Abnormal autonomic modulation of QT interval in patients with idiopathic ventricular tachycardia associated with clinically normal hearts.
نویسندگان
چکیده
BACKGROUND Idiopathic ventricular tachycardia (VT) occurs in a small but important subset of patients without clinically overt heart disease. The mechanism of the arrhythmogenesis remains unclear in these patients. This study examines modulation of the QT interval by the autonomic nervous system in a group of patients with idiopathic ventricular tachycardia. METHODS Cardiac autonomic activity and ventricular repolarisation were studied in 27 patients with VT associated with a clinically normal heart (NHVT) and in 20 normal subjects. All the patients were in sinus rhythm, had normal atrioventricular conduction, and were in a drug free state. Cardiac efferent autonomic activity was measured by spectral analysis of heart rate variability from 24 hour ambulatory electrocardiograms on a Holter analysis system (Marquette). Ventricular repolarisation was evaluated by measuring the QT intervals from the same 24 hour Holter tapes at one hour intervals. RESULTS There was no difference in any of the QT interval variables including the maximum, minimum, and mean of both the QT interval and its corrected value (Bazett's formula) between patients with NHVT and normal subjects. The high frequency component (0.04-0.15 Hz) of heart rate variability was significantly decreased in patients with NHVT compared with normal subjects (16 (8) v 21 (12) ms, p < 0.05). There was a significant correlation between the spectral variables of heart rate variability and the mean, maximal, and minimal QT intervals in normal subjects, whereas the relation was lost in patients with NHVT. No difference was found in mean heart rate between normal subjects and patients with NHVT (70 (9) v 72 (13) beats/min, NS). CONCLUSIONS The high frequency component of heart rate variability is significantly decreased and the relation of QT interval to heart rate variability is significantly altered in patients with NHVT as compared with normal subjects. These findings suggest that abnormal modulation of the QT interval by the autonomic nervous system may play an important part in the arrhythmogenesis of NHVT. This might result from impaired vagal efferent cardiac activity in these patients.
منابع مشابه
Atrial and Ventricular Electrocardiographic Dromotropic Disturbances in Down Syndrome Patients with Structurally Normal Heart: A Cross-Sectional Study
Background: We designed a cross-sectional study to determine electrocardiographic disorders in Down syndrome patients with congenitally normal hearts in a bid to predict fatal cardiac arrhythmia in the future. Materials and Methods: We investigated 60 children with DS without congenital abnormal hearts. Sixty healthy juveniles were also included in the study as a control group. Physical examina...
متن کاملBackground & Objective : Heart failure is a clinical syndrome and increases in rate by aging. Because changes in ECG and electrolytes are variable, specific and sometimes independent to the disease with different methods to be diagnosed, in this study we tried to find a way to diagnose them. Materials & Methods: This is a retrospective descriptive-analytic study. Data was collected from dec...
متن کاملAutonomic modulation of repolarization instability in patients with heart failure prone to ventricular tachycardia.
QT variability (QTV) signifies repolarization lability, and increased QTV is a risk predictor for sudden cardiac death. The aim of the present study was to investigate the role of autonomic nervous system activity on QTV. This study was performed in 29 subjects: 10 heart failure (HF) patients with spontaneous ventricular tachycardia [HFVT(+)], 10 HF patients without spontaneous VT [HFVT(-)], an...
متن کاملDetermination of sensitivity and specificity of QT interval in ECG of diabetic patients for ndiagnosis of cardiac autonomic neuropathy
one of the important complications of diabetes mellitus that physicians pay less attention to is diabetic autonomic neuropathy(DNA) ,especially cardiac autonomic neuropathy (CAN).this has a poor prognosis and is accompanied by sudden death risk,recently several investigations that were carried out for CAN detection ,suggested that QT-interval prolongation in these patients is an important diagn...
متن کاملLong QT Syndrome (LQTS) Panel
The Blueprint Genetics Long QT Syndrome (LQTS) Panel provides efficient and rapid genetic diagnostics for all reported long QT syndrome subtypes (LQTS 1-13). Long QT syndrome is a disorder resulting from abnormal ion-channel functions leading to prolonged repolarization of cardiac muscle and manifests as long Q-T interval on electrocardiogram (ECG). LQTS can present as unexpected fainting, vent...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- British heart journal
دوره 69 4 شماره
صفحات -
تاریخ انتشار 1993