Thursday, May 28, 2009

Nobel Laureate: Willem Einthoven


The Nobel Prize in Physiology or Medicine 1924

"for his discovery of the mechanism of the electrocardiogram"

Willem Einthoven (1860 - 1927) won the Noble Prize in 1924 for discovering a practical machine for detecting the electrical actions of the heart. He discovered the electrocardiogram and identified its characteristic features.

Einthoven's apparatus was based on the string galvanometer, which he had developed a number of years earlier. The importance of an accurate electrocardiogram in diagnosing various heart conditions was instantly recognized. But first, the actions of a normal heart had to be carefully recorded and explained. The explanation put forth by Einthoven proved to be substantially correct.

Here's how the standard electrocardiogram is described in the Presentation Speech.
Nobel Laureates
However, in his work in 1908 Einthoven gave an interpretation of the electrocardiogram. He starts from the fact that the stimulus (of the contraction process, the «negativity») is propagated as a wave in the muscular system of the heart. The string of the galvanometer, connected with the heart in a closed circuit in one of the usual ways, remains in the original position not only when the heart is at rest, but also when the «negativity» of the assemblage of points of the heart wall show the same value. A deflection is therefore in the first place to be expected at the beginning and at the end of a systole, and it presupposes that the condition of activity does not occur, respectively cease, simultaneously in all elements of the muscle. Further: if the contraction process (the stimulus) is propagated symmetrically in relation to the points connected to the galvanometer, then no deflection would take place either. Under such circumstances the electrocardiogram must be determined partly by the starting-point of the stimulus to the heart beat, partly by the conduction system within the heart. The point of departure for the normal heart beat has been sufficiently well known since the middle of the 1890's, the bundle of His also since that time, and Tawara's description of the ramification of the conduction system inside the ventricles known since 1906. According to Einthoven the P-peak is an expression of the propagation of the stimulus wave in the muscular system of the auricle. The negativity wave, corresponding to the stimulus wave in the His-Tawara system, is considered too weak by Einthoven to cause any deflection in the galvanometer. The QRS-complex is determined by the propagation of the stimulus wave in the muscular system of the two ventricles, proceeding in unsymmetrical fashion to the points of lead, starting at different moments at the transition of the tree-like ramified Purkinje's fibres into the various parts of the proper muscular system of the heart. When the contraction process has reached its maximum in all the points of the ventricular wall, the string returns to its original position. When the contraction ceases in the various parts at different moments, a T-peak is obtained.

It is unnecessary in this connection to consider the interpretations proposed by other investigators, as Einthoven's concept is the only one which has proved to be tenable. The interpretation that the P-peak belongs to the auricular systole is mainly based on his observation of electrocardiograms in cases of heart block in patients or during vagus stimulation in dogs. With regard to the interpretation of the QRS-complex Einthoven was evidently the first who has clearly recognized the significance of the conduction system in this connection. The train of thought in the interpretation of the T-peak can already be detected in Burdon-Sanderson's previously mentioned work.

The images of the Nobel Prize medals are registered trademarks of the Nobel Foundation (© The Nobel Foundation). They are used here, with permission, for educational purposes only.

No comments :

Post a Comment