Paroxysmal tachycardia derives its name from the characteristic paroxysms of extremely rapid heart action that occur from time to time. These usually begin abruptly, last for minutes, days or weeks, and finally end almost as abruptly as they began. During the paroxysm the pulse rate ordinarily ranges between 180 and 300 a minute. At times the patient is hardly conscious of his condition. More frequently, however, he suffers from various cardiac symptoms, such as palpitation, dyspnea and painful or oppressive sensations in the precordium. In severe cases, well-marked signs of cardiac insufficiency, such as venous stasis and edema, may be present.
No adequate physiologic explanation of this form of tachycardia has been given. In many of its features it suggests a neurosis, yet attempts to produce a similar acceleration experimentally, either by stimulation of the accelerator or by division of the inhibitory nerves to the heart, have failed. Recent observations