Tetralogy of Fallot with flap valve VSD

Tetralogy of Fallot with flap valve VSD

In Tetralogy of Fallot with flap valve VSD, there is a flap attached to the ventricular septal defect (VSD) which will restrict the flow across the VSD and can cause supra systemic right ventricular pressure. Usually right ventricular pressure is just systemic in Tetralogy of Fallot because the large unrestrictive VSD equalizes the pressures in the two ventricles.

P R Kumar, A D Rakshak, P Rajagopal, T N Padmanabhan, D S Rao, S Jaishanker reported five cases of TOF with flap valve VSD [1]. TOF with restrictive VSD and suprasystemic right ventricular pressure has a high mortality rate. In all of their 5 cases, accessory or excessive tricuspid valve tissue obstructed the ventricular septal defect. Early recognition is important because of the poor prognosis.

In these cases with restrictive VSD, right ventricular systolic pressure shows post ectopic potentiation and ventricular pressure trace shows characteristic ‘isosceles triangle pattern’ [2]. This is in contrast to the rectangular shape seen in those with non-restrictive ventricular septal defect [3]. Post ectopic potentiation is not seen in usual TOF as the right ventricular pattern is influenced by the left ventricular pressure changes due to unrestrictive VSD. Normal left ventricular pressure shows mild or no systolic augmentation after a premature ventricular beat because of reflex systemic vasodilatation.

These patients are prone for right heart failure. A prominent ‘a’ wave in the jugular venous pulse, not expected in usual TOF, is an important physical finding suggesting suprasystemic right ventricular pressure.

References

1. P R Kumar, A D Rakshak, P Rajagopal, T N Padmanabhan, D S Rao, S Jaishanker. Tetralogy of Fallot With Flap Valve Ventricular Septal Defect Producing Suprasystemic Right Ventricular Pressure: Echocardiographic Observations. Indian Heart J. Jul-Aug 1998;50(4):446-50.
2. Soni MR, Bohara DA, Mahajan AU, Nathani PJ. Tetralogy of Fallot with restrictive ventricular septal defect by accessory tricuspid leaflet tissue. Indian Heart J. 2012 Jul-Aug;64(4):412-5. doi: 10.1016/j.ihj.2012.06.009. Epub 2012 Jun 22. PMID: 22929828; PMCID: PMC3860792.
3. Kannan BR. Tetralogy of fallot. Ann Pediatr Cardiol. 2008 Jul;1(2):135-8. doi: 10.4103/0974-2069.43880. PMID: 20300256; PMCID: PMC2840752.