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Rh the immobility render all manipulations much more difficult than they are elsewhere. All technical procedures at the root of the lung are made easier if the parts near the hilum are fixed by the special light forceps of Duval. They not only withdraw the lung from the path of the surgeon, but give a stable field in which to work." Another point emphasized by Moynihan is the "mimicry of a projectile by the hard rounded but irregular condition of a bron- chus." Most foreign bodies which have entered a bronchus by the mouth can now be removed by bronchoscopy, and unless they have caused abscess would rarely call for the trans-pleural operation.

Disease. Operations on the lung and pleura for disease have for their object: (i) The removal of morbid products from the lung by incision and drainage or by excision of portions of lung. (2) The induction of collapse of the lung for the arrest of haemo- ptysis or to give it rest and assist in recovery from tuberculous disease or to allow a cavity to close. (3) The removal of morbid products from the pleura and the separation of adhesions.

1. Incision of lung and drainage have been carried out (a) for hydatid cyst of lung; the cyst is incised, its contents evacuated, and the adventitious cyst wall left in place, either marsupialised and drained or sutured; (b) for gangrene and abscess of lung; (c) for tuberculous cavities.

Excision of portions of lung for tuberculous disease has been performed; in one case with survival for seven years. But Tuffier and Martin wrote in 1910: " Pneumotomy for tuberculous cavities has now fallen into disfavour, as likewise pneumectomy for early tuberculosis."

2. Collapse of lung is induced either by opening the pleura and admitting air, by injecting nitrogen, or by incising the chest wall down to the pleura, with or without resection of rib, detaching the parietal pleura and plugging the resulting cavity with gauze so as to bring about an extra-pleural pneumo-thorax.

3. Fluid is removed from the pleura by aspiration or by'incision. Aspiration is employed for serous effusions and sometimes for haemo- thorax. Incision with excision of a portion of one or more ribs is the current treatment for acute empyema, though some cases have been cured by aspiration only.

Recent experience seems to show that a wider opening into the pleural cavity than that usually made is desirable in empyema, so that the cavity can be inspected, the hand introduced, and all ad- hesions separated and false membranes and lymph removed. This is the only sure way to detect an inter-lobar abscess, and to secure expansion of the lung.

Immediate suture, after complete evacuation of the pus, has been carried out, but unless done very early does not seem likely to suc- ceed. It has been suggested the pus should be removed as completely as possible by aspiration, and then 20-60 c.c. of a 2 % solution of formalin in glycerine injected into the pleura. Chronic empyema in which the lung fails to expand and a persistent sinus has resulted has until recently been dealt with by extensive thoracotomy such as Estlander's operation with the object of making the chest contract down to the level of the contracted lung; the more recent operation has for its object the expansion of Ae lung. A free opening is made in the chest by the method of Duval or some analagous method, and the false membranes, often of considerable density, which bind down the lung are stripped off, and the pleural cavity closed.

Of the various intra-thoracic operations that have been suggested and tried, some will doubtless be abandoned while others will be developed and pass into current surgical practice. The war demanded new methods of diagnosis and treatment, and these were evolved and perfected amid stress and strain.

It was found that the chest cavity hitherto treated with undue deference could be opened and its contents inspected, palpated and dealt with as readily and as safely as the contents of the abdomen. This knowledge, won at the cost of so much suffering, has now to be applied to civil surgery, and when this is done even more successful results may be expected. Mr. G. E. Cask, in his Lettsomian lectures for 1921 gave an able exposition of the surgery of the lung and pleura as influenced by the experience of the World War; these lectures have been published in the Transactions of the Medical Society of London. (C. A. B.) HEART DISEASES (see 13.132). The study of disease of the heart entered on a new phase in the second decade of the 20th century as a result of the researches of the Scottish physician, Sir James Mackenzie (b. 1853). His work, which first made a public appearance in 1902 with his Study of the Pulse, and later was embodied in Diseases of the Heart (1908) and Principles of Diagnosis in Heart Affections (1916), followed three lines. In the first place there were new observations on the rhythm of the heart itself; secondly there were observations and conclusions regarding the meaning of heart failure and its recognition; finally the importance of the early signs of disease as opposed to its later manifestations was emphasized.

