The significance of early changes of positive and negative dp/dt following contrast ventriculography
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The contrast agents used for cardiac angiography have pharmacologic effects on the myocardium and on peripheral and coronary circulations. These effects are a stress to the left ventricle. We have studied the sequential changes in heart rate, LVEDP, positive and negative dP/dt in 34 patients following left ventriculography. These patients were divided into three groups: nine normal patients, 14 patients with valvular or coronary artery disease and abnormal left ventricular function at rest, and 11 patients with significant coronary artery stenosis but normal left ventricular function at rest. Changes in dP/dt most clearly defined the normal and abnormal response. In the normal group the mean positive dP/dt rose abruptly at 30 sec after the ventriculogram, whereas the abnormal group showed a mean decrease. The extent of change varied, however, for patients within each group. Negative dP/dt decreased in both groups but more so in the abnormal group. As did the other groups, patients with coronary artery disease but with normal ventricular function showed individual variation in response. Their mean changes in positive and negative dP/dt were intermediate. Positive dP/dt decreased at 30 sec (similar to, but less than, the group with abnormal ventricular function) and negative dP/dt also diminished at 30 sec with a mean value between the normal and abnormal groups. The results of this study support the concept that left ventricular dysfunction may be elicited by the stress of contrast injection. More importantly, such dysfunction seen both with abnormal and normal left ventricles at rest, may be reflected by the relatively simple measurement of positive dP/dt after ventriculography.