Aortic valve tumour trapped in the right coronary ostium

Objective-To investigate the haemodynamic eVects of varying the angle of head up tilt.Methods-20 healthy subjects (12 female, eight male; mean (SD) age 33.6 (8.4) years) underwent head up tilt for five minutes to each of four angles of tilt in random order, with a five minute rest period at the horizontal between each angle.Forearm blood flow was measured using intermittent occlusion mercury strain gauge plethysmography at two and five minutes.Subjects underwent continuous monitoring of heart rate, systolic blood pressure (SBP), and diastolic blood pressure (DBP) by Finapres and cardiac output and stroke volume by impedance cardiography.Each variable was measured at two and five minutes, averaged over the period of blood flow measurement.Results-Every haemodynamic variable at each angle was significantly diVerent from supine values.Head up tilt produced progressive increases in heart rate (11-21%), SBP (12-21%), and DBP (20-33%) with increasing tilt angle.However, although 45°produced significantly less haemodynamic eVect, there were no significant diVerences for angles between 60°and 90°.Cardiac output fell on head up tilt by 17-20% and stroke volume by 28-34%, but increasing tilt angle produced no significant additional reduction in cardiac output and stroke volume because of increases in heart rate and vasoconstriction.Conclusions-Angles < 60°produce significantly less haemodynamic eVects than steeper angles.Increasing tilt angle beyond 60°produces no apparent additional eVect on cardiac output or sympathetic tone.Increasing tilt angle beyond 60°confers no additional orthostatic stress and may not aVect the sensitivity and specificity of head up tilt testing as previously thought.Sixty degrees of tilt is a more practical angle for support of a syncopal patient and is recommended.