Cardiac resynchronization induces favorable neurohumoral changes.

Aim: The aim of this article is to examine whether cardiac resynchronization therapy (CRT) induces improvements in the neurohumoral system.

Methods And Results: Thirteen patients with HF (left ventricular (LV) ejection fraction <35%) were included. Before and after 6 months of CRT, myocardial (123)I-metaiodobenzylguanidine ((123)I-MIBG) uptake indices, used as an index of neural norepinephrine reuptake and retention, and brain natriuretic peptide (BNP) levels, used as an index of LV end-diastolic pressure, NYHA classification and echocardiographic indices were assessed.

Individual optimization of pacing sensors improves exercise capacity without influencing quality of life.

Introduction: Programmable pacemaker sensor features are frequently used in default setting. Limited data are available about the effect of sensor optimization on exercise capacity and quality of life (QOL). Influence of individual optimization of sensors on QOL and exercise tolerance was investigated in a randomized, single blind study in patients with VVIR, DDDR, or AAIR pacemakers.

Undersensing of VF in a patient with optimal R wave sensing during sinus rhythm.

We describe a case of potentially fatal undersensing of VF by a third generation ICD with predetermined automatic gain control. In this patient, ventricular sensing was optimal, as R wave amplitudes during sinus rhythm were at least 16 mV. Cyclical, high amplitude signals during VF elevated the sensing floor to such an extent that complete undersensing of subsequent lower amplitude local electrograms occurred.