Correlation between a Mid-ventricular Volume Segment and Global Left Ventricular Volume Measured by the Conductance Catheter

Abstract

Objectives - To investigate whether acute volume changes in single volume segments of the left ventricle can be correlated with global volume changes. If so, changes in global volume might be predicted from changes in segmental volumes. Design - Volume changes were recorded in six pigs in five intraventricular segments, from apex to heart base, using the conductance catheter (at baseline, after 60 min of apical ischaemia, during preload reduction and afterload increase). A computer algorithm was created to calculate the instantaneous absolute difference between the curve shape of global and normalized segmental volume as a percentage of global stroke volume. Results - For a mid-cardiac volume segment constituting 34 (14-39)% [median (range)] of global stroke volume, the mean difference over a cardiac cycle was 4 (1-8)% at baseline. Apical ischaemia resulted in apical dyskinesia, but did not influence the mid-cardiac segment. Conclusions - The volume curve from a segment at mid-cardiac level seems to be a good estimator of the global volume curve, thus giving a foundation for estimation of global volume changes from such a segment.