Five years after Rehn's historic article, Brunton published a proposal suggesting the feasibility of surgical correction of mitral stenosis. In his notes, he focused on three technical aspects: the method of increasing the mitral orifice size, the surgical approach to get access to the valve, and the choice of appropriate surgical instruments. Regarding the first question, he preferred "elongating the natural orifice" rather than cutting the leaflets in the middle. On the 2nd question, he suggested a ventricular approach as the ventricular wall was significantly thicker than the atrial wall. In his proposal, Brunton wrote:
"Mitral stenosis is not only one of the most distressing forms of cardiac disease, but in its severest form it resists all treatment by medicine. On looking at the contracted mitral orifice in a severe case of this disease one is impressed by the hopelessness of ever finding a remedy which will enable the auricle to drive the blood in sufficient stream through the small mitral orifice, and the wish unconsciously arises that one could divide the constriction as easily during life as one can after death. The risk which such an operation would entail naturally makes one shrink from it.... The risk of such an operation might be well worth while.... against the certainty of a prolonged period of existence which could hardly be called life....But no one would be justified in attempting such a dangerous operation as dividing a mitral stenosis on a fellow-creature without having first tested its practicability.... on animals.... I therefore think that may be worth-while to write this preliminary note, especially as, after all, if the operation is to be done in man it will be surgeons who will do it, and they must, of course, make their own preliminary experiments....The first question that arises is whether the mitral orifice should be enlarged by elongating the natural opening or whether the valves should be cut through their middle at right angles to the normal opening. I think there can be no doubt that the former would be the better plan.... The good results that have been obtained by surgical treatment of wounds in the heart emboldens one to hope that before very long similar good results may be obtained in cases of mitral stenosis."
Brunton's article raised significant amount of controversy and criticism. The following week the editors of the journal published a letter indicating their strong opposition to Brunton's proposal.
The general view of the physicians of that era, led by Sir James MacKenzie, was that the state of the ventricular myocardium was more important than the function of the mitral valve. MacKenzie in his classic work, "Diseases of the heart," wrote: "In chronic valvular affection the symptoms only arise where exhaustion of the heart muscle sets in. In organic lesions of the valves there may also be present advancing changes in the heart muscle."
Regarding Brunton's proposal, Sir James MacKenzie stated in a communication that he had considered this proposal carefully but felt that he "would rather leave the troubles and the dangers for others."
Mackenzie J. Diseases of the heart. London, H. Frowde, 1908