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350 sion of the contracting auricles. When, however, auricular fibrilla- tion begins this compulsion is removed and then the pre-systolic murmur is no longer heard. A curious point, too, is that patients who have suffered from attacks of angina pectoris before auricular fibrillation began seldom so suffer after its appearance. The con- dition is amenable to treatment. Mackenzie advises that digitalis is the drug for auricular fibrillation and that it must be exhibited in large doses, 15 minims four times a day, until the pulse slows down. Thereafter the drug must be stopped or, rather, given in small doses sufficient to maintain the slowing. The results of this treatment in favourable cases are remarkable.

Heart Block. Stanley Kent and the junior His showed that there exists in the heart a neuro-muscular mechanism whereby stimuli pass from a node of tissue situated on the sinus venosus (and so known as the sino-auricular node), where they arise, to the auricles and ventricles. The means of their passage is the auriculo-ventricu- lar bundle, a strand of fibres of neuro-muscular type which bifurcates and supplies a branch to each ventricle. In cases of disease this bundle may be affected and so the passage of stimuli be prevented. Thus the auricles and ventricles will be dissociated from each other.

Partial Heart Block occurs when the dissociation is not complete. In this condition only alternate stimuli may pass (" 2-1 block ") or only every third stimulus. The patient is apt to suffer fainting attacks and also a condition known as the Stoke Adams syndrome. This occurs when a period of more than 18 seconds elapses before a stimulus passes. It is characterized by a convulsion, by stertorous breathing and by the bringing-up of frothy expectoration. As the disease causing the block advances the dissociation becomes more complete and then, curiously enough, the ventricle takes on its own rhythm and beats regularly at about 40 to 50 beats per minute. The fainting attacks now pass away.

Complete Block. Auricle and ventricle beat separately without relation to one another. The ventricular rate is slow (40 to 50). The auricular may be fast or normal. The patient may go on for a long time with this dissociated rhythm.

Block is not always caused by disease of the bundle. Certain in- fections and certain drugs may cause it temporarily. Treatment is not of much avail, but if the condition is diagnosed much may be done to prevent ill-effects from exercising their full force.

The main cardiac arrhythmies was elucidated by Mackenzie, Lewis and others. This work has now been accepted throughout the whole medical world. Lewis has pursued further the electro- cardiographic study of arrhythmia and has recently suggested differ- entiation between "homologous" and " heterogenous " rhythms. A type of the former is the youthful irregularity; of the latter the extra systole auricular flutter and auricular fibrillation.

Not less momentous than the researches on cardiac irregular- ities was Mackenzie's contribution to the subject of heart failure. He pointed out that the study of valvular disease had been large- ly a study of sounds heard through the stethoscope. It was the habit of the profession to relate an abnormal sound to a supposed gross abnormality of structure e.g. a broken valve and to make a prognosis on this supposition. This method led to many mis- takes and even to abuses, for time had shown that patients with murmurs of various kinds might yet be well able to carry on active lives and even to live to old age without any symptoms of distress. It seemed therefore to be necessary to discover some more sure ground of diagnosis than that existing.

Mackenzie asked himself the question : " What is it that I am afraid of when I examine the patient?" The answer evidently was: " Heart failure." Thus a new direction was given to the assessment of the significance of cardiac symptoms. These symptoms were no longer to be accepted and read in terms of the post-mortem room. They were to be put to the test of their relationship with failure of cardiac power, that is to say of the myocardium or heart muscle.

The effect of this re-statement was an increased interest in such subjective symptoms as breathlessness and pain. These symptoms, it was remarked, vexed the patient as a rule when he attempted exer- tion, at which times one or other might make its appearance. The breathlessness seemed to be due to an excitation of the respiratory centre by lack of oxygen weak circulation; the origin of the pain was more obscure. Mackenzie, however, called attention to the fact that in cardiac pain there is present as a rule an area of tenderness or hyperalgesia on the left side of the chest, below or surrounding the nipple. This is clearly a " referred " tenderness and corresponds to similar areas found in the skin of the abdomen in cases of visceral disturbance, e.g. gall-stone colic or appendicitis. The view was therefore formulated that the cardiac pain represented an effort of the heart to deal with large quantities of blood, that organ being incompletely prepared for its task. Thus the pain pointed to a weakness of the heart muscle.

The upshot of this work was a system of relating such findings as a murmur to the general state of the patient. Thus, if a murmur was heard and it was found that the individual was also breathless or suffered from marked pain and that these subjective symptoms were increasing, a tendency to myocardial exhaustion might be inferred.

