|HISTORY OF MEDICINE
|Year : 2018 | Volume
| Issue : 3 | Page : 117-120
The pulse from ancient to modern medicine: Part 3
Department of Cardiology, Heart Hospital, Hamad Medical Corporation, Doha, Qatar
|Date of Web Publication||18-Mar-2019|
Sr. Consultant Cardiologist, Director of HH Publications, Executive Coordinator for Research, Director of Non-invasive Cardiology (1981–2014), Heart Hospital, Hamad Medical Corporation, Doha
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Hajar R. The pulse from ancient to modern medicine: Part 3. Heart Views 2018;19:117-20
| Introduction|| |
Medical students are taught that examination of the pulse is important and basic to medicine. Taking the pulse is a rudimentary technique of physical diagnosis. Enter any intensive care or coronary care unit and you will see patients attached to screens which display the arterial pulse tracing. Examination of the arterial pulse contour is a clinical tool capable of sometimes providing us important information on cardiovascular function. Terms such as anacrotic, bisferiens, bigeminal, pulsus paradoxus, dicrotic, collapsing pulse, and pulsus alternans give us an overview of the patient's underlying condition. We still use these Latin terms when describing the pulse. However, in the screen display, many physicians consider only the numeric display of the pulse and blood pressure worthy of attention.
Historically, Galen and Avicenna wrote extensively on the pulse and their teachings were passed on for centuries to medical students without major advancement in the understanding of the physiology of the arterial pulse and circulation until Harvey described the circulation. However, Ibn al-Nafis, an Arab Muslim physician, was the first to describe the pulmonary circulation. His work on the pulmonary circulation predates that of Harvey's De motu cordis in 1628. Ibn Nafis disproved the 1000-year-old theory of Galen that blood could pass from the right to the left side of the heart through small pores in the interventricular septum. Both theories (Ibn Nafis and William Harvey) attempt to explain the circulation.
Galen also believed that the heart and arteries contracted simultaneously and that the arterial pulse is the result of an active force generated in the arterial surface. The concepts were passed down to generations of doctors for centuries until Harvey challenged such dogma. Through his experiments, he proved that the pulse is due to contraction of the left ventricle and that the source of the heartbeat is in the right atrium. Harvey also described that the arteries and veins contained only blood.
| The Pulse in Ancient Civilizations|| |
Doctors in antiquity palpated the pulse noting its rate, regularity, and volume. Modern doctors note the same; some palpate the pulse while some just look at the screen display of the pulse tracing. The digital display is considered much more objective than palpation. Techniques used to analyze the arterial pulse and its characteristics have advanced, but our understanding of the various characteristics of the arterial pulse relies on our ancestors' observation and experiments.
| Ancients Linked the Heart to Life|| |
Ancient civilizations linked the heart and heart or pulse rate to life. We know that the Egyptians and Chinese of antiquity were masters in pulse diagnosis and Chinese traditional medicine still emphasizes such art. The ancient Egyptians believed that the heart gives rise to vessels that lead to different parts of the body and that its motion can be felt at different peripheral sites.
In the Mesopotamian epic Gilgamesh written in 2600 BC, the hero-king Gilgamesh uttered the following lament at the death of his best friend Enkidu: “I touch his heart, but it does not beat at all.” Historians say that this passage is the earliest reference that at that point in time man already understood that the heart is the life-sustaining organ of the body. It is an important measure of health and well-being.
A prehistoric cave drawing dated to 15,000 years ago depicts a mammoth with a leaf-shaped dark area where the heart should be. Historians claim that if it were truly the drawing of a heart, it would be the first anatomical illustration – a really fascinating theory. Prehistoric societies of course were primarily hunting communities. They must have found the heart of an animal beating as long as it was alive and that the best way to kill it was to hit it through the heart. They also must have felt their own hearts hammering in their chests when they felt fear. Hence, it should not be surprising that as early as 5000 years ago when man settled into city-states, man realized that the heart was an organ vital to life. Even today, it is a very important measure of health and well-being.
| Modern Medicine|| |
Today, the cathode ray tube oscilloscope displays the heart/pulse rate and contour.
| Clinical Value of Heart Rate and Pulsation|| |
Seneca, the Roman philosopher, said, The physician cannot prescribe by letter; he must feel the pulse. And so, we must – if we are to intimately know what is happening to our patient.
From ancient times, the pulse has been recognized as the most fundamental sign of life. If somebody collapses on the street, a bystander automatically feels for the victim's pulse. Early physicians paid great attention to the character of the pulse in health and disease. For thousands of years, books on the pulse and how important it is have been written, with Galen the most prolific and who has written volumes on the pulse. Many of his descriptions are still being used today.
Briefly, pulse rate was first measured by ancient Greek physicians and scientists. The first person to measure the heart beat was Herophilus of Alexandria, Egypt (c. 335–280 BC) who designed a water clock to time the pulse. He is said to have written the first fragmentary descriptions of heart rate as measured by the pulse. Herophilus wrote nine volumes of his findings, but they have been lost. His findings survive in the writings of subsequent ancient medical scholars such as Galen. However, the Chinese and Indians date their pulse lore back to mythological antiquity, long before Galen's time.
In the 18th century (1707) with the invention of the “Physician's Pulse Watch” (a watch with a second hand that could be stopped), changes in pulse rate in health and disease could be accurately assessed. The electrocardiogram (ECG) was invented in 1895 so that analysis of the pulse' contours advanced further. In the 1960s, digital signal processing techniques proliferated so that now physicians have only to look at the screen display by the patient's bedside to assess a patient's clinical condition. Many doctors feel that feeling the pulse of a patient is no longer necessary and many physicians ignore the arterial pressure tracings displayed on cathode ray tubes in intensive care unit and consider only the numeric display of blood pressure worthy of attention. However, examination of the arterial pressure contour is a clinical tool capable of sometimes providing important information on cardiovascular function. Hence, besides the pulse rate, its regularity and volume are noted.
