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Information about Heart Rate

Age Normal heart rate
(beats per minute)[1]
newborn130
3 months150
6 months135
1 year125
2 years115
3 years100
4 years100
6 years100
8 years90
9 years95
12 years85
Adult60-100
Heart rate is a term used to describe the frequency of the cardiac cycle. It is considered one of the four vital signs. Usually it is calculated as the number of contractions (heart beats) of the heart in one minute and expressed as "beats per minute" (bpm). See "Heart" for information on embryofetal heart rates. The heart beats up to 120 times per minute in childhood.

When resting, the average adult human heart beats at about 70 bpm (males) and 75 bpm (females); however, this rate varies among people and can be significantly lower in athletes. The infant/neonatal rate of heartbeat is around 130-150 bpm, the toddler's about 100–130 bpm, the older child's about 90–110 bpm, and the adolescent's about 80–100 bpm.

The pulse is the most straightforward way of measuring the heart rate, but it can be deceptive when some heart beats do not have much cardiac output. In these cases (as happens in some arrhythmias), the heart rate may be considerably higher than the pulse rate.

Auscultation is also a method of heart rate measurement.

Control of heart rate

The heart contains two cardiac pacemakers that spontaneously cause the heart to beat. These can be controlled by the autonomic nervous system and circulating adrenaline. The vagus nerve (which is pneumogastric nerve or cranial nerve X) which governs heart rate can be controlled through breathing. Heart rate variability (HRV) is the variation of beat-to-beat intervals. A healthy heart has a large HRV, while decreased or absent variability may indicate cardiac disease. HRV also decreases with exercise-induced tachycardia. HRV has been the focus of increased research to use it as a physiological marker to classify different pathological disorders.

One aspect of heart rate variability can be used as a measurement of fitness, specifically the speed at which one's heart rate drops upon termination of vigorous exercise. The speed at which a person's heart rate returns to resting is considerably faster for a fit person than an unfit person. A drop of 19 beats in a minute is typical for a healthy person. A drop of less than 12 beats per minute after maximal exercise has been correlated with a significant increase in mortality [2].

Measuring heart rate

Enlarge picture
Measuring the pulse at the neck and wrist


The pulse rate (which in most people is identical to the heart rate) can be measured at any point on the body where an artery's pulsation is transmitted to the surface - often as it is compressed against an underlying structure like bone. Some commonly palpated sites are as listed.
  1. The inside of the wrist on the side of the thumb (radial artery) , (and less commonly ulnar artery on the pinky side which is deeper and harder to palpate )
  2. The neck (carotid artery),
  3. The inside of the elbow, or under the biceps muscle (brachial artery)
  4. The groin (femoral artery),
  5. Behind the medial malleolus on the feet (posterior tibial artery)
  6. Middle of dorsum of the foot (dorsalis pedis).
  7. Behind the knee (popliteal artery)
  8. Over the abdomen (abdominal aorta)
  9. The chest. (aorta)This can be felt with one's hands or fingers but it is possible to auscultate the heart by utilizing a stethoscope.


''NOTE: The thumb should never be used for measuring heart rate, as its strong pulse may interfere with discriminating the site of pulsation, and you may count the thumb's pulse accidentally when measuring'[3]

Producing an electrocardiogram, or ECG (also abbreviated EKG), is one of the most precise methods of heart rate measurement. Continuous electrocardiographic monitoring of the heart is routinely done in many clinical settings, especially in critical care medicine. Commercial heart rate monitors are also available, consisting of a chest strap with electrodes. The signal is transmitted to a wrist receiver for display. Heart rate monitors allow accurate measurements to be taken continuously and can be used during exercise when manual measurement would be difficult or impossible (such as when the hands are being used).

Maximum heart rate

Maximum heart rate (also called MHR, or HRmax) is the maximum heart rate that a person should achieve during maximal physical exertion. Research indicates it is most closely linked to a person's age; a person's HRmax will decline as they age. [4] People who have participated in sports and athletic activities in early years will have a higher MHR than those less active as children.

