Amoore J N
Department of Biomedical Engineering, University of Cape Town Medical School, Republic of South Africa.
Cardiovasc Res. 1987 Jun;21(6):407-15. doi: 10.1093/cvr/21.6.407.
A mathematical model of the circulation was developed and used to study the transient variations in ventricular volumes with inspiration. The contributions of increased left ventricular afterload, ventricular interdependence, and reduced pulmonary venous flow to the initial decrease in left ventricular stroke volume were examined. Heart rate was kept constant. Right ventricular end diastolic volume increased rapidly, but transiently, with inspiration. Ventricular interdependence affected left ventricular function; it increased the magnitude of the decrease in left ventricular stroke volume, reduced the corresponding increase in end systolic volume, and appeared to be responsible for an initial decrease in end diastolic volume. Despite a 10% pooling of blood in the pulmonary circulation the decrease in pulmonary venous flow was small. It is suggested that the decrease in left ventricular stroke volume is caused both by the reduced intrathoracic pressure, which increases the afterload on the left ventricle, and by the increase in the diastolic elastance of the left ventricle caused by the increase in right ventricular volume (ventricular interdependence). The increased afterload reduces the effective ejection pressure, decreases the stroke volume, and increases the end systolic volume. The increase in left ventricular diastolic elastance, secondary to the increase in right ventricular volume, further reduces the stroke volume by increasing the left ventricular diastolic pressure at a given volume and thus decreases the end diastolic volume.
建立了一个循环系统的数学模型，并用于研究吸气时心室容积的瞬态变化。研究了左心室后负荷增加、心室相互依赖以及肺静脉血流减少对左心室搏出量初始下降的影响。心率保持恒定。右心室舒张末期容积随吸气迅速但短暂地增加。心室相互依赖影响左心室功能；它增加了左心室搏出量下降的幅度，减少了收缩末期容积相应的增加，并且似乎是舒张末期容积初始下降的原因。尽管肺循环中有10%的血液淤积，但肺静脉血流的减少很小。提示左心室搏出量的下降是由胸腔内压力降低（增加了左心室的后负荷）以及右心室容积增加（心室相互依赖）导致的左心室舒张弹性增加共同引起的。后负荷增加降低了有效射血压力，减少了搏出量，并增加了收缩末期容积。继发于右心室容积增加的左心室舒张弹性增加，通过在给定容积下增加左心室舒张压进一步减少了搏出量，从而降低了舒张末期容积。
