“Abu Ali placed his hand on the patient’s pulse, and mentioned the names of the different districts and continued until he reached the name of a quarter at the mention of which, as he uttered it, the patient’s pulse gave a strange flutter. Then Abu Ali repeated the names of different streets of that district and different houses till he reached the name of a house at the mention of which the patient’s pulse gave the same flutter. Finally, he uttered the name of different households of that house until he reached a name at the mention of which that strange flutter resumed. Thereupon he said: This man is in love with such-and-such a girl, in such-and-such a house, in such-and-such a street, in such-and-such a quarter: the girl’s face is the patient’s cure” [
The above paragraph about Abu Ali Ibn Sina, known by his Latinized name Avicenna, a Persian scholar and a prominent physician of the Middle Ages, illustrating what was called “the quickened pulse of a lover” shows how physicians used the arterial pulse to diagnose certain illnesses in the medieval times. The simplicity of its evaluation had drawn even ancient physicians’ attention to itself. Physicians of antiquity used the examination of the pulse not only for diagnosis, but also as an indicator of prognosis.
This paper will review the history of the assessment of pulse from ancient times to the present. The different methodologies for evaluation of arterial pulse characteristics will also be discussed briefly during three different historical eras of medicine, namely, ancient, medieval, and modern medicine.
“Immediately after pressing the pulse just below the hand joint, firstly, there is a perception of the beating of bayu; secondly, or between bayu and kaph, there is the perception of pitta; thirdly or the last, the perception of the beating of slesma or kaph is gained” [
This passage describes the examination and interpretation of the arterial pulse by ancient Indian physicians. Sage Kanada (600 BCE), an ancient Indian physician, alchemist, and philosopher, in his book, “Science of Sphygmica”, describes a variety of pulses during different physiological and pathological states. Based on his theory, each pulse has three stages, abnormality in any of which reflects diseases of three main humours of the human body, bayu/vata (air), pitta (bile), and kaph/kapha (phlegm) [
Ayurveda (knowledge of life) is an ancient medical science that has been originated in the Indian subcontinent and has been practiced since the time of Buddha (500 BCE). The examination of the pulse is an integral part of Ayurvedic medicine. Eight parts of a patient’s body are described for physical examination, the first one being the arterial pulse [
Arterial pulse was studied in China about two and a half thousand years ago. It was first mentioned in the “Internal Medicine Classics, Nei Ching”. This manuscript is reported to be written by the Yellow Emperor, Huang Ti (698–598 BC). The principal means of diagnosis employed in the Nei Ching is the physical examination of the arterial pulse. The theory of the pulse is based upon the various stages of interaction between Yin (disease) and Yang (health).
The ancient Chinese physicians had to develop the ability and skill to judge the state of disease—its cause, duration, and prognosis—by the volume, strength, weakness, regularity, or interruption of the four main varieties of pulse beats (superficial, deep, slow, and quick) [
“There are canals (or vessels) in it (the heart) to every limb. Now if the priests of Sekhmet or any physician put his hands (or) his fingers on the head, on the hands, or his fingers on the back of the head, upon the two hands, upon the pulse, upon the two feet, he measures the heart, because its vessels are in the back of the head and in the pulse; because its pulsation is in every vessel of every member” [
The quotation above suggests that the relationship between the heart beat and the peripheral circulation was conceptualized in ancient Egyptian medicine [
The word “artery” originated from the Greek word “
Herophilus was the first to compare the pulsation of blood vessels to musical rhythm and this theory had an enormous impact on both medical and musical literature until the late middle ages and the Renaissance. Upbeats and downbeats were the units Herophilus used to establish a basic analogy between musical rhythm and pulse rhythm. Herophilus defined the “perceptible time” as the interval of time in which the artery of a newborn would dilate. This perceptible time became the basic unit by which the length of each contraction and dilation was measured, and hence the basic unit by which the pulse rhythm was established [
Clepsydra or Greek water clock: a portable water clock used by Herophilus for the purpose of arterial pulse examination. This water clock was capable of containing a specified amount of water for natural pulse beats of every age.
