Postgraduate Program in Internal Medicine, Internal Medicine Department, Federal University of Parana, Curitiba, Parana, Brazil.
Postgraduate Program in Internal Medicine, Internal Medicine Department, Federal University of Parana, Curitiba, Parana, Brazil.
Am J Cardiol. 2023 Jun 15;197:3-12. doi: 10.1016/j.amjcard.2023.03.027. Epub 2023 Apr 25.
It is of paramount importance to characterize the individual hemodynamic response of patients with postural orthostatic tachycardia syndrome (POTS) to select the best therapeutic intervention. Our aim in this study was to describe the hemodynamic changes in 40 patients with POTS during the head-up tilt test and compare them with 48 healthy patients. Hemodynamic parameters were obtained by cardiac bioimpedance. Patients were compared in supine position and after 5, 10, 15, and 20 minutes of orthostatic position. Patients with POTS demonstrated higher heart rate (74 beats per minute [64 to 80] vs 67 [62 to 72], p <0.001) and lower stroke volume (SV) (83.0 ml [72 to 94] vs 90 [79 to 112], p <0.001) at supine position. The response to orthostatic challenge was characterized by a decrease in SV index (SVI) in both groups (ΔSVI in ml/m: -16 [-25 to -7.] vs -11 [-17 to -6.1], p = NS). Peripheral vascular resistance (PVR) was reduced only in POTS (ΔPVR in dyne.seg/cm:-52 [-279 to 163] vs 326 [58 to 535], p <0.001). According to the best cut-off points obtained using the receiver operating characteristic analysis for the variation of SVI (-15.5%) and PVR index (PVRI) (-5.5%), we observed 4 distinct groups of POTS: 10% presented an increase in both SVI and PVRI after the orthostatic challenge, 35% presented a PVRI decrease with SVI maintenance or increase, 37.5% presented an SVI decrease with PVRI maintenance or elevation, and 17.5% presented a reduction in both variables. Body mass index, ΔSVI, and ΔPVRI were strongly correlated with POTS (area under the curve = 0.86 [95% confidence interval 0.77 to 0.92], p <0.0001). In conclusion, the use of appropriate cut-off points for hemodynamic parameters using bioimpedance cardiography during the head-up tilt test could be a useful strategy to identify the main mechanism involved and to select the best individual therapeutic strategy in POTS.
了解体位性心动过速综合征（POTS）患者的个体血液动力学反应对于选择最佳治疗干预措施至关重要。本研究旨在描述 40 例 POTS 患者在头高位倾斜试验期间的血液动力学变化，并将其与 48 例健康患者进行比较。通过心脏生物阻抗法获得血液动力学参数。将患者在仰卧位和直立 5、10、15 和 20 分钟时进行比较。与仰卧位时相比，POTS 患者的心率更高（74 次/分钟[64 至 80]比 67 次/分钟[62 至 72]，p<0.001），每搏量（SV）更低（83.0ml[72 至 94]比 90ml[79 至 112]，p<0.001）。两组患者对直立挑战的反应均表现为 SV 指数（SVI）降低（ml/m 降低的毫升数：-16[-25 至-7]比-11[-17 至-6.1]，p=NS）。只有 POTS 患者的外周血管阻力（PVR）降低（dyn.seg/cm 降低的 dynes 数：-52[-279 至 163]比 326[58 至 535]，p<0.001）。根据 SVI 变化（-15.5%）和 PVRI 指数（PVRI）变化（-5.5%）的受试者工作特征分析获得的最佳截断点，我们观察到 4 种不同的 POTS 组：10%的患者在直立后 SVI 和 PVRI 均增加，35%的患者在 SVI 维持或增加的情况下 PVRI 下降，37.5%的患者 SVI 下降而 PVRI 维持或升高，17.5%的患者两种变量均下降。体重指数、ΔSVI 和 ΔPVRI 与 POTS 呈强相关（曲线下面积为 0.86[95%置信区间为 0.77 至 0.92]，p<0.0001）。总之，在头高位倾斜试验中使用生物阻抗心动图为血液动力学参数设置适当的截断点可能是一种有用的策略，可以识别涉及的主要机制，并为 POTS 患者选择最佳的个体化治疗策略。
