Myocardial and Coronary Involvement in Hemorrhagic Shock

摘要

Hemorrhagic shock is still a major therapeutic challenge for military physicians. Pathophysiologic processes involved in this disorder remains incomplete. Ischemic myocardial dysfunction might complicate hemorrhagic shock, causing reduced cardiac function and reserve even after volume replacement. Prior experimental studies of the heart in hemorrhagic hypotension have not yielded a clear and consistent concept of the extent and duration of myocardial and coronary involvement in this disorder. In part, this relates to drastic changes in cardiac loading that accompany hemorrhage. To overcome these difficulties this research protocol evaluates myocardial contractility by quantifying the relationship between end-systolic pressure and volume (ESPVR), a technique that minimizes the effects of loading conditions. Analysis of the data from these studies should result in a more complete understanding of hemorrhagic shock and may provide a rational basis for improvement in selection of therapeutic strategies. The first year of this project has been devoted to developing the instrumentation to be used, validating the ESPVR technique in this environment, and performing a study on the effects of a ten-minute period of severe hemorrhage on contractility. Both the use of ultrasound crystals sewn on the heart and conductance catheters introduced into the left ventricle through a peripheral vessel have ben explored as methods to derive the required high-fidelity left ventricular volume measures.