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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 ...
Arrhythmias, also known as cardiac arrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. [ 2] A resting heart rate that is too fast – above 100 beats per minute in adults – is called tachycardia, and a resting heart rate that is too slow – below 60 beats per minute – is called bradycardia. [ 2]
See media help. The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. [ 1] It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, called systole. [ 1]
The rate at which these impulses fire controls the rate of cardiac contraction, that is, the heart rate. The cells that create these rhythmic impulses, setting the pace for blood pumping, are called pacemaker cells, and they directly control the heart rate. They make up the cardiac pacemaker, that is, the natural pacemaker of the heart.
A normal resting heart rate is 60 to 100 beats per minute. A resting heart rate of more than 100 beats per minute is defined as a tachycardia. During an episode of SVT, the heart beats about 150 to 220 times per minute. [9] Specific treatment depends on the type of SVT [5] and can include medications, medical procedures, or surgery. [5]
Claudius Galen was perhaps the first physiologist to describe the pulse. [1] The pulse is an expedient tactile method of determination of systolic blood pressure to a trained observer. Diastolic blood pressure is non-palpable and unobservable by tactile methods, occurring between heartbeats. Pressure waves generated by the heart in systole move ...
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 ...
Beat (acoustics) In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies. With tuning instruments that can produce sustained tones, beats can be readily recognized.