The Legacy of Laënnec

Abstract

In 1816, the forerunner of the modern stethoscope came to be discovered in France. Before that time, physicians listened to the mysterious sounds of the heart by placing their ears directly on a patient's chest. The stethoscope of René Théophile Hyacinthe Laënnec revolutionized the diagnosis of cardiopulmonary diseases and opened new horizons to a hitherto undiscovered world. The inventor of the stethoscope was also an ardent pathologist; his classic masterpiece, “De l'auscultation médiate,” included an excellent correlation of the sounds of the chest with anatomical lesions, documented by careful postmortem observations. His name is also immortalized in the micronodular “Laënnec's cirrhosis” of the liver.Laënnec (1781–1826) was born in Quimper, Brittany, France. He was not quite 5 years old when his mother succumbed to tuberculosis. His father, a lawyer, was unable to care for him. Laënnec thus spent most of his boyhood and youth in the care of his uncles. He had a good grounding in the classics and became well versed in Greek and Latin.His uncle, Guillaume François Laënnec, was the Dean of the Faculty of Medicine at the University of Nantes, France. He gave the young Laënnec a sound education despite the turbulent times of the French Revolution. A diligent student, Laënnec was inspired by his uncle to pursue a career in medicine. In 1795, at age 14, Laënnec was already helping in the care of the sick and the wounded at the Hôtel Dieu in Nantes. At 18, he was serving in the Military Hospital in Nantes with the rank of third class surgeon.In 1801, Laënnec studied at the University of Paris to further his medical education. His illustrious teachers included Guillaume Dupuytren, Xavier Bichat, and Jean Nicolas Corvisart. Laënnec was influenced by Corvisart's teachings, which stressed bedside examination and autopsy studies. In his first three years, Laënnec wrote histories of some 400 patients.In 1804, Laënnec graduated in medicine, with a thesis entitled, “Propositions sur la doctrine d'Hippocrate, relativement à la médecine practique.” While still a student, he published a number of papers, notably on peritonitis, amenorrhea, and liver disease. He also served as editor of the Journal de Médecine. In 1816, Laënnec accepted a position as physician at the Necker Hospital in Paris. His most important contribution to medicine would be realized here.In those days, tuberculosis was rife, accounting for many deaths. Laënnec himself suffered from tuberculosis and many family members had died of tuberculosis, including his mother and brother. His mentors Bichat and Bayle also succumbed to tuberculosis.When Laënnec was appointed physician to the Necker Hospital in Paris, it was only natural that he would focus on tuberculosis and chest diseases. But examining the chest, critical for a proper diagnosis of tuberculosis, was not easy. Laënnec became deeply absorbed in the mysteries of the chest. During autopsies, he saw the chests of tubercular patients filled with fluid or pus, and cavities.Prior to the development of the stethoscope in the early 19th century, physicians had limited means at their disposal to unravel the mysteries of the chest. Unlike the abdomen, the rigid thorax within its bony rib cage held many secrets. Leopold Auenbrugger gave the world of medicine the invaluable tool of “percussion.” The son of an innkeeper, Auenbrugger had seen his father tap a barrel to see if it was empty or full. To the musically gifted Auenbrugger, the human thorax was in many ways like a wine barrel and, if tapped, would resonate. If filled with morbid secretions, the sound would be dull and low-pitched. Auenbrugger effectively adapted this principle as a diagnostic tool for diseases of the human chest.Jean Nicolas Corvisart, who was personal physician to Napoleon and Laënnec's teacher, translated Auenbrugger's little book, “Inventum Novum,” and popularized the use of percussion. Laënnec practiced “percussion” in his repertoire of diagnostic tools.Aside from percussion, the other option available to the early 19th century physician was the ancient practice of direct or “immediate” auscultation—listening to the chest sounds and heart beat by pressing the ear to the chest wall. This was known to Hippocrates and practiced in ancient Greece. Robert Hooke realized the value of auscultation and stated that it may be possible to discover the motions of the internal parts of bodies by the sound they make.But direct auscultation was hardly an ideal way to examine patients. Some patients were too obese and no sounds could be heard, or if heard, they were faint and muffled and difficult to