One more cause for acquired VSD : His bundle pacing
His bundle pacing is the new kid in EP lab. It involves exploration of few 3-dimensional cubic areas of His bundle (4-6mm³ ? ) in the crest of the IVS looking for optimal His pacing site. It aims to provide better recruitment of His Purkinje and hence more synchronous pacing. Still, the modality is in the early stages and has few key limitations. They are, requirement of very specialised leads,(Select Secure 3830 , Medtronic) lead instability (Susceptible to RV ejectile forces*), high threshold, and lower battery life and finally uncertainty of distal bundle disease. A need for temporary RV back up the leads in some centers will tell us how confident we are, about the concept of his bundle pacing.
The success rate of HPB pacing has not reached the desired levels.Meanwhile, the area His bundle lead explores is so thin and delicate that requires working around membranous septum. No surprise, a new adverse event is reported. Yes, the first case of acquired VSD reported following his bundle pacing. (Ref 1)
Now, experts are moving down in the septum to capture LBBB to avoid the above-said limitations of HBP. I will not be surprised we ultimately reach the RV apex , the good old destination again, for absolute safety and stability.
*RV leads are naturally isolated and not much affected by RV contractile hemodynamics
Wish the concerns about His pacing are exaggerated , best of luck for this new mode of pacing. Medtronic is a pioneer and has a long passionate history. After all, cardiac pacing is one of their top Innovation in cardiology in the last century that made a huge impact in the management of electrical ailments of the heart.