Bazett’s Formula: Is it Rational to be Used?

2017

Background and Aim: In the present study, the role of ethanolic extract of olive ( Olea europaea ) leaf administration against the cerebral hypoperfusion-induced electrophysiological alterations and left ventricular thickness in rat heart was studied. Materials and Methods: The right carotid artery was occluded with a 5-0 silk suture and the left carotid artery was occluded after a week. The olive (Olea europaea) leaf extract was administered orally (by gavage) to three experimental groups of rats in 100, 200 and 300 mg/kg/day for two weeks after the left carotid artery occlusion and processed in 25 days. The sham and hypoperfusion groups were fed with normal saline. Each group had 6 rats. After 25 days, electrophysiological heart parameters, i.e. HR, QTc, QRS duration, QT interval, PR interval, RR interval, ST amplitude, T wave amplitude and also the thickness of left ventricle (TLV) were assessed. Results: The administration of olive leaf extract (100, 200 and 300 mg/kg) exhibited...

Journal of Research in Medical Sciences

resting heart rate in athletes is lower compared with nonexercise individual because their heart muscle becomes stronger as a result of exercise, so with less effort, their hearts can pump up more blood volume in each heartbeat. [5] Therefore, proper and regular exercise plays an important role in preventing and increasing the survival of cardiovascular disease. [6] Electrocardiography (ECG) is an important noninvasive clinical test for determination of cardiac contractility and electrical conductivity status. [7] ECG patterns vary from person to person and even in a person under different physiological conditions. Few studies have been done on the effects of exercise on ECG parameters. [8] Background: There is evidence that regular activity can prevent of cardiovascular diseases. There are many reports that exercise and the consumption of olive leaf extract (OLE) have a positive effect on cardiovascular parameters. This study was conducted to compare the effects of exercise and OLE alone and together on electrocardiographic parameters in rats. Materials and Methods: Male Sprague-Dawley rats were randomly divided into six groups (n = 8 rats in each): Control, exercise, OLE (100, 200, and 400 mg/kg, orally for 14 days), and exercise + OLE (200 mg/kg of extract, orally for 14 days). Exercise training in rats was performed using treadmill for 28 days (1 h/day). Electrophysiological parameters including heart rate, PR interval, QT interval, QT corrected (QTc), RR interval, QRS voltage, and duration were obtained from lead II electrocardiogram (ECG) recorded by a PowerLab system. Statistical evaluation was done by one-way analysis of variance followed by Fisher's least significant difference test and P < 0.05 was considered statistically significant. Results: The amounts of QT (P = 0.0009) and QTc interval (P = 0.0004), RR interval (P < 0.0001), QRS duration (P = 0.004), and QRS voltage (P = 0.003) in the exercise group were significantly higher than those of the control group. However, there were no significant differences in PR interval in comparison with the control group. Exercise (P < 0.0001) and OLE (400 mg/kg, P = 0.043) alone and both in combination (P = 0.007) reduced heart rate and increased the amount of QRS voltage (P = 0.003, P = 0.047, and P = 0.046, respectively) and RR interval (P < 0.0001, P = 0.046, and P = 0.0009, respectively). Conclusion: Results of this study indicated that administration of OLE alone and in combination with exercise has negative chronotropic and positive inotropic effects and also it can prevent of prolongation of QT and QTc interval induced by severe exercise.

Arzneimittelforschung, 2011

The purpose of this prospective, placebo-controlled, randomized double-blind study was the examination of changes in the basic vegetative rhythms due to Cardiodoron ® . This medicine is a composition of extracts of blossoms from Primula officinalis and Onopordon acanthium and from the herbs of Hyoscyamus niger. In its clinical use it is known as a modulating medicine in the treatment of functional disturbances of the cardiovascular system. With use of Holter monitoring, 24-h ECG recordings were obtained from 100 healthy subjects of whom 50 took the composition and 50 a placebo. Heart rate variability was evaluated from the 24-h ECGs by means of a power spectral analysis based on the Fast Fourier Transformation (FFT). Regulative influences of changes on the rhythmic system due to the medicine were found. After four weeks of medication half of the verum group showed a tendency to an increased variability in the low and high frequency range at night (LFn: 0.04 -0.15 Hz, HFn: 0.15 -0.4 Hz) in contrast to the placebo group. The mean heart rate at night (HRn) showed a tendency of normalization in the verum group: in subjects with a low HRn the heart rate was increased and in subjects with a high HRn the heart rate was decreased. This effect could not be observed in the placebo group. After two fur ther weeks without any medication this difference between verum and placebo was abolished.

