Latham R D, Rubal B J, Sipkema P, Westerhof N, Virmani R, Robinowitz M, Walsh R A
Department of Medicine, Brooke Army Medical Center, Fort Sam Houston, Texas 78234-6200.
Circ Res. 1988 Oct;63(4):798-811. doi: 10.1161/01.res.63.4.798.
Ventricular/vascular coupling dynamics and regional hemodynamics of five hypertensive baboons with concentric left ventricular (LV) hypertrophy (mean arterial pressure +/- SD, 148 +/- 16 mm Hg; LV mass/body weight ratio 3.42 +/- 0.8) were compared with five normotensive controls (mean arterial pressure 89 +/- 3 mm Hg; LV mass/body wt ratio 2.73 +/- 0.5) at different mean arterial pressures. Ventricular/vascular dynamics were assessed by aortic input impedance, pulsatile/total power ratio, effective arterial elastance and compliance from a three-element Windkessel "lumped" model of the circulation. Regional arterial dynamics were assessed by pulse-wave velocities and local reflection coefficients. Systemic arterial compliance was similarly decreased with elevated pressure in both groups but was significantly more reduced for the hypertensive group compared with control animals at control (0.49 +/- 0.16 vs. 0.96 +/- 0.09 ml/mm Hg; p less than 0.05) and acutely lowered arterial pressure (0.62 +/- 0.26 vs. 1.41 +/- 0.24 ml/mm Hg, respectively). Changes in compliance were paralleled by differences in effective arterial elastance derived from cineventriculographic pressure-volume ratios. Regional foot-foot and apparent phase pulse-wave velocities were significantly increased for distal aortic segments of the hypertensive animals during elevated pressures compared with controls (cff, 17.5 +/- 7.5 vs. 8.7 +/- 3.0 m/sec; p less than 0.05). Histology of the aorta revealed significant increases in collagen content (microgram/mg dry wt) from proximal to distal aortic segments (27 +/- 2 vs. 38 +/- 6; p less than 0.005) in hypertensive animals but not in controls (27 +/- 2 vs. 32 +/- 6; NS). With pharmacological normalization of systemic arterial pressures, hypertensive baboons developed aortic wave speeds similar to controls but manifested significantly reduced compliance compared with controls. In contrast, with acute elevations of pressure, systemic arterial aortic compliances were similar for both groups, but distal pulse-wave velocities were significantly increased for hypertensive animals compared with controls. We conclude that measures of ventricular/vascular coupling and arterial dynamics are determined by both the level of arterial pressure and the physical characteristics of the cardiovascular system in chronic systemic hypertension and pressure overload ventricular hypertrophy.
在不同平均动脉压水平下，将5只患有同心性左心室（LV）肥厚的高血压狒狒（平均动脉压±标准差，148±16 mmHg；LV质量/体重比3.42±0.8）的心室/血管耦合动力学和局部血流动力学与5只血压正常的对照动物（平均动脉压89±3 mmHg；LV质量/体重比2.73±0.5）进行了比较。通过主动脉输入阻抗、脉动/总功率比、有效动脉弹性和基于循环的三元风箱“集总”模型的顺应性来评估心室/血管动力学。通过脉搏波速度和局部反射系数评估局部动脉动力学。两组中，系统性动脉顺应性均随压力升高而同样降低，但与对照动物相比，高血压组在对照（0.49±0.16 vs. 0.96±0.09 ml/mmHg；p<0.05）和急性降低动脉压（分别为0.62±0.26 vs. 1.41±0.24 ml/mmHg）时显著降低得更多。顺应性的变化与通过心室造影压力-容积比得出的有效动脉弹性差异平行。与对照组相比，高血压动物在压力升高时，远端主动脉段的局部足-足和表观相脉搏波速度显著增加（cff，17.5±7.5 vs. 8.7±3.0 m/sec；p<0.05）。主动脉组织学显示，高血压动物从主动脉近端到远端段的胶原蛋白含量（微克/毫克干重）显著增加（27±2 vs. 38±6；p<0.005），而对照动物未增加（27±2 vs. 32±6；无显著性差异）。随着系统性动脉压的药物性正常化，高血压狒狒的主动脉波速发展为与对照组相似，但与对照组相比，顺应性显著降低。相反，在急性压力升高时，两组的系统性动脉主动脉顺应性相似，但与对照组相比，高血压动物的远端脉搏波速度显著增加。我们得出结论，在慢性系统性高血压和压力超负荷心室肥厚中，心室/血管耦合和动脉动力学的测量值由动脉压水平和心血管系统的物理特性共同决定。
