Central blood pressures
In clinical trials, some patients benefit from blood pressure medications, while others do not despite equal reduction in blood pressures measured in the arms. This led to the question of whether pressures in the arm are reflective of the pressure at the root of the aorta. The pressure in the aorta is felt by the major organs, such as the kidney and the brain. These organs are directly connected to the aorta and suffer from the consequence of high blood pressures. While earlier determination of central blood pressures required invasive heart catheterizations, recent technology allows us to accurately determine central blood pressures by analyzing the pulse wave form in the arm.
Why the test is performed
Central blood pressure readings provide accurate and reliable assessments of:
- Central blood pressure: Blood pressure at the root of the aorta.
- Central pulse pressure: A measure of stiffness of the aorta.
- Augmentation index: A measure of stiffness of peripheral blood vessels.
Central blood pressure is a valuable tool for customizing management of high blood pressures in patients.
- In 1/3rd of patients, the pressures in the arm do not correlate to pressures at the aorta. Patients with elevated systemic vascular resistance (SVR) will respond better to vasodilators, or the widening of blood vessels, than diuretics or beta-blockers.
- Approximately half of individuals with an arm blood pressure between 120-140 will have a raised central systolic blood pressure.
- In patients with increased vascular stiffness, improving stiffness might have benefits that extend beyond controlling blood pressure.
Measurement of central blood pressures is non-invasive, quick and has no serious risks or adverse consequences.
How the test is performed
Four pairs of electrodes, as used to perform an electrocardiogram, are placed on the neck and chest wall. A high frequency, low magnitude signal is transmitted from the outer to inner electrodes. The timing and speed of the signal is used to calculate the hemodynamic parameters.
After the test
When the patient returns, these measurements are transferred to a computer where they can be easily viewed and documented in a report.
Central blood pressures provide a better and more comprehensive assessment of the future risk of stroke and heart disease from high blood pressures.
- Hajjar I, Goldstein FC, Martin GS, Quyyumi AA. Roles of Arterial Stiffness and Blood Pressure in Hypertension-Associated Cognitive Decline in Healthy Adults. Hypertension. 2016 Jan;67(1):171-5. doi: 10.1161/HYPERTENSIONAHA.115.06277. Epub 2015 Nov 2. PubMed PMID: 26527049; PubMed Central PMCID: PMC4715367.
- Williams B, Lacy PS, Thom SM, Cruickshank K, Stanton A, Collier D, Hughes AD, Thurston H, O'Rourke M; CAFE Investigators; Anglo-Scandinavian Cardiac Outcomes Trial Investigators; CAFE Steering Committee and Writing Committee. Differential impact of blood pressure-lowering drugs on central aortic pressure and clinical outcomes: principal results of the Conduit Artery Function Evaluation (CAFE) study. Circulation. 2006 Mar 7;113(9):1213-25. Epub 2006 Feb 13. PubMed PMID: 16476843.
- Morgan T, Lauri J, Bertram D, Anderson A. Effect of different antihypertensive drug classes on central aortic pressure. Am J Hypertens. 2004 Feb;17(2):118-23. PubMed PMID: 14751652.
- McEniery CM, Cockcroft JR, Roman MJ, Franklin SS, Wilkinson IB. Central blood pressure: current evidence and clinical importance. Eur Heart J. 2014 Jul;35(26):1719-25. doi: 10.1093/eurheartj/eht565. Epub 2014 Jan 23. Review. PubMed PMID: 24459197; PubMed Central PMCID: PMC4155427.