Sympathetic nerve activity following Acute Type B Aortic Dissection: a pilot study.

Introduction Control of blood pressure following acute type B aortic dissection usually requires sympatholytic antihypertensive medication. Although sympathetic nerve activity is central to blood pressure control, its role in the hypertensive response to acute aortic dissection has not been assessed. Methods A prospective pilot study was performed over an 18-month period.

Mesenteric blood flow and muscle sympathetic nerve activity during vasovagal syncope.

Purpose: Vasovagal syncope is thought to be mediated by a progressive fall in cardiac output secondary to venous pooling of blood in the splanchnic circulation. How and when this occurs before syncope has not been determined.

Methods: A total of 20 patients who became hypotensive during head-up tilt (age 40.