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10/9/14. Congenital Heart Diseases. Dr. Ksheera Cariappa Assistant Professor. The Heart. Embrology. Lateral mesoderm moves to midline Crescent of cells ---- first and second heart fields by day 15. First heart field – TBX5, Hand1 transcription factor expression
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10/9/14 Congenital Heart Diseases Dr. Ksheera Cariappa Assistant Professor
Embrology • Lateral mesoderm moves to midline • Crescent of cells ---- first and second heart fields by day 15. • First heart field – TBX5, Hand1 transcription factor expression • Second heart field--- Hand 2, FGF10 • Endocardium, myocardium, smooth muscle cells
Embrology • First heart field -- LV • Second heart field – RV, RA,LA, Outflow tract • Day 20 beating tube • Heart chambers by 28days • Cells from neural crest migrate to form septae, endocardial cushions, aortic arches
Embrology • Day 50– septation of ventricles, atria, atroventricular valves – four chambered heart • Signaling pathways – Wnt, VEGF, TGF- b, FGF, Notch pathways, bone morphogenetic factor. • Coordinated by micro RNA.
Etiopathogenesis • Sporadic genetic abnormalities • Single gene mutations • Small chromosomal deletions • Trisomy/monosomy • Single gene mutations encoding transcription factors for normal heart development
CHD • Acyanotic • Cyanotic • Obstructive
Acyanotic CHD • Left to right shunts • VSD • ASD • Patent foramen ovale • PDA
Cyanotic CHD • Right to left shunts • TOF • TGV • TA • TAPVC • PTA • Ebstein’s Anomaly
Obstructive Congenital Heart Lesions • Impede the forward flow of blood and increase ventricular afterloads. • Pulmonary Stenosis and atresia • Aortic Stenosis and atresia • Coarctation of the Aorta
Coarctation of the Aorta • Absent or weak femoral pulses. • Systolic pressure higher in upper extremities than in lower extremities; diastolic pressures are similar. • Harsh systolic murmur heard in the back.
Coarctation of the Aorta • Males twice as frequently as females. • 98% of all coarctations at segment of aorta adjacent to ductus arteriosus. • Produced by both an external narrowing and an intraluminal membrane. • Blood flow to the lower body maintained through collateral vessels.
COA • Turners syndrome • Infantile form with PDA • Do not survive neonatal period • Adult form without PDA • LVH, Cardiomegaly
CHD • that INCREASE Pulmonary Arterial Blood Flow • that DECREASE Pulmonary Arterial Blood Flow
Congenital Heart Lesions that INCREASE Pulmonary Arterial Blood Flow • Atrial Septal Defect • Complete Atrioventricular Canal • Ventricular Septal Defect • Patent Ductus Arteriosis • CYANOTIC: • Total Anomalous Pulmonary Venous Connection • Truncus Arteriosus
1. Atrial Septal Defect • Acyanotic; asymptomatic, or dyspnea on exertion. • Right ventricular lift. • Fixed, widely split second heart sound. • Depending upon the location of the defect, there are 3 types of ASD
Atrial Septal Defect • i) Fossa ovalis type or ostium secundum type is the most common form (90%). The defect is in the region of the fossa ovalis • ii) Ostium primum type about (5%)cases. The defect lies low in the interatrial septum adjacent to atrioventricular valves. There may be cleft in the aortic leaflet of the mitral valve producing mitral insufficiency.
Atrial Septal Defect • iii) Sinus venosus type accounts for about 5% cases of ASD.The defect is located high in the interatrial septum near the entry of the superior vena cava.
Morphologic Features The effects of ASD are produced due to left-to-right shunt at the atrial level with increased pulmonary flow. These effects are • Volume hypertrophy of the right atrium and right ventricle. • Enlargement and haemodynamic changes of tricuspid and pulmonary valves. • Focal or diffuse endocardial hypertrophy of the right atrium and right ventricle. • Volume atrophy of the left atrium and left ventricle. • Small-sized mitral and aortic orifices.
