Inappropriately long post-ventricular atrial blanking leading to 'unnecessary' defibrillator discharge.

A 55-year-old lady with non-ischemic cardiomyopathy (NICM) was referred for multiple implantable cardioverter defibrillator (ICD) shocks. Stored electrograms (EGM) revealed atrial flutter (AFL) with A > V. Morphology match was good and RR-intervals were irregular. Despite all these, the dual-chamber-ICD (Abbott medical) classified this as ventricular tachycardia (VT-2) via V > A algorithm where it did not analyze morphology/stability and delivered therapy. Anti-tachycardia-pacing (ATP) was delivered which induced a true VT (rate in VF-zone) and immediate shock was delivered. It was hence appropriate but an 'unnecessary' shock. The offender was found to be an inappropriately programmed long post-ventricular atrial-blanking (PVAB) of 200 ms which led to undersensing of several atrial electrograms, falsely making V > A during a clear AFL.

Congenital right ventricular diverticulum: An atypical presentation.

Congenital ventricular diverticulum is a rare congenital malformation of the heart. It remains mostly asymptomatic unless associated with other congenital cardiac defects. We present a case of a 4-month-old child who had dextrocardia, large inlet ventricular septal defect, amounting to single ventricle, and severe pulmonary artery hypertension. There was a right ventricular diverticulum which passed through the foramina of Morgagni to give rise to a pulsating lump in the epigastrium. Right ventricular diverticulum presenting with a pulsating mass in the abdomen is a rare entity. The confirmation of diverticulum was made with histopathology.