Patient Selection and Choice of Access
Selecting the right group of patients to undergo TAVI can be challenging. Those who have been referred for a TAVI are already considered a high surgical risk and encompass features which are difficult to anaesthetist. Being able to determine those who can undergo GA and those who can’t is complex, and the approach must be adapted to each patient. When evaluating patients detailed physical examination, up to date blood tests and appropriate imaging such as TTE, baseline electrocardiogram and 24-hour tape, and cardiac catheterisation needs to be performed to ensure fitness for the procedure. Pulmonary function tests and cardiopulmonary exercise testing (CPEX) can aide in assessment of cardiovascular and respiratory function and can help quantify general anaesthetic risk. Scoring systems such as logEuroSCORE II, National surgical quality improvement program (NSQIP), Society of thoracic surgeons (STS) risk score can help determine cardiac operative risk which may be transferred over to assess anaesthetic risk. Those who are elderly, and frail will need to be assessed for functional status and care support which can factor into the decision to use sedation rather than GA. Patients with co-morbidities such as heart failure, chronic kidney disease, history of stroke, chronic obstructive pulmonary disease, and atrial fibrillation will not be able to tolerate periods of hypotension and hypoperfusion which can arise with the use of anaesthetic agents, which may require adjustment of anaesthetic approach or adjusted of doses of medications given. Conversely, they may be sensitive to fluid resuscitation, inotrope and vasopressor use, and hypothermia. The decision between GA and Sedation will ultimately be down to the clinician based on their experience and weighing up the risks and benefits of each technique along with the severity of AS, symptomology and associated co-morbidities and whether the intervention will improve the patient’s quality of life. [2,3]
Transfemoral approach is typically the preferred route for TAVI, in some cases due to peripheral vascular disease the patient may not have suitable anatomy for the procedure. There are several approaches that can be considered such as trans-axillary, subclavian, transapical. Each comes with its own set of risks which the anaesthetist and cardiologist need to be mindful of such as vascular injuