Dept. of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
Dept. Of Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
Cardiovasc Eng Technol. 2024 Feb;15(1):1-11. doi: 10.1007/s13239-023-00671-5. Epub 2023 Dec 21.
Pulmonary vascular impedance (PVZ) describes RV afterload in the frequency domain and has not been studied extensively in LVAD patients. We sought to determine (1) feasibility of calculating a composite (c)PVZ using standard of care (SoC), asynchronous, pulmonary artery pressure (PAP) and flow (PAQ) waveforms; and (2) if chronic right ventricular failure (RVF) post-LVAD implant was associated with changes in perioperative cPVZ.PAP and PAQ were obtained via SoC procedures at three landmarks: T(1), Retrospectively, pre-operative with patient conscious; and T(2) and T(3), prospectively with patient anesthetized, and either pre-sternotomy or chest open with LVAD, respectively. Additional PAP's were taken at T(4), following chest closure; and T(5), 4-24 h post chest closure. Harmonics (z) were calculated by Fast Fourier Transform (FFT) with cPVZ(z) = FFT(PAP)/FFT(PAQ). Total pulmonary resistance Z(0); characteristic impedance Zc, mean of cPVZ(2-4); and vascular stiffness PVS, sum of cPVZ(1,2), were compared at T(1,2,3) between +/-RVF groups.Out of 51 patients, nine experienced RVF. Standard hemodynamics and changes in cPVZ-derived parameters were not significant between groups at any T.In conclusion, cPVZ calculated from SoC measures is possible. Although data that could be obtained were limited it suggests no difference in RV afterload for RVF patients post-implant. If confirmed in larger studies, focus should be placed on cardiac function in these subjects.
肺血管阻抗（PVZ）在频域中描述 RV 的后负荷，在 LVAD 患者中尚未得到广泛研究。我们旨在确定：（1）使用标准护理（SoC）、异步、肺动脉压力（PAP）和流量（PAQ）波形计算复合（c）PVZ 的可行性；（2）LVAD 植入后慢性右心室衰竭（RVF）是否与围手术期 cPVZ 的变化相关。PAP 和 PAQ 通过 SoC 程序在三个标记处获得：T（1），回顾性，患者清醒时的术前；T（2）和 T（3），前瞻性，患者麻醉时，分别为胸骨切开术或开胸前和 LVAD 后。在 T（4），在胸廓关闭后，T（5），在胸廓关闭后 4-24 小时，再次进行 PAP。通过快速傅里叶变换（FFT）计算谐波（z），cPVZ（z）= FFT（PAP）/FFT（PAQ）。总肺阻力 Z（0）；特征阻抗 Zc，cPVZ（2-4）的平均值；以及血管僵硬 PVS，cPVZ（1,2）的总和，在 T（1,2,3）在 +/-RVF 组之间进行比较。在 51 名患者中，有 9 名患者发生 RVF。在任何 T 时，两组之间的标准血流动力学和 cPVZ 衍生参数的变化均无统计学意义。总之，从 SoC 测量中计算出的 cPVZ 是可能的。尽管获得的数据有限，但这表明植入后 RVF 患者的 RV 后负荷没有差异。如果在更大的研究中得到证实，应将重点放在这些患者的心脏功能上。