interpret. Some patients did not bathe, others were infested with vermin, and modesty was an issue, especially with female patients.In 1816, Laënnec stumbled upon the basic principle of the stethoscope. The following is Laënnec's illuminating description of his first clinical application of this technique. “In 1816, I was consulted by a young woman labouring under general symptoms of diseased heart, and in whose case percussion and the application of the hand were of little avail on account of the great degree of fatness.” With immediate auscultation being rendered inadmissible by the age and sex of the patient, Laënnec happened to recollect a simple and well-known fact in acoustics: “The augmented impression of sound when conveyed through certain solid bodies, as when we hear the scratch of a pin at one end of a piece of wood, on applying our ear to the other.” Laënnec rolled a quire of paper into a sort of cylinder and applied one end of it to the region of the heart, and the other end to his ear. He “was not a little surprised and pleased, to find that I could thereby perceive the action of the heart in a manner much more clear and distinct than I had ever been able to do by the immediate application of the ear.”Laënnec experimented with various types of materials to make tubes and eventually developed a wooden instrument, which was the forerunner of the modern stethoscope. His instrument was about a foot long and 1½ to 2 inches in diameter, perforated in the center and fitted with a plug when used to listen to the heart. To make it portable, it was made in parts that could be assembled. Laënnec derived the name “stethoscope” for his invention from two Greek words, to mean, “examining at the chest.” Laënnec's wooden tube was the first true stethoscope. Wooden stethoscopes were used until about the latter half of the 19th century, when rubber tubing came along.Laënnec studied many chests, comparing his observations with postmortem findings. He learned to recognize pneumonia, bronchiectasis, pleurisy, emphysema, pneumothorax, phthisis, and other lung diseases from the sounds he heard with his stethoscope. Laënnec distinguished two heart sounds but attributed the first heart sound to ventricular systole and the second sound to atrial systole. He described murmurs and thrills, pectoriloquy (as a sign of tubercular cavities), egophony, bronchophony, a variety of râles, and normal and abnormal lung sounds.In 1818, Laënnec presented his findings and research on the stethoscope to the Academy of Sciences in Paris, and in 1819, he published his masterpiece, “De l'auscultation médiate ou Traité du Diagnostic des Maladies des Poumon et du Coeur,” in two volumes. Later, the emaciated Laënnec embarked on a revised edition of this epochal work with a masterful correlation of stethoscopic sounds and diseases of the chest documented by postmortem findings. Laënnec made several stethoscopes, the intent being to present one with each copy of his revised book to the purchaser.The first English translation of “De l'auscultation médiate” was by John Forbes, published in London in 1821. Laënnec's treatise aroused intense interest abroad, with physicians from throughout Europe flocking to Paris to gain first-hand experience of this new diagnostic tool.Laënnec received many honors and in 1822 became professor of medicine at the College of France. He was in charge of the clinic at the Charité Hospital in Paris. In 1824, he was made a Chevalier of the Legion of Honor. Laënnec married in 1824, but his married life would be short lived, for he succumbed to tuberculosis on August 13, 1826.While Laënnec's stethoscope revolutionized diagnosis of diseases of the chest, his name is eponymously associated with micronodular cirrhosis of the liver (Laënnec's cirrhosis). Although not the first to recognize this pathological entity, Laënnec gave cirrhosis its name, from the Greek word “kirrhos,” referring to the tawny yellow nodules associated with this entity. He divided these lesions into three or four types—masses, plaques, cysts and degenerations, with the main description devoted to “cirrhoses en masses,” characterized by granulations disseminated throughout a firm, shrunken liver.Ironically, the disease Laënnec helped to understand and elucidate with his stethoscope took his own life; Laënnec died of tuberculosis at the age of 45. But his invention is still used in medical practice today and his painstaking work provided correlation of sounds of the chest with pathological findings at autopsy, thus linking the signs of physical diagnosis at the bedside with organ pathology.

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