Heart rate variability
Reduced heart rate variability carries an adverse prognosis in patients who have survived an acute myocardial infarction. This article reviews the physiology, technical problems of assessment, and clinical relevance of heart rate variability. The sympathovagal influence and the clinical assessment of heart rate variability are discussed. Methods measuring heart rate variability are classified into four groups, and the advantages and disadvantages of each group are described. Concentration is on risk stratification of postmyocardial infarction patients. The evidence suggests that heart rate variability is the single most important predictor of those patients who are at high risk of sudden death or serious ventricular arrhythmias.
Heart rate variability: a review
Heart rate variability (HRV) is a reliable reflection of the many physiological factors modulating the normal rhythm of the heart. In fact, they provide a powerful means of observing the interplay between the sympathetic and parasympathetic nervous systems. It shows that the structure generating the signal is not only simply linear, but also involves nonlinear contributions. Heart rate (HR) is a nonstationary signal; its variation may contain indicators of current disease, or warnings about impending cardiac diseases. The indicators may be present at all times or may occur at random—during certain intervals of the day. It is strenuous and time consuming to study and pinpoint abnormalities in voluminous data collected over several hours. Hence, HR variation analysis (instantaneous HR against time axis) has become a popular noninvasive tool for assessing the activities of the autonomic nervous system. Computer based analytical tools for in-depth study of data over daylong intervals can be very useful in diagnostics. Therefore, the HRV signal parameters, extracted and analyzed using computers, are highly useful in diagnostics. In this paper, we have discussed the various applications of HRV and different linear, frequency domain, wavelet domain, nonlinear techniques used for the analysis of the HRV.
Analysis of Heart Rate Variability
Spontaneous variability of heart-rate has been related to three major physiological originating factors: quasi-oscillatory fluctuations thought to arise in blood-pressure control, variable frequency oscillations due to thermal regulation, and respiration; frequency selective analysis of cardiac interbeat interval sequences allows the separate contributions to be isolated. Using this method, a laboratory and field study of the effects of mental work load on the cardiac interval sequence has been carried Out. Results suggest that mean heart rate and variance are unreliable measures, but that consistent changes in interval spectrum occur; these have been traced to alterations mainly in the 0·1 Hz region, perhaps originating with changes in the patterns of respiration which interact with the 0·1 Hz vasomotor activity.
Delayed Heart Rate Recovery and Exaggerated Blood Pressure Response during Exercise Testing in Nigerian Normotensive Diabetics
Aim: The aim of this study was to identify the clinical profile of normotensive Type 2 diabetes mellitus (T2DM) with exercise related exaggerated systolic blood pressure (ESBP) and delayed heart rate recovery (HRR); and explore if there is relationship between ESBP and delayed HRR in them.
Materials and Methods: A total of 67 normotensive T2DM subjects underwent symptom limited maximal treadmill exercise using Bruce protocol. ESBP was defined as a peak exercise systolic blood pressure (BP) ≥210 mmHg in men and ≥190 mmHg in women. HRR was defined as the difference in HR from peak exercise to 1 min in recovery; delayed HRR was defined as ≤12 beats/min. Parameters of 36 subjects with ESBP were then compared with those of 31 subjects without ESBP.
Results: There were 36 (53.7%) of the subjects with ESBP. Subjects with ESBP response had higher BMI, 2-hours post-prandial plasma glucose, resting SBP and DBP. Of those with ESBP, 41.7% were males and 58.3% were females (X2=8.75, P=0.003). HRR was lower in subjects with ESBP compared with those without (23.00 ± 12.18 vs 38.55±22.69 beats/minute; P =0.001). The presence of abnormal HRR was 30.6% in subjects with ESBP response compared with 9.7% in subjects without (X2= 4.39, P = 0.036).
Conclusion: ESBP response to exercise is present in more than half of normotensive diabetics and about a third of those patients with ESBP have delayed HRR. Imbalance in the autonomic nervous system, probably heightened sympathetic nervous system, may be responsible for these pathologies.
Comparative Study of Effect of Honey on Blood Pressure and Heart Rate in Healthy Male and Female Subjects
Aims: The aim of this study was to evaluate the effect of honey on blood pressure and heart rate on healthy male and female subjects.
Methodology: 20ml honey orally administered was evaluated in hundred healthy male and female subjects. Their basal systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were taken as the control values. After measuring their basal SBP, DBP and HR, 20ml of honey was orally administered and the systolic blood pressure, Diastolic blood pressure and heart rate were measured at 15, 30, 60 minutes with a digital sphygmomanometer and analogue sphygmomanometer as a check.
Results: The results of this study showed that mean SBP decreased (p=.05) significantly in female compared to male at control, after 15, 30 and 60 minutes of oral administration of 20ml of honey. DBP decreased (p=.05) significantly in female compared to male at control, after 15 minutes and 60 minutes of oral administration of 20ml of honey and HR decreased (p=.05) significantly in female compared to male at 60 minutes of oral administration of 20ml of honey. Conclusion: The effect of honey on systolic blood pressure, diastolic blood pressure and heart rate shows that it has a hypotensive effect in healthy male and female subjects.
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 Ajayi, E.A., Oyedeji, A.T. and Ajayi, A.O., 2016. Delayed Heart Rate Recovery and Exaggerated Blood Pressure Response during Exercise Testing in Nigerian Normotensive Diabetics. Cardiology and Angiology: An International Journal, pp.1-7.
 Olusola, A.E., Helen, O.T., Enobong, I.B. and Ezekiel, A.D., 2013. Comparative study of effect of honey on blood pressure and heart rate in healthy male and female subjects. Journal of Advances in Medicine and Medical Research, pp.2214-2221.