TIMING AND VELOCITY OF EJECTION AS MAJOR DETERMINANTS OF END-SYSTOLIC PRESSURE IN ISOLATED RABBIT HEARTS

Article

关键词: CANINE LEFT-VENTRICLE;    CLOSED-CHEST DOGS;    CONDUCTANCE VOLUME CATHETER;    CONSCIOUS DOGS;    CONTRACTILE STATE;    DIASTOLIC VOLUME;    STROKE VOLUME;    PRELOAD;    CURVILINEARITY;    RELAXATION;   

DOI  :  10.1161/01.CIR.90.6.3055

来源: SCIE

【 摘 要 】

Background Systolic shortening is known to produce muscle deactivation. The present study was designed to analyze whether the velocity and the timing of ejection play a role on end-systolic pressure-volume relations (ESPVR). Methods and Results In isolated rabbit hearts, left ventricular pressure and volume were recorded and digitized, and left ventricular volume was controlled by a servosystem (4-milli-second cycles) to alter the timing of ejection. A significant deficit in end-systolic pressure was observed when ejection was late in systole with respect to earlier ejection. This was associated with a significantly reduced end-systolic elastance. End-systolic pressure of beats with slow ejection was intermediate between that of the beats with early ejection and that of beats with late ejection with a significantly increased end-systolic volume compared with beats with early rapid ejection. The same results were obtained with hypertrophied hearts (abdominal aortic stenosis). Pressure-volume loop areas were significantly increased in beats with slow ejections and with rapid delayed ejections versus early rapid ejections. No change in the positive peak of dP/dt was observed when the timing and the velocity of ejection were modified. Conclusions ESPVR is modified by the ejection profile, with a decreased end-systolic pressure and an increased pressure-volume loop area related to the velocity and the amount of shortening during the end-systolic phase. These indices of ventricular function thus must be used with caution when the timing of ejection is altered, and the end-diastolic volume-peak dP/dt relation may be a better index of ventricular function.

【 授权许可】

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