Central blood pressure

• Main Author: Guilcher, Antoine
• Published: King's College London (University of London) 2012
• Subjects: 612.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.628106

Central aortic systolic blood pressure (cSBP) differs from peripheral systolic blood pressure (pSBP) measured in the arm. cSBP may be estimated non-invasively by application of a generalised transfer function (GIF) to a high fidelity peripheral arterial waveform or from the late systolic shoulder (SBP2) of such a waveform. The relative accuracy of these estimates and the degree to which they depend on the accuracy of peripheral blood pressure is unknown. The interest in estimates of central blood pressure is driven in large part by the fact that aortic pulse pressure (cPP) is thought to be a better predictor of cardiovascular risk and response to antihypertensive treatment than peripheral BP. However, little is known concerning the mechanism by which drugs may reduce cPP independently of effects on peripheral BP. Objectives of this thesis were to: 1. Examine the relative accuracy of different methods (GTF and SBP2) for estimating cSBP and cPP from a high fidelity peripheral arterial waveform. 2. Determine errors introduced by non-invasive calibration of this waveform (as would be the case when such methods are used in practice), 3. Explore the use of a simplified method for estimating cSBP based upon pressure oscillations within an arm cuff. 4. Determine the mechanism by which nitroglycerin (NTG, a drug that has relatively selective actions to lower cSBP) lowers cPP. Pressure and in some cases combined pressure and flow velocity were acquired at the aortic root during cardiac catheterisation. Peripheral blood pressure was measured by oscillometry and peripheral blood pressure waveforms were obtained from blood pressure cuffs, radial tonometry and a servo-controlled finger cuff. To address objective 4 additional measurements of ventricular and arterial mechanics where made using ultrasound and magnetic resonance imaging.