Aim: The aim of this study was to examine the relation between cardiac haemodynamics and parameters extracted from the intracardiac electrogram obtained during pacing, i.e. ventricular evoked response.
Methods and results: In the course of routinely scheduled right heart catheterization, intracardiac electrograms and cardiac haemodynamics were monitored simultaneously in ten heart transplant patients (two females, aged 48 +/- 12 (18-59) years), using pacemaker telemetry and Swan-Ganz thermodilution techniques. Different haemodynamic states were induced by pacemaker programming (pacing rate changes) and table tilting (postural changes). Forty different haemodynamic states were assessed, with an average of three (2.4) haemodynamic variations in each patient. Linear regression analysis between relative stroke volume changes and relative changes in the R wave slew rate as extracted from the evoked responses revealed a strong, inverse, and highly significant correlation (r= - 0.93, P<0.0001) between those parameters. Similar results were obtained for pacing rate and postural variations alone, respectively.
Conclusions: The strong correlation between changes in stroke volume and R slew rate indicates that paced intracardiac electrograms reflect changes in the size and geometry of the heart. Telemetrically recorded intracardiac electrograms may thus be used non-invasively to assess key aspects of cardiac haemodynamics.