A study of the effect on myocardial contractility of various pacemaker implantation sites suggests that the choice of a site can affect cardiac function.
A group of investigators at the State University of New York, Downstate Medical Center, New York City, undertook the study in dogs after a previous investigation of the relationship between cardiac output and pacemaker site produced findings which were at variance with the reports of other workers.
This previous study had indicated that the most effective site for pacemaker implantation in terms of cardiac output was the epicardial surface of the left ventricle at the apex anteriorly.
In the current study, dogs with experimental complete heart block were placed on cardiopulmonary bypass and the effect of pacemaker site on contractility studied with the left ventricle maintained at a given known volume load. This was achieved by placing a fluid-filled balloon in the ventricle.
This preparation obviated