Lane G K, Kennelly B M
Cardiovasc Res. 1978 Dec;12(12):712-9. doi: 10.1093/cvr/12.12.712.
Idioventricular rate, QRS width, site of block and responses to ventricular overdrive pacing were studied in 29 patients with chronic complete heart block in an attempt to distinguish patients liable to syncopal attacks. Ten patients were asymptomatic, 5 gave a history of presyncope and 14 of syncope. Although the mean idioventricular rate of the 10 patients in the narrow QRS group (40.0 per min) was significantly faster than that of the 19 patients in the wide QRS group (35.5 per min; P less than 0.02), the rate did not distinguish symptomatic patients in either the narrow or the wide QRS groups. His bundle studies of the site of block were also unhelpful. Overdrive right ventricular pacing at increasing rates was used to assess ventricular escape times which were not significantly different in symptomatic and asymptomatic wide QRS patients. There was, however, a significant difference in the product of maximum ventricular escape time X overdrive cycle length between symptomatic and asymptomatic narrow QRS patients after 30 s overdrive (3.850+/-1.670 vs 1.070+/-0.475; P less than 0.01); 60 s overdrive (5.020+/-2.170 vs 1.240+/-0.515; P less than 0.01) and 120 s overdrive (6.040+/-2.900 vs 1.460+/-0.275; P less than 0.01) which may have clinical predictive values.
对29例慢性完全性心脏传导阻滞患者的心室自主心律、QRS波宽度、阻滞部位及对心室超速起搏的反应进行了研究，以试图鉴别易发生晕厥发作的患者。10例患者无症状，5例有晕厥前期病史，14例有晕厥病史。虽然窄QRS波组10例患者的平均心室自主心律（每分钟40.0次）显著快于宽QRS波组19例患者的平均心室自主心律（每分钟35.5次；P<0.02），但该心律在窄QRS波组或宽QRS波组中均无法区分有症状的患者。对阻滞部位的希氏束研究也无帮助。采用逐渐增加速率的右心室超速起搏来评估心室逸搏时间，有症状和无症状的宽QRS波患者的心室逸搏时间无显著差异。然而，在30秒超速起搏后，有症状和无症状的窄QRS波患者的最大心室逸搏时间×超速起搏周期长度的乘积存在显著差异（3.850±1.670对1.070±0.475；P<0.01）；60秒超速起搏（5.020±2.170对1.240±0.515；P<0.01）和120秒超速起搏（6.040±2.900对1.460±0.275；P<0.01），这可能具有临床预测价值。
