Institute of Cardiovascular Science, University College London, London, UK.
Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
Ann Biomed Eng. 2019 May;47(5):1291-1299. doi: 10.1007/s10439-019-02221-4. Epub 2019 Feb 12.
Mechanical alternans (MA) is a powerful predictor of adverse prognosis in patients with heart failure and cardiomyopathy, but its use remains limited due to the need of invasive continuous arterial pressure recordings. This study aims to assess novel cardiovascular correlates of MA in the intact human heart to facilitate affordable and non-invasive detection of MA and advance our understanding of the underlying pathophysiology. Arterial pressure, respiration, and ECG were recorded in 12 subjects with healthy ventricles during voluntarily controlled breathing at different respiratory rate, before and after administration of beta-blockers. MA was induced by ventricular pacing. A total of 67 recordings lasting approximately 90 s each were analyzed. Mechanical alternans (MA) was measured in the systolic blood pressure. We studied cardiovascular correlates of MA, including maximum pressure rise during systole (dPdt), pulse arrival time (PAT), pulse wave interval (PI), RR interval (RRI), ECG QRS complexes and T-waves. MA was detected in 30% of the analyzed recordings. Beta-blockade significantly reduced MA prevalence (from 50 to 11%, p < 0.05). Binary classification showed that MA was detected by alternans in dPdt (100% sens, 96% spec), PAT (100% sens, 81% spec) and PI (80% sens, 81% spec). Alternans in PAT and in PI also showed high degree of temporal synchronization with MA (80 ± 33 and 73 ± 40%, respectively). These data suggest that cardiac contractility is a primary factor in the establishment of MA. Our findings show that MA was highly correlated with invasive measurements of PAT and PI. Since PAT and PI can be estimated using non-invasive technologies, these markers could potentially enable affordable MA detection for risk-prediction.
机械性交替（MA）是心力衰竭和心肌病患者不良预后的有力预测指标，但由于需要进行有创性连续动脉压力记录，其应用仍然受到限制。本研究旨在评估 MA 在完整人心中的新型心血管相关性，以促进 MA 的经济实惠和非侵入性检测，并深入了解潜在的病理生理学。在 12 名心室健康的受试者中，在自愿控制呼吸时，在不同呼吸频率下，在给予β受体阻滞剂前后，记录动脉压、呼吸和心电图。通过心室起搏诱导 MA。共分析了大约 90 秒的 67 个记录。在收缩压中测量机械性交替（MA）。我们研究了 MA 的心血管相关性，包括收缩期最大压力上升（dPdt）、脉搏到达时间（PAT）、脉搏波间隔（PI）、RR 间隔（RRI）、心电图 QRS 复合物和 T 波。在分析的记录中，有 30%检测到 MA。β受体阻滞剂显著降低了 MA 的发生率（从 50%降至 11%，p<0.05）。二分类显示，MA 通过 dPdt（100%灵敏度，96%特异性）、PAT（100%灵敏度，81%特异性）和 PI（80%灵敏度，81%特异性）的交替检测到。PAT 和 PI 中的交替也与 MA 具有高度的时间同步性（分别为 80±33%和 73±40%）。这些数据表明，心脏收缩力是 MA 形成的主要因素。我们的发现表明，MA 与 PAT 和 PI 的侵入性测量高度相关。由于 PAT 和 PI 可以使用非侵入性技术来估计，因此这些标志物可能能够实现经济实惠的 MA 检测以进行风险预测。