The heart starts beating at 4 months in utero. We do not know much about our first heartbeat except that it is generated by several ion movements across the sarcolemma of the sinus node cells. We know about depolarization and repolarization. We know also that a normal resting heartbeat for an adult ranges from 60 to 100 beats per minute and is influenced by age, fitness and activity levels, smoking, emotions, medications and disease conditions, especially cardiovascular. An unusually high or low heart rate may indicate an underlying medical problem.
| Basic Pulse Examination|| |
It is undoubted that an examination of the peripheral pulses is extremely helpful.
The carotid artery, brachial, femoral, popliteal, posterior tibial, and dorsalis pedis are peripheral arteries. Palpation of the peripheral arteries can be performed whenever they are close enough to the skin surface to be compressed. The greater the distance from the heart to a peripheral artery, the greater will be the distortion of contour. The carotid artery is the most central and so necessary for pulse contour information.
We know that peripheral pulse contour is determined by left ventricular ejection as well as the elasticity or distensibility of the peripheral arteries. Hence, there is much emphasis on the presence or absence of a pulse, and whether it is hypokinetic or hyperkinetic (volume and amplitude). Absence of a pulse could suggest occlusion by thrombus, embolus, or dissection. Absence or diminished leg pulses may confirm a vascular etiology of intermittent claudication.
If the pulse is present, but of low volume and amplitude, it could suggest low cardiac output in shock or myocardial infarction. Idiopathic dilated cardiomyopathy, valvular stenosis, pericardial tamponade, or constrictive pericarditis can also cause low cardiac output and small peripheral pulses. In severe aortic stenosis, a small pulse known as pulsus parvus et tardus (refers to a weak and delayed carotid upstroke) is noted. Medical students are taught that this is the best bedside method to estimate the severity of aortic stenosis.
Large amplitude and strong pulse (hyperkinetic) are considered normal. Anxiety, exercise, fever, hyperthyroidism, and anemia can all cause such pulse in a normal person. It indicates a large left ventricular stroke volume and an otherwise normal cardiovascular system. However, a hyperkinetic pulse can also occur where there is a rapid peripheral runoff of blood in addition to a large stroke volume from the left ventricle. Patent ductus arteriosus with normal pulmonary pressures, large arterial venous fistulas, and severe aortic regurgitation can cause these hyperkinetic pulses. The pulse of severe aortic regurgitation is described as water-hammer and collapsing. Some of these patients will have a double systolic pulse called a bisferiens pulse. This is most commonly noted on examining the carotid upstroke – two systolic peaks (double pulse) per cardiac cycle. The Latin “bisferiens” means “beat twice.”
There are other abnormal pulses described in textbooks. Among them, pulsus alternans consists of an alternating strong and weak beats and is associated with severe left ventricular failure of any cause. Pulsus paradoxus, also paradoxic pulse or paradoxical pulse, is an abnormally large decrease in stroke volume, systolic blood pressure, and pulse wave amplitude during inspiration. The normal fall in blood pressure is <10 mmHg. When the drop is >10 mmHg, it is referred to as pulsus paradoxus.
Simultaneous palpation of two pulses can be helpful and diagnostic. Simultaneous palpation of the radial and the femoral pulse should give identical pulse. If there is a palpable delay from the radial to the femoral pulse, it suggests coarctation of the aorta or at least an aortic obstruction below the takeoff of the left subclavian artery. All hypertensive patients should have this examination. Unilateral absence of a pulse can aid in the diagnosis of a dissected aortic aneurysm.
The radial pulse is palpated for rate and rhythm because the pulse rate and regularity are easily felt here. An irregular pulse can be caused by atrial fibrillation; by premature beats arising in the atria, the atrioventricular junction, or the ventricles; and by second-degree atrioventricular block.
A slow, bounding hyperkinetic pulse can be found in complete heart block. Atrial fibrillation causes an irregularly, irregular pulse. Not only will the rate of the pulse be irregular, but the pulse amplitude will also vary. This results from variable stroke volumes during systole. If the ventricular rate is rapid, some pulses may not be transmitted to the peripheral circulation. Simultaneous auscultation of the heart and palpation of the radial pulse can allow measurements of an apical to radial pulse deficit. Controlled atrial fibrillation should have no pulse deficit, that is, all central heartbeats are transmitted to the radial pulse and the peripheral circulation.
Premature beats of any origin can cause irregularities of the pulse. If the premature beats alternate with normal sinus beats, bigeminy results. Irregularities of the pulse rate or rhythm require an ECG for final diagnosis of the cardiac arrhythmia. Palpation of the pulse is a time-honored part of the physical examination that still contains important information.
| Conclusions|| |
Taking the patient's pulse is one of the oldest physical examination techniques that doctors have to diagnose and prognosticate. Even though we are now in the 21st century, there has been no change in the descriptions and analysis of the pulse wave contour – we are still using the same terminology. One finds little advance of significance and necessitates a review.
Nowadays, there are many researches on the pulse, and hopefully, the results will give us more insight. The association of heart rate and mortality has been well documented, but we still do not know why mortality increases with a faster resting heart rate. Tachycardia portends a worse prognosis in many different conditions.
There is no doubt that taking a patient's pulse is still useful even though there are many new technologies devised to aid in a clearer display of the pulse than just palpation; so much so that many doctors no longer take a patient's pulse. However, taking a patient's pulse may have brought about relation and interaction with the patient, inducing patient's willingness to talk about the illness, resulting in better communication between physician and patient.
The pulse can give us many clues as to what the root problems of a patient could be.
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Conflicts of interest
There are no conflicts of interest.
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