta; 10% goes to lungs, 90% goes to aorta

AVSD Partial vs Complete

Partial (top) vs Complete (bottom) Complete - from above, looks like "Batman" sign

List the obstructive congenital anomalies, describing their gross appearance and physiologic consequences - Pulmonary Stenosis or Atresia (PS/PA) - Aortic Stenosis or Atresia (AS/AA)

Pulmonary Stenosis or Atresia (PS/PA). Narrowing of the pulmonic valve, or failure to develop (similar to tricuspid atresia, above). PV obstruction due to hypoplasia, dysplasia, or abnormal number of cusps. (may be asymptomatic until adulthood) PDA needed for survival. Aortic Stenosis or Atresia (AS/AA). Narrowing of the aortic valve, or failure to develop (similar to tricuspid atresia, above) due to hypoplasia, dysplasia, or abnormal number of cusps. Can range from mild to critical. PDA-dependent lesion. Results in fibrotic tiny ventricle on side of stenosis (with tiny artery).

Describe the cause(s) and significance of pulmonary hypertension in congenital heart disease

Pulmonary hypertension occurs in congenital heart disease due to shunting of blood from the left side of the heart to the right side of the heart, increasing volume that the right heart must pump into the pulmonary circulation. Over time, pulmonary blood pressures will rise, and everntually pulmonary hypertension will result. This can cause a shift to right-to-left shunting that causes the patient to be cyanotic (not enough oxygen reaching the tissues). Can occur with ventricular septal defect

List the common causes of *right-to-left* shunts, describing their gross morphology and physiologic consequences Total Anomalous Pulmonary Venous Connection (TAPVC)

Pulmonary veins do not connect with the left atrium; may return to another vein or the coronary sinus. ASD or PDA present.

What is a shunt?

Shunt: Blood flow directly from one circulatory bed (systemic or pulmonary) to the other Shunts can either be: 1) Left to right - oxygenated blood returning to the pulmonary arteries without first going to the body 2) Right to left - deoxygenated blood circulating to the body without first going to the lungs Shunts allow for redundant blood flow, which is inefficient Therefore, the body is still getting the same amount of blood, but more of it is going to the lungs.

List the common causes of *right-to-left* shunts, describing their gross morphology and physiologic consequences Tricuspid Atresia

Tricuspid valve is missing or abnormally developed. Hypoplastic right ventricle. ASD present. 1% of congenital heart disease.