Figure 1.

Instrumentation of the heart. A solid-state micromanometer catheter was introduced into the right ventricle (RV) via an internal jugular vein. An array of four sonomicrometry crystals (indicated by x) was inserted into the mid-RV free wall and used to calculate wall area (see online supplement). Chord lengths used to calculate area are designated by a, b, c, d, p, and q. Ultrasonic transit-time flow probes were placed around the main pulmonary artery for the measurement of cardiac output, and around the proximal right coronary artery for the measurement of coronary artery flow. An umbilical tape snare was placed around the pulmonary artery to produce right ventricular pressure overload (RVPO), and a hydraulic occluder was placed around the inferior vena cava to alter preload. In addition to the instrumentation illustrated here, a micromanometer catheter was inserted into the left ventricle via apical puncture, pacing wires were affixed to the left atrial appendage, and a 26-gauge catheter was inserted into the proximal right coronary artery. A lead II electrocardiogram was recorded from needle electrodes placed subcutaneously in the four limbs. Ao, aorta; RA, right atrium; PA, pulmonary artery; RV, right ventricle; IVC, inferior vena cava.