Measuring HRmax

Enlarge picture
Fox and Haskell formula
The most accurate way of measuring HRmax for an individual is via a cardiac stress test. In such a test, the subject exercises while being monitored by an electrocardiogram (ECG). During the test, the intensity of exercise is periodically increased (if a treadmill is being used, through increase in speed or slope of the treadmill) until the subject can no longer continue, or until certain changes in heart function are detected in the ECG (at which point the subject is directed to stop). Typical durations of such a test range from 10 to 20 minutes. Since the HRmax declines with age, this test does not hold permanent value.

Conducting an accurate maximal exercise test requires expensive equipment, and should only be performed in the presence of medical staff due to risks associated with high heart rates. Instead, people typically use predictive formulae to estimate their individual Maximum Heart Rate. The most common formula encountered is:

HRmax = 220 − age (can vary)


This is attributed to various sources, often "Fox and Haskell". While the most common (and easy to remember and calculate), this particular formula is not considered by some to be a good predictor of HRmax.

A 2003 study [1] of 43 different formulae for HRmax (including the one above) concluded the following:

1) No "acceptable" formula currently existed, (they used the term "acceptable" to mean acceptable for both prediction of , and prescription of exercise training HR ranges)

2) The most accurate formula of those examined was:

HRmax = 205.8 − (0.685 * age)


This was found to have a standard of error that, although large (6.4 bpm), was still deemed to be acceptable for the use of prescribing exercise training HR ranges.

Other often cited formulae are:

HRmax = 206.3 − (0.711 * age)


(Often attributed to "Londeree and Moeschberger from the University of Missouri–Columbia")

HRmax = 217 − (0.85 * age)


(Often attributed to "Miller et al. from Indiana University")

Sally Edwards, CEO of Heart Zones proposes a set of gender specific formula for predicting Maximum Heart Rate.[5]

For males: 210 - 1/2 your age - 5% of total body weight (in pounds) + 4 = HRmax


For females: 210 - 1/2 your age - 5% of total body weight (in pounds) + 0 = HRmax


These figures are still dependent on physiology and fitness - for example an endurance runner's rates will typically be lower due to the increased size of the heart required to support the exercise, while a sprinter's rates will be higher due to the improved response time and short duration.

Recovery heart rate

The recovery heart rate is that taken 2–10 minutes after exercise. It is measured over a 15-second sampling interval. The goal is not to exceed 150 Bpm. NOTE: The thumb should never be used for measuring heart rate, as it has a pulse of its own.[2] A drop of 20 beats in a minute is typical for a healthy person. A drop of less than 12 beats per minute after maximal exercise has been correlated with a significant increase in mortality [3].

Target heart rate

Target heart rate (THR), or training heart rate, is a desired range of heart rate reached during aerobic exercise which enables one's heart and lungs to receive the most benefit from a workout. This theoretical range varies based on one's physical condition, age, and previous training. Below are two ways to calculate one's Target Heart Rate. In each of these methods, there is an element called "intensity" which is expressed as a percentage. THR can be calculated by using a range of 50%–85% intensity.

Karvonen method

The Karvonen method factors in Resting Heart Rate (HRrest) to calculate Target Heart Rate (THR):

THR = ((HRmax – HRrest) × %Intensity) + HRrest


Example for someone with a HRmax of 180 and a HRrest of 70:
50% intensity: ((180 − 70) × 0.50) + 70 = 125 bpm
85% intensity: ((180 − 70) × 0.85) + 70 = 163 bpm

Zoladz method

An alternative to the Karvonen method is the Zoladz method, which derives exercise zones by subtracting values from HRmax.

