Infective endarteritis in patent ductus arteriosus (PDA)

Infective endarteritis is less likely in a very small PDA as well as a large PDA. It is more likely in moderate sized PDAs and small PDAs. Hence there is no role for closing very small PDA without continuous murmur. In PDA infective endarteritis, the vegetations occur either at the pulmonary end of the ductus or in the wall of the pulmonary artery opposite the ductus, where the jet strikes.

Why is neonatal myocardium more prone for cardiac failure?

Contractile elements form 30% of the fetal heart while it forms 60% in the adult. Immature myocytes lack sufficient sarcoplasmic reticulum and mitochondria. Hence the neonatal myocardium is more cardiac failure.

Angina in Eisenmenger PDA

In general angina due to right ventricular ischemia is rarer in Eisenmenger PDA compared to other forms of Eisenmenger syndrome. Angina has been reported in Eisenmenger PDA due to compression of left main coronary artery [Am Heart J. 1993;125:1767-71].