We have developed a new, relatively noninvasive-method of quantitatively studying the heart which provides measures of left- ventricular (LV) end-diastolic volume, end-systolic volume, ejection fraction (EF), stroke volume (SV), and cardiac output (CO). Our studies in dogs comparing ultrasonic determinations by this method to those made using conventional radionuclide and thermal dilution techniques have been found to be in close agreement. This agreement is equivalent to results found when other commonly used clinical methods are compared. Furthermore, with little change in protocol and development of some additional processing algorithms several other cardiac measures can be made. Our major purpose of the proposed research is to investigate these additional measures. First, we will study the assessment of cardiac function by using end-diastolic and end-systolic volumes and pressures, taken under different conditions of preload and afterload. The relationships between these variables at end- diastole will give compliance, a measure of cardiac diastolic performance, while regression analysis of the pressure-volume curve at end-systole provides for measuring contractility. These measures should be useful to study the deleterious effects of anesthetics on the heart and the benefitical effects of inotropes and other drugs used during surgery. Next, we plan to utilize the 3-D information we acquire of LV borders by our method, to investigate regional measures of cardiac function. We propose to calculate and display regional EF and regional wall motion, not just of a single plane, but of the entire LV wall. We will study these new measures in an acute animal model of myocardial ischemia and in two surgical human populations: a group with normal hearts and a group with documented persistent regional wall motion abnormalities. The results of the study will determine whether the methodology is suitable for clinical investigation and ultimately if incorporated into real time analysis would it be useful in patient management.
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