None listed
Conditions
Brief summary
Aortic dissection is a highly fatal and morbid condition. Half of patients experiencing an aortic dissection die before reaching hospital and of those who survive until admittance, a further 50% will die within 30 days. Hypertension is the most prevalent and modifiable risk factor associated with aortic dissection (over 75%). For many with prior history of hypertension, this high blood pressure is very difficult to control despite taking tables (i.e., resistant hypertension). Many survivors of aortic dissection remain at an elevated risk of aortic rupture an death as a result of poorly controlled blood pressure. The hypertension in these patients share features with neurogenic hypertension / sympathetic nervous system hyperactivity, making traditional antihypertensive medications a poor match for managing their blood pressure. We aim to investigate the origin of hypertension in survivors of aortic dissection. We hypothesise that sympathetic hyperactivity is a dominant driver of hypertension and the risk of aortic dissection in this population. Understanding the origin of resistant hypertension will allow us to develop new therapies aimed at achieving better blood pressure control.
Interventions
This observational study will consist of a 30-60 min screening visit, followed by a 2-3 hour experimental visit. Studies will be conducted in Human Cardiorespiratory Physiology Laboratory within the Clinical Research Centre, Faculty of Health and Medical Science, University of Auckland. The following physiological measures will be made in survivors of Type A and Type B dissection, patients with stable ascending aortic aneurysms and healthy control participants. All assessments will be one-on-one
This observational study will consist of a 30-60 min screening visit, followed by a 2-3 hour experimental visit. Studies will be conducted in Human Cardiorespiratory Physiology Laboratory within the Clinical Research Centre, Faculty of Health and Medical Science, University of Auckland. The following physiological measures will be made in survivors of Type A and Type B dissection, patients with stable ascending aortic aneurysms and healthy control participants. All assessments will be one-on-one. n=20 participants per group (total 80 participants). Assessments: Screening / familiarisation: Obtain written informed consent. Health Screening Questionnaires (Health screening questionnaire, EQ-5D-5L, IPAQ) Virtual or in-person consult (30-60 min) conducted by a research nurse. Experimental protocol - one experimental visit: Conducted by a trained investigator. The experimental visit will last ~2-3 hours. Arterial stiffness Measured by the placement of a pen-shaped probe over arteries at the participants neck, wrist, and ankle. A cuff will be placed around the participants upper thigh that will inflate for a couple of minutes. Delivered by a trained investigator. Delivered face-to-face. Delivered once. Takes 10-15 min to complete this assessment. Flow mediated dilatation While brachial artery is imaged with ultrasound a cuff around the upper arm will be inflated [for 5 minutes] and then deflated [5 minutes]. Delivered by a trained investigator. Delivered face-to-face. Delivered once. Takes 10-15 min to complete this assessment. Sympathetic nerve activity. Sympathetic nerve activity recordings involve the insertion of a small, sterile wire (measuring 1-5 um) into the peroneal nerve near the fibular head. Standardised cardiovascular tests will then be administered separated by a ~10 minute break. All measures will be delivered by a trained investigator. Delivered face-to-face. This will involve: 1) Resting baseline (10 min): Participant will rest quietly while physiological signals are recorded. 2) Slow deep breathing at 6 breaths/min (5 min): The participant will be asked to take slow deep breaths for 5 minutes with the guidance of an investigator. 3) Mental arithmetic: Paced auditory serial addition test (PASAT) (6 min): The participant will be required to add two sequentially presented single-digit numbers, while retaining the latter of the two numbers in their memory for subsequent addition to the next number presented. 4) Cold pressor test (2 min): The participant will be asked to place a hand in cold water for 2 minutes, followed by 2 minutes of recovery. 5) Handgrip (2 min): The participant will be asked to hold a device that measures the force of the handgrip. The participant will do some short handgrip trials to establish the maximum grip strength, then hold ~30% of this for 2 min
Sponsors
The University of Auckland
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
• Participants with a clinical diagnosis of aortic dissection (type A or type B) or ascending aortic aneurysm • Normotensive controls (office SBP < 120 mmHg and DBP < 80 mmHg) participants • Men and women • Aged over 18 years
Exclusion criteria
• Severe untreated arterial hypertension at rest (>200 mmHg systolic, >120 mmHg diastolic) • Significant pulmonary hypertension • Unstable angina • Abdominal aortic aneurysm >8.0 cm • Active endocarditis, myocarditis or pericarditis • Significant arterial desaturation at rest on room air <85% • Severe aortic stenosis • Severe aortic regurgitation • History of connective tissue disorders (including Marfan’s, Loeys-Dietz, Ehlers-Danlos syndrome) • History of coarctation of the aorta • Upper limb arterio-venous fistulas • Use of radial artery conduit • Aortic arch surgery • Upper limb amputation • Significant arrhythmias (e.g., atrial fibrillation, previous VT / significant ventricular ectopy) • Severe left ventricular dysfunction • Recent (< 3 months) ischemic stroke • Current smoker • Body mass index < 18 kg/m2. • Current pregnancy • Users of recreational drugs • Abusers of alcohol • Inability to fully or appropriately provide consent (e.g., language issue, reading capability) • Underlying medical conditions, which in the opinion of the Investigator place the participant at unacceptably high risk for participating in the study
Outcome results
None listed