10 research outputs found
173 Study of the circadien variation of the QT dynamics in myocardial infarction
No full textIntroductionThe relation between the QT interval and heart rate is linear. The QT interval/RR interval relationship is generally described as QT dynamics. the linear QT/RR slope is influenced by the autonomic nervous system. In healthy individuals, the slope exhibits circadian variations: it is steeper during the day than during the night.AimThe aim of this study is to evaluate the circadian variation of the QT interval and the QT/RR slope in patients experiencing myocardial infarction.MethodsThis prospective study included 90 patients having myocardial infarction. They underwent 21 days after the acute phase, 24 hours ambulatory ECG (Holter) recording. The following parameters were studied : the QT end interval (QTe), the QT apex interval (QTa) and the slopes of QTe/RR and QTa/RR during diurnal and nocturnal periods.ResultsThere was no significant difference regarding the QTe and the QTa intervals during the day and night. The mean diurnal slope and nocturnal slopes of QTe/RR were similar (0,147±0,073 vs 0,131±0,062, p=NS). The mean diurnal slope and nocturnal slopes of QTa/RR were also comparable (0,123±0,067 vs 0,119±0,065, p=NS).ConclusionThe lack of circadian variation of the QT interval and the linear QT/RR slope in myocardial infarction patients reflects an imbalance in the autonomic nervous system. These results suggest an increase in the nocturnal sympathic tone and may be associated with a higher risk of arrhythmia in this population. Further studies are needed to evaluate the role of the QT/RR slope in risk stratification after myocardial infarction
236 The effects of dipper and non dipper status on heart rate variability and heart rate turbulence in essential hypertension
No full textIntroductionThe relation between the autonomic nervous system and the circadian pattern of blood pressure in hypertensive patients is not well established.AimThe aim of this prospective study is to compare parameters of heart rate variability (HRV) and heart rate turbulence (HRT), non invasive measures reflecting the sympathetic and parasympathetic modulations of heart rate, in dipper and non dipper hypertensive patients.Methods47 hypertensive patients (24 males and 23 females, age = 57±10 years old) underwent 24 hour Holter recording and 24 hour ambulatory blood pressure monitoring (ABPM). Patients whose nocturnal average blood pressure (BP) levels decreased by more than 10% compared to their day time BP levels were considered as dippers, and those whose levels did not decrease as non dippers. Diabetes and ischemic heart disease were exclusion criteria.Results30 patients were dippers and 17 patients were non dippers. Dipper and non dipper patients were comparable regarding age, sex and mean blood pressure. There was no significant difference in average HRV and HRT parameters between both groups (table 1).Table. Comparison of HRV and HRT parametersDippers N = 30Non dippers N = 17PSDNN 5 min (ms)53±547±3NSSDANN 5 min (ms)106±3597±24NSRMSSD (ms)38±3131±13NSLF (ms2)620±146411±134NSHF (ms2)387±133194±32NSTO (%)-0.0244-0.0152NSTS (ms/RIR)7.72±1.977.43±1.36NSIn dipper patients the LF/HF was higher during daytime compared to the night (3.3±0.5 vs 2.05±0.27, p=0.0041) where as no significant difference was noticed in non dipper patients (3.3±0.24 vs 2.7±0.33, p = NS).Conclusionthese results suggest that despite similar global HRV and HRT parameters in dippers and non dippers, non dipper patients have an imbalance of the circadian sympathic-vagal tonus pattern with a high nocturnal sympathic tonus. These data may partially explain the higher incidence of cardiovascular events reported in non dipper patients
175 Is high sensitive C reactive protein related to clinical and echocardiographic risk of thrombo-embolism in patients with atrial fibrillation?
No full text212 Study of the effect of mode of pacing on ventricular repolarization in heart failure patients
No full textBackgroundCardiac resynchronization therapy (CRT) is a well established treatment in selected patients with heart failure. The non physiological ventricular activation sequence has been implicated in the occurrence of sudden death after CRT. There is conflicting date concerning the effect of different pacing modes on ventricular repolarization in heart failure patients.PurposeAssessing the effects of biventicular (Bi V), left ventricular (LV) epicardial pacing and right ventricular endocardial pacing (RV) on QT intervals (QT end, QT apex, JT) and transmural dispersion of repolarization (TDR) in patients with heart failure having CRT.Methods20 patients (15 men and 5 women, age = 63.4±11 years) with NYHA III-IV heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony received CRT. We measured QT end intervals, JT intervals and TDR according to recommended methods on a 12 lead ECG recorded at baseline and after implant. After implant, ECG was recorded with temporary right ventricular pacing, temporary left ventricular pacing and then the final pacing mode : simultaneous biventricular pacing.ResultsThere was no significant difference between QT end interval, JT interval and TDR at baseline and after implant with different pacing modes.ConclusionIn our study, we noticed no effect of pacing modes on repolarization in patients with heart failure. The high incidence of sudden death observed in CRT may be explained by competitvity of modes of death rather than induced abnormal repolarization
216 Assessment of the impact of myocardial infarction localization on heart rate variability, heart rate turbulence and QT intervals
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069 Evaluating in a “real-world” the performance of CRUSADE and MEHRAN bleeding risk scores to predict major bleeding complications among Tunisian patients with ACS
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