TREATMENT OF ACUTE CIRCULATORY FAILURE

SYNCOPE
Sudden loss of consciousness, brief or prolonged, from circulatory causes occurs under a wide variety of conditions, some of cardiac origin and others unconnected with the heart itself. It varies in importance from arrival incident to one of the utmost gravity.
Vaso-vagal Attacks.—Recurrent fainting attacks, while most frequent in the young asthenic girl, occur in either sex at any age and are not associated with cardiac disease. Generally the patient has some warning of the impending attack and is able to sit or lie down before becoming unconscious. Provided he is laid flat, the clothes around the neck loosened and the tongue prevented from falling back to block the airway, recovery is usually rapid. Attempts on the part of • sympathetic well-wishers to force brandy or other stimulants between the lips of the unconscious patient should be discouraged, since an aspiration pneumonia is • a possible sequel. Smelling salts are no longer included among the contents of a lady's handbag, and the lack of their availablity seems to have little effect on the recovery rate from fainting. The most important aspect of the management is' probably the establishment of the diagnosis. Fainting attacks can occur following ‘haemorrhage which, if it is into the gut, may not be immediately apparent. Again sudden loss of consciousness may occur as the result of a subarachnoid' haemorrhage, cerebral embolism, and a host of other non-cardiac conditions.

Cough Syncope.—In a number of people fainting is regularly precipitated by a heavy bout of coughing—the post-tussive or cough syncope. Prevention by cough sedatives or the avoidance of known irritants (e.g. tobacco smoke) is the only treatment.

Carotid Sinus Syndrome.—Recurrent syncopal attacks in patients in the older age-group may be due to a hypersensitive carotid sinus reflex. In such persons light cutaneous stimulation of the neck over the bifurcation of the carotid artery may lead to syncope. This may occur as a result of turning the, head to one side, thereby compressing the carotid sinus, particularly if the subject is wearing a tight neckband. Vagal inhibition of the heart and vasodilatory vascular effects predominate in different cases, while in others cerebral features are predominant. If the diagnosis is established, treatment is surgical denervation of the affected sinus which generally effects a cure.

Syncope due to Low Cardiac Output.—In patients with severe stenotic lesions of the aortic or pulmonary valves, it may be impossible for the cardiac output to rise with exercise. Under such circumstances syncope is likely to occur during strenuous activity. A similar mechanism is responsible for syncope occurring during physical activity in a patient with established complete heart block ; in these individuals the heart rate is fixed at about 30 per minute and acceleration with exercise is impossible. This again leads to deficient cardiac output under stress, impaired cerebral blood supply and syncope.
Cases of valvular stenosis with such symptoms should be considered as candidates for surgical relief. The patient with established complete block must be cautioned to live within his cardiac reserve.
Postural Syncope.—Postural hypotension, a fall in blood pressure with the assumption of the erect posture, may be sufficiently severe to cause unconscious¬ness. Severe postural hypotension of this type is uncommon : it is most often due today to treatment with hypotensive drugs, and should be regarded as an indication for revievdng the dosage of such preparations. It may also follow operations for hypertension, e.g. extensive bilateral sympathectomy.
In such patients some improvement may be effected by simple mechanical means—the application of a tight abdominal binder when the patient is lying flat in bed and before he rises. This prevents to some extent pooling of the blood in the splanchnic bed, which is largely responsible for the profound drop in pressure in the erect posture. The action of vasoconstrictive drugs (adrenaline, noradrenaline) is too short to be of value in this condition, but 15 to 30 mg. ephedrine given by the mouth may be helpful.

Syncope due to Primary Cardiac Causes.—While in infancy marked tachycardia can be tolerated without upset of cerebral function, attacks of paroxysmal tachycardia in the adult, and particularly in the elderly, are generally associated with loss of consciousness if the heart rate is over zoo/min. The extremely rapid inco-ordinate ventricular activity of ventricular fibrillation is comparable to cardiac arrest in its effects. At the other end of the scale very slow heart action, as occurs sometimes in long-standing complete heart block, may also be associated with loss of consciousness. Cardiac standstill, occurring in the course of an Adams-Stokes attack or at the onset of a coronary infarction, leads to unconsciousness of greater or longer duration and may, of course, be fatal .

