Relative ventricular volume measurements by intracardiac impedance

The purpose of this study was to investigate whether changes of the right ventricular end-diastolic and end-systolic volumes can be detected by the DC-coupled electrical intracardiac impedance signal. Measurements were conducted in 13 patients with an implanted or external pacemaker, testing various measurement configurations. Volume changes were induced by incremental overpacing and by postural changes. The pulse contour systolic integral from the peripheral blood pressure was used as a marker of stroke volume changes. The results show, that DC-coupled impedance can detect volume changes of the right ventricle. The quadrupolar impedance measurement configurations offer better amplitude resolution, but the tripolar and intraventricular bipolar configurations are better hemodynamic markers.