Download A normal pulse is regular in rhythm and force. In healthy patients

Guide to prepare for the module
control on the physiology of the
cardiovascular system
Recording and analysis of ECG.
Electrocardiography (ECG or EKG from Greek: kardia, meaning heart) is the recording of the electrical
activity of the heart. Traditionally this is in the form of a transthoracic (across the thorax or chest) interpretation
of the electrical activity of the heart over a period of time, as detected by electrodes attached to the surface of the
skin and recorded or displayed by a device external to the body.
An electrocardiogram (EKG or ECG) is done to:

Check the heart's electrical activity.

Find the cause of unexplained chest pain, which could be caused by a heart attack, inflammation of
the sac surrounding the heart (pericarditis), or angina.

Find the cause of symptoms of heart disease, such as shortness of breath, dizziness, fainting, or rapid,
irregular heartbeats (palpitations).

Find out if the walls of the heart chambers are too thick (hypertrophied).

Check how well medicines are working and whether they are causing side effects that affect the
heart.

Check how well mechanical devices that are implanted in the heart, such as pacemakers, are working
to control a normal heartbeat.

Check the health of the heart when other diseases or conditions are present, such as high blood
pressure, high cholesterol, cigarette smoking, diabetes, or a family history of early heart disease.
Fig. 1. Positioning of the electrodes during ECG in the three standard bipolar limb leads and chest leads.
2. Positioning of the electrodes during ECG (see fig. 1)
In the three standard bipolar limb leads:
The first lead:
left hand – right hand
The second lead:
right hand – left leg
The third lead:
2
left hand – left leg
Augment unipolar limb leads:
aVL – active electrode on the left hand
aVR – active electrode on the right hand
aVF – active electrode on the left leg
Chest leads (active electrodes are placed):
V1 - in the fourth intercostal space on the right edge of the sternum
V2 - in the fourth intercostal space at the left edge of the sternum
V3 - midway between the second and fourth positions
V4 - in the fifth intercostal space at the left midclavicular line
V5 - at the same level on the left anterior axillary line
V6 – at the same level on the left mid-axillary line
The chest unipolar leads characterize the heart electromotive force on the horizontal plane.
3. ECG components (see fig. 2):
Normal ECG tracings consist of waveform components that indicate electrical events during one heart beat.
1.
Isoelectrical line (isoline) – horizontal sections of ECG
2.
Positive (upward) waves are the ECG rises above the isoline. P, R, T are positive waves.
3.
Negative (downward) waves are the ECG falls below the isoline. Q, S are negative waves.
4.
Segment is a section of the isoline between two waves:

PQ-segment is a section of the isoline between the waves P & Q

ST-segment is a section of the isoline between the waves S & T

ТР-segment is a section of the isoline between the waves Т & Р.
Interval – a complex of a wave and a segment or a segment and a wave.

PQ-interval is from the P-wave beginning to the Q-wave beginning (includes P-wave and PQsegment) The duration of PQ-interval varies from 0.12 to 0.20 sec.

ST-interval is from the S-wave end to the T-wave (includes ST-segment and T-wave).

