Davos Constantinos H, Francis Darrel P, Leenarts Marjolein F E, Yap Sing-Chien, Li Wei, Davlouros Periklis A, Wensel Roland, Coats Andrew J S, Piepoli Massimo, Sreeram Narayanswami, Gatzoulis Michael A
Royal Brompton Adult Congenital Heart Programme, and Department of Clinical Cardiology, Royal Brompton Hospital and National Heart and Lung Institute, Imperial College School of Medicine, London, UK.
Circulation. 2003 Sep 9;108 Suppl 1:II180-5. doi: 10.1161/01.cir.0000087946.47069.cb.
Atrial tachyarrhythmia is a common cause of morbidity and mortality in patients with univentricular physiology undergoing the Fontan operation. We examined cardiac autonomic nervous activity, a predictor of arrhythmia and sudden death in other cardiovascular disease, in patients late after the Fontan operation, employing heart rate variability (HRV) and baroreflex sensitivity.
We measured HRV and baroreflex sensitivity in 22 consecutive patients (8 male, age 26+/-9 years) who had undergone the Fontan operation 13+/-6 years previously, and 22 age- and sex-matched healthy controls. Fontan patients had significantly lower HRV (P<0.0001). Baroreflex sensitivity was measured by the alpha-index method (square root of ratio of RR interval spectral power to systolic blood pressure (SBP) spectral power, in the LF and the HF band) and was also significantly depressed in the Fontan group (P<0.0001 for both). Both low frequency (LF) and high frequency (HF) components of HRV were reduced in the Fontan patients (P<0.0001), but there was interindividual variation so that the LF/(LF+HF) ratio may be high, normal, or low, and decreased with increasing right atrial dimensions (r=-0.62, P=0.006). Patients with a history of sustained atrial arrhythmia had a stronger baroreflex than those without (P=0.005).
Autonomic nervous control of the heart is markedly deranged in patients late after the Fontan operation, with reduced HRV and baroreflex sensitivity. A relative suppression of the sympathetic-compared with the parasympathetic-system was observed in patients with marked right atrial dilation within the Fontan group. Furthermore, stronger baroreflexes were seen in Fontan patients in association with a higher incidence of sustained atrial tachyarrhythmia, implying that sinus node dysfunction is unlikely to be the dominant mechanism. Additional studies are clearly required to examine the prognostic importance of impaired BRS and HRV in these patients.
房性快速心律失常是接受Fontan手术的单心室生理患者发病和死亡的常见原因。我们采用心率变异性（HRV）和压力反射敏感性，研究了Fontan手术后晚期患者的心脏自主神经活动，这是其他心血管疾病中心律失常和猝死的一个预测指标。
我们测量了22例连续患者（8例男性，年龄26±9岁）的HRV和压力反射敏感性，这些患者在13±6年前接受了Fontan手术，以及22例年龄和性别匹配的健康对照者。Fontan手术患者的HRV显著降低（P<0.0001）。通过α指数法（低频和高频频段RR间期频谱功率与收缩压（SBP）频谱功率之比的平方根）测量压力反射敏感性，Fontan组也显著降低（两者均P<0.0001）。Fontan手术患者的HRV低频（LF）和高频（HF）成分均降低（P<0.0001），但个体之间存在差异，因此LF/（LF+HF）比值可能高、正常或低，并随右心房尺寸增加而降低（r=-0.62，P=0.006）。有持续性房性心律失常病史的患者比没有的患者压力反射更强（P=0.005）。
Fontan手术后晚期患者心脏的自主神经控制明显紊乱，HRV和压力反射敏感性降低。在Fontan组中，右心房明显扩张的患者中观察到交感神经系统相对于副交感神经系统的相对抑制。此外，Fontan手术患者中压力反射更强，持续性房性快速心律失常的发生率更高，这意味着窦房结功能障碍不太可能是主要机制。显然需要进一步研究来探讨这些患者中压力反射敏感性（BRS）和HRV受损的预后重要性。
