HR: what is it, transcript
The results of clinical and functional studies of the person, you can often find the abbreviation HR. It is acronym for the heart rate. This indicator is one of the main to evaluate the functional activity of the cardiovascular system.
The heart rate – what is it?
The main function of the heart is providing blood flow through the vessels. This is achieved by the rhythmic contractions of the myocardium (heart muscle), which leads to the ejection of blood from the cavities of the heart in the main vessels (aorta and pulmonary artery). Reduction of muscle fibers (systole) is provided by the generation of impulse in the nerve node the sinus pacemaker, which is localized in the right atrium. The pulses are propagated through a conducting system (represented by nerve fibers) reach of cardiomyocytes (cardiac muscle cells), forcing them to contract with appropriate rate and rhythm. The determination of the frequency of the beats is a mandatory routine study, which allows to evaluate the functional activity of the heart. For convenience, entries in medical records this indicator was reduced to the acronym curves.
How to measure the indicator?
To determine the number of beats, they are counting (the time of contraction of muscle fibers of the myocardium). This is done using several techniques:
- Counting the pulse – pulse wave is generated at the time of systole in the aorta due to stretching of the walls of the ventricle ejected blood volume (the walls of the arterial blood stream are characterized by a significant elasticity), it applies to smaller blood vessels and gradually fades away in the microvasculature. The pulse can be felt in the larger arterial vessels in the region of their passage near the bone. The most common is the measurement of the pulse at the radial artery, to which it is pressed against the bone in the wrist side of the thumb.
- Direct counting beats with the aid of auscultation during auscultation of the heart medical stethoscope at the time of myocardial contraction, you can define the tones (beats). The number indicator is determined.
- Palpation (probing) of the tissues in the region of the apex of the heart (usually to the left of the sternum, 2 cm below the left nipple), and the time of systole is felt in the form of aftershocks, the number of which the calculation of this indicator of the functional activity of the heart.
- Count the heart rate on the ECG is the most accurate method of determining the measure. In medicine, doctors-cardiologists use Holter monitoring, which is an ECG over a long period of time (usually 1 day) that allows to reveal the physiological and pathological deviations.
To determine the number of beats, its calculation is necessarily performed for a certain period of time. In modern medicine the heart rate expressed in number of beats per minute. It is necessary to calculate the frequency using one of the methods. Sometimes with the right heart-rate is counting beats for 30 seconds, and the result is then multiplied by 2.
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The norm indicator
Normal functional activity of the cardiovascular system and other organs is determined by the rate of heartbeats. The average values of the index vary in the range of 60 to 80 beats per minute. They have certain differences, depending on the age and gender of the person:
- In men this figure is slightly higher due to a more intense metabolism and high muscle mass.
- In children the frequency is higher than in adults. The younger the child, the higher the figure. In newborns, a heart rate in the rate may reach 180 beats per minute. While performing the ultrasound examination of the fetus of a pregnant woman today, there is a method, enabling to determine the baby’s gender on heart rate.
The normal deviation of the heart rate also have a functional origin. Alone are always smaller than a physical or emotional burden. To detect pathological deviations of the functional activity of the body defining the norms of heart rate and respiratory rate (respiratory rate), as these indicators have a close relationship.
Depending on changes in the number of beats there are several results that are determined by the following medical terms:
- Tachycardia – a significant increase in the number of beats above normal. The maximum frequency can reach values of 200 beats per minute, which is a very dangerous condition requires therapeutic correction. Before you can reduce this figure with the help of medications, doctor must determines the functional state of other organs and systems, and also clarifies the reason for the tachycardia. Submaximal frequency can be a normal variant associated with increased activity of the body (after physical exertion).
- Bradycardia – a decrease in the number of beats below normal, which may be due to the influence of cardiac and noncardiac causes.
During the Holter monitoring will be determined on the circadian index, representing the value of the cyclical indicator. The circadian index is lowered in the presence of cardiac causes changes in the frequency of the beats, and increased over-stimulation of the sympathetic part of the autonomic nervous system. A doctor with a decreased frequency of heart contractions can make a preliminary conclusion about the nature, character and localization of functional or organic changes in the body. Depending on the severity change indicator, it may make the Outlook for further changes in the functional state of the heart.