Roche Frédéric, Gaspoz Jean-Michel, Court-Fortune Isabelle, Costes Frédéric, Geyssant André, Duverney David, Pichot Vincent, Barthélémy Jean-Claude
Service d'Exploration Fonctionnelle CardioRespiratoire, Faculté de Médecine Jacques Lisfranc, Saint-Etienne, France.
Pacing Clin Electrophysiol. 2003 Jul;26(7 Pt 1):1446-53. doi: 10.1046/j.1460-9592.2003.t01-1-00209.x.
QT rate dependence is one of the major properties of ventricular repolarization with its circadian and autonomic modulations. The authors postulated that dynamic alterations in QT interval adaptation could help characterize patients with cardiac autonomic alterations, like those with obstructive sleep apnea syndrome (OSAS). To assess ventricular repolarization features in patients with OSAS, QT parameters and their dynamicity along RR intervals were compared from 24-hour ECG data of patients with and without this syndrome, assessing cardiac autonomic nervous system equilibrium by means of time-domain and frequency-domain analyses of heart rate variability (HRV). The study group consisted of 74 consecutive patients referred to the Sleep Laboratory for clinically suspected OSAS. The syndrome was confirmed in 30 (40.5%) patients according to standard polysomnographic criteria. QT length related to heart rate (HR) was found significantly shorter for HR < 70 beats/min in patients with OSAS(-1.32 +/- 0.35)compared with patients without OSAS(-1.99 +/- 0.40; P < 0.01). This flattened relationship was correlated with the severity of the sleep related disorder. Using multiple linear regression analysis, the apnea/hypopnea index and nocturnal normalized high frequencies (HFnu) were the most significant predictors of the QT/RR slope(R = 0.61; P < 0.0001). OSAS is significantly associated with a flattened relationship between QT duration and RR interval at low HRs. The alteration of cardiac parasympathetic tone occurring in severe OSAS patients may explain this altered rate dependent adaptation of myocardial repolarization.
QT 心率依赖性是心室复极的主要特性之一，存在昼夜节律和自主神经调节。作者推测，QT 间期适应性的动态变化有助于对心脏自主神经改变的患者进行特征描述，比如阻塞性睡眠呼吸暂停综合征（OSAS）患者。为了评估 OSAS 患者的心室复极特征，比较了有或无该综合征患者 24 小时心电图数据中的 QT 参数及其沿 RR 间期的动态变化，并通过心率变异性（HRV）的时域和频域分析来评估心脏自主神经系统平衡。研究组由 74 例因临床怀疑 OSAS 而转诊至睡眠实验室的连续患者组成。根据标准多导睡眠图标准，30 例（40.5%）患者确诊为该综合征。与无 OSAS 的患者相比，OSAS 患者心率（HR）<70 次/分钟时，与心率相关的 QT 长度明显缩短（-1.32±0.35），而无 OSAS 的患者为（-1.99±0.40；P<0.01）。这种变平的关系与睡眠相关障碍的严重程度相关。使用多元线性回归分析，呼吸暂停/低通气指数和夜间标准化高频（HFnu）是 QT/RR 斜率最显著的预测因素（R = 0.61；P<0.0001）。OSAS 与低心率时 QT 间期和 RR 间期之间变平的关系显著相关。重度 OSAS 患者发生的心脏副交感神经张力改变可能解释了心肌复极这种改变的心率依赖性适应性。
