Friday, July 17, 2009

Lets continue with our fascinating journey into Historical aspects of Pediatric cardiology. Its time to remember the father of auscultation and stethoscope. Prior to that, lets have a few words on Senec again.

Senec continued to be a major influence to the generations of Cardiac anatomists and physicians. His systematic approach starting from anatomy and going on to post-mortem studies found him devoted followers. His text Traite remained an influential work throughout the eighteenth century, finding many reprints and revisions. The section on heart diseases itself appeared in 2 editions under the title Traite' des maladies du coeur in AD 1778 and AD 1783. An Italian translation in AD1773 and a German translation in AD 1781 have also been recorded. As a rare achivement for the period, even Senac's contemporaries and rivals regarded the Traite as an authoritative work in cardiology. Authorities on subject of Cardiology in the likes of von Haller and Giovanni Morgagni spoke highly of Senac's treatise.

(Ref: Renouard PV. History of Medicine, from its Origin to the Nineteenth Century. Philadelphia, Lindsay & Blakiston, 1867, p 387)

Cardiac physical diagnosis altogether changed with the idea of stethoscope. Prior to this era, in one of the Royal Society meetings, celebrated physician Robert Hooke had wondered, “I have been able to hear very plainly the beating of a man's heart.... Who knows I say that it may be possible to discover the motions of the internal organs."

Within few years of this comment, a French physician by name Rene Theophile Hyacinthe Laennec revolutionized the diagnosis of cardiopulmonary diseases and opened new horizons to a hitherto undiscovered world. Before that time, physicians listened to the mysterious sounds of the heart by placing their ears directly on a patient’s chest, with interpretations that were ambiguous and highly subjective, not to forget the embarrassment both to patient and listener. Laennec was a student of Covisart, a celebrated physician who had refined the technique of percussion proposed by Leopold Auenbrugger. His association paved Laennec to think beyond percussion. Incidentally, Auenbrugger was a son of innkeeper and had devised the system of percussion to note the level of wine in barrels. Auenbrugger did not see much difference in diseased human chest filled with secretions and wine barrel. The resonation mattered. He was musically gifted enough to make a physical diagnosis with this invaluable technique.

Laennec’s era was also that of tuberculosis, with large number of deaths in Europe. He had not only lost many members of his family to this dreaded disease, he himself suffered from it. His knowledge of medical history had told him the Hippocratean way of direct auscultation over the chest. His knowledge of physics was sound enough to recognize acoustic principles: “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”. In AD 1816, when confronted with an aristocratic woman of exceptional obesity who proved nearly impossible for “direct auscultation”, he rolled some sheets of paper into a cylindrical shape and applied one end of it to the region of the heart, and the other end to his ear. He noted his experiment in one of his landmark articles as “I 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”.

His experiment encouraged him to try tubes of various materials for clarity and he finally decided to go with a wooden instrument, which served as the prototype of present stethoscope. It was a foot long and 2 inches wide, perforated in the center and fitted with a plug for listening to heart. It was made portable by making it in parts, which were assembled as per need. The name “stethoscope” was derived from two Greek words, which meant, “examining at the chest”, the name derived by Laennec himself. Wooden stethoscopes were in use until second half of the 19th century, when rubber tubing came along.

Although his idea of stethoscope was primarily for the evaluation of lungs, Laennec’s curious mind did not stop at that. He distinguished two heart sounds and correctly attributed the first heart sound to ventricular systole. However, his idea of second sound to atrial systole made him unable to make accurate correlations between murmurs and pathological findings. Nevertheless, it was valiant attempt to classify the heart sounds in a way that was hitherto unheard of.

In AD1818, Laennec presented his saga on the stethoscope to the Academy of Sciences in Paris. In the subsequent year, he published his masterpiece, “De l’auscultation me´diate ou Traite´ du Diagnostic des Maladies des Poumon et du Coeur,” in two volumes. Already hit by tuberculosis and frial, Laennec still brought out a revised edition of his epochal work in the subsequent year with a masterly correlation of stethoscopic sounds and diseases of the chest documented by postmortem findings. He made an innovative marketing strategy by presenting one of his stethoscopes to each buyer of copy of his revised book! The pinnacle of his glory came with the English translation of his work by John Forbes in AD 1821. A number of Physicians from Europe came to Paris to understand and gain “first-hand” experience with this new diagnostic tool. He was perhaps the most honored and talked about man in Europe at the time of his death in AD 1826, at the age of 45 years. He succumbed to the same disease that he tried to make the world understand better. 13th of August happens to be the day Laennec died and is an opportunity for us to commemorate a man who gave us the symbol by which doctors are recognized worldwide.

(Ref: 1. Laennec RTH. De l'Auscultation Mediate ou Traite du Diagnostic des Malades des Polmons et du Coeur fonde` principalement sur ce nouveau moyen d'exploration. Paris; JA Brosson & JS Chaude, 1819.
2. McKusick VA. Cardiovascular sound. London: Bailliere Tindall and Cox, 1958)

Next time, lets dwell upon the refinement in auscultation and further developments.

On a personal note, the week saw kids of team members getting ill. The work schedule became a bit of haywire with unexpected leaves and absences. Hope things will get better soon.

This problem may be seen exclusively in developing countries; how do you manage a 35-year-old single ventricle man, who is found to be fit for Fontan surgery in Cath? Are we really offering him any benefit? Is the natural history better than surgical outcome? Our senior cardiac surgeon, Dr Shekar Rao, is of the opinion that if a patient has earned his surgery, it should be given to him. Others did not approve of this. Any experiences in this regard?

What should be done for an adolescent patient with single ventricle with complete heart block? The cath study showed an increased ventricular EDP, a clear contraindication for Fontan repair. But bradycardia is known to increase the EDP; it may be more augmented with AV dissociation. How to put a correction factor for this? Our surgeons informed us that single ventricle patients with complete heart block have undergone Fontan surgeries in the past. But, if high EDP is the only contraindication, is there any way of dissociating the bradycardic component from innate problem? Any takers for temporary transvenous pacing for few hours prior to cath procedure? Can it nullify the high EDP secondary to bradycardia, leaving only the other factor? Any suggestions or experiences?

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