Cheng C P, Noda T, Nozawa T, Little W C
Section of Cardiology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157-1045.
Circ Res. 1993 Apr;72(4):795-806. doi: 10.1161/01.res.72.4.795.
The exercise response of left ventricular (LV) filling dynamics may be altered by congestive heart failure (CHF). Accordingly, we studied 18 conscious dogs, instrumented to measure micromanometer LV and left atrial (LA) pressures and determine LV volume from three dimensions. CHF was produced by 4-5 weeks of right ventricular rapid pacing. Before CHF, exercise (5.5-8.5 mph for 8-15 minutes) increased the maximum rate of LV filling (dV/dtmax) (197 +/- 37 versus 297 +/- 56 ml/sec [mean +/- SD], p < 0.05) in response to an increase in the maximum early diastolic LA to LV pressure gradient (5.8 +/- 2.0 versus 9.8 +/- 1.9 mm Hg, p < 0.05) produced by a fall in minimum LV pressure (1.0 +/- 2.9 versus -3.9 +/- 3.1 mm Hg, p < 0.01), whereas mean LA pressure was unchanged (6.4 +/- 3.1 versus 6.4 +/- 4.2 mm Hg, p = NS). The time constant of LV relaxation was shortened (28.1 +/- 3.2 versus 21.0 +/- 4.2 msec, p < 0.05). After CHF, dV/dtmax (141 +/- 51 versus 200 +/- 59 ml/sec, p < 0.05) and the maximum LA to LV pressure gradient (6.0 +/- 1.1 versus 11.1 +/- 2.7 mm Hg, p < 0.05) continued to increase with exercise (3-5.0 mph for 4-8 minutes). However, the time constant of LV relaxation was prolonged (35.6 +/- 4.8 versus 38.9 +/- 5.5 msec, p < 0.05), and minimum LV pressure (15.1 +/- 5.6 versus 17.6 +/- 5.9 mm Hg, p < 0.05) and mean LA pressure increased (22.6 +/- 7.2 versus 29.1 +/- 7.3 mm Hg, p < 0.05). These altered effects of exercise on LV diastolic filling dynamics persisted when heart rate and wall stress during exercise before and after CHF were matched by varying the level of exercise. We conclude that, during normal exercise, mitral valve flow is augmented by a fall of early diastolic LV pressure without a rise in LA pressure. After CHF, early diastolic LV pressure does not fall but increases during exercise. Thus, the increase in the early diastolic LA to LV pressure gradient and the rate of mitral valve flow results from an increase in LA pressure during exercise after CHF. This study suggests that the failure of the enhancement of LV relaxation and an increase in early diastolic LV pressure with exercise after CHF may contribute to exercise intolerance in CHF.
充血性心力衰竭（CHF）可能会改变左心室（LV）充盈动力学的运动反应。因此，我们研究了18只清醒犬，通过仪器测量微压计LV和左心房（LA）压力，并从三个维度确定LV容积。通过右心室快速起搏4 - 5周产生CHF。在CHF发生前，运动（5.5 - 8.5英里/小时，持续8 - 15分钟）会使LV最大充盈率（dV/dtmax）增加（197±37对比297±56毫升/秒[平均值±标准差]，p<0.05），这是由于LV最小压力下降（1.0±2.9对比 - 3.9±3.1毫米汞柱，p<0.01）导致最大舒张早期LA与LV压力梯度增加（5.8±2.0对比9.8±1.9毫米汞柱，p<0.05），而平均LA压力未改变（6.4±3.1对比6.4±4.2毫米汞柱，p =无显著性差异）。LV舒张时间常数缩短（28.1±3.2对比21.0±4.2毫秒，p<0.05）。在CHF发生后，dV/dtmax（141±51对比200±59毫升/秒，p<0.05）和最大LA与LV压力梯度（6.0±1.1对比11.1±2.7毫米汞柱，p<0.05）在运动（3 - 5.0英里/小时，持续4 - 8分钟）时仍会增加。然而，LV舒张时间常数延长（35.6±4.8对比38.9±5.5毫秒，p<0.05），LV最小压力（15.1±5.6对比17.6±5.9毫米汞柱，p<0.05）和平均LA压力增加（22.6±7.2对比
