Rocha Ana Luiza Lunardi, Lombardi Federico, da Costa Rocha Manoel Otávio, Barros Márcio Vinícius Lins, Val Barros Vladimir da Costa, Reis Adelina Martha, Ribeiro Antonio Luiz Pinho
Postgraduate Course of Tropical Medicine, School of Medicine, Cardiology Service, Hospital das Clínicas, Federal University of Minas Gerais, Belo Horizonte, Brazil.
Ann Noninvasive Electrocardiol. 2006 Jan;11(1):3-11. doi: 10.1111/j.1542-474X.2006.00054.x.
Chagas disease (ChD) patients might present chronotropic incompetence during exercise, although its physiopathology remains uncertain. We evaluated the heart rate (HR) response to exercise testing in ChD patients in order to determine the role of autonomic modulation and left ventricular dysfunction in the physiopathology of chronotropic incompetence.
ChD ambulatory patients (n = 170) and healthy controls (n = 24) underwent a standardized protocol including Doppler echocardiography, Holter monitoring, HR variability analysis, brain natriuretic peptide (BNP) measurement, and maximal exercise testing. The chronotropic response was calculated as the percentage of predicted HR achieved and the HR increment (DeltaHR) during exercise. ChD patients were divided according to the absence or presence of cardiopathy and chronotropic incompetence (<85% predicted HR).
Chronotropic incompetence was present in 34 (20%) of all ChD patients. The group with cardiopathy displayed reduced DeltaHR (91 +/- 19 bpm) during exercise in comparison with ChD patients without cardiopathy (100 +/- 19 bpm). Both the values observed in ChD groups were significantly different from those of controls (112 +/- 13 bpm). Exercise duration, maximal oxygen consumption, and systolic blood pressure increment were significantly reduced in patients with abnormal chronotropic response. DeltaHR during the exercise was significantly correlated with markers of autonomic control of sinus node, such as rest HR (r =-0.498, P <or= 0.001), peak HR during exercise (r = 0.775, P <or= 0.001), minimal HR during Holter recording (r =-0.231, P = 0.003), and high- and low-frequency components of short-term HR variability (r = 0.188, P = 0.042 and r = 0.203, P = 0.027). Neither left ventricular function nor BNP levels were independently related to the presence of chronotropic incompetence.
Chronotropic incompetence may be considered an early sign of autonomic dysfunction in ChD patients.
恰加斯病（ChD）患者在运动时可能出现变时性功能不全，但其病理生理学仍不明确。我们评估了ChD患者运动试验时的心率（HR）反应，以确定自主神经调节和左心室功能障碍在变时性功能不全病理生理学中的作用。
ChD门诊患者（n = 170）和健康对照者（n = 24）接受了标准化方案，包括多普勒超声心动图、动态心电图监测、HR变异性分析、脑钠肽（BNP）测量和最大运动试验。变时反应计算为达到的预测HR百分比和运动期间的HR增量（DeltaHR）。ChD患者根据是否存在心脏病和变时性功能不全（<预测HR的85%）进行分组。
所有ChD患者中有34例（20%）存在变时性功能不全。与无心脏病的ChD患者相比，有心脏病的组在运动期间的DeltaHR降低（91±19次/分），而无心脏病的ChD患者为（100±19次/分）。ChD组观察到的值与对照组（112±13次/分）均有显著差异。变时反应异常的患者运动持续时间、最大耗氧量和收缩压增量显著降低。运动期间的DeltaHR与窦房结自主控制标志物显著相关，如静息HR（r = -0.498，P≤0.001）、运动期间的峰值HR（r = 0.775，P≤0.001）、动态心电图记录期间的最低HR（r = -0.231，P = 0.003）以及短期HR变异性的高频和低频成分（r = 0.188，P = 0.042和r = 0.203，P = 0.027）。左心室功能和BNP水平均与变时性功能不全的存在无独立相关性。
变时性功能不全可能被认为是ChD患者自主神经功能障碍的早期迹象。
