Department of Bioengineering, University of Strathclyde, Glasgow, UK.
Eur J Cardiothorac Surg. 2013 Oct;44(4):664-72. doi: 10.1093/ejcts/ezt096. Epub 2013 Mar 13.
Hybrid palliation for hypoplastic left heart syndrome (HLHS) is associated with mortality and late ventricular dysfunction. Increased ventricular workload and coronary perfusion limitation may be the important factors. Using mathematical modelling, this study investigated the effects of differing hybrid configurations on the demands on this single ventricle circulation.
A multicompartmental Windkessel model of hybrid HLH-aortic atresia circulation was adopted, with a time-varying elastance representing ventricular functionality. The effects of diameter increases in bilateral pulmonary artery bandings (PABs) (+0.5, 2.5-4 mm) and ductal stent (+1, 4-10 mm) on cardiovascular haemodynamics, systemic oxygenation and ventricular energetics were assessed.
Simulations showed that an increase in PAB diameter of 2.5-4 mm resulted in an increased Q (0.61-2.66), and diastolic stent backflow (-0.2 to -0.78 l/min) with reduced systemic perfusion (0.82-0.77 l/min) and diastolic pressures (48.3-41.2 mmHg). Arterial and venous saturations increased, SaO2 (%) was 62-88 and SvO(2) 41-65. To maintain mean systemic pressures, substantial increases in cardiac output (1.3-2.8 l/min) and ventricular stroke work (576-1360 mmHg ml) were required. A decrease in the ductal stent diameter over the range 10-7 mm had a negligible haemodynamic effect: reduced systemic systolic pressure (77-72 mmHg) and increase in ventricular stroke work (781-790 mmHg ml). When the ductal diameter was restricted to <7 mm, it resulted in a significant reduced systemic flow and increased stroke work. Optimal hybrid configuration was defined at PAB 3 mm and ductal stent ≥7 mm.
In this model, increasing the PAB diameter, or a stent diameter <7 mm, substantially increased single ventricle workload and reduced systemic perfusion and diastolic pressure. This may compromise myocardial oxygen demand-supply, particularly in the setting of retrograde-dependent coronary perfusion.
左心发育不全综合征（HLHS）的杂交姑息治疗与死亡率和晚期心室功能障碍有关。增加心室工作量和冠状动脉灌注限制可能是重要因素。本研究使用数学模型，研究了不同杂交构型对这种单心室循环需求的影响。
采用 HLH 主动脉狭窄杂交循环的多腔室风箱模型，采用时变顺应性代表心室功能。评估双侧肺动脉环缩带（PAB）直径增加（+0.5、2.5-4mm）和导管支架（+1、4-10mm）对心血管血液动力学、全身氧合和心室能量的影响。
模拟结果表明，PAB 直径增加 2.5-4mm 会导致 Q 增加（0.61-2.66），舒张期支架反流（-0.2 至-0.78l/min），全身灌注减少（0.82-0.77l/min），舒张压降低（48.3-41.2mmHg）。动脉和静脉饱和度增加，SaO2（%）为 62-88，SvO2 为 41-65。为了维持平均全身血压，需要大量增加心输出量（1.3-2.8l/min）和心室每搏功（576-1360mmHgml）。导管支架直径在 10-7mm 范围内减小几乎没有血液动力学影响：全身收缩压降低（77-72mmHg）和心室每搏功增加（781-790mmHgml）。当导管直径限制在<7mm 时，会导致全身流量显著减少和每搏功增加。最佳杂交构型定义为 PAB 3mm 和导管支架≥7mm。
在该模型中，增加 PAB 直径或支架直径<7mm 会显著增加单心室工作量，并降低全身灌注和舒张压。这可能会损害心肌氧供需平衡，尤其是在逆行依赖冠状动脉灌注的情况下。