Atrial septal defect fossa ovalis type, a schematic representation (LA = Left atrium; LV = Left ventricle; PV = Pulmonary vein; AO = Aorta; PT = Pulmonary trunk; RA = Right atrium; RV = Right ventricle; SVC = Superior vena cava; IVC = Inferior vena cava).
2. Ventricular Septal Defect • M/C of all CHDs (30%) • Asymptomatic if defect is small. • Heart failure with dyspnea, frequent respiratory infections, and poor growth if defect is large. • Membranous VSD (90%) • Infundibular VSD (Subpulmonic/subaortic) • Multiple : Swiss cheese septum
Ventricular Septal Defect • Often one component of another more complex congenital heart lesion. • Heart is enlarged and lung fields are overcirculated. • Many of the defects will close spontaneously by age 7-8 years.
Morphologic Features • The effects of VSD are produced due to ltrt shunt at the ventricular level, increased pulmonary flow and increased volume in the left side of the heart. These effects are: • Volume hypertrophy of the right ventricle. • Enlargement and haemodynamic changes in the tricuspid and pulmonary valves. • Endocardial hypertrophy of the right ventricle. • Pressure hypertrophy of the right atrium. • Volume hypertrophy of the left atrium & ventricle. • Enlargement and haemodynamic changes in the mitral and aortic valves.
3. Patent Ductus Arteriosis • Accounts for 10% of CHDs • Murmur usually systolic, sometimes continuous, “machinery” • Poor feeding, respiratory distress, and frequent respiratory infections in infants with heart failure. • Physical exam and echocardiography.
Cause • is not known but possibly it is due to continued synthesis of PGE2 after birth which keeps it patent as evidenced by association of PDA with respiratory distress syndrome in infants and pharmacologic closure of PDA with administration of indomethacin to suppress PGE2 synthesis
In about 90% of cases, it occurs as an isolated defect, while in the remaining cases it may be associated with other anomalies like VSD, coarctation of aorta and pulmonary or aortic stenosis. • A patent ductus may be upto 2 cm in length and upto 1 cm in diameter
Morphologic Features The effects of PDA on heart occur due to left-to-right shunt at the level of ductus resulting in increased pulmonary flow and increased volume in the left heart. These effects are: i) Volume hypertrophy of the left atrium and left ventricle. ii) Enlargement and haemodynamic changes of the mitral and pulmonary valves. iii) Enlargement of the ascending aorta.
Congenital Heart Lesions that DECREASE Pulmonary Arterial Blood Flow • Tetralogy of Fallot • Transposition of the Great Arteries • Tricuspid Atresia • Ebstein’s Anomaly
4.Tetralogy of Fallot • M/C cyanotic CHD (10% of all) • Its components are: i) Ventricular septal defect (VSD) (‘shunt’). ii) Displacement of the aorta to right so that it overrides the VSD. iii) Pulmonary stenosis(‘obstruction’). iv) Right ventricular hypertrophy.
Tetralogy of Fallot • Addition of an atrial septal defect falls in the category of Pentalogy of Fallot. • Absence of PS Triology • Hypoxic spells and squatting. • Cyanosis and clubbing.
Clinically • The severity of the clinical manifestations is related to two factors: extent of pulmonary stenosis and the size of VSD. • Boot shaped heart • Accordingly, there are two forms of tetralogy: cyanotic and acyanotic:
Cyanotic Tetralogy • PS is > VSD so that there is more resistance to the outflow of blood from rt ventricle resulting in rtlt shunt at the ventricular level and cyanosis. The effects on heart are : i) Pressure hypertrophy of the right atrium and right ventricle. ii) Smaller and abnormal tricuspid valve. iii) Smaller left atrium and left ventricle. iv) Enlarged aortic orifice.
Acyanotic Tetralogy • VSD is larger and pulmonary stenosis is mild so that there is mainly left-to-right shunt with increased pulmonary flow and increased volume in the left heart but no cyanosis. The effects on heart are : i) Pressure hypertrophy of the right ventricle and right atrium. ii) Volume hypertrophy of the left atrium and left ventricle. iii) Enlargement of mitral and aortic orifices.
