Patient co-morbidities
Importantly, many patients undergoing TAAA repair will have pre-existing coronary artery disease (CAD) and associated risk factors20. Significant (but possibly silent) cardiac disease may reduce patient tolerance of thoracic aortic cross-clamping, an obligatory procedure that immediately increases afterload, and left ventricular stress, upon the heart21. Oxygen deprivation in proximal tissues and sympathoadrenal discharge constricts arterioles and is typically accompanied by arteriovenous shunting. Whilst acute (CPET) exercise may not replicate the profound physiological challenges imposed by cross-clamping, assessing the patient’s body under ‘simulated’ (physical) stress and corresponding systemic response to microcirculatory hypoxaemia may determine how well systemic tissue perfusion adapts to the surgical insult.
Furthermore, there is mounting evidence that the risk of developing spinal cord ischaemia is increased by up to 80% in those with CAD23. Identification of disease may not negate surgery but may lead to optimisation by coronary artery stenting or instigating antiplatelet therapy prior to any planned procedure21, 24. Connective tissue disorders represent an additional major risk factor for thoracic aortic disease with up to 20% of patients expressing at least one ‘high-risk’ gene25. Marfan syndrome (MS) is one such genetic disorder and typically presents in younger patients26. Giske et al. focused on pulmonary function and rehabilitation in patients with MS and found that O2PEAK was 30% and 50% lower in females and males respectively, compared to healthy (non-MS) controls27.