ACUTE ALTERATIONS OF SYSTOLIC AND DIASTOLIC FUNCTION IN RESPONSE TO ACUTE GLOBAL LEFT-VENTRICULAR DYSFUNCTION

Well-defined abnormalities of left ventricular (LV) systolic and diastolic function have been noted during coronary ischemia. Though diastolic filling has been demonstrated to be redistributed to early in diastole in severe LV dysfunction, characterization of the time course and extent of systolic emptying and diastolic filling has received little attention. Utilizing a model of acute ischemic LV dysfunction induced by coronary artery microsphere embolization, we studied 10 anesthetized closed-chest canines who received coronary artery microsphere embolization until their LV end-diastolic pressure was greater-than-or-equal-to 15 mm Hg. Coronary embolization resulted in LV dilatation and systolic dysfunction. Total LV systolic time was prolonged due to an increase in both the pre-ejection period and LV ejection time. Parameters of relaxation and compliance became markedly abnormal. The onset of diastolic filling was delayed and length of the diastolic filling period was shortened (baseline 382 +/- 114 ms vs. congestive heart failure 207 +/- 107 ms, p < 0.001). Diastolic filling was redistributed to the rapid filling period as characterized by an increased rapid filling fraction (baseline 61.5 +/- 16.8% vs. congestive heart failure 76.5 +/- 4.3%, p < 0.05) and a decreased atrial filling fraction and was associated with an increased mean right atrial pressure, an estimate of intrapericardial pressure. Acute ischemic global dysfunction results in alterations in the time course of both systole and diastole, the extent of ejection, and the pattern of diastolic filling.