Archigenes (98–117 CE) discovered the dicrotic pulse as quoted by Horine [
Galen (129–200 CE) thought that the dilation of the artery might be unequal on all sides and a variety of pulses could be felt based on the degree of dilation on each side. For instance, there could be a full upward dilation with a less lateral dilation making a high and narrow pulse. Likewise, there could be a full lateral dilation and a smaller one upward, resulting in a low and broad pulse. He described several types of arterial pulse such as saw-edged pulse, undulating pulse, and worm-like pulse. Other types of arterial pulsation in different temperatures or illnesses including hot pulses and cold pulses, the pulse of pain, inflammation, lethargy, convulsions, jaundice, and even of elephantiasis are described by him [
Arterial pulse continued to be one of the most important diagnostic and prognostic signs in medieval medicine. As an example, arterial pulse was mentioned to be valuable in prognostication of epilepsy. A medieval physician who felt the particular pulse of a patient suffering from epilepsy would project that the patient would have a seizure at some point during the natural course of the illness [
Avicenna (981–1037 CE) like his predecessors believed that health was based on the interplay of four different humours—blood, phlegm, yellow bile, and black bile [ the size of dilation: strong, weak, and intermediate, the duration of each movement: short, long, and intermediate, the duration of the pause: hurried pulse, sluggish pulse, or intermediate pulse, the temperature of the pulse: hot, cold, or intermediate, the compressibility of the artery: easily compressible, incompressible, and moderately compressible, the fullness or emptiness of the artery: full of humour, containing no humour, and intermediate, the equality or inequality of force in consecutive beats, the regularity of the rhythm: regular or irregular (irregularly regular and irregularly irregular).
This classification is similar to what we know currently of the arterial pulse characteristics in arrhythmias such as atrial fibrillation. He described the irregularity both in a single pulsation and in a succession of pulse beats. In terms of irregularities of a single pulse beat, he described premature and dropped beats [
Avicenna came close to a general understanding of the various arrhythmias based on the characteristics of the pulse. He described different pulses similar to the pulses being observed in arterial and ventricular arrhythmias [
“The pulse which is very abnormal and totally irregular demonstrates that the cause for its abnormal condition migrates”.
This quotation from Moses Maimonides (1135–1204 CE) one of the most eminent physicians of the Middle Ages clearly shows that Maimonides understood various arrhythmias based on his findings of the pulse. Similar to his predecessors, he attributed these irregularities to the abnormal constitution of the humours of the heart. Furthermore, he correlated the arterial pulse rhythm with the severity of illness, with more severe illnesses having more irregular pulses [
From the days of Hippocrates to the thirteenth century, physicians generally believed that the human heart consisted of four chambers. The lower chambers, the ventricles, were thought to contain blood and the upper chambers to contain air. It was believed that with pores between the two ventricles, venous blood coming from the liver would mix with the air coming from the lungs to make the vital
“When I first tried animal experimentation for the purpose of discovering the motions and functions of the heart by actual inspection and not by other people’s books, I found it so truly difficult that I almost believed with Francastorius, that the motion of the heart was to be understood by God alone. I could not really tell when systole or diastole took place, or when and where dilatation or constriction occurred, because of the quickness of the movement. In many animals this takes place in the twinkling of an eye, like a flash of lighting. Systole seemed at one time here, diastole there, and then all reversed, varied and confused. So I could reach no decision. Finally using greater care every day, with very frequent experimentation, observing a variety of animals, I felt my way out of this labyrinth, and gained information, which I desired, of the motions and functions of the heart and arteries…” [
From the 13th until the 16th century, when William Harvey (1578–1657 CE) discovered the greater circulation, there was no major advancement in the understanding of the physiology of the arterial pulse and circulation. Harvey fully described the circular blood flow in the body from the heart to the extremities via arteries and from extremities back to the heart via the venous system [
Although the arterial pulse had been an integral guide to reach a diagnosis in antiquity and medieval eras, general concepts of its generation were misunderstood. Both the heart and the arteries were thought to have their own pulsation and to contract simultaneously. It was thought before Harvey’s dogma-shattering observations that the arterial pulse is the result of an active force generated in the arterial surface. It was William Harvey who for the first time attributed the generation of the arterial pulse to the contraction of the left ventricle and found the source of the heart beat in the right atrium. He contradicted his forefathers, Galen and Vesalius, in their belief of the origin of the arterial pulse in the arterial wall and with his meticulous observations attributed the generation of the arterial pulse to a passive dilation caused by the blood inflow [
These major discoveries were made with the aid of his meticulous experiments on both humans and animals. In the “Anatomical Studies on the Motion of the Heart and Blood” he comprehensively described his experiments on a variety of animals such as snakes, frogs, snails, shell-fish, and fish [
Quantitative hemodynamic measures like stroke volume, cardiac output, ejection fraction are described by him for the first time in the history of medicine [
By taking a closer look at Harvey’s description of the blood circulation, it will become obvious that nothing was known about the capillaries at that time except from an earlier description of the capillaries by Moses Maimonides as the narrow transits communicating arteries with veins. This observation came to the actual discovery of the capillaries by Marcello Malpighi, a professor of anatomy in the seventeenth century [
In regard to assessing the frequency of the pulse, the first physician who counted the pulse rate was Herophilus by using his
Pulsilogy of Sanctorius: this device consisted of a scale of inches and a cord with a movable weight marked with a transverse line. The physician would move the pendulum and note the pulse with his fingers simultaneously. Then, the physician would change the length of the line until the speed of the running pendulum would coincide with the pulse rate, thus showing the pulse rate as the number of inches.
