Pilhall M, Riha M, Jern S
Department of Clinical Physiology, Ostra Hospital, University of Gothenburg, Sweden.
Clin Physiol. 1993 Mar;13(2):113-31. doi: 10.1111/j.1475-097x.1993.tb00373.x.
Changes in the QRS complex during exercise may provide information with respect to ischaemic heart disease. The intention with present investigation was to shed light on mechanisms behind QRS changes and to study the possibly confounding effects of beta-blockade on such alterations with exercise. Placebo or propranolol respectively was infused in randomized and double-blinded order in seven young healthy men before a maximum exercise test. Advanced computerized vectorcardiography and impedance cardiography was recorded continuously together with blood pressures and blood samples. The Y-lead magnitude increased significantly with propranolol infusion (P < 0.05), but it tended to decrease in the Z-lead (P < 0.07). While the serum potassium concentrations increased (P < 0.0005), the spatial QRS magnitude tended to decrease irrespective of treatment (P < 0.07). These changes correlated with changes in QR-duration (adj r2 > 0.58). With exercise, the mean spatial QRS magnitude decreased with similar amounts irrespective of treatment. However, propranolol made the magnitude decrease earlier (P < 0.01). No effect of treatment was detected on the decrease in QRS-duration. Immediately after exercise, the QRS complex continued to change as during exercise in the placebo investigations, but did not with propranolol (P < 0.05). These different patterns were most obvious in the first half of the QRS complex in the Y-lead. It is concluded that acute beta-blockade modifies QRS alterations both during and after exercise in healthy subjects. This indicates that such drugs may have confounding effects in evaluations of the diagnostic value of QRS alterations.
运动期间QRS波群的变化可能提供有关缺血性心脏病的信息。本研究的目的是阐明QRS变化背后的机制，并研究β受体阻滞剂对运动时此类变化可能产生的混杂效应。在七名年轻健康男性进行最大运动试验前，分别以随机双盲的顺序输注安慰剂或普萘洛尔。同时连续记录高级计算机化向量心电图、阻抗心电图、血压和血样。输注普萘洛尔后Y导联幅度显著增加（P<0.05），但Z导联幅度有下降趋势（P<0.07）。尽管血清钾浓度升高（P<0.0005），但无论治疗如何，空间QRS幅度均有下降趋势（P<0.07）。这些变化与QR间期的变化相关（调整r2>0.58）。运动时，无论治疗如何，平均空间QRS幅度均以相似幅度下降。然而，普萘洛尔使幅度下降得更早（P<0.01）。未检测到治疗对QRS间期缩短有影响。运动后即刻，在安慰剂组中，QRS波群继续像运动期间一样变化，但在普萘洛尔组中则没有（P<0.05）。这些不同模式在Y导联QRS波群的前半部分最为明显。结论是，急性β受体阻滞剂可改变健康受试者运动期间及运动后的QRS变化。这表明此类药物在评估QRS变化的诊断价值时可能产生混杂效应。