QRST-complex (corresponds to the electrical systole). Its duration is from the Q-wave beginning to
the T-wave end. The QRS complex indicates the ventricular depolarization, T-wave indicates the ventricular
repolarization.
Fig. 2. The main ECG components.
4. Isoelectric line is recorded when there is no potential difference in the heart.
5. Р-wave indicates an atrial depolarization (the ascendant part of P-wave indicates the depolarization of right
atrium and the descendant part of P-wave indicates the depolarization of left atrium). ECG doesn’t indicate an
atrial repolarization because this process fits in with the ventricular depolarization (QRS-complex). The P-wave
duration is not above 0.1 sec, its amplitude is 0.15 – 0.25 mV.
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6. Q-wave reflects the interventricular septum depolarization. Its amplitude is 1/4 of R-wave in the same lead,
and its duration is 0.03 sec.
7. R-wave reflects spreading of the excitative impulse to the left ventricular and right one and the
depolarization of the outer layers of the myocardium and the cardiac apex. Its amplitude is 2 mV at most.
8. S-wave indicates the depolarization of the outer layers of the ventricular myocardium at the base of the
heart. Its amplitude is 2 mV at most but ranges depending on the lead. In the standard limb leads the S-wave
amplitude is not above 1/3 R-wave.
9. Т-wave indicates the ending rapid ventricular repolarization. Its amplitude is not above 0.5 – 0.6 mV in the
standard limb leads (not above 1/2 R-wave), its duration is 0.16 – 0.24 sec.
10. Sometimes U-wave occurs in 0.02 – 0.04 sec after the T-wave. The U-wave indicates the recovery of the
Purkinje conduction fibers. This wave component may not be observable.
11. РQ-segment indicates the AV node depolarization. The РQ-segment duration is 0.1  0.02 sec and
corresponds to the AV delay duration.
12. РQ-interval (see fig. 2) reflects the period of the atrial and AV node depolarization. The РQ-interval
duration varies from 0.12 to 0.20 sec.
13. SТ-segment (see fig. 2) corresponds to the period of the total ventricular depolarization. At this moment
the potential difference of the heart is very small that’s why the ST-segment is situated on the isoline and its
shifts from the isoline to up and down are not above 0.05 mV.
14. Calculation of the wave amplitudes.
To find the wave amplitude you should measure the height of a wave in millimeters (the distance from the
isoline to the peak of the wave). The calibration signal is 1 mV in 10 mm. That’s why 1mm = 0.1 mV. The
amplitude of the wave is calculated by the equation:
Amplitude of the wave (mV) = height of the wave (mm) * 0.1mV
15. Calculation of heart rate.
1.
Determine the sum of five typical RR intervals in mm. Divide this sum into 5.
2.
Knowing that the velocity of ECG tape is 50 mm/sec the distance in 1 mm of the ECG-tape
corresponds to 0.02 sec. Therefore the average duration of one heart cycle is calculated by the equation:
The average duration of one heart cycle = the average RR-interval (mm) * 0.02sec/mm
3.
Heart rate equation:
Heart rate = 60 sec : the average duration of one heart cycle (sec)
16. Analysis of ECG allows to determine:

location of pacemaker

velocity of conduction in atrii, AV node, bundle of His and Purkinje fibers, ventricles.
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Blood pressure measurement
Basic definitions
Blood pressure
Force exerted by blood against a vessel wall
•
Depends on
•
Volume of blood forced into the vessel
•
Compliance (distensibility) of vessel walls
Systolic pressure
•
Peak pressure exerted by ejected blood against vessel walls during cardiac systole
•
Averages 120 mm Hg
Diastolic pressure
•
Minimum pressure in arteries when blood is draining off into vessels downstream
•
Averages 80 mm Hg
Pulse pressure
•
Difference between systolic and diastolic pressures. The normal rate 30-40 mm Hg.
•
Increases when stroke volume increases or vascular compliance decreases
•
Pulse pressure can be used to take a pulse to determine heart rate and rhythmicity
Arterial blood pressure
•
Blood pressure in elastic arteries near the heart is pulsatile (BP rises and falls)
•
Pulse pressure – the difference between systolic and diastolic pressure
•
Mean arterial pressure (MAP) – pressure that propels the blood to the tissues
•
MAP = diastolic pressure + 1/3 pulse pressure
In order to obtain accurate data with the indirect blood pressure methods that are used in surveys, it is
important to follow the prescribed procedures precisely.
There are three types of sphygmomanometers used to measure blood pressure: mercury, aneroid,
and digital.
Equipment
For survey blood pressure measurements the following equipment is required