Hellenic journal of cardiology : HJC = Hellēnikē kardiologikē epitheōrēsē

Reperfusion arrhythmias could be due to free radicals, while contraction excitation feedback is the cause of arrhythmias generated by blood pressure elevation (BPE). The aim of this study was to test the antiarrhythmic effects of an antioxidant (vitamin C [vit C], 1.5 g), an iron-binding agent (deferoxamine [Def], 1 g), and their combination in an experimental model of arrhythmia based on these 2 mechanisms. Thirty anaesthetised sheep were divided into 4 groups, depending on the infused agent: saline (8 sheep), combination of vit C and Def (8), Def (6), and vit C (8). Induction of ventricular arrhythmias was attempted in all animals using both ischaemia-reperfusion (phase I) and a combination of ischaemia and BPE (phase II). In all cases ischaemia was caused by ligating the left anterior descending coronary artery distally to the origin of the 1st diagonal artery, while reperfusion was achieved by releasing the ligation 45 min later. BPE was achieved by obstructing the ascending aor...

The American journal of …, 1984

Cureus

Bukhari et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 4.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

European Heart Journal Supplements, 2001

To determine whether n-3 polyunsaturated fatty acids (PUFAs) have cardiac antiarrhythmic effects and, if so, to determine the basis(es) for such an effect.

Veterinární medicína, 2011

The QT interval has been the objective of exhaustive attention in the past and also in recent times. A number of conditions, congenital and acquired, can have a direct effect on cardiac repolarization. Also drug regulatory agencies have showed increasing interest in the topic because certain drugs can prolong the QT interval to a level that produces ventricular arrhythmias. The dog is a species that shares some similarities with the human electrical system and has been used in human and veterinary research. We here present the current recommendations for QT measurement in dogs for use in clinical and experimental practice.

Journal of …, 2010

Drug-Induced QTc Interval Assessment. Introduction: There is debate on the optimal QT correction method to determine the degree of the drug-induced QT interval prolongation in relation to heart rate ( QTc).

Journal of Electrocardiology, 2004

The corrected QT interval (QTc) is widely used in pharmaceutical studies and clinical practice. Bazett's QT correction formula is still the most popular, despite Simonson's warning in 1961 that it could not be recommended. Other QTc formulae, e.g. Fridericia, Framingham, and Hodges, are also used. This study compares these four formulae using 10,303 normal ECGs recorded from four US hospitals. QT intervals were measured by the same computer program on ECGs confirmed by physicians. The distributions of QTc based on Fridericia, Framingham, and Hodges formulae were similar but Bazett's was significantly wider. The global group QTc-heart rate (HR) correlation coefficients were calculated as Bazett 0.33, Fridericia 0.24, Framingham 0.26, and Hodges 0.11, with the uncorrected QT-HR correlation being 0.82. Overall by far, Hodges QTc is significantly less correlated with HR compared to the others. Certain subgroup correlations of gender and low, mid, or high HR show that one individual formula can out-perform the others, whereby automated selection of QT correction formula based on the patient's HR and gender could be implemented as another option in products. The upper normal limits of corrected QTc were determined by excluding the top 2% from the global distribution charts as follows: Bazett 483 ms, Fridericia 460 ms, Framingham 457 ms, and Hodges 457 ms. Whether for males and/or females, the middle range of HR from 60 to 99 bpm has similar upper normal limits of QTc for all formulae except Bazett. Numerous references recommend 420 to 440 ms as the threshold for reporting prolonged QTc when using Bazett's formula. Based on this database, 30% of apparently normal ECGs would be reported as having abnormal QT intervals for the 440 ms threshold, or 10% if 460 ms is chosen, compared to Ͻ2% for the other formulae. It was also noted that QT has a linear trend with HR but not with RR.