heart rate measurement.pptx
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Heart Rate Measurement
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Heart Rate Phases
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Heart Beat The heart generates its own electrical impulse
The cardiac electrical signal controls:
the number of electrical impulses ( heart rate)
It triggers the heart muscle to contract in the correct
sequence as it spreads across the heart
Lubb-dubb heart sounds are caused by closing of heart valves Valves of the heart close when heart contracts to prevent
blood from flowing back into the ventricles3
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Heart Beat
Steps:
1. Atria relax, fill with blood Diastole
2. Atria pushes blood into ventricle3. Ventricles contract, pushing blood into arteries Systole
Increased pressure during systole causes AV valves to close
lubb sound Ventricles relax, pressure decreases, causes Semilunar valves
to close dubb sound 4
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Heart Rate
It is a Speed of heartbeat
The number of heartbeats per unit of time
The heart rate is typically expressed as beats per minute(bpm).
The heart rate can vary according to the body's physical
needs, including the need to absorb oxygen and excrete
carbon dioxide.5
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Average Heart Rate
The normal heart rate ranges from 60 100 bpm
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It is below 60 bpm, refers to slow heart rate
- Bradycardia It is above 100 bpm, refers to fast heart rate
- Tachycardia
If Heart rate is not regular in a regular pattern, this is referred
as,
- Arrhythmia.
Activities that can provoke change include physical exercise,
sleep, illness, ingesting, and drugs. 7
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Measurement
Heart rate is measured by finding the pulse of the heart.
This pulse rate can be found at any point on the body
where the artery's pulsation is transmitted to thesurface.
The radial artery is the easiest to use to check the heart
rate.
For emergency situations the most reliable arteries to
measure heart rate are carotid arteries.8
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ECG
Electrical activity of the heart is measured using an
electrocardiograph:
Instrument that detects electrical activity of the heart
Electrocardiograph produces electrocardiogram (ECG or EKG)
Graphical record of heart rate and rhythm
A more precise method of determining pulse involves the useof an electrocardiograph, or ECG (also abbreviated EKG).
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ECG
An ECG the heart rate is measured using the R wave to R
wave interval (RR interval).
Additionally pulse oximeters measure heart rate by pulsedetection.
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http://en.wikipedia.org/wiki/File:ECG-RRinterval.svghttp://en.wikipedia.org/wiki/File:ECG-RRinterval.svg -
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Basal heart rate
The basal or resting heart rate (HR rest ) is measured while
the subject is relaxed but awake.
The typical resting heart rate in adults is 60 80 beats perminute (bpm) .
This is the firing rate of the heart Sinoatrial Node (SAN),
where are located the faster heart pacemaker cells
driving the self-generated rhythmic firing and
responsible for the cardiac muscle automaticity 11
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Maximum heart rate
The most accurate way of measuring HR max is via a cardiacstress test.
In such a test, the subject exercises while being monitored by
an ECG. During the test, the intensity of exercise is periodically
increased through increasing speed or slope of the treadmill ,
continuing until certain changes in heart function are
detected in the ECG, at which point the subject is directed to
stop.12
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Stethoscopes
Stethoscopes are used to transmit heart sounds from chest
wall to the human ear.
When the stethoscopes chest piece is firmly applied, low
frequencies are attenuated more then high frequencies.
the stethoscopes is in shape of a bell and it makes contact
with skin which serves as the diaphragm at the bell rim.
The diaphragm becomes taut with pressure, thereby low
frequencies are attenuated.13
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AED (automated external defibrillator)
Machine that delivers electric shock to the heart to restart
the heart
Used when:
Heart contractions are not coordinated and muscles are quivering not
contracting (ventricular fibrillation)
Heart rate is abnormal (cardiac arrhythmia)
Heart rate is too fast (ventricular tachycardia)
Improves survival rates by up to 30% if delivered in the first
few minutes.14
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