Role of the Capacitance and Resistance Vessels in Vasovagal Syncope

摘要: Withdrawal of sympathetic tone to the veins resulting in peripheral pooling blood has been suggested as an important factor contributing decrease cardiac output and hence arterial pressure that occurs during vasovagal syncope. However, no measurements venous syncope have reported. In course other studies on circulatory effects negative below iliac crests, 80° head-up tilt, reactions occurred 10 subjects. Heart rate, central pressure, forearm flow, vascular resistance, or hand were measured. The typical reaction could be divided into two phases. A gradual fall signified onset phase I, which resistance did not change significantly. duration I was highly variable. II denoted by abrupt heart rate a 62% resi...