Paridon S M, Humes R A, Pinsky W W
Division of Cardiology, Children's Hospital of Michigan, Wayne State University School of Medicine, Detroit 48201.
J Am Coll Cardiol. 1991 Mar 1;17(3):729-32. doi: 10.1016/s0735-1097(10)80191-3.
To better understand the role of chronotropic impairment on exercise performance after the atrial switch (Mustard) operation, 20 patients who had undergone this operation for uncomplicated d-transposition of the great arteries exercised to maximal volition using a 1 min incremental treadmill protocol. Heart rate, oxygen consumption, carbon dioxide production and minute ventilation were monitored continuously. Two-dimensional echocardiograms were obtained before testing to calculate the right ventricular inflow volume indexed to body surface area. All patients achieved maximal aerobic capacity based on their ventilatory patterns and respiratory exchange ratio. Maximal heart rate was reduced (175 beats/min; 87% of predicted for age) and maximal oxygen consumption was decreased (31 ml/kg per min; 75% of predicted for age and gender). There was no correlation between maximal oxygen consumption and maximal heart rate. Right ventricular volume index, however, had a significant inverse correlation with maximal heart rate (r = -0.62, p less than 0.005). There was no correlation between right ventricular volume index and heart rate at rest. These results suggest that decreased maximal oxygen consumption in patients after the Mustard procedure is not a result of chronotropic impairment. Right ventricular dilation may be a compensatory response to chronotropic impairment.
为了更好地理解变时性功能不全在心房调转术（Mustard术）后运动表现中的作用，20例因单纯性大动脉d-转位接受该手术的患者采用1分钟递增式跑步机方案进行最大意愿运动。持续监测心率、耗氧量、二氧化碳生成量和分钟通气量。在测试前获取二维超声心动图以计算体表面积指数化的右心室流入量。所有患者根据其通气模式和呼吸交换率均达到最大有氧能力。最大心率降低（175次/分钟；为年龄预测值的87%），最大耗氧量下降（31毫升/千克每分钟；为年龄和性别的预测值的75%）。最大耗氧量与最大心率之间无相关性。然而，右心室容量指数与最大心率呈显著负相关（r = -0.62，p小于0.005）。右心室容量指数与静息心率之间无相关性。这些结果表明，Mustard术后患者最大耗氧量降低并非变时性功能不全所致。右心室扩张可能是对变时性功能不全的一种代偿反应。