If on the other hand the murmur was unaccompanied by symptoms its presence was not to be regarded as of so serious a character. This applied specially to systolic murmurs occurring at the moment of the cardiac beat and replacing the first sound. It applied also, how- ever, to the two murmurs which are generally regarded as betokening organic disease, the presystolic murmur of mitral stenosis and the diastolic murmur of aortic disease.

In connexion with the presystolic murmur Mackenzie pointed out that when auricular fibrillation occurred this sign disappeared, leav- ing however a mid-diastolic murmur, which is also frequently found in mitral stenosis. The disappearance of the murmur is occasioned by the failure of the auricle to beat. In the case of aortic disease the accompanying hypertrophy of the heart is an important additional sign of muscle damage, even though the cause of the hypertrophy is by no means clearly understood.

Evidently the value of this method of determining the degree and progressive character of heart failure must lack in value without some system of correction and test. Mackenzie early apprehended this difficulty and set himself to supply the want. He conceived that in the last issue the proof of the danger or otherwise of a symptom is the after-life of its possessor. Consequently while still a young man he undertook the laborious task of following up a large number of patients during a long period of years.

The test was continued for some 20 years and its results then pub- lished in a series of books and monographs. A great many symptoms had been recorded in the first instance and their after-histories were therefore, when revised collectively, a commentary on the prognosis of heart affections of a unique kind, both as respects content and value. It was found that certain symptoms which had an evil reputation had not at all interfered with healthy life an example is the systolic murmur met with in toxic persons; these murmurs are very frequent and the irritable type of hearts in which they appear is also a commonplace of the consulting-room. Mackenzie named the general condition "X-disease," because its exact nature was doubtful.

Another dreaded symptom which proved more or less without harm was the missed beat or extra systole. Another, the so-called caput medusae or group of injected venules seen on the margin of the ribs of many persons. Still another was the tendency to occasional palpitation or heavy beating of the heart after an acute illness.

On the other hand it was found that persons suffering from auri- cular fibrillation, attacks of true anginous pain (angina pectoris), from the curious cardiac rhythm known as pulsus alternans because every alternate beat is smaller, and from various forms of dyspnoea, tended to succumb at more or less early periods. In some cases, for example auricular fibrillation, much could be accomplished by proper treatment (digitalis) ; in others, for example pulsus alternans, little or nothing could be achieved.

This body of evidence is now at the disposal of the medical pro- fession and constitutes a contribution of enormous value.

Another aspect of the cardiological problem, which was brought into prominence by the war, is the so-called " nervous or irritable heart." Attention was first called to this condition in 1915, when it was found by the British army medical authorities that a very large number of soldiers were being sent to hospital and being invalided out of the service on account of heart disease. The extent of the mischief was so great that it was rightly con- cluded that some inquiry was called for and application was made to the Medical Research Committee to take the matter in hand. Sir James Mackenzie, Dr. Thomas Lewis, Capt. Thomas Cotton and Dr. R. M. Wilson were appointed to study the cases. At a later date a committee consisting of Sir Clifford Allbutt, professor of medicine at Cambridge, the late Sir Wm. Osier, professor of medicine at Oxford, and Sir James Mackenzie was constituted, and a separate hospital, Mount Vernon, Hampstead, was set apart for soldiers with heart complaints. This hospital had on its staff, in addition to the above mentioned, Dr. Thomas Parkinson of the London .hospital, Professor Francis Fraser now at St. Bartholomew's hospital, Professor Meakins now of Edinburgh University, Dr. Nigel Drury and others. A very pro- longed and careful research was carried out.

The symptoms of the condition were found to be breathlessness on exertion, pain over the praecordium, exhaustion and giddiness and fainting In addition palpitation was often complained of, as also were headache, lassitude, coldness of the extremities and irri- tability of temper. The signs, as opposed to symptoms, were in- creased heart rate, raised blood pressure in patients up and about, diffusion of the apex beat and irregularity of the heart's action. The temperature was frequently raised to 99-5 F. or to 100 F., such elevations being of a fleeting character. Respiration rate was also raised on exertion and tremor was the rule.

Lewis, who directed the research, gave to this picture the name of " Effort Syndrome " and wrote of it in an early publication: " A generalization which has been shown to approximate to the truth in respect of the exaggerated rise of heart rate, blood pressure