Cuomo S, De Caprio L, Di Palma A, Lirato C, Lombardi L, De Rosa M L, Vetrano A, Rengo F
Divisione di Cardiologia, Ospedale Cardarelli, Napoli.
Cardiologia. 1997 Oct;42(10):1071-6.
The autonomic tone has been shown to influence the duration of the QT interval, however the independent contribution of sympathetic and parasympathetic tone is not fully elucidated. The influence of autonomic tone on QT duration was studied in 10 young healthy volunteers by evaluating the changes in QT and RR duration induced by i.v. isoproterenol infusion and by standing before and after i.v. administration of propranolol or atropine. Furthermore, the relationship between RR interval and QT duration was evaluated during nocturnal sinus arrhythmia and submaximal exercise test. Low doses of isoproterenol reduced RR (p < 0.01) but not QT interval duration, while higher doses influenced both RR (p < 0.0001) and QT (p < 0.001) duration. Propranolol did not influence standing-induced shortening of RR and QT intervals; on the contrary, atropine administration abolished standing-induced QT interval shortening, without influencing RR changes. QT duration resulted significantly related to preceding RR interval at peak exercise (r = 0.87, p < 0.001) and during nocturnal sinus arrhythmia (r = 0.73, p < 0.0005), however, the regression lines showing the correlation between QT and preceding RR interval were different. Both sympathetic and parasympathetic tone appear to contribute to heart rate-independent changes in QT duration. In the basal state parasympathetic more than sympathetic tone influences the relation QT-heart rate. Major increases of sympathetic nervous system activity may change the relation QT-heart rate. Thus, in case of abrupt autonomic changes, any proposed formula for heart rate correction of QT may result inappropriate, also in the normal range of heart rate.
自主神经张力已被证明会影响QT间期的时长，然而交感神经和副交感神经张力的独立作用尚未完全阐明。通过评估静脉注射异丙肾上腺素以及静脉注射普萘洛尔或阿托品前后站立所诱发的QT和RR间期变化，对10名年轻健康志愿者自主神经张力对QT间期时长的影响进行了研究。此外，还在夜间窦性心律不齐和次极量运动试验期间评估了RR间期与QT间期时长之间的关系。低剂量异丙肾上腺素可缩短RR间期（p<0.01），但不影响QT间期时长，而高剂量则会影响RR间期（p<0.0001）和QT间期时长（p<0.001）。普萘洛尔不影响站立诱发的RR和QT间期缩短；相反，注射阿托品可消除站立诱发的QT间期缩短，而不影响RR间期变化。在运动峰值（r = 0.87，p<0.001）和夜间窦性心律不齐期间（r = 0.73，p<0.0005），QT间期时长与前一个RR间期显著相关，然而，显示QT间期与前一个RR间期之间相关性的回归线有所不同。交感神经和副交感神经张力似乎都对QT间期时长的心率非依赖性变化有影响。在基础状态下，副交感神经张力比交感神经张力对QT间期与心率之间的关系影响更大。交感神经系统活动的大幅增加可能会改变QT间期与心率之间的关系。因此，在自主神经突然变化的情况下，任何提出的用于校正QT间期的心率公式可能都不合适，即使在正常心率范围内也是如此。
