| Abstrakt: |
To explore the mechanisms of change of left ventricular diastolic filling associated with preload and afterload reduction, the influence of nitroprusside on the transmitral flow velocity pattern, pulmonary capillary wedge pressure and left ventricular pressure interaction was studied in 11 patients with end-stage heart failure. Pulsed Doppler echocardiographic recordings of mitral inflow were obtained with simultaneous high fidelity left ventricular and phase-corrected pulmonary capillary wedge pressure recordings before and during levels of nitroprusside infusion. With nitroprusside, left ventricular systolic and end-diastolic pressures decreased by 14% and 41% (p < 0.05, p < 0.05), respectively, and cardiac output increased by 67% (p < 0.05). The pulmonary cspillary wedge-left ventricular crossover pressure decreased by 41% (p < 0.05), but the time constant of isovolumetric left ventricular pressure decrease T was insignificantly changed. Isovolumetric relaxation time and acceleration and deceleration times of the early diastolic filling wave were significantly prolonged with nitroprusside infusion (p < 0.05, p < 0.05 and p < 0.85, respectively). Peak early diastolic filling velocity was maintained (65 ± 11 to 62 ± 13 cm/s, p = NS) in spite of the decreased absolute crossover pressure. Changes in peak early diastolic filling velocity correlated weakly with changes in the crossover pressure (r = 0.48, p < 0.05) and correlated better with the crossover to left ventricular minimal pressure difference (r = 0.78, p < 0.05). Peak early diastolic filling velocity appears to be most affected by the early diastolic pulmonary capillary wedge to left ventricular pressure difference rather than the absolute pulmonary capillary wedge pressure. |
