Electrocardiogram, case of auricular fibrillation in a man of 45 years. Patient had a very large heart and multiple murmurs. (Tracing kindly made for me by Dr. H. B. Williams, New York.)

wave, synchronous with the carotid wave. In this regard it somewhat resembles the picture of fibrillation (see below), but no one could confuse these two for any length of time; for the pulse of paroxysmal tachycardia is very rapid and almost perfectly regular.

As to the prognosis of extrasystoles, they are generally innocuous. When they present themselves in a man of middle age, with a normal percussion area and no murmurs, he is, in my opinion, still a firstclass insurance risk, and should be accepted without hesitation. The diagnosis should, however, be established in every case by a double tracing, and the tracing should be sent in as a routine practice by the medical examiner with the other data of the application blank.

Extrasystoles usually require no treatment. They come and go like the wind, which bloweth where it listeth. Hypodermics of atropine sulphate may be tried when the patient is rendered nervous or apprehensive by the subjective discomfort they sometimes entail. The essential cause of their coming and going is entirely unknown. The coupled beat after digitalis overdosage is a special form of extrasystole which has peculiar clinical meaning, and will be mentioned again.

Auricular Fibrillation.-Clinically this is the most important of all the irregularities of the heart, and in most instances it cannot be understood or successfully treated without the graphic records. This is specially the case in mitral stenosis, where extrasystoles are often tumultuous and frequent, simulating perfectly the irregularity of auricular fibrillation, and quite indistinguishable from it without mechanical aids.

Thomas Lewis describes the condition in this way: "Fibrillation of the auricles is a state in which coördinate contraction has ceased in both these heart chambers, and in which the individual strands of the musculature exhibit independent and constant twitching movements." These movements do not, however, drive blood into the ventricles; they only serve to upset the normal ventricular rhythm, and make its contractions "haphazard "-often rapid, nearly always irregular. The electrocardiogram (Fig. 13) shows this irregularity. It shows also that the ventricle in these cases is apt to be driven not only by relatively normal impulses from above, but also by extrasystoles of ventricular origin. These are indicated by the anomalous ventricular curves appearing at long intervals. It will be noted that there are

no normal P waves, but that abnormal undulations of the thread (auricular twitchings) occur from time to time, where P waves should appear.

In Fig. 14 is a polygraphic tracing of the same phenomenon in another patient. It will be observed that the jugular pulse here no longer shows v, a, c cycles at all; only systolic waves are seen (coincident with the carotid), together with an occasional coupled beat, of which only the first appears on the arterial line. The second beat of the couple is a ventricular extrasystole, and of this I shall say something more later on.

Auricular fibrillation is usually a condition of some gravity. It is associated with valvular disease and myocardial damage. Once well developed it usually persists. Sometimes, apparently, a patient has the good fortune to recover his sinus rhythm again, but these cases seem to grow rarer as I become more proficient in reading tracings. Paroxysmal fibrillation has been reported.

The fibrillating heart is the one which has created the reputation of digitalis in cardiac failure. The effect of the drug upon this condition in many cases is little short of a miracle. It is one of the great contributions of Dr. James Mackenzie to modern practice that he first discriminated the precise cardiac lesion with which digitalis stands in this relation. The rationale appears to be in part that digitalis lessens the conductivity of the bundle of His (see below), giving the ventricle, in this way, more time to fill up and rest between beats. But this explanation is evidently not a complete one. The matter is discussed at length and with great clearness and interest in Mackenzie's own writings, to which the reader is referred.

more.

In the multitude of additional facts touching upon this part of my subject there is only space for the mention of coupled beats once When digitalis has been pushed in cases of auricular fibrillation, and the condition of the patient has considerably improved, the irregularity of the heart does not disappear; on the contrary, it be comes more marked, and there become evident certain groups of double beats which have a characteristic in common, namely, the second beat of the couple appears imperfectly or not at all in the radial and carotid line, while both are well marked in the venous one. As digitalis acts further, there is a further slowing of the heart, with increase in the number of couples. This is called "digitalis coupling." The

Man, 37 years old. Rheumatic lesion of many years' duration. Fibrillation, the tracings showing at intervals ventricular coupling, the second beat of each couple being very large on the venous line, and small or absent on the arterial. (Tracings made at interval of some days. Jugular below.) This patient had received for a long while large doses of digitalis. (Alignment lines omitted through error of engraver.)

Man of 76. Block. Ventricles beating regularly, 24 to the minute; auricles (lower line) also beating regularly, 72 to the minute. Patient had most of the symptoms of the Stokes-Adams syndrome. (Patient seen with Dr. W. L. Baner, of New York, to whom I am indebted for permission to publish this tracing. The case will be reported fully by Dr. Baner elsewhere.)