Source:  Snow, John. Med. Times and Gazette 15 (1857): 561. [ltr. to ed., 21 November 1857].

On the case of congenital fissure of the sternum

To the Editor of the Medical Times and Gazette.

Sir, --When I had the opportunity of examining the case of Eugene Groux, in the summer of 1855, I arrived at a conclusion respecting the cause of the pulsation seen and felt in the situation of the right auricle, which differed from the opinion which had been expressed on the case, so far as I am aware, and involved a point in the healthy action of the heart which was novel, so far as I know, though I may be mistaken. I recorded my conclusions in the book which M. Groux carries with him, and a little time afterwards sent a short communication to the Lancet on the subject.

I am very much gratified to find, from the Medical Times and Gazette of to-day, that Dr. Pavy has arrived at exactly the same conclusion as myself with regard to the cause of this pulsation, and I trust that it will not be unpleasant to Dr. Pavy to find that he and I are of the same opinion with regard to the cause of a phenomenon which exists, no doubt, in every healthy heart.

The following short passage from my communication will show that Dr. Pavy and I have given exactly the same explanation of the cause of the pulsation.

"When the ventricles contract, the portion of blood which is at their entrance is necessarily driven back into the auricles before the closing auriculo-ventricular valves, and the moment the ventricles become relaxed, the blood in the auricles is drawn onward again into them. It is the wave of blood so driven back into the right auricle by the tricuspid valve, as it is closed by the contraction of the right ventricle, which causes the pulsation seen and felt in the situation of the right auricle in the case of M. Groux, while the relaxation of the ventricle causes the sudden subsidence of the tumour."--Lancet, July 7, 1855, p. 17.

It is with regard to the pulsation, or rising up of the tumour, that we are entirely agreed, while there is a little difference between our explanations of its subsidence. Dr. Pavy has illustrated his conclusions, and possibly arrived at them originally, by vivisections on the dog, and he also makes some important remarks respecting the time when the auricles contract, a point on which I did not treat. I expressed the opinion, however, that "the filling of the tumour caused by the right auricle seems to be exactly synchronous with the first sound of the heart."

I made a remark respecting the time of the impulse of the apex of the heart and the pulsation of the aorta, which was not quite correct, as I find after I have had an opportunity, kindly offered me by Dr. Scott Alison, of examining the case with his sphygmoscope, but this slight error did not affect the main features of the case.

I am, etc.

John Snow, M.D.

Sackville-street, November 21, 1857.