THR = HRmax – Adjuster ± 5 bpm
:Zone 1 Adjuster = 50 bpm
:Zone 2 Adjuster = 40 bpm
:Zone 3 Adjuster = 30 bpm
:Zone 4 Adjuster = 20 bpm
:Zone 5 Adjuster = 10 bpm


Example for someone with a HRmax of 180:
Zone 1 (easy exercise) : 180 - 50 = 130; ± 5 → 125 to 135 bpm
Zone 4 (tough exercise): 180 - 20 = 160; ± 5 → 155 to 165 bpm

Heart rate reserve

Heart rate reserve (HRR) is a term used to describe the difference between a person's measured or predicted maximum heart rate and resting heart rate. Some methods of measurement of exercise intensity measure percentage of heart rate reserve. Additionally, as a person increases their cardiovascular fitness, their HRrest will drop, thus the heart rate reserve will increase. Percentage of HRR is equivalent to percentage of VO2 reserve.

HRR = HRmax − HRrest

Heart rate abnormalities

Tachycardia

Main article: Tachycardia


Tachycardia is a resting heart rate more than 100 beats per minute. This number can vary as smaller people and children have faster heart rates than adults.

Bradycardia

Main article: Bradycardia


Bradycardia is defined as a heart rate less than 60 beats per minute although it is seldom symptomatic until below 50 bpm. Trained athletes tend to have slow resting heart rates, and resting bradycardia in athletes should not be considered abnormal if the individual has no symptoms associated with it. Again, this number can vary as smaller people and children have faster heart rates than adults.

Miguel Indurain, a cyclist and five times Tour de France winner, had a resting heart rate of 28 beats per minute, one of the lowest ever recorded in a healthy human.[6]

See also

References

1. ^ Daniel Limmer and Michael F. O'Keefe. 2005. Emergency Care 10th ed. Edward T. Dickinson, Ed. Pearson, Prentice Hall. Upper Saddle River, New Jersey. Page 214.
2. ^ Erna Obenza Nishime, MD; Christopher R. Cole, MD; Eugene H. Blackstone, MD; Fredric J. Pashkow, MD; Michael S. Lauer, MD: "Heart Rate Recovery and Treadmill Exercise Score as Predictors of Mortality in Patients Referred for Exercise ECG", JAMA, 2000;284:1392-1398
3. ^ Regulation of Human Heart Rate. Serendip. Retrieved on June 27, 2007.
4. ^ Physical Activity for Everyone. Department of Health and Human Services, Centers for Disease Control and Prevention. Retrieved on May 1, 2007.
5. ^ Fitness Tips Sally Edwards. Retrieved on June 27, 2007.
6. ^ Cardiac Output. LiDCO Ltd. Sales and Marketing. Retrieved on May 1, 2007.
Cardiac cycle is the term referring to all or any of the events related to the flow of blood that occur from the beginning of one heartbeat to the beginning of the next.[1] The frequency of the cardiac cycle is the heart rate.
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Vital signs are often taken by health professionals in order to assess the most basic body functions. Vital signs are an essential part of a case presentation.

Primary four

There are four vital signs which are standard in most medical settings:
  1. Body Temperature

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heart is a muscular organ responsible for pumping blood through the blood vessels by repeated, rhythmic contractions, or a similar structure in the annelids, mollusks, and arthropods.
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minute is a unit of time equal to 1/60th of an hour and to 60 seconds. (Some rare minutes have 59 or 61 seconds; see leap second.)

The minute is not a SI unit, however it is accepted for use with SI units. The correct abbreviation for minute or minutes is "min".
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heart is a muscular organ responsible for pumping blood through the blood vessels by repeated, rhythmic contractions, or a similar structure in the annelids, mollusks, and arthropods.
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Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
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In medicine, a person's pulse is the throbbing of their arteries as an effect of the heart beat. It can be felt at the neck (carotid artery), at the wrist (radial artery), behind the knee (Popliteal artery), on the inside of the elbow (Brachial artery), near the ankle joint
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Cardiac arrhythmia
Classification & external resources

Ventricular Fibrillation or V-Fib, an example of cardiac arrhythmia.
ICD-10 I 47. - I 49.
ICD-9 427