simple aneroid sphygmomanometer with a cuff
stethoscope
Measurement procedures
Preparation for measurement
Before the blood pressure measurement begins the following conditions should be met:
1. Subjects should abstain from eating, drinking (anything else than water), smoking and taking drugs
that affect the blood pressure one hour before measurement.
2. Because a full bladder affects the blood pressure it should have been emptied.
3. Painful procedures and exercise should not have occurred within one hour.
4. Subject should have been sitting quietly for about 5 minutes.
5. Subject should have removed outer garments and all other tight clothes. The sleeve of shirts, blouses,
etc. should have been rolled up so that the upper right arm is bare. The remaining garments should
not be constrictive and the blood pressure cuff should not be placed over the garment.
6. Blood pressure should be measured in a quiet room with comfortable temperature.
Position of the subject
Measurements should be taken in sitting position so that the arm and back are supported. Subject's feet should
be resting firmly on the floor, not dangling.
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Position of the arm
The measurements should be made on the right arm whenever possible.
The subject's arm should be resting on the desk so that the antecubital fossa (a triangular cavity of the elbow
joint that contains a tendon of the biceps, the median nerve, and the brachial artery) is at the level of the heart
and palm is facing up.
Number of measurements
Three measurements should be taken one minute apart. If three measurements are not feasible, two will suffice
with a certain loss in data stability.
Procedure of the pulse rate and blood pressure measurement
o
To begin blood pressure measurement, use a properly sized blood pressure cuff. The
length of the cuff's bladder should be at least equal to 80% of the circumference of the upper arm.
o
Wrap the cuff around the upper arm with the cuff's lower edge 2cm above the antecubital
fossa.
1. The radial pulse is palpated and the pulse rate is counted for 30 seconds, measured by a digital wrist watch
or one with second hand.
The manometer should be placed so that the scaleplate is at eye level. The subject should not be able to see the
scale of the manometer.
2. Determining the peak inflation level:
1. The needle of the scale has to be at 0 level.
2. The subject's radial pulse is again palpated.
3. The cuff is inflated and the needle of the scale is noted at the point when the radial pulse disappears. The
cuff is immediately deflated by completely opening the valve.
4. The peak inflation level is determined by adding 30 mm to the pressure where the radial pulse disappeared.
3. Venous blood pool in the forearm is normalized by waiting at least 30 seconds or by raising the arm for 5-6
seconds.
4. The brachial pulse is located and the bell of the stethoscope is placed immediately below the cuff at the
point of maximal pulsation. The bell should not touch the cuff, rubber or clothing.
5. The cuff is rapidly inflated to the peak inflation level and then deflated at a rate of 2 mmHg per second.
6. The pressure should be reduced steadily at this rate until the occurrence of the systolic level at the first
appearance of a clear, repetitive tapping sound (Korotkoff Phase 1) and diastolic level at disappearance of
repetitive sounds (Phase 5) have been observed. Then the cuff should be rapidly deflated by fully opening the
valve of the inflation bulb. Note: There may be a brief period (auscultatory gap) between systolic and diastolic
pressure, when no Korotkoff sounds are heard. Therefore, the 2mmHg/second deflation should be continued
until the diastolic blood pressure is definitely established. If Korotkoff sounds persist until the cuff is completely
deflated, a diastolic blood pressure of 0 should be recorded. The "auscultatory gap" is felt to be associated with
carotid atherosclerosis and a decrease in arterial compliance in patients with increased blood pressure.
7. After two minutes of wait to allow redistribution of blood in the forearm a second measurement is made by
repeating steps.
The Korotkoff sounds
Korotkoff's sounds are sounds heard during auscultatory determination of blood pressure in humans,
thought to be produced by vibratory motion of the arterial wall as the artery suddenly distends when compressed
by a pneumatic blood pressure cuff. Origin of the sound may be within the blood passing through the vessel or
within the wall itself.
1.
The first Korotkoff sound is the snapping sound first heard at the systolic pressure. Clear tapping,
repetitive sounds for at least two consecutive beats is considered the systolic pressure.
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2.
The second sounds are the murmurs heard for most of the area between the systolic and diastolic
pressures.
3.
The third sound was described as a loud, crisp tapping sound.
4.
The fourth sound, at pressures within 10 mm Hg above the diastolic blood pressure, was described as
"thumping" and "muting".
5.
The fifth Korotkoff sound is silent as the cuff pressure drops below the diastolic blood pressure. The
disappearance of sound is considered diastolic blood pressure – 2 mmHg below the last sound heard.
Pulse palpation
Pulse is a regularly recurrent wave of distension in arteries that results from the progress through an
artery of blood injected into the arterial system at each contraction of the ventricles of the heart
This systematic examination of the pulse will give a great deal of information. Examination of the
rest of the cardiovascular system should give a very clear idea of the diagnosis or at least put the examiner in a
position to make a rational request for further investigations. Systematic examination of the pulse remains an
essential part of clinical practice.
Arterial pulses can be examined at various sites around the body. Systematic examination normally
involves palpating in turn radial, brachial, carotid, femoral and other distal pulses.
The pulses are felt in the various sites. In general:
 Palpate the artery wall with the tips of the index and middle fingers. The tips are very sensitive. Don’t try
to palpate with the thumb, as it risks mistaking one's own pulse for the patient's.

Do not press too hard for fear of obliterating the pulse.

