Atrial and ventricular force of contraction influenced by intracoronary injections

¹ Department of Pharmacology, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania

A technique is presented for studying direct effects of drugs on atrial and ventricular contraction in the open-chest or closed-chest preparation. Selective coronary artery catheterization was combined with the Walton strain gauge for investigating local changes in atrial and ventricular contraction. This combined technique permitted observation of cardiac effects of a drug without the occurrence of generalized circulatory effects which frequently occur during intravenous administration. In addition, an increase or decrease in myocardial contraction could be confined strictly to the area supplied by the coronary artery injected. Generally, the strain gauge on the area of the heart within the distribution of the coronary vessel injected was the only one affected by the drug, whereas strain gauges on other parts of the heart outside the area supplied by the vessel were not affected. However, when a strain gauge was placed on the same or adjacent ventricle, but outside the area supplied by the vessel, directional changes occurred in this latter strain gauge which were opposite to those in the area injected.