NHC Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Department of Cardiology, Peking University Third Hospital, Beijing, China.
School of Biomedical Engineering, Capital Medical University, Beijing, China.
PLoS One. 2020 Mar 19;15(3):e0230144. doi: 10.1371/journal.pone.0230144. eCollection 2020.
Enhanced External Counterpulsation (EECP) can chronically relieve ischemic chest pain and improve the prognosis of coronary heart disease (CHD). Despite its role in mitigating heart complications, EECP and the mechanisms behind its therapeutic nature, such as its effects on blood flow hemodynamics, are still not fully understood. This study aims to elucidate the effect of EECP on significant hemodynamic parameters in the coronary arterial tree.
A finite volume method was used in conjunction with the inlet pressure wave (surrogated by the measured aortic pressure) before and during EECP and outlet flow resistance, assuming the blood as newtonian fluid. The time-average wall shear stress (TAWSS) and oscillatory shear index (OSI) were determined from the flow field.
Regardless of the degree of vascular stenosis, hemodynamic conditions and flow patterns could be improved during EECP. In comparison with the original tree, the tree with a severe stenosis (75% area stenosis) demonstrated more significant improvement in hemodynamic conditions and flow patterns during EECP, with surface area ratio of TAWSS risk area (SAR-TAWSS) reduced from 12.3% to 6.7% (vs. SAR-TAWSS reduced from 7.2% to 5.6% in the original tree) and surface area ratio of OSI risk area (SAR-OSI) reduced from 6.8% to 2.5% (vs. SAR-OSI of both 0% before and during EECP in the original tree because of mild stenosis). Moreover, it was also shown that small ratio of diastolic pressure (D) and systolic pressure (S) (D/S) could only improve the hemodynamic condition mildly. The SAR-TAWSS reduction ratio significantly increased as D/S became larger.
A key finding of the study was that the improvement of hemodynamic conditions along the LMCA trees during EECP became more significant with the increase of D/S and the severity degree of stenoses at the bifurcation site. These findings have important implications on EECP as adjuvant therapy before or after percutaneous coronary intervention (PCI) in patients with diffuse atherosclerosis.
增强型体外反搏（EECP）可长期缓解缺血性胸痛并改善冠心病（CHD）的预后。尽管 EECP 在减轻心脏并发症方面发挥了作用，但 EECP 及其治疗性质的机制（例如对血流动力学的影响）仍未得到充分理解。本研究旨在阐明 EECP 对冠状动脉树中重要血流动力学参数的影响。
使用有限体积法，结合 EECP 前后的入口压力波（由测量的主动脉压力代替）和出口流量阻力，假设血液为牛顿流体。从流场中确定平均壁切应力（TAWSS）和振荡剪切指数（OSI）。
无论血管狭窄程度如何，在 EECP 期间都可以改善血流动力学条件和血流模式。与原始树相比，严重狭窄（75%面积狭窄）的树在 EECP 期间显示出更显著的血流动力学条件和血流模式改善，其 TAWSS 风险区域表面积比（SAR-TAWSS）从 12.3%降低到 6.7%（与原始树中从 7.2%降低到 5.6%相比），OSI 风险区域表面积比（SAR-OSI）从 6.8%降低到 2.5%（与原始树中由于轻度狭窄，在 EECP 前后 SAR-OSI 均为 0%相比）。此外，还表明，舒张压（D）与收缩压（S）的小比值（D/S）只能轻度改善血流动力学条件。随着 D/S 的增大，SAR-TAWSS 降低率显著增加。
本研究的一个重要发现是，随着 D/S 的增加和分叉处狭窄程度的增加，EECP 期间 LMCA 树的血流动力学条件改善变得更加显著。这些发现对 EECP 作为弥漫性动脉粥样硬化患者经皮冠状动脉介入治疗（PCI）前后的辅助治疗具有重要意义。
