Carlioz R, Graux P, Haye J, Letourneau T, Guyomar Y, Hubert E, Bodart J C, Lequeuche B, Burlaton J P
Department of Cardiology, H.I.A. Percy, Clamart, France.
Am Heart J. 1997 Mar;133(3):346-52. doi: 10.1016/s0002-8703(97)70231-x.
The sensitivity of the passive head-up tilt test (HUT) in the evaluation of unexplained short-lasting syncope in young adults remains insufficient. The infusion of isoproterenol was proposed to improve the benefit. To evaluate the sensitivity-specificity relationship during isoproterenol dosing, we studied 76 young adults (aged 20.9 +/- 1.7 years) (group S) with recurrent (mean 3.8 +/- 1.6) losses of consciousness that remained unexplained after clinical and noninvasive assessment and 35 young healthy volunteers (aged 22.6 +/- 2.7 years) (group V). Subjects underwent either passive HUT (45 min, 60 degrees without drug dosing for 48 subjects in group S (S1) and 17 in group V (V1), or HUT with isoproterenol infusion at progressive doses (2 then 5 micrograms/min) after 30 minutes of passive tilting for 28 patients in group S (S2) and 18 in group V (V2). During passive HUT, the test was positive (asystole, bradycardia, or fall in systolic blood pressure) in 2 of 17 (11.8%) patients in group V1 and in 7 of 48 (14.6%) in group S1 before 30 minutes, and in 3 of 17 (17.6%) in group V1 compared with 10 of 48 (20.8%) in group S1 at the end of the 45-minute infusion, with no difference in delay before the appearance of a positive result. During HUT with isoproterenol dosing, the test was positive in 2 of 18 (11.1%) patients in group V2 and in 18 of 28 (64.2%) in group S2 before 45 minutes (2 micrograms/min; p < 0.01) in 7 of 18 (38.8%) in group V2 compared with 24 of 28 (85.7%) in group S2 before 60 min (5 micrograms/min; p < 0.01). In both cases the mean delay in evoking a positive response was significantly shorter. No asystolic response was observed in the volunteers regardless of the protocol used. The most characteristic response to isoproterenol injection was the appearance of a junctional escape rate with a fall in systolic blood pressure (61.5% of subjects in group S2). The infusion of isoproterenol considerably improves the sensitivity of the HUT with satisfactory specificity if low doses are used (< 3 micrograms/min). These results support the use of HUT with isoproterenol in the evaluation of unexplained syncope in young adults.
被动直立倾斜试验（HUT）在评估年轻成人不明原因的短暂性晕厥时敏感性仍不足。有人提出输注异丙肾上腺素可提高其有效性。为评估异丙肾上腺素给药期间的敏感性 - 特异性关系，我们研究了76名年轻成人（年龄20.9±1.7岁）（S组），他们反复出现（平均3.8±1.6次）意识丧失，经临床和无创评估后仍无法解释，以及35名年轻健康志愿者（年龄22.6±2.7岁）（V组）。受试者接受被动HUT（45分钟，60度，S组48名受试者（S1）和V组17名受试者（V1）未给药），或S组28名患者（S2）和V组18名患者（V2）在被动倾斜30分钟后接受递增剂量（先2μg/min然后5μg/min）的异丙肾上腺素输注的HUT。在被动HUT期间，V1组17名患者中有2名（11.8％）、S1组48名患者中有7名（14.6％）在30分钟前试验呈阳性（心脏停搏、心动过缓或收缩压下降），在45分钟输注结束时，V1组17名患者中有3名（17.6％），S1组48名患者中有10名（20.8％），出现阳性结果前的延迟无差异。在异丙肾上腺素给药的HUT期间，V2组18名患者中有2名（11.1％）、S2组28名患者中有18名（64.2％）在45分钟前（2μg/min；p<0.01）试验呈阳性，V2组18名患者中有7名（38.8％），S2组28名患者中有24名（85.7％）在60分钟前（5μg/min；p<0.01）试验呈阳性。在这两种情况下，诱发阳性反应的平均延迟均明显缩短。无论采用何种方案，志愿者均未观察到心脏停搏反应。对异丙肾上腺素注射最典型的反应是出现交界性逸搏心律并伴有收缩压下降（S2组61.5％的受试者）。如果使用低剂量（<3μg/min），输注异丙肾上腺素可显著提高HUT的敏感性且特异性良好。这些结果支持在评估年轻成人不明原因晕厥时使用异丙肾上腺素激发的HUT。
