Auricular Fibrillation
In this condition the auricle is widely dilated and over its surface are countless twitchings of individual muscles giving to the auricle the appearance of a squirming bunch of worms. Such a condition may be readily produced in a dog's exposed heart by direct faradization of the auricle. It should be seen by every physician in order fully to appreciate the passive, dilated sac part which the auricle plays when in such a state. There is no auricular wave on the electrocardiogram (Figs. 41 and 42) only a series of fine tremulous lines, and the ventricles beat irregularly with many dropped beats and variations in the size and force of individual beats. Extrasystoles are also frequent. The heart is absolutely irregular. Such a condition is readily recognizable as the state of broken compensation. Graphic records are not essential as in auricular flutter to establish the condition. Inspection of the root of the neck for jugular pulsations and examination of the pulse with the patient's evident dyspneic, cyanotic, edematous condition settles the diagnosis.
Fig. 41.—Electrocardiogram showing auricular fibrillation in Leads I (upper) and II (middle and lower). (Courtesy of Dr. G. C. Robinson.)
Fig. 42.—Auricular fibrillation. (After Hart.)
In no case of auricular fibrillation is the heart muscle free from extensive fibrous changes. These may be the result of general arteriosclerotic changes or may result from toxic changes. It is the general consensus of opinion that auricular fibrillation may persist for months or even years. Some hold that the state of perpetual irregular pulse is associated with auricular fibrillation. If that is true, then auricular fibrillation may last for many years. Patients may go about their work but always live with the imminent danger of a sudden dilatation of the ventricle and symptoms of acute cardiac decompensation.
In these cases the blood pressure is of particular interest. It is often stated that the blood pressure is lowered as compensation returns and digitalis has exhibited its full action. As a matter of fact this statement needs some modification. If one takes the highest pressure at the strongest beat, which may be only one in a dozen or more, that may be true, but that does not represent the action of the much embarrassed heart. We know that the circulation is much interfered with, that there is hypostatic congestion, that the mass action is slow. The pulse pressure is greatly disturbed and the head of pressure which should force the blood to the periphery is so little that the circulation almost ceases.