Kolh P, D'Orio V, Lambermont B, Gerard P, Gommes C, Limet R
Haemodynamic Research Center, University of Liège, Belgium.
Eur J Cardiothorac Surg. 2000 Mar;17(3):272-8. doi: 10.1016/s1010-7940(00)00341-9.
The aim of this study was to investigate left ventricular contractility and energetic cost of cardiac ejection under conditions of acute increase in aortic compliance.
In six anaesthetized pigs, ascending aortic compliance was increased by adding a volume chamber in parallel to the ascending aorta. Systemic vascular parameters, including characteristic impedance, peripheral resistance, total vascular compliance, and inertance, were estimated with a four-element windkessel model. Arterial elastance was derived from these parameters. Left ventricular systolic function was assessed by end-systolic pressure-volume relationship (end-systolic elastance), and stroke work. Pressure-volume area was used as a measure of myocardial oxygen consumption. Heart rate remained constant during the experimentation.
Adding the aortic volume chamber significantly increased vascular compliance from 0. 95+/-0.08 to 1.17+/-0.06 ml/mmHg (P<0.01), while inductance, characteristic impedance, peripheral resistance, and arterial elastance remained statistically at basal values, respectively 0. 0020+/-0.0003 mmHg.s(2)/ml, 0.105+/-0.009 mmHg.s/ml, 1.27+/-0.12 mmHg.s/ml, and 2.43+/-0.21 mmHg/ml. During the same interval, stroke work and pressure-volume area decreased respectively from 2700+/-242 to 2256+/-75 mmHg.ml (P<0.01), and from 3806+/-427 to 3179+/-167 mmHg.ml (P<0.01). Stroke work and pressure-volume area decreased at matched end-diastolic volumes. In contrast, end-systolic elastance, ejection fraction, and stroke volume remained statistically unchanged, respectively at 2.29+/-0.14 mmHg/ml, 48.1+/-2.1 %, and 32. 4+/-1.7 ml.
These data suggest that, when facing an increased aortic compliance, the left ventricle displays unchanged contractility, but the energetic cost of cardiac ejection is significantly decreased. These data may be of clinical importance when choosing an artificial prosthesis for ascending aortic replacement.
本研究旨在探讨主动脉顺应性急性增加情况下左心室收缩性及心脏射血的能量消耗。
在六只麻醉猪中，通过在升主动脉旁并联一个容积腔来增加升主动脉顺应性。用四元件风箱模型估算包括特性阻抗、外周阻力、总血管顺应性和惯性在内的全身血管参数。从这些参数推导出动脉弹性。通过收缩末期压力-容积关系（收缩末期弹性）和每搏功评估左心室收缩功能。压力-容积面积用作心肌氧消耗的指标。实验过程中心率保持恒定。
添加主动脉容积腔使血管顺应性从0.95±0.08显著增加至1.17±0.06 ml/mmHg（P<0.01），而电感、特性阻抗、外周阻力和动脉弹性分别在统计学上保持在基础值，分别为0.0020±0.0003 mmHg·s²/ml、0.105±0.009 mmHg·s/ml、1.27±0.12 mmHg·s/ml和2.43±0.21 mmHg/ml。在同一时间段内，每搏功和压力-容积面积分别从2700±242降至2256±75 mmHg·ml（P<0.01），以及从3806±427降至3179±167 mmHg·ml（P<0.01）。在匹配的舒张末期容积下，每搏功和压力-容积面积降低。相比之下，收缩末期弹性、射血分数和每搏量分别在统计学上保持不变，分别为2.29±0.14 mmHg/ml、48.1±2.1%和32.4±1.7 ml。
这些数据表明，当面对主动脉顺应性增加时，左心室收缩性不变，但心脏射血的能量消耗显著降低。这些数据在选择升主动脉置换的人工假体时可能具有临床重要性。