DiseasesDB 15206
MedlinePlus 001101

MeSH D001145 Cardiac arrhythmia
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For the ancient monasterial worker, see Auscultare


Auscultation is the technical term for listening to the internal sounds of the body, usually using a stethoscope.
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pacemaker cells, and they directly control the heart rate. Artificial devices also called pacemakers can be used after damage to the body's intrinsic conduction system to produce these impulses synthetically.
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autonomic nervous system (ANS) (or visceral nervous system) is the part of the peripheral nervous system that acts as a control system, maintaining homeostasis in the body. These maintenance activities are primarily performed without conscious control or sensation.
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Epinephrine (INN) (IPA: [ˌɛpɪˈnɛfrən]) or adrenaline (European Pharmacopoeia and BAN) (IPA: [əˈdrɛnələn]
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The vagus nerve (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem (within the medulla oblongata) and extends, through the jugular foramen, down below the head, to the
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Tachycardia
Classifications and external resources

ICD-10 R 00.0
ICD-9 785.0

MeSH D013610 Tachycardia is a form of cardiac arrhythmia which refers to a rapid beating of the heart.
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In medicine, a person's pulse is the throbbing of their arteries as an effect of the heart beat. It can be felt at the neck (carotid artery), at the wrist (radial artery), behind the knee (Popliteal artery), on the inside of the elbow (Brachial artery), near the ankle joint
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Arteries are muscular blood vessels that carry blood away from the heart.[1] All arteries, with the exception of the pulmonary and umbilical arteries, carry oxygenated blood.

The circulatory system is extremely important for sustaining life.
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wrist is the flexible and narrower connection between the forearm and the palm. The wrist is essentially a double row of small short bones, called carpals, intertwined to form a malleable hinge.
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In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm.

Course

The radial artery arises from the bifurcation of the brachial artery in the cubital fossa.
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The ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspect of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial artery.
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Palpation is used as part of a physical examination in which an object is felt (usually with the hands of a healthcare practitioner) to determine its size, shape, firmness, or location.
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The neck is the part of the body on many limbed vertebrates that distinguishes the head from the torso or trunk.

Anatomy of the human neck

Bony anatomy: The cervical spine

The cervical portion of the human spine
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In human anatomy, the common carotid artery is an artery that supplies the head and neck with oxygenated blood; it divides in the neck to form the external and internal carotid arteries.
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elbow-joint is a ginglymus or hinge joint. Three bones form the elbow joint: the humerus of the upper arm, and the paired radius and ulna of the forearm.

The bony prominence at the very tip of the elbow is the olecranon process of the ulna.
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The brachial artery is the major blood vessel of the upper arm.

It is a continuation of the axillary artery and it originates from the lower margin of teres major muscle and continues down the arm, until it reaches the cubital fossa at the elbow.
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The groin is the at the junction of the torso with the legs and the adjacent region that includes the external genitals. The term may be used as a euphemism for genitals, since the names of the latter are taboo words in some cultures.
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The femoral artery is a large artery in the muscles of the thigh.

Structure

The femoral artery is a continuation of the external iliac artery, which comes from the abdominal aorta.
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medial malleolus.
  • The medial surface of this process is convex and subcutaneous;
  • its lateral or articular surface is smooth and slightly concave, and articulates with the talus;
  • its anterior border

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The posterior tibial artery of the lower limb carries blood to the posterior compartment of the leg and plantar surface of the foot, from the popliteal artery. It is accompanied by a deep vein, the posterior tibial vein, along its course.
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Dorsum (plural Dorsa) is a Latin word. In science, it could mean:
  • Dorsum (biology), a term for an animal's back
  • Dorsum (astrogeology), a term used in astrogeology for a ridge http://planetarynames.wr.usgs.gov/jsp/append5.

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In human anatomy, the dorsalis pedis artery (dorsal artery of foot), is a blood vessel of the lower limb that carries oxygenated blood to the dorsal surface of the foot. It arises at the anterior aspect of the ankle joint and is a continuation of the anterior tibial artery.
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