Relation betwEen Abdominal Aorta and Carotid Artery Responses to SymPathetic stimulatiON uSing duplEx Ultrasound

Overview

Abdominal aortic aneurysm (AAA) is a common vascular disease and associated with risk of rupture, but also with a high cardiovascular (CV) event rate. A key difficulty in AAA is predicting these life-threatening complications. Recent studies suggest that the endothelial function of the abdominal aorta might have a correlation with the disease development. A novel, easy to perform, non-invasive test can assess central artery endothelial function (i.e. the carotid artery reactivity (CAR)). The CAR test is based on the cold pressure test (CPT), which induces sympathetic stimulation by placing one hand in cold water. Using duplex ultrasound, central artery blood flow and diameter responses can be examined. Previous work has demonstrated that the CPT is associated with an increase in abdominal aortic diameter, whilst others found that the carotid and coronary artery diameter also shows dilation. Interestingly, a previous study found a strong correlation between carotid and coronary artery diameter responses to the CPT, whilst these artery responses show independent prognostic value for future cardiovascular events in patients with peripheral arterial disease. Possibly, similarity may be present in central artery reactivity to the CPT. To date, no study examined whether carotid and aorta responses are in agreement during the CPT. Given the potential importance of central artery vasoreactivity for AAA, the CAR-test may have potential in this group, especially given the relative simplicity of measuring the carotid artery. The aim of this explorative study is to investigate the correlation between the magnitude of the abdominal aorta and the carotid artery diameter and blood flow responses during the sympathetic stimulation (using the cold pressor test) between healthy young, healthy older and individuals with AAA.

The present study is an explorative, observational study, which will include in total 60 participants divided over 3 groups; healthy young adults, healthy older adults and patients with a stable abdominal aortic aneurysm (i.e. 30-50 mm), who are currently under threshold for repair. When participants meet the criteria, they will be informed about the study and they will be asked for their written informed consent, when they are willing to participate. Every participant only need to visit one time, which takes approximately 30 minutes. Participant characteristics will be registered, including traditional risk factors and CV history. Subsequently, the investigators will perform the CAR-test, which takes approximately 15 minutes. Prior to the CAR-test, participants should follow some instructions with regard to food and fluid intake according to a physiological guideline, which can influence this test.