Etienne Jules Marey was a French physician and physiologist with major contributions to the field of cardiovascular physiology. He is remembered as one of the most outstanding physiologists of the 19th century.
Marey's major research interest was the development of new instruments in the graphic recordings of physiological events. In 1860, he significantly improved Vierordt's sphygmograph in a way that the entire device could be attached to the patient's arm. Furthermore, physicians were able to obtain graphics of the arterial pulse with greater detail with this new and refined instrument. Marey's first publication on the study of the pulse with sphygmograph appeared in 1860. He then published his major textbook entitled, "Physiologie medicale de la circulation du sang," in 1863, which became a reference textbook in cardiovascular physiology. An updated and expanded version of this work appeared under the title, "La circulation du sang a l'etat physiologique et dans les maladies," in 1881. This new generation of sphygmograph was increasingly used in clinical practice and by many investigators in their research studies on cardiac arrhythmias during the second half of 19th century (section Sphygmomanometry).
In early 1860's, Marey started his investigational work in cardiac catheterization. Marey worked extensively with Jean Baptiste Auguste Chauveau who was a professor of veterinary physiology in Lyon. Their collaboration started in 1860 and led to the invention of an instrument named cardiograph to study intra-cardiac pressures in animals (see below). They introduced air-filled ampoules in the cardiac chambers of large animals and recorded simultaneously the variations of pressure in different chambers during the cardiac cycle. The revolving drum which would allow them to obtain graphic recordings on paper was called kymograph. Marey and Chauveau obtained recordings of the pressure in the right atrium, the right ventricle, and the left ventricle (see below). One of their first observations was that the right atrial systole was accompanied with an increase of the pressure in the right ventricle. Using a manometer, they reported a peak pressure in the right atrium of 2.5 mm whereas the peak pressure in the right and left ventricles was 25 mm and 128 mm respectively.
Marey and Chauveau used their cardiograph to obtain simultaneously the pressures in the right atrium and the right ventricle and also recorded the apical pulse ("choc du coeur"). These authors were able to demonstrate that the apical pulse occurred at the time of ventricular contraction. In their text, they wrote: "...The atrium enters in systole before the ventricle and does not produce the apical pulse, the latter , in contrast, takes place at the precise moment when starts the ventricular systole." The figure on the top right indicates the blood pressure in the right atrium, and the right ventricle along with the recording of the apical pulse. As shown, the right ventricular systole and the apical pulse occur at the same time. Prior to this scientific demonstration, the common belief was that during atrial systole, there was a significant expansion of the left ventricle which pushed against the thoracic walls and produced the apical pulse (Beau's theory).
Marey and Chauveau used these pressure tracings to calculate the duration of different phases of the cardiac cycle. They reported that the time interval between the onset of atrial systole and the onset of ventricular systole was 0.2 seconds. The duration of the atrial and ventricular systole was calculated at 0.1 and 0.4 seconds respectively.
Chauveau and Marey reported the results of their experiments in a landmark article entitled, "Appareils et experiences cardiographiques," in 1863. The same year, Marey published his memorable monograph, "Physiologie medicale de la circulation du sang," which is considered the first work on the physiology of cardiovsacular system based on cardiac catheterization.
The experimental work of Bernard, Marey and Chauveau, three giants in the history of cardiovascular medicine, laid the foundation for cardiac catheterization in the 20th century.
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