The impedance catheter: potential for differentiation between hemodynamically stable and unstable arrhythmias

An assessment is made of the efficacy of the impedance catheter in sensing relative volumetric changes in the right ventricle as a means of monitoring the hemodynamic status during an arrhythmia. During electrophysiologic testing, 37 arrhythmias were induced in 12 patients. Stroke impedance (peak value minus minimum value) was significantly lower in hemodynamically unstable ventricular arrhythmias (ventricular tachycardia and ventricular fibrillation) than in stable tachyarrhythmias (supraventricular tachycardia and stable monomorphic ventricular tachycardia). Implementation of hemodynamic sensing can improve arrhythmia specificity of the sensing algorithm of future implantable defibrillators and may add options for selective pace termination or cardioversion