Gary L. Copenhaver

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The contributions of thromboxane A2 (TXA2) and prostacyclin (PGI2) to the effects of acute pulmonary embolism were evaluated in 18 open-chest rabbits. All rabbits received autologous whole-blood-clot embolus (.4 cc) by way of a catheter in the right ventricle. Pulmonary artery (PA) and left atrial (LA) pressures, and aortic flow (AOQ) were recorded. The(More)
Past studies of the changing three-dimensional shape of the heart in the closed chest during the cardiac cycle have been restricted to the measurement of local deformations at a relatively few specific locations, and often have required surgical procedures that alter the measurements obtained. In the study reported here, high precision displacement and(More)
A new technique induces localized myocardial infarction in closed-chest dogs by placing discrete plugs in coronary arteries without using cumbersome coaxial catheters or guide wires. Flexible plugs, essential to this method, are formed by extruding a dental impression polymer, rendered radiopaque with sodium iodide, into spaghetti-like strands. Segments of(More)
A nonradioactive tracer technique for the evaluation of heart disease is presented. A microprocessor controlled scanning system is used to position a germanium detector such that it interrogates an isolated segment of myocardial tissue. Iodine based contrast agent in intravenously injected while irradiating the tissue segment with a low energy X-ray spot(More)
To determine if ischemia-induced depressed myocardial thickening can be augmented by remote coronary occlusion, posterior wall function (pulsed Doppler crystal) was measured before and after left anterior descending coronary artery occlusion in the presence of reduced circumflex coronary artery flow (of sufficient severity to reduce resting function) in an(More)
To assess the effect of diltiazem on left ventricular systolic regional wall motion and diastolic function in patients with coronary artery disease (CAD), 22 patients underwent biplane left ventricular cineangiography before and after intravenous diltiazem (plasma concentration 154 +/- 12 ng/ml). Left ventricular and right ventricular pressures were(More)
RATIONALE AND OBJECTIVES Because of the complex relationships between the dynamic three-dimensional cardiac surface shape and its projected image, errors arise with the use of two-dimensional silhouettes to measure displacements of the heart. The character and frequency of such errors are examined. METHODS A high-precision x-ray scatter imaging technique(More)
Many reports note expansive events occurring in the left ventricle during isovolumic relaxation. Expansions during isovolumic relaxation require compensatory inward displacements elsewhere in the ventricle. The location and character of such compensatory displacements have been a continuing source of speculation. Using a high-precision Compton backscatter(More)
A Compton X-ray backscatter imaging (CBI) system using a single detector and a mechanically rastered "flying spot" X-ray beam has been designed, built, and tested. While retaining the essential noninvasive imaging capability of previous multiple detector CBI devices, this single detector system incorporates several advances over earlier CBI devices: more(More)
A new technique for the simultaneous measurement of left ventricular epicardial and endocardial wall dynamics is presented. X-rays scattered from the surface of the heart are used to monitor motion at the epicardial surface and iodine fluorescence induced in the blood pool is used to monitor motion of the endocardium. Continuous wall thickness measurements(More)