A century after the invention of the
Bryan Robinson, an Irish physician (1680–1754 CE), studied the pulse rate in different times during a day, and in people with different heights [
Herrison’s sphygmometer: this device was composed of a graduate glass tube containing mercury with a semiglobular ball at one end. With the semiglobular end being placed over an artery, it would show the action of the vessel and the force of its impulse. It was designed in a manner that would enable the examination of the pulse in relation to its force, regularity, and rhythm.
The
Twelve years later in 1847, Carl Ludwig, a German physiologist, invented the
Ludwig’s kymograph (wave writer): this device was able for the first time to graphically record hemodynamic measures.
In 1860, the French physiologist Etienne Marey revised the previously invented
Marey’s sphygmograph: this device had graphical recording capabilities of the arterial pulse. Applying this device to the wrist would record the motion of the arterial pulse and enable the examiner to interpret rate and rhythm.
The first formal study on the arterial pulse wave was done by Marey with the help of his
Mahomed’s sphygmograph: this device was a revised form of Marey’s sphygmograph with an added screw. It was capable of measuring the pressure needed to occlude the arterial wave along its graphical recordings of the arterial pulse wave dynamics.
Graphical depictions of the arterial pulse wave form by Mahomed in an asymptomatic male (a) and female (b) with arterial hypertension. Reproduced from [
Arterial pulse wave form in a man with arterial hypertension
Arterial pulse wave form in a woman with arterial hypertension
Modern studies on the pulse wave and arterial hemodynamics stem from the pioneering studies of the early modern era. Stephen Hales (1677–1746) in a series of papers called “Statical Essays: Containing Haemostatics” presented his contributions to the arterial hemodynamics before the Royal Society. The following quotation from his third experiment clearly shows the earliest studies on the mechanics of the circulation:
“… But the systole of the ventricle during which that quantity of blood is propelled, being estimated to be done in one third of the space of time between each pulse, the velocity of the blood during each systole will be thrice as much, at the rate of 5211 feet, that is, 0.98 of a mile in an hour, or 86.85 feet in a minute” [
Hales’s studies were followed by other scientists such as Leonhard Euler who formulated quantitative measures of the arterial hemodynamics. However, he was quite unsuccessful in proposing a formula that could simply show the relationship between the mechanical forces and the dynamic measures of the arterial pulse wave [
Crighton Bramwell a scientist in the early twentieth century was first to introduce the concept of pulse wave velocity (PWV). He described the velocity to vary in proportion to the arterial wall tension and the blood pressure and to be an indirect measure of the arterial wall elasticity. Bramwell and Hill introduced a simple formula by which the arterial elasticity could be calculated from the PWV. With this formula he found a positive correlation between PWV and age and a negative correlation between arterial wall elasticity and PWV [
Bramwell’s formula:
Since the invention of the
(a) This graph illustrates time marker as the lowest line, cardiogram tracing as the line above that, and femoral pulse waves as the two top tracings. (b) Distance “a” represents the distance between aortic arch and the position of the microphone over the femoral artery “Reproduced from [
Woolam and his colleagues in 1962 used a crystal microphone for recording the pulse wave. By applying two crystal microphones, one to the wrist and the other to the carotid artery they recorded the pulse wave and its velocity travelling along the course of the brachial artery. They demonstrated a higher PWV in diabetic patients. Other studies on the velocity of the arterial pulse wave showed that higher values are in a strong correlation with the atherosclerotic changes of the arteries [
Gradually, studies of PWV changed from the peripheral circulation to the more reliable studies on the central circulation. Investigators started to study the pulse wave characteristics of the abdominal aorta mainly because it was more reliable, less variable, and more easily reproducible [
Asmar et al. in a study of 56 subjects compared a new automated device with manual calculation for determination of PWV and found that the findings from the two were very close and reproducible [
Doppler echocardiography with a high-resolution echo-tracking system is also used to estimate arterial compliance and augmentation index based on carotid artery diameter change [
In contrast to applanation tonometry which can be applied to a limited number of peripheral arteries, the arterial distension waves obtained by echo-tracking systems can be recorded from a variety of sites and has an advantage of being very useful in obese patients for whom the applanation tonometry method might not be easily used.
