A pulse represents the tactile, arterial palpation of the heartbeat (pulse rate) by trained fingertips. We can feel for a pulse in any place that allows compression of an artery near the body surface: in the neck (carotid artery), on the inside of the elbow (brachial artery), at the wrist (radial artery), at the groin (femoral artery), behind the knee (popliteal artery), near the ankle joint (posterior tibial artery), and on foot (dorsalis pedis artery).
Pulse rate (the count of arterial pulse per minute) is equivalent to measuring the heart rate. We can also measure the heart rate when we listen to the heartbeat by auscultation, traditionally using a stethoscope and counting it for a minute. Sphygmology is the study of the pulse.
We describe the pulse by seven characteristics – rate, rhythm, volume, force, tension, form, and equality.
We measure the pulse rate in beats per minute (BPM). We use it to check overall heart health and fitness level. Lower is superior, but depressed heart rates (bradycardia) are dangerous at times. Symptoms of a dangerously slow heartbeat include weakness, loss of energy and fainting.
A normal pulse is regular in rhythm and force. An irregular pulse may be due to sinus arrhythmia, ectopic beats, atrial fibrillation, paroxysmal atrial tachycardia, atrial flutter, and partial heart block.
Intermittent dropping out of beats at pulse is called “intermittent pulse”. Examples of regular, intermittent (regularly irregular) pulse include pulsus bigeminus, second-degree atrioventricular block. An example of a non-uniform, intermittent (irregularly irregular) pulse is atrial fibrillation.
The degree of expansion displayed by artery during the diastolic and systolic state is called volume. It is also known as the amplitude or size of the pulse.
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, and valvular heart disease (such as aortic outflow tract obstruction, mitral stenosis, aortic arch syndrome).
Hyperkinetic pulse: A bounding pulse signifies high pulse pressure. It may be due to low peripheral resistance, increased cardiac output, increased stroke volume, decreased extensibility of the arterial system.
We report the pulse strength as: 0 (absent), 1 (barely palpable), 2 (easily palpable), 3 (full), and 4 (aneurysmal or bounding pulse).
Force is also known as the compressibility of a pulse. It is a rough measure of systolic blood pressure.
Tension corresponds to diastolic blood pressure. A low-tension pulse (pulsus Mollis), the vessel is soft or impalpable between beats. In high tension pulse (pulsus durus), blood vessels feel rigid even between pulse beats.
A form or contour of a pulse is the palpatory estimation of arteriogram. We observe a quickly rising and quickly falling heartbeat (pulsus celer) in aortic regurgitation. We also see a slow rising and slowly falling pulse (pulsus tardus) in aortic stenosis.
Comparing pulses at different places gives valuable clinical information. We observe a discrepant or unequal pulse between left and right radial artery in an anomalous or aberrant arterial course, coarctation of the aorta, aortitis, dissecting aneurysm, and peripheral embolism. We see an unequal pulse between upper and lower extremities in coarctation of the aorta, aortitis, and other obstructive lesions of the aorta.
Several pulse patterns are clinically significant. These include:
Pulsus alternans: an ominous medical sign that indicates progressive systolic heart failure. To trained fingertips, the examiner notes a pattern of a pertinent pulse followed by a weak pulse repeatedly. This pulse signals a flagging effort of the heart to sustain itself in systole.
Pulsus bigeminus: indicates a pair of heartbeats within each heartbeat. Concurrent auscultation of the heart may reveal a gallop rhythm of the native heartbeat.
Pulsus bisferiens: an unusual, physical finding that we typically see in patients with aortic valve diseases. If the aortic valve does not normally open and close, trained fingertips will observe two pulses to each heartbeat instead of one.
Pulsus tardus et parvus: It is slower than the optimal rise in the pulse caused by an increasingly stiff aortic valve. Loss of compliance in the aortic valve makes it progressively harder to open, thus requiring the increased generation of blood pressure in the left ventricle.
Pulsus paradoxus: a condition in which we cannot detect some heartbeats at the radial artery during the inspiration phase of respiration. It is caused by an exaggerated decrease in blood pressure during this phase and is diagnostic of a variety of cardiac and respiratory conditions of varying urgency.
Tachycardia: an elevated resting heart rate. In general, we require an electrocardiogram (ECG) to identify the type of tachycardia.
We perfect the skill of taking a pulse and identify its anomalies through experience. It improves with more examinations and comparisons.
Read Bate’s pocket guide to physical examination and history taking to learn more.