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Heart rate is the frequency of the heartbeat measured by the number of contractions of the heart per minute ( beats per minute, or bpm). The heart rate varies according to the body's physical needs, including the need to absorb oxygen and excrete carbon dioxide. It is also modulated by numerous factors, including (but not limited to) genetics ...
Heart rate variability ( HRV) is the physiological phenomenon of variation in the time interval between heartbeats. It is measured by the variation in the beat-to-beat interval. Other terms used include "cycle length variability", "R–R variability" (where R is a point corresponding to the peak of the QRS complex of the ECG wave; and R–R is ...
The crude death rate is defined as "the mortality rate from all causes of death for a population," calculated as the "total number of deaths during a given time interval" divided by the "mid-interval population", per 1,000 or 100,000; for instance, the population of the U.S. was around 290,810,000 in 2003, and in that year, approximately 2,419,900 deaths occurred in total, giving a crude death ...
The QT interval is a measurement made on an electrocardiogram used to assess some of the electrical properties of the heart.It is calculated as the time from the start of the Q wave to the end of the T wave, and approximates to the time taken from when the cardiac ventricles start to contract to when they finish relaxing.
The Kaplan–Meier estimator is one of the most frequently used methods of survival analysis. The estimate may be useful to examine recovery rates, the probability of death, and the effectiveness of treatment. It is limited in its ability to estimate survival adjusted for covariates; parametric survival models and the Cox proportional hazards ...
The interval between two successive R waves (the RR interval) is a measure of the heart rate. The heart rate normally varies slightly: during a deep breath, it speeds up and during a deep exhalation, it slows down. (The RR interval will shorten when the heart speeds up, and lengthen when it slows.) An RR tachograph is a graph of the numerical ...
Cardiac index ( CI) is a haemodynamic parameter that relates the cardiac output (CO) from left ventricle in one minute to body surface area (BSA), [1] thus relating heart performance to the size of the individual. The unit of measurement is litres per minute per square metre (L/min/m 2 ).
In cardiac physiology, cardiac output ( CO ), also known as heart output and often denoted by the symbols , , or , [ 2] is the volumetric flow rate of the heart 's pumping output: that is, the volume of blood being pumped by a single ventricle of the heart, per unit time (usually measured per minute). Cardiac output (CO) is the product of the ...