Department of Medicine, Academic Medical Centre, University of Amsterdam, The Netherlands.
Clin Auton Res. 2011 Dec;21(6):405-13. doi: 10.1007/s10286-011-0134-6. Epub 2011 Jul 28.
During hypotension induced by tilt-table testing, low presyncopal blood pressure (BP) usually recovers within 1 min after tilt back. However, in some patients prolonged post faint hypotension (PPFH) is observed. We assessed the hemodynamics underlying PPFH in a retrospective study.
Seven patients (2 females, aged 31-72 years) experiencing PPFH were studied. PPFH was defined as a systolic BP below 85 mmHg for at least 2 min after tilt back. In 6 out of 7 presyncope was provoked by 0.4 mg sublingual NTG, administered in the 60° head-up tilt position following head-up tilt for 20 min. Continuous BP was monitored and stroke volume (SV) was computed from pressure pulsations. Cardiac output (CO) was calculated from SV × heart rate (HR); and total peripheral resistance (TPR) from mean BP/CO. Left ventricular contractility was estimated by dP/dt (max) of finger pressure pulse.
Systolic BP (SYS), diastolic BP (DIAS) and HR during PPFH were lower compared to baseline: SYS 75 ± 14 versus 121 ± 18 mmHg, DIAS 49 ± 9 versus 71 ± 9 mmHg and HR 52 ± 14 versus 67 ± 12 beats/min (p < 0.05). Marked hypotension was associated with a 47% fall in CO 3.1 ± 0.6 versus 5.9 ± 1.3 L/min (p < 0.05) and decreases in dP/dt, 277 ± 77 versus 759 ± 160 mmHg/s (p < 0.05). The difference in TPR was not significant 1.1 ± 0.3 versus 1.0 ± 0.3 MU (p = 0.229). In four patients, we attempted to treat PPFH by 30° head-down tilt. This intervention increased SYS only slightly (to 89 ± 12 mmHg).
PPFH seems to be mediated by severe cardiac depression.
在倾斜试验引起的低血压期间，低先兆血压（BP）通常在倾斜复位后 1 分钟内恢复。然而，在一些患者中，观察到长时间后晕厥低血压（PPFH）。我们在一项回顾性研究中评估了 PPFH 的血流动力学基础。
研究了 7 名（2 名女性，年龄 31-72 岁）经历 PPFH 的患者。PPFH 定义为倾斜复位后至少 2 分钟内收缩压低于 85mmHg。在 7 名患者中的 6 名，在倾斜 20 分钟后，舌下给予 0.4mg 硝酸甘油，在 60°头高位引发预晕厥。连续监测血压，从压力搏动计算每搏量（SV）。心输出量（CO）由 SV×心率（HR）计算；总外周阻力（TPR）由平均血压/CO 计算。左心室收缩性通过手指压力脉搏的 dP/dt（max）估计。
PPFH 期间的收缩压（SYS）、舒张压（DIAS）和心率（HR）均低于基线：SYS 75±14 与 121±18mmHg，DIAS 49±9 与 71±9mmHg，HR 52±14 与 67±12 次/分（p<0.05）。明显的低血压与 CO 下降 47%相关，3.1±0.6 与 5.9±1.3L/min（p<0.05），dP/dt 下降 277±77 与 759±160mmHg/s（p<0.05）。TPR 差异无统计学意义，1.1±0.3 与 1.0±0.3MU（p=0.229）。在 4 名患者中，我们尝试通过 30°头低位治疗 PPFH。该干预措施仅使 SYS 略有增加（至 89±12mmHg）。
PPFH 似乎由严重的心脏抑制介导。
