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 (SVT) is a common heart abnormality that presents as a fast heart rate. This heart rhythm disturbance can occur in healthy individuals and may include such symptoms as chest pain, palpitations, shortness of breath, sweating, and feeling faint. In rarer instances, unconsciousness may occur.