Cardiovascular biomarkers and echocardiographic findings at rest and during graded hypovolemic stress in women with recurrent vasovagal syncope.

Women prone to vasovagal syncope demonstrate reduced cardiac preload, lower cardiac output, as well as increased release of vasopressin in rest and during hypovolemic challenge. The results emphasize the importance of venous return and cardiac output in the pathogenesis of vasovagal syncope.