CONTRIBUTION OF CHAMBER COMPLIANCE AND LEFT-VENTRICULAR MINIMUM PRESSURE TO ABNORMAL LEFT-VENTRICULAR FILLING DYNAMICS

This study was designed to clarify whether changes in transmitral flow velocity patterns in left ventricular (LV) dysfunction are determined primarily by changes in left atrial (LA) pressure and LV relaxation, and, if not, to determine the contribution of changes in other paramet ers. Two levels of acute LV dysfunction were produced in 11 dogs by co ronary microembolization, and pulsed Doppler transmitral now velocity patterns and hemodynamic parameters were recorded. The mean ratio of p eak early diastolic filling velocity (E) to peak late diastolic fillin g velocity decreased with mild LV dysfunction (LV end-diastolic pressu re of between 12 and 17 mmHg), and redistribution of diastolic filling to early diastole was observed with severe LV dysfunction (LV end-dia stolic pressure of greater than or equal to 18 mmHg). Changes in E cor related best with those in the LA-LV pressure gradient integral. Multi ple linear regression analysis of the changes in possible determinants of the pressure gradient integral, i.e., LA to LV crossover pressure, LV time constant, LV minimum pressure, and LA and LV chamber complian ce, yielded a highly significant correlation with the changes in E. Ho wever, analysis of only the changes in the crossover pressure and the time constant showed a very poor correlation. Thus, changes in chamber compliance and LV minimum pressure, in addition to the changes in LA pressure and LV relaxation, may significantly affect the changes in E that are associated with LV dysfunction.