Beat-by-beat monitoring of systemic vascular resistance during head-up tilt for assessment of orthostatic stress response

A method is described for noninvasive cardiovascular evaluation of vasovagal syncope. Continuous electrocardiogram, impedance cardiogram, and finger-cuff blood pressure recordings are acquired and analyzed on a beat-by-beat basis for calculation of heart rate, cardiac contractility, cardiac output, mean arterial pressure, and systemic vascular resistance. In a patient with near-syncopal head-upright tilt response, a 200% increase in cardiac contractility 20% decrease in mean arterial pressure, and 66% reduction in systemic vascular resistance was demonstrated. Comprehensive cardiovascular assessment of orthostatic stress response may improve diagnosis and understanding of vasovagal syncope