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

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.

Eligibility Criteria:
Inclusion Criteria:

* Young healthy group: Male or female between the age of 18 and 40 years old;
* Older healthy group: Male or female, which are age-/sex-matched with the AAA patients group;
* AAA patients group: Male or female with an abdominal aortic aneurysm who is still under surveillance, with a diameter between 3.0 and 5.0 cm and at least 18 years old. These patients may participate in the 1-2-3 Trial, which is a similar approved investigation by CMO region Arnhem-Nijmegen with registration number 2019-5216.
* Informed consent form understood and signed;

Exclusion Criteria:

* Psychiatric or other conditions that may interfere with the study;
* Participating in another clinical study, interfering on outcomes;
* With regard to the necessary quality of the ultrasound images, BMI ≥ 30 kg/m2;
* Increased risk for coronary spasms (score Rose-questionnaire ≥2; this questionnaire can be found in the Appendix);
* Known carotid artery disease
* Presence of Raynaud's phenomenon, Marfan syndrome, chronic pain syndrome at upper extremity(s), presence of an AV fistula or shunt, open wounds to the upper extremity(s), and/or scleroderma associated with placing the hand in ice water;
* Recent (\<3 months) presence of angina pectoris, myocardial infarction, cerebral infarction, and/or heart failure, or PAD treatment.
* Healthy groups:

  * Systolic blood pressure \>140 and/or diastolic blood pressure \>90
  * Cardiovascular history
  * Antihypertensive medication