Pulse pressure, another important characteristic of the pulse wave, has been studied extensively in more recent years. Its association with cardiovascular outcomes and its application in clinical pharmacologic studies are of clinical importance. As mentioned previously, with the invention of Riva Rocci’s cuff sphygmomanometer in the early twentieth century clinicians made important observations regarding pulse pressure (pulsatile component of blood pressure) which was ultimately found to be an important risk factor for cardiovascular disease [
Other than the pulse pressure, both the systolic and the diastolic components have been studied in relation to cardiovascular outcomes. Despite earlier misbelief that only systolic pressure is a predictor of outcome The Multi Risk Factor Intervention Trial (MRFIT) showed that both are independent predictors of cardiovascular outcomes [
Augmentation index (AI) as a measure of pulse pressure was first defined by Kelly and his colleagues in 1989. They defined AI for each pulse wave as the ratio of height of the peak above the shoulder of the pulse wave to the pulse pressure using a micromanometer probe over the carotid and radial arteries. They showed that the augmentation index was in direct correlation with age [
During the last twenty years, studies on the pathophysiology of atherosclerosis have shown endothelial dysfunction to play an integral role in the development of atherosclerosis in its preclinical stages. Endothelial dysfunction also has been shown to be an independent predictor of cardiovascular outcomes [
Some of the most important instruments that have been used for the examination of the pulse throughout the history of medicine are listed with their inventors in Table
Instruments used for the examination of the arterial pulse.
Instrument | Inventor |
---|---|
Clepsydra | Herophilus (Third century BC) |
Pulsilogy | Santorio Sanctorius (Sixteenth-Seventeenth century) |
Pulse watch | Sir John Floyer (Seventeenth-Eighteenth century) |
Sphygmometer | Jules Herisson (Nineteenth century) |
Kymograph | Carl Ludwig (Nineteenth century) |
Sphygmograph | Etienne Marey (Nineteeth century) |
Hemotachometer | Karl Vierordt (Nineteenth century) |
Plethysmograph | Otto Schmitt (Twentieth century) |
Current knowledge of the arterial pulse has culminated from the beliefs, observations, interpretations, dogmas, and the rejection of dogmas throughout the history of medicine. Our intention with this historical review is to make the reader appreciate how the understanding of the arterial pulse has progressed over the centuries to the present time and give the reader an insight for future developments.
In this paper, we describe the significance of the arterial pulse in clinical practice from ancient to modern eras. Several methodologies for the analysis of pulse wave and its characteristics including velocity, pressure, and volume have been discussed. These methods range from simple examination of the arterial pulse by touch to more complex techniques and devices that are being used and developed. Between all these methods, the only practical devices that have been shown in several studies to impact cardiac outcomes are cuff sphygmomanometer and noninvasive measurement of PWV. Despite its known limitations including limited precision, the cuff sphygmomanometer has held its place in routine evaluation and determination of arterial pulse pressure, globally. Despite the fact that measurement of PWV is recommended by the European Society of Cardiology as a prognostic factor [
Scientific progress in arterial biology and physiology continues at a faster pace with the help of advanced technologies, designed by astute clinical observers, hypothesis-driven scientists and technical innovators; this body of work will certainly continue to grow and further our understanding of the arterial circulation.
The authors express their gratitude to Mr. Ted Willi at Emory University School of Medicine’s Woodruff Health Sciences Center Library for his generous help in searching for the references of this paper and Mr. Donn Johnson at the Atlanta Veterans Affairs Medical Center, Media Production Services for his technical assistance with the graphical depictions for this paper.