Sensing lead failure in implantable defibrillators: a comparison of two commonly used leads.

Introduction: Despite major technological advances, structural problems in implantable cardioverter defibrillator (ICD) endocardial sensing leads remain a significant problem. There are two types of ICD sensing leads: (1) dedicated bipolar leads and (2) integrated lead systems that include defibrillation coils. The long-term performance of these two lead systems has not been directly compared.

Diagnostic value of a pacemaker high rate episode counter when programming the ventricular tachycardia zone of an ICD.

A 72-year-old man with an ICD and a pacemaker was presented with an episode of sustained VT that accelerated to VF. The ICD failed to detect the event and deliver therapy, despite a VT apparently within the VT detection zone. The ICD detected the event after degeneration to VF and delivered appropriate therapy.

Papillary muscle rupture after chordal sparing mitral valve replacement.

Complete papillary muscle rupture is a catastrophic complication of acute myocardial infarction which usually leads to acute severe mitral regurgitation requiring urgent or emergent surgery. A case in which this complication occurred after chordal sparing mitral valve replacement is described. The severed papillary muscle was removed surgically.

Use of atrial and ventricular electrograms from a dual chamber implantable cardioverter defibrillator to elucidate a complex dysrhythmia.

Stored intracardiac electrograms provided by third-generation ICDs have proved their use in the analysis of the mechanism of tachydysrhythmic events. There are cases in which the analysis of ventricular electrograms is insufficient for the elucidation of certain dysrhythmias. The availability of atrial electrograms provided by dual chamber ICDs improves the diagnostic capability of electrogram analysis and could prove most useful especially in complex dysrhythmias.

Calculation of the aortic valve gradient from the left ventricular-femoral and aortic-femoral pairs of pressure waveforms.

Accurate measurement of the transaortic gradient is important in the invasive assessment of the significance of aortic stenosis. The mean gradient obtained from simultaneous left ventricular and aortic pressure recordings is the gold standard, but requires two central catheters. We hypothesized that a gradient calculated by subtracting the aortofemoral from the ventriculofemoral gradient would reproduce the ventriculoaortic gradient.