Chen M Y, Goldenberg I F, Milstein S, Buetikofer J, Almquist A, Lesser J, Benditt D G
Department of Medicine, University of Minnesota Medical School, Minneapolis 55455.
Am J Cardiol. 1989 Jan 1;63(1):66-72. doi: 10.1016/0002-9149(89)91077-1.
This study assessed the temporal relation of RR interval, AH interval and systemic blood pressure changes during induced symptomatic bradycardia-hypotension episodes in 14 patients with recurrent syncope suspected of being neurally mediated. Upright tilt with isoproterenol reproduced symptoms in 9 of 14 patients (positive response) and was negative in 5 of 14 (negative response). Isoproterenol alone shortened supine RR intervals in all patients. With tilt, however, isoproterenol prolonged RR intervals in those with positive results (supine 519 +/- 124 ms vs tilt 845 +/- 212 ms, p less than 0.005) while further shortening RR intervals among negative responders (supine 436 +/- 90 ms vs tilt 377 +/- 82 ms, p less than 0.05). Similarly, tilt with isoproterenol prolonged AH intervals in patients with positive responses despite RR prolongation, while shortening AH in negative responders. Additionally, with combined tilt and isoproterenol, systemic arterial pressure decreased significantly in patients with positive responses (systolic 99 +/- 13 vs 57 +/- 13 mm Hg, p less than 0.001, diastolic 62 +/- 17 vs 28 +/- 9 mm Hg, p less than 0.001) but not in patients with negative responses. Further, onset of hypotension (42 +/- 14 seconds after tilt) preceded onset of RR interval prolongation (52 +/- 23 seconds after tilt). Syncope (142 +/- 72 seconds after tilt) coincided closely with nadir of systemic pressure (136 +/- 74 seconds) and both tended to precede maximum RR prolongation (152 +/- 87 seconds). Thus, the bradycardia and hypotension associated with neurally mediated syncope exhibit characteristic but distinctly different time courses, with arterial pressure changes developing earlier and coinciding more closely with symptom development.
本研究评估了14例疑似神经介导性反复晕厥患者在诱发症状性心动过缓-低血压发作期间RR间期、AH间期和全身血压变化的时间关系。14例患者中，9例（阳性反应）在异丙肾上腺素激发下直立倾斜试验再现症状，5例（阴性反应）试验结果为阴性。单独使用异丙肾上腺素可使所有患者仰卧位RR间期缩短。然而，在倾斜试验时，异丙肾上腺素使阳性结果患者的RR间期延长（仰卧位519±124毫秒，倾斜位845±212毫秒，p<0.005），而使阴性反应者的RR间期进一步缩短（仰卧位436±90毫秒，倾斜位377±82毫秒，p<0.05）。同样，尽管RR间期延长，但在阳性反应患者中，异丙肾上腺素激发下的倾斜试验使AH间期延长，而在阴性反应者中AH间期缩短。此外，在倾斜试验联合使用异丙肾上腺素时，阳性反应患者的体动脉压显著下降（收缩压99±13对比57±13毫米汞柱，p<0.001；舒张压62±17对比28±9毫米汞柱，p<0.001），而阴性反应患者则无明显变化。此外，低血压发作（倾斜后42±14秒）先于RR间期延长发作（倾斜后52±23秒）。晕厥（倾斜后142±72秒）与体循环压力最低点（136±74秒）密切相符，且两者均倾向于先于RR间期最大延长（152±87秒）出现。因此，与神经介导性晕厥相关的心动过缓和低血压表现出特征性但明显不同的时间进程，动脉压变化出现更早且与症状发展更为密切相符。
