Rene-Theophile Laennec, a pupil of Corvisart, was the inventor of the stethoscope (1816) and the founding father of pneumonology. He is considered one of the greatest physicians of the 19 century and his invention a major advance in the field of physical diagnosis.
During physical examination, Laennec was accustomed to use immediate auscultation by applying directly his ear on the patient's chest. During his practice, examining an obese patient, he was uncomfortable to perform a direct auscultation; he then rolled a quire of paper into a cylinder which he applied on the precordial region while listening from the other side. He was extremely surprised by the quality of cardiac sounds that he could hear. He then applied this technique routinely during his practice at Necker Hospital and designed a wooden version of this instrument, the stethoscope. When Laennec's treatise was published in 1819, each purchaser was also receiving a wooden stethoscope which was made by the hands of Laennec in his country house. The first genertaion of wooden stethoscope was made of two elements as shown in the figure which appeared in the first edition of his treatise. The size of this instrument was a foot long and one and a half inches in diameter. Later, Laennec made wooden stethoscopes composed of three elements.
This stethoscope was made and used by Laennec. He gave it to Dr Mabit, a famous physician in Bordeaux, as a sign of friendship. Later, Dr Mabit "a transmis" (transmitted) this stethoscope to Dr Dubreuil, author of a vaulable textbook on aortic aneurysms at the middle of the 19th century. Currently, It is in the collection of Dr Farzan Filsoufi.
Laennec identified two sounds to each heart beat and contributed them mistakenly to the contraction of the ventricles (first sound) and the contraction of atria (second sound).The exact identification of the origin of cardiac sounds and murmurs required the ingenuity of several investigators and expanded over several decades.
Laennec described three types of murmurs:
"Bruit de Soufflet", simulating the noise produced by bellows when blowing up the fire
"Bruit de lime,de scie, and bruit de rape", simulating the noise made by filing, sawing and rasping
Musical or hissing bellows sound audible over the arteries.
In his treatise, Laennec explained that the narrowing (stenosis) of cardiac valves produced a murmur which was either a soft bellows ("bruit de soufflet") or occasionally a rough rasping ("bruit de scie ou de rape"). He associated the "bruit de soufflet" or soft bellows with mitral stenosis. He also associated the rasping murmur with aortic stenosis. Laennec used the timing and the location of a murmur to diagnose the valve affected by the disease process.
Finally, he described "fremissement cataire" (cat-like purring) that was due to valvular lesions. Corvisart used the term "bruissement" or thrill.
Similar to his mentor Corvisart, Laennec described several cases of induration of cardiac valves and more specifically the mitral valve. He explained that left-sided valves were more frequently affected by the process of induration and ossification compared to right-sided valves. He analyzed with precision valvular lesions in the setting of mitral stenosis: leaflet thickening particularly at the margin, fusion of the commissures and the involvement of the subvalvular apparatus. He clearly described the clinical manifestations associated with mitral and aortic stenosis. Throughout his monograph, Laennec emphasized on the application of the four elements of physical diagnosis: inspection, palpation, percussion and auscultation. He also stressed that "fremissement cataire" and auscultatory findings were present if valvular lesions were well advanced producing significant narrowing of their orifices.
Laennec also reported a case of mitral valve affected with vegetations leading to chordal rupture as observed at the autopsy examination. He did not believe that syphilis was at the origin of these vegetations. Based on his clinical experience, Laennec wrote that he has seen several patients with valvular vegetations at autopsy that did not have venereal diseases during their lifetime. He also treated numerous patients with venereal diseases who did not suffer from these cardiac vegetations. Laennec's views on cardiac and valvular vegetations are discussed in the Infective Endocarditis section.
Laennec RTH. A treatise on the diseases of the chest. Translated by J forbes. London, Underwood, 1821