Management of Adams-Stokes Attacks.—A patient with high-grade partial heart block in an unstable state may pass repeatedly from partial to
-complete heart block and back again, with repeated attacks of ventricular arrest. Patients in whom complete heart block has been stable over a period of months or years may also develop seizures of this type, sometimes twenty or more in a day. The prognosis in this second group is in general much worse than in the first. Treatment of the syndrome is directed on the one hand to that of individual episodes and secondly to the prevention of recurrent attacks.
Initial attacks are apt to occur when medical aid is not at hand. Patients who have survived such an episode should be admitted to a hospital unit with facilities for " monitoring " and for cardiac resuscitation. In an emergency external cardiac compression and mouth-to-mouth respiration should be attempted. The correction of the inevitable rapidly-developing metabolic acidosis is vital . If all simple measures fail, puncture of the heart with a needle inserted in the fourth left interspace some two inches from the sternum may be tried, and the prick may suffice to provoke a contraction. Adrenaline 0-3 ml. (5 min.) of a i : 1,000 solution may be injected directly into the ventricular cavity with some hope of restoring normal rhythm. To be effective such measures must be carried out within three to four minutes of the onset. The vital necessity of maintaining both an adequate circulation and pulmonary ventilation throughout cannot be over-stressed.
The frequency of attacks may be reduced by the administration of a sympa-thomimetic drug, e.g. ephedrine, 30 mg., or isoprenaline in sublingual tablets of 20 mg., given four-hourly. The long-acting preparation of isoprenaline has in the writer's experience proved effective in long-term use. If possible an electrocardiogram should be taken during an attack, since a proportion of patients suffer not from cardiac standstill but from paroxysmal ventricular fibrillation. In such people the administration of those sympathomimetic drugs fails to help and may in fact aggravate the state; patients who prove refractory to ephedrine may on investigation be shown to belong to this group. Such patients pose a difficult therapeutic problem, since quinidine given to damp down the ventricular fibrillation may produce standstill through depression of the idio-ventricular centre. There is no accepted effective treatment for this arrhythmia, which is commoner than previously supposed. The new beta-receptor blocker (propranolol) may have an, as yet undetermined, place in treatment.
Electrical devices, designed to provide rhythmic stimuli to the heart as a substitute for the normal excitation wave, have been devised in considerable variety and are now commercially available. These vary considerably in design, and some are so compact that the patient may wear an apparatus carrying a small battery as motive power. In some models the electrodes are sewn directly to the heart; the leads are brought out through the chest wall and connected to an external stimulator. In another type electrodes in the heart are connected to a coil buried subcutaneously and, through a simple induction effect from a second coil worn outside the skin, rhythmic stimulation can be achieved from a compact battery-driven apparatus. In another, an electrode-tipped cardiac catheter lies in the right ventricle, connected to a unit sewn into the fold of the right axilla, driving the heart at a predetermined rate. It is possible with many to arrange that the pace maker comes into action automatically if the patient's heart rate falls below a pre-determined figure. Such devices, made possible through modern electronic techniques, are now available commercially.
Cardiac Resuscitation.—Reference has been made in the section on myocardial infarction to the possibilities of cardiac resuscitation. Such measures have a valuable role to play in many other conditions, for example, in the revival of individuals who have been electrocuted or in those who suffer cardiac arrest or ventricular fibrillation during a surgical operation. Such apparatus is now widely distributed and readily available in hospitals, and the medical and nursing staff should be familiar with its use. Time is the over¬riding factor in successful resuscitation, for in the event of the circulation being re-established after more than three or four minutes of cardiac arrest permanent anoxic cerebral damage is probable. Artificial respiration is as important as maintaining the circulation, and in default of electrical apparatus, bold and timely recourse must be had either to external cardiac massage or to thoracotomy. The importance of the immediate correction of metabolic acidosis cannot be over emphasised.