Heart rate variations

B. Neubauer and H. J. G. Gundersen, Analysis of heart rate variations in patients with multiple sclerosis. A simple measure of autonomic disturbances using an ordinary ECG. J. Neurol. Neuosurg. Psychiatry 41, 417—419 (1978). 

With innervation intact, the circulation at rest maintains constant ventricular stroke volume and blood pressure, on average. In addition, the regulation of cardiac output is accomplished primarily through the control of peripheral resistance. Then, the slow changes in heart rate ( ) are directly related to cardiac output (CO) and inversely to peripheral resistance (Rs), so that, fh oc CO oc 1/Rg [Berne and Levy, 1977]. This relationship is fundamental to the vascular theory of heart rate variation [Hering, 1924] and underscores the role of a time varying peripheral resistance. In this chapter, the dynamics of peripheral resistance control is examined analytically as an explanation of the very low frequency variation in heart rate. 

Based on embedded pulse rate sensor on steering wheel the low frequency to high frequency ratio of heart rate variation, or say pulse rate, in frequency domain is suggested as an indicator for drowsiness detection in [4]. With predefined Low Frequency band 0.04-0.15 Hz (LF) and High Frequency band 0.15-0.4 Hz (HF) the LF/HF ratio of pulse rate course within a measurement time frame is computed. The mean value of pulse rate is taken up in feature computation as well. 

There have been a number of clinical trials involving the inhalation of lavender essential oil that indicate a reduction in anxiety and stress (e.g., Motomura et al, 2001 Toda and Morimoto, 2008 Kritsidima et al., 2010). One study employing oral lavender essential oil in 100 and 200 pL capsules found that heart rate variation signi cantly increased compared to placebo while watching an anxiety-provoking Im. This suggested that lavender had anxiolytic effects under conditions of low anxiety (Bradley et al., 2009). 

Another industry focus relates to the detector with more and more rows added. A complete Ccffdiac dataset can nowadays be acquired in less than 6 sec with detector sizes >8 cm in z-direction. This renders the method less susceptible to arrhythmia and heart rate variations. The best, currently available, solution operates at a detector size of 16 cm covering the heart at a single rotation, albeit compromising on temporal resolution. 

The QT interval is a dynamic physiological variable depending on multiple factors such as cardiac cycle length (heart rate), autonomic nervous system activity, age, gender, plasma electrolyte concentrations, genetic variations in ion channels involved in cardiac repolarization. In addition, circadian and seasonal variations of the QT interval have been described [93]. 

Accompanying the variations in heart anatomy are variations in function as well. In a series of 182 normal young men8 it was found that the heart rates ranged from 45 to 105 beats per minute. The pumping capacities of normal hearts vary from 3.16 to 10.81 liters of blood per minute.9... 

Decreases in heart rate and cardiac output are the most obvious results of administration of p-blockers. Initially, blood pressure is not much affected, since peripheral vascular resistance will be reflexly elevated as a result of the drug-induced decrease in cardiac output. The reduction of blood pressure that occurs in chronic treatment correlates best with changes in peripheral vascular resistance rather than with a drug-induced variation in heart rate or cardiac output. 

Flushing, sweating, pruritus, disorientation, headache, dizziness, hyperactivity convulsions, dyspnea, cough, tachypnea, hiccough, rebound hypoventilation, phlebitis, variations in heart rate, arrhythmias, chest pain, nausea, vomiting, diarrhea, stimulation of urinary bladder with spontaneous voiding. 

Specifically, blood pressure rises by about 25%, and the heart rate is increased in the area of 20%. There is wide variation in the kinds of responses individuals can have to the drug, and occasionally, alarming increases in blood pressure can occur. 

Given this proviso (that maximum bradycardia values are similar in laboratory or field situations), the data indicate that the lowest heart rates observed during diving (maximum bradycardia) show little variation within pinnipeds (figure 4.6). As one of our colleagues put it all pinnipeds seem to be able to suppress heart rate down to the rock bottom PIC analysis of these data indicated that... 

The heart rates of the volunteers given no Injection, injections of sterile water, or injections of 750 og of P2S had closely similar variations with time. The graphs of heart rate after injections of 2 mg of atropine sulfate, of 2 mg of atropine sulfate and 500 mg of P2S, and of 2 mg of atropine sulfate and 750 mg of P2S followed closely similar courses with time after injection. These were distinctly different from the first set of lines. 

Pethidine 50 mg plus promethazine 25 mg given intravenously to 14 mothers in labor caused a significant change in fetal heart rate indices 40 minutes after administration (18). There were significant changes in fetal heart rate acceleration of at least 10 beats/minute, acceleration of at least 15 beats/minute, time spent in episodes of high variation, and short-term variation. 

For most species it has been shown that the duration of the QT interval is inversely related to the heart rate.51 Thus, any changes in the raw QT interval must be carefully interpreted and corrected for this physiological variation to isolate the drug-induced component from the QT interval modulation. Since the QT interval has a rate-dependent nature, various mathematical formulae were developed to adjust this variable for values obtained at different heart... 

Cannabinoids are able to cause different effects at the level of various systems and/or organs the most important effects occur on the central nervous system and on the cardiovascular system. In fact, they are able to affect mood, memory, motor coordination and cognition, and they increase heart rate and variate the systemic arterial pressure. Furthermore, it is well known the capability of cannabinoids to reduce intraocular pressure and to affect the respiratory and endocrine systems (L. E. Hollister, Health Aspects of Cannabis, Pharmacological Reviews, 38,1-20,1986). More recently, it was found that they suppress the cellular and humoral immune response and have antiinflammatory properties (A. W. Wirth et al.. Antiinflammatory Properties of Cannabichromene, Life Science, 26,1991-1995,1980). 

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