Mackenzie showed that by making tracings from the neck as

well as from the wrist it was possible to obtain information regarding the activity of all the chambers of the heart. The neck tracings gave a wave when the auricles contracted, This was caused by a reflux of blood up the jugular veins; following this came the ordinary pulse beat in the carotid artery, which lies close to the jugular vein and so can be recorded by the same tambour. Thereafter a third wave in the vein indicated the muscular tightening-up of the organ at full systole.

The three waves were named respectively a (auricular), c (carotid) and v (ventricular). Normally the a wave occurs J /5 sec. before the c wave. The tracing which shows these waves is a continuous line and thus it is difficult to determine in the first instance which wave is which. This difficulty can be over- come by putting an ordinary pulse tracing on the same piece of paper. The carotid pulse occurs Vio sec. before the radial pulse. Thus the wave occurring in the composite tracing Vio sec. before any beat in the wrist pulse tracing is the c wave. It is then easy to determine the other waves.

This work led to the differentiation of cardiac irregularities a subject which had been shrouded in mystery. It was much facilitated by the discovery of the string galvanometer or " elec- trocardiograph." This instrument depends for its working on the oscillations of a special string between the poles of a magnet. Currents are set up when the heart beats, separate currents for auricles and ventricles, and these cause the string to move. Its movements are photographed onto a moving plate in such a way that a line tracing is produced. The nomenclature of elec- trocardiograms differs from that of pulse tracings in that the a wave is called the p wave, the c wave the r and the i> wave the t wave. (It must be noted, however, that the tracings are produced in entirely different ways and therefore there is no real compari- son between these waves.) There are several " leads " to the electrocardiograph i.e. the patient may have a hand and a foot in the salt pails which constitute its terminals or he may have both hands.

The electrocardiograph confirmed Mackenzie's findings and enabled them to be extended. In this work Thomas Lewis, who had assisted Mackenzie, played a great part and was able to clear up some points which had not been fully understood. Thus the discovery of the fact that in a certain irregularity of the heart the auricles of that organ are no longer beating is due to Lewis. He named the condition " auricular fibrillation."

The following types of irregularity are described by Mackenzie :

Youthful Irregularity. The pulse varies with_ the breathing. It is quickened by inspiration and slowed by expiration. When the breath is held the irregularity disappears. This condition is occa- sioned by the vagus nerve which exercises a slowing influence on the heart. It is common in young persons and is of no evil significance.

Extra Systoles. These are the popular " missed beats." They are not, however, missed beats at all, but beats which occur out of their normal time. The so-called " auricular extra systoles " are produced by the whole heart, both auricles and ventricles taking part; the " ventricular extra systoles " are produced by the ventricles only, the auricles beating at their normal time. These beats occur too soon and so the heart is not fully charged with blood. In consequence, the beat may not be discernible at the wrist. The heart pauses after the beat to recover itself. There is then a big beat. Extra systoles in the absence of signs of cardiac failure may be ignored.

Paroxysmal Tachycardia: Auricular Flutter. In this condition a period of abnormal rhythm suddenly occurs. The pulse rushes off and the patient is pulled up and feels a soft fluttering in his chest. A tracing shows that the auricles are beating more rapidly than the ventricles, only a few of the beats being followed by ventricular contractions. The auricles may achieve very great speed, even 200 beats a minute. The condition, as a rule, ends suddenly.

Auricular Fibrillation. In this condition the patient suddenly becomes very unwell. His feet may swell and his liver dilate. He becomes breathless on exertion and may have much cyanosis. The pulse is often rapid and is always markedly irregular. There are small and big beats but no two beats are of the same length. More- over the irregularity does not disappear on exertion as does that caused by extra systoles a useful means of distinguishing the con- ditions. The cause of the trouble is a fibrillation of the auricles which are no longer contracting. In tracings the a wave and in electrocardiographs the p wave is absent. The condition points as a rule to grave cardial mischief; it frequently occurs in mitral stenosis narrowing of the orifice of the mitral valve. In this disease a rough murmur is heard just before systole of the heart and is caused by the rush of blood through the narrowed orifice under the compul-