Tang Elaine, Wei Zhenglun Alan, Whitehead Kevin K, Khiabani Reza H, Restrepo Maria, Mirabella Lucia, Bethel James, Paridon Stephen M, Marino Bradley S, Fogel Mark A, Yoganathan Ajit P
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Emory University, Atlanta, Georgia, USA.
Heart. 2017 Nov;103(22):1806-1812. doi: 10.1136/heartjnl-2016-310855. Epub 2017 May 18.
Exercise intolerance afflicts Fontan patients with total cavopulmonary connections (TCPCs) causing a reduction in quality of life. Optimising TCPC design is hypothesised to have a beneficial effect on exercise capacity. This study investigates relationships between TCPC geometries and exercise haemodynamics and performance.
This study included 47 patients who completed metabolic exercise stress test with cardiac magnetic resonance (CMR). Phase-contrast CMR images were acquired immediately following supine lower limb exercise. Both anatomies and exercise vessel flow rates at ventilatory anaerobic threshold (VAT) were extracted. The vascular modelling toolkits were used to analyse TCPC geometries. Computational simulations were performed to quantify TCPC indexed power loss (iPL) at VAT.
A highly significant inverse correlation was found between the TCPC diameter index, which factors in the narrowing of TCPC vessels, with iPL at VAT (r=-0.723, p<0.001) but positive correlations with exercise performance variables, including minute oxygen consumption (VO) at VAT (r=0.373, p=0.01), VO at peak exercise (r=0.485, p=0.001) and work at VAT/weight (r=0.368, p=0.01). iPL at VAT was negatively correlated with VO at VAT (r=-0.337, p=0.02), VO at peak exercise (r=-0.394, p=0.007) and work at VAT/weight (r=-0.208, p=0.17).
Eliminating vessel narrowing in TCPCs and reducing elevated iPL at VAT could enhance exercise tolerance for patients with TCPCs. These findings could help plan surgical or catheter-based strategies to improve patients' exercise capacity.
运动不耐受困扰着接受全腔静脉肺动脉连接术（TCPC）的患者，导致生活质量下降。据推测，优化TCPC设计对运动能力有有益影响。本研究调查了TCPC几何结构与运动血流动力学及运动表现之间的关系。
本研究纳入了47例完成心脏磁共振（CMR）代谢运动应激试验的患者。在仰卧位下肢运动后立即采集相位对比CMR图像。提取通气无氧阈（VAT）时的解剖结构和运动血管流速。使用血管建模工具包分析TCPC几何结构。进行计算模拟以量化VAT时TCPC的指数功率损失（iPL）。
在考虑TCPC血管狭窄因素的TCPC直径指数与VAT时的iPL之间发现高度显著的负相关（r = -0.723，p < 0.001），但与运动表现变量呈正相关，包括VAT时的每分钟耗氧量（VO）（r = 0.373，p = 0.01）、运动峰值时的VO（r = 0.485，p = 0.001）以及VAT时的功/体重（r = 0.368，p = 0.01）。VAT时的iPL与VAT时的VO（r = -0.337，p = 0.02）、运动峰值时的VO（r = -0.394，p = 0.007）以及VAT时的功/体重（r = -0.208，p = 0.17）呈负相关。
消除TCPC中的血管狭窄并降低VAT时升高的iPL可提高TCPC患者的运动耐力。这些发现有助于规划手术或基于导管的策略以改善患者的运动能力。
