Undersensing of ventricular fibrillation due to interference between a pacemaker and defibrillator in the same patient

Sensing in pacemakers (PMs) and implantable cardioverter defibrillators (ICDs) is crucial to normal device behaviour. Since both devices treat different arrhythmias, the technical approach to signal detection is also completely different. A PM has a fixed threshold of sensing, above which events are sensed and therapy of the device withheld. On the other hand, the defibrillator has a variable threshold of sensing to detect tachyarrhythmias, with sometimes very small and changing electrogram amplitudes. In this case report, we describe interference between a PM and an ICD caused by these differences in the detection of cardiac events, leading to undersensing of ventricular fibrillation at defibrillation threshold testing.

Arrhythmias in heart transplant recipients

The suture between the recipient and donor atrium in a heart transplant patient usually gives complete electric isolation. In this case report, we describe two transplant patients with an atrial tachycardia in the recipient atrium. In the first patient there was no conduction to the donor atrium, whereas the second patient had a breakthrough with 2-to-1 conduction.

Cytomegalovirus colitis in an apparently immunecompetent host after biliopancreatic diversion for obesity

CMV colitis in an immunocompetent host is a rare occurrence. We report a case of CMV colitis after biliopancreatic diversion surgery. The diagnosis of primary CMV infection with CMV colitis was based on histological examination of tissues biopsies obtained at colonoscopy, serology positive for CMV-IgM and CMV-IgG antibodies and a good response to systemic gancyclovir treatment. Malnutrition and colonic mucosal damage, both consequences of biliopancreatic diversion surgery, were thought to be predisposing factors. To our knowledge this is the first report in the English language literature of an association between CMV colitis and status following biliopancreatic diversion surgery.