Bartoletti A, Gaggioli G, Menozzi C, Bottoni N, Del Rosso A, Mureddu R, Musso G, Foglia-Manzillo G, Bonfigli B, Brignole M
Arrhythmologic Center, Department of Cardiology, Ospedali Riuniti, Lavagna, Italy.
Europace. 1999 Jul;1(3):183-6. doi: 10.1053/eupc.1999.0036.
Since the pharmacological challenge with nitroglycerin (NTG) follows the initial drug-free phase in current tilt testing protocols, the effects of nitroglycerin alone and the appropriate duration of the basal phase are unknown.
To optimize the test, a randomized intra-patient comparison of two protocols was undertaken: a conventional nitroglycerin test (cHUT) consisting of passive upright posture at 60 degrees for 45 min followed, if negative, by sublingual NTG 0.4 mg spray, with the test continued for 20 min; and, accelerated nitroglycerin test (aHUT) consisting of passive upright posture at 60 degrees for 5 min--to rule out orthostatic hypotension--followed by sublingual NTG 0.4 mg spray, with the test continued for 20 min. Eighty-four consecutive patients (33 males; mean age 55+/-22) with unexplained syncope underwent both cHUT and aHUT in a randomized sequence with a 24-72 h interval between them. Additionally, 25 age-matched control subjects underwent aHUT.
In the drug-free phase, cHUT was positive in 15/84 patients (18%) and aHUT in 1/84 patients (1%). After NTG, cHUT and aHUT showed the same positivity rate of 33% (28/84 patients). The overall positivity rate was therefore higher with cHUT than with aHUT (51% vs 35%, P=0.04). Times to syncope were 29+/-12 min, (range 2-44) for cHUT drug-free phase, 5+/-2 min (range 2-9) for cHUT NTG phase, and 5+/-2 min (range 2-9) for aHUT. Only one (4%) of the control subjects had a positive response to aHUT.
The contribution of NTG to the diagnosis is independent of the presence of an unmedicated phase. The appropriate duration of the NTG phase is 10 min. aHUT has good specificity, but a positivity rate lower than cHUT; thus a drug-free phase is necessary to increase the sensitivity of the test.
在当前的倾斜试验方案中，硝酸甘油（NTG）药理学激发试验是在初始无药阶段之后进行的，因此单独使用硝酸甘油的效果以及基础阶段的适当持续时间尚不清楚。
为了优化该试验，对两种方案进行了患者内随机比较：一种是传统硝酸甘油试验（cHUT），包括60度被动直立姿势持续45分钟，如果结果为阴性，则舌下喷入0.4毫克NTG，试验持续20分钟；另一种是加速硝酸甘油试验（aHUT），包括60度被动直立姿势持续5分钟（以排除直立性低血压），然后舌下喷入0.4毫克NTG，试验持续20分钟。84例连续的不明原因晕厥患者（33例男性；平均年龄55±22岁）以随机顺序先后接受了cHUT和aHUT，两次试验间隔24 - 72小时。此外，25例年龄匹配的对照受试者接受了aHUT。
在无药阶段，cHUT在84例患者中有15例（18%）呈阳性，aHUT在84例患者中有1例（1%）呈阳性。使用NTG后，cHUT和aHUT的阳性率相同，均为33%（28/84例患者）。因此，cHUT的总体阳性率高于aHUT（51%对35%，P = 0.04）。cHUT无药阶段至晕厥的时间为29±12分钟（范围2 - 44分钟），cHUT使用NTG阶段为5±2分钟（范围2 - 9分钟），aHUT为5±2分钟（范围2 - 9分钟）。对照受试者中只有1例（4%）对aHUT有阳性反应。
NTG对诊断的贡献与是否存在无药阶段无关。NTG阶段的适当持续时间为10分钟。aHUT具有良好的特异性，但阳性率低于cHUT；因此需要一个无药阶段来提高试验的敏感性。
