The Effect of Surgery on Central Aortic Pressure & haEmodynamics Study

Study Overview
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Brief Summary
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The present study will investigate the effect of artificially stiffening the aorta by means of an aortic stent on central aortic haemodynamics (CAH). This study will determine whether aortic stenting inadvertently adversely impacts on CAH, thereby providing the rational for subsequent therapeutic intervention to reduce the associated cardiovascular risk.

Detailed Description
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Increased pulse pressure and pulse-wave velocity are recognized indices of arterial stiffness (Laurent, Boutouyrie, Asmar et al., 2001; Qiu, Winblad, Viitanen et al., 2003). An increased pulse pressure (indicative of increased central aortic pressure) is independently associated with an increased incidence of postoperative neurological and cardiac complications (Fontes, Aronson, Matthew et al., 2008). Pulse pressure has been identified as an independent predictor of cerebrovascular events after cardiac surgery (Benjo, Thompson, Fine et al., 2007). Moreover, many studies have demonstrated that pulse-wave velocity is an independent predictor of morbidity and mortality in a range of study populations (for a review see Vlachopoulos, Aznaouridis, Stefanadis, 2010). An increasing body of evidence suggests that brachial artery pressure, although representative, is not an accurate reflection of central aortic pressure. The Conduit Artery Function Evaluation study, for example, revealed that certain drugs preferentially reduce central aortic pressure, whilst having similar effects on brachial artery pressure. Moreover, in this study central aortic pulse pressure was demonstrated to be an independent predictor of clinical outcomes (Williams, Lacy, Thom et al., 2006). Other studies support the finding that markers of CAP are more closely related to surrogate measures of cardiovascular risk such as left ventricular mass (Haider, Larson, Franklin et al., 2003) and carotid intima-media thickness (Kostis, Davis, Cutler et al., 1997). One inadvertent effect of stenting is the introduction of a semi rigid conduit into the circulation. This could potentially increase pulse wave velocity and adversely affect central aortic pressures and haemodynamics. The investigators thus aim to investigate the effect of aortic aneurysm of surgery on central aortic pressures and haemodynamics

Conditions
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Abdominal Aortic Aneurysm, Pulse Wave Analysis, Risk

Intervention / Treatment
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* Other: This observational study will not entail an intervention.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All participants undergoing abdominal aortic aneurysm repair, with non-atheromatous common carotid arteries. Exclusion Criteria: Atheromatous carotid arteries

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Observational<br>The cohort will have their central aortic pressure, and carotid-femoral and brachio-femoral pulse-wave velocities measured. These measurements will take place pre-operatively, within a week of surgery, 6-weeks and 1-year post-operatively also. The surgery will be abdominal aortic aneurysm repair. | Other: This observational study will not entail an intervention.<br>* This study will entail measurement of central aortic haemodynamics before and after (clinically indicated) abdominal aortic aneurysm repair<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Pulse wave velocity |  | One year | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Central aortic pressure |  | 1 Year |