The part of the autonomic nervous system originating in the brain stem and the lower part of the spinal cord that, in general, inhibits or opposes the physiological effects of the sympathetic nervous system, as in tending to stimulate digestive secretions, slow the heart, constrict the pupils, and dilate blood vessels.
Paroxysmal supraventricular tachycardia (PSVT) Alternative names PSVT; Supraventricular tachycardia Definition: Paroxysmal supraventricular tachycardia (PSVT) is a rapid heart rate, which occurs from time to time (paroxysmal). PSVT starts with events taking place above the ventricles.
Supraventricular tachycardia is a series of rapid heartbeats that begin in or involve the upper chambers (atria) of the heart. SVT can cause the heart to beat very rapidly or erratically. As a result, the heart may beat inefficiently, and the body may receive an inadequate blood supply.