instead of a simultaneous, closing of the pulmonary semilunar and aortic semilunar valves, the pulmonary valves continuing to act in their proper order, and closing twice in the same time that the aortic valves close once, until the simultaneous action is restored. I am, however, induced, by further research, to believe that this view does not quite correctly explain or define what really occurs, and I therefore beg to offer a revision of the subject in a separate chapter.

CHAPTER II.

CAUSE OF INTERMITTENT PULSE, MECHANICAL AND ORGANIC.

Mechanical Cause of Intermittent Pulse.

When we write the sounds down in order, before, during, and after an intermittent act, thus

Ventricular intermittency

Natural.

with loss of pulse.

Returning long
ventricular
systole with
return of pulse.

Natural.

Lūb dúp dúp

Lub dúp 0

Lüb dùp 0 0 dúp 0 the phenomenon of intermittency is seen clearly enough, I think, as dependent on failure of the action, I will say first, of the left ventricle. In what does that failure consist? Does the ventricle not contract, or does it contract and find no blood upon which to close? The evidence on this point is very sound. It goes at once to show that the ventricle does not contract; if there were no blood in the ventricle, there must be blood in excess in the pulmonary circuit and in a hugely distended auricle, of which conditions we have no indications whatever. That is the negative side; but there is positive, almost speaking, evidence of what has occurred in the long thud of the returning systolic sound which proclaims the ventricle again at its work, and which tells that it is contracting on a more than ordinary volume of blood within its cavity. If these evidences, then, be true, the intermittency of the arterial pulse occurs from an independent failure of action of the left ventricle of the

heart. The ventricle continues in diastole for two or more strokes of the systole of its auricle, and then relieves itself by a prolonged effort; it is like a smith who, striking at the forge a number of strokes in rhythmical succession until tired, changes the action for a moment to give a more deliberate and determinate blow, and then rings on again in regular time.

This no doubt is true in relation to the left ventricle, but is the failure confined to the left ventricle as originally assumed, or do both right and left ventricles fail? I am now of opinion that both ventricles fail, and that the order of change from the natural through the unnatural and again to the natural is as follows.

The ventricles, filled by the systole of the auricles, fail to contract on the blood contained in them; thus the system altogether is left with the arterial side of the heart full, with the arteries contracted on a small column of blood, with the veins full, and with the right side of the heart full both in auricle and ventricle. In a word, the whole circulating system is left containing blood, so that the line of the blood current continues unbroken. During the interval of the cessation of the action of the ventricles, blood is, moreover, still entering the right auricle from the two cave, by that continuous force which the older writers called the vis a fronte, and the auricle remains in motion, contracting on its contained blood. column of blood is in this way still carried into the pulmonary artery, and, the artery contracting, a feeble second sound is produced, after the loss of the systolic sound, by the closure of the pulmonary semilunar valves. Lastly, when the ventricles again contract, contracting as they do at this time on a double charge of blood, there is produced the long heavy systolic sound, followed by the two sharp faint second sounds, the reduplication of the second sound being due either to a separate

A

closure of the pulmonary and aortic sets of valves, or to a simultaneous double but feeble closure of both.

Organic Cause of Intermittent Pulse.

In the above explanations I have dealt simply with the mechanical cause of the abnormal phenomenon of intermittency of the pulse. Now arises the question-what is the more elementary, the organic, cause? Let us study this question by the process of exclusion.

We should naturally begin by looking into the structure of the heart for a cause. We should be wrong. The fact alone that during the intervening periods of intermittency the heart is natural in its action, would go far to indicate that in it there need be no serious organic lesion. Still, this of itself would be little were it unsupported by more direct evidence. Being greatly interested in this matter, I seized once the opportunity of examining after death the heart of an aged man, who for many years presented the phenomenon of intermittency more determinately than I ever before had seen; his pulse, never, as far as I could learn, failed to intermit less often than once in eight beats. His death was from senile decay, but his circulation may be said to have outlived all the other of his systemic powers. When quite insensible, the pulse with long hesitations, came up again, and the pulse was beating at the end, even when the respiration had ceased. After death, instead of a diseased heart, the heart was found the healthiest of the organs of the body. There was no trace of valvular disThere was no departure from the natural size and condition of the cavities or the thicknesses of the walls; the coronary arteries were normal, and the muscular structure, quite free from fatty and granular degeneracy, was merely, as the tissues are in the aged, a shade paler than is common in the young and robust. Since the occurrence of that case, I

ease.

have confirmed the experience then gained by three other expeperiences. I feel bound, therefore, to say, from what I have seen, as positive truth, that the most marked intermittency of the heart may be present without evidence of any known form of organic disease of the organ itself; and, as one fact carefully assured is as good as a thousand, I am driven to accept that there is no known morbid condition of the heart itself, structurally considered, that produces the phenomenon of intermittent action. Intermittency may co-exist with other signs of cardiac derangement essentially of structural origin ; a fatty heart may intermit; a heart with faulty valvular mechanism may intermit; and intermittency with structural change may form, and often does form, a most serious complication. These facts we must at once allow, but we must allow them feeling that the intermittent action, having no necessary connection with the structural disorder, is evoked by a cause remote and independent. Pre-existent diseases of a special kind, such as acute rheumatism, do not, so far as I can learn, leave intermittency specially in their train; neither, as far as I know, is the phenomenon more common in those who have structural disease of the heart than in those who have not.

From the study of the heart itself we may turn naturally to the digestive system, and ask if there can be any cause for the symptom in functional or organic disease there? May not the symptom, that is to say, be due to some one of the many forms of dyspepsia? On this point my observations lead me to assume that intermittency of the heart has no relation to what is commonly called "dyspepsia." It is true that many dyspeptic persons have intermittent pulse, but this fact does not affect the question, because it is equally true that many persons who have determinate intermittency of pulse have the most keen and excellent digestion. I have a patient at this very time whose case is strictly in point: his pulse intermits every sixteenth beat, but his tongue is clean, his urine natural, his