Pathology-Congenital Heart Defects

Left to Right Shunts

1. VSD (Ventricular Septal Defect) 2. ASD (Atrial Septal Defect) 3. PDA (patent ductus arteriosus) 4 AV Septal Defect

Right to Left Shunts

1.Tetralogy of Fallot 2. Transposition of Great Arteries 3. Persistent Truncus Arteriosus 4. Tricuspid Atresia 5. Total anomalous pulmonary venous connection

Coarctation of the Aorta

Narrowing or constriction of the aorta Males affected twice as often as females Females with Turner Syndrome frequently affected with coarctation Types: Infantile: hypoplasia of the aortic arch proximal to a PDA Adult: Ridge-like infolding of the aorta, opposite to a closed ductus arteriosus distal to the arch vessels Accompanied by a bicuspid aortic valve in 50% May be seen in other congenital anomalies as well

TAPVC

No pulmonary veins directly join the left atrium TAPVC usually drains into the left innominate vein or coronary sinus A patent foramen ovale or ASD is always present allowing pulmonary venous blood to enter the left atrium Consequences include hypertrophy of right atrium and ventricle with dilation of these chambers and the pulmonary trunk The left atrium is hypoplastic; the left ventricle is usually normal Cyanosis may be present. pulmonary veins are not where they are supposed be.

Pulmonary Stenosis and Atresia

Obstruction at the pulmonary valve May be mild or severe (atresia) Isolated or part of a complex, such as Tetralogy of Fallot or Transposition of the Great Arteries Right ventricular hypertrophy may develop In atresia, the right ventricle may be hypoplastic with an associated ASD/VSD

Tricuspid Atresia

Occlusion of the tricuspid valve orifice Almost always associated with a hypoplastic right ventricle Right-to-left shunt VSD and ASD or patent foramen ovale Cyanosis and high early mortality

Congenital Heart Disease

Abnormalities of the heart or great vessels present from birth Most arise from faulty embryogenesis during gestational weeks 3 through 8 Incidence approximately 1% of live births Incidence higher in premature and stillborn Well-defined genetic or environmental causes identified in only 10% of cases Malformations causing a left-to-right shunt,right-to-left shunt, obstruction, A shunt is an abnormal communication between chambers or blood vessels.

Obstructive Congenital Disease

1. Aortic Valve Stenosis 2. coarctation of the aorta 3. Pulmonary Valve Stenosis

Aortic Stenosis and Atresia

1.Valvular aortic stenosis Cusps hypoplastic, dysplastic (thickened), or abnormal in number Severe cases lead to hypoplasia of the left ventricle and ascending aorta, with fibroelastosis of the left ventricular endocardium (hypoplastic left heart syndrome) Nearly always fatal in the first week of life after the ductus closes 2. Subaortic stenosis: Thickened ring or collar of dense endocardial fibrous tissue below the level of the cusps 3. Supravalvular stenosis: Inherited form of aortic dysplasia in which the ascending aortic wall is greatly thickened, causing luminal constriction Caused by mutation in the elastin gene

ASD

An abnormal opening in the atrial septum that allows communication of blood between the left and right atria. Secundum ASD: 90%, due to a fenestrated or deficient fossa ovalis Primum: 5%, adjacent to AV valves, "partial AV septal defect: Sinus venosus: 5%, near entrance of the superior vena cava Usually asymptomatic until adulthood. Irreversible pulmonary hypertension develops in fewer than 10% of subjects with isolated, uncorrected ASD These are NOT the same as a patent foramen ovale! blood goes from left to right. increase in blood volume leads to splitting of the S2 sound due to late closure of the pulmonary valve. paradoxical emboli important concern

Right to Left Shunt

Cyanosis due to diminished pulmonary blood flow and poorly-oxygenated blood entering the systemic circulation Paradoxical emboli: bland or septic emboli arising in peripheral veins that enter the systemic circulation and may cause brain infarcts or abscesses Long-standing cyanosis can cause clubbing of the tips of fingers and toes and polycythemia

