The commonest cyanotic hea disease manifesting as congestive cardiac failure during first week of life is -
Ans. is 'd' i.e., Hypoplastic left hea syndrome o Amongst the given options, hypoplastic left hea syndrome causes CHF in First week. o Different congenital diseases have different time of onset of CHF : - 1)Left to right shunt o At bih, pulmonary vascular resistance is high, i.e., the pressure on side of circulation is high --> Pulmonary pressure is almost equal to systemic pressure. So, left to right shunt is small, whether the communication is atrial, ventricular or pulmonary aery level. As the neonate grows, pulmonary vascular resistance falls with maximum fall at the age of six to eight weeks (Note - In normal neonate, maximum fall is between 1 to 3 weeks). o This is the time (six to eight weeks) when the size of shunt is maximum as pulmonary vascular resistance is least at this time. So, patients with left to right shunts tend to develop CCF around six to eight weeks of life. 2)Right to left shunt Patients with right to left shunt may have : ? a) Shunt at the ventricular or pulmonary aery level. b)Shunt at atrial level o Patients with shunt at the ventricular or pulmonary aery level do not develop CCF because the right ventricle is dompressed by the shunt. o Patients with shunt at atrial level may have. i) Obstruction at right ventricular outlet (Pulmonary stenosis or atresia) --> CCF develops in the first few days of life as ventricle does not decompress fully because shunt is at atrial level. ii) Obstruction at right ventricular inlet (Tricuspid atresia) CCF usually does not occur as there is no volume overload to right ventricle. But these patients develop congestive symptoms when the shunt is small. 3) Obstructive lesions o If the stenosis is critical (e.g., in aoic or pulmonary atresia), CCF may develop early because of impaired ventricular decompression. o Coarctation of aoa may develop CCF with in 1-4 weeks of life. However, if these patients do not manifest CCF in the first year of life, collaterals develop and prevent onset of failure by decompressing the obstruction. 4) Transposition o Patients with transposition of great aeries, develop CCF within first week of life, when there is no ventricular communication and the only mixing site is at the atrial level --> Hypoxemia along with anoxic myocardium results in tachycardia that causes CCF. o Patients with transposition of great aeries with an adequate ventricular defect and patients with transposition of pulmonary veins develop CCF somewhat later, usually by the age of six to eight weeks, following the fall in pulmonary vascular resistance as in patient with left to right shunt.
Pulmonary stenosis
Fallot's tetralogy
Tricuspid atresia
Hypoplastic left hea syndorme