The patient’s arm must be at heart level.
The pulse amplitude of one hand can differ from another. In this case
we mean pulsus difference. It meets in case of structural abnormality,
obstruction or vascular embarrassment of artery with a tumor etc.
Characteristics of pulse
Rate
A normal pulse rate after a period of rest is between 60
and 80 beats per minute (bpm). It is faster in children. However, if
tachycardia is defined as a pulse rate in excess of 100 bpm and
bradycardia is less than 60 bpm, then between 60 and 100 bpm must
be seen as normal.
An irregular pulse or a slow pulse (pulsus rarus) should be
measured over a longer time. If the pulse rate more than normal it is
pulsus frequens. As a guide, it is unwise to measure a regular rate for
less than 20 seconds (30 seconds being preferable) and an irregular
pulse should not be measured over less than 30 seconds, preferably a
full minute.
Normal pulse rates at rest, in beats per minute (BPM)
The heart rate may be greater or lesser than the pulse rate depending upon physiologic demand. The
pulse deficit (difference between heart beats and pulsations at the periphery caused by weak ventricular systoles
and shortage of ejected blood in aorta) is determined by simultaneous palpation at the radial artery and
auscultation at the heart apex. It may be present in case of premature beats or atrial fibrillation.
The pulse rate can be used to check overall heart health and fitness level. Generally lower is better,
but bradycardia can be dangerous. Symptoms of a dangerously slow heartbeat include weakness, loss of energy
and fainting.
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Rhythm
A normal pulse is regular in rhythm and force. In healthy patients heart beats and pulse waves follow
each other with equal periods and the pulse is rhythmic (pulsus regularis). An irregular pulse when pulse waves
occur with unequal periods (pulsus irregularis) may be due to sinus arrhythmia, premature beats, atrial
fibrillation, paroxysmal atrial tachycardia, atrial flutter, partial heart block etc.
Intermittent dropping out of beats at pulse is called "intermittent pulse". Examples of regular
intermittent pulse include pulsus bigeminus, pulsus trigeminus. Pulse rhythm is a guide to the state of sinoatrial
nodal activity.
Tension
To examine the pulse tension you should put three fingers on radial artery, then slowly press the
artery with your proximal finger to shut off the blood flow to the distal site till you stop feeling the pulse with
your proximal finger. Depending on the strength you applied to press the artery we can judge about pulse
tension. The pulse tension depends on the systolic blood pressure. The greater pressure the harder to press
artery. Such pulse is called tense or cordy one (pulsus durus). Under low pressure the artery is pressed easily, it
is a soft pulse (pulsus mollis)
Pulse tension increases under BP increasing, atherosclerosis, vessels feels rigid even between pulse
beats. When BP and the cardiac pump activity decrease the pulse tension also decreases. According to this
characteristic we can judge about the cardiac pump activity, condition of artery walls and circulating blood
volume.
Volume
The degree of expansion displayed by artery during diastolic and systolic state is called volume. It
also known as amplitude, expansion or size of pulse.
To examine the pulse volume you should press the artery with your proximal finger to shut off the
blood flow to the distal site and then stop pressing quickly. Then you feel with your distal finger the maximal
pulse. Pulse volume lets us judge about cardiac pump activity and circulating blood volume. The pulse volume
reflects filling of the artery with blood determined the amount of blood which ejects in aorta during ventricular
systole and causes the fluctuation of artery walls. It depends on stroke volume and circulating blood volume.
Under normal stroke volume and you find a full pulse (pulsus plenus). Under circulation failure, blood loss the
pulse volume reduces, it will be pulsus vacuus.
Hypokinetic pulse
A weak pulse signifies narrow pulse pressure. It may be due to low cardiac output (as seen in shock,
congestive cardiac failure), hypovolemia, valvular heart disease (such as aortic outflow tract obstruction, mitral
stenosis, aortic arch syndrome) etc.
Hyperkinetic pulse
A bounding pulse signifies high pulse pressure. It may be due to low peripheral resistance (as seen in
fever, anemia, thyrotoxicosis, hyperkinetic heart syndrome, A-V fistula,Paget's disease, beriberi, liver cirrhosis),
increased cardiac output, increased stroke volume (as seen in anxiety, exercise, complete heart block, aortic
regurgitation), decreased distensibility of arterial system (as seen in atherosclerosis, hypertension).
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