Coarctation of the Aorta (Adult)

Most children asymptomatic; discovered later Hypertension in the upper extremities Weak blood pressure/pulses in the lower extremities Collateral circulation may develop and cause visible erosions ("notching") on the undersurfaces of ribs hypertension in UE hypotension in LE. discovered in adlthood. associated with bicuspid aortic valve

Truncus Arteriosus

Developmental failure of separation of the embryologic truncus arteriosus into the aorta and pulmonary artery Results in single great artery that receives blood from both ventricles Underlying VSD provides systemic, pulmonary, and coronary circulations Early cyanosis and increased pulmonary blood flow May result in pulmonary hypertension truncus fails to divide.

PDA

Ductus arteriosus remains open after birth 90% are isolated anomalies "Machinery-like" murmur Initially no cyanosis Isolated PDA should be closed as early in life as feasible Preservation of duct patency (administration of prostaglandin E) may be vital in the survival of infants with some congenital heart diseases (obstructed pulmonary or systemic blood flow). go in and close it with surgery. can give patient indomethacin which decreases PGE which will close the PDA. also see lower extremity cyanosis.

VSD

Due to incomplete closure of ventricular septum Forms a shunt between left and right ventricles The most common congenital cardiac anomaly May be associated with other cardiac anomalies, such as Tetralogy of Fallot 90% are located in the membranous portion of the interventricular septum; the remainder are infundibular (below pulmonic valve) or muscular. Muscular ones may be multiple (swiss cheese septum) associated with fetal alcohol syndrome About 50% of small muscular VSDs close spontaneously. Large defects are usually membranous or infundibular Irreversible pulmonary vascular disease develops in almost all patients with large, uncorrected VSD's>>>leads to shunt reversal, cyanosis, and death. Eisenmenger Syndrom- (R ventricular hypertrophy, polycythemia vera, clubbing)

Left to Right Shunt

Expose the post-natal low-pressure, low-resistance pulmonary circulation to increased pressure and/or volume resulting in right ventricular hypertrophy The muscular pulmonary arteries first respond to the increased pressure by medial hypertrophy and vasoconstriction. Chronic exposure to high pressure leads to irreversible intimal lesions, causing increased pulmonary vascular resistance (pulmonary hypertension). Eventually, the shunt reverses (right-to-left) with poorly-oxygenated blood in the systemic circulation (late cyanotic congenital heart disease, or Eisenmenger syndrome).

Tetralogy of Fallot

Four Features: VSD Obstruction to the right ventricular outflow tract (subpulmonary stenosis) An aorta that overrides the VSD Right ventricular hypertrophy Result from anterosuperior displacement of the infundibular septum "Boot-shaped" heart due to right ventricular hypertrophy The severity of obstruction to right ventricular outflow determines the direction of blood flow As the obstruction increases, right-to-left shunting occurs, and cyanosis results Most infants with tetralogy are cyanotic from birth or soon thereafter. patients learn to squat to reduce the spell.

Coarctation of the Aorta (Child)

Manifestations early in life Many do not survive without intervention Delivery of unsaturated blood through the PDA produces cyanosis in the lower half of the body Turner Syndrome. Deox blood crosses the PDA so you see cyanosis in LE

AVSD (Atrioventricular Septal Defect)

Superior and inferior endocardial cushions fail to fuse adequately Incomplete closure of AV septum and inadequate formation of tricuspid and mitral valves May be complete or partial Complete AVSD, all four chambers of the heart communicate More than one-third of patients with complete AVSD have Down Syndrome

Transposition of the Great Arteries

Ventriculoarterial discordance: the aorta arises from the right ventricle and the pulmonary artery emanates from the left ventricle Due to abnormal formation of the truncal and aortopulmonary septa Creates separation of the systemic and pulmonary circulations Incompatible with postnatal life unless a shunt is present, i.e. VSD, PDA Give PGE to repair. Associated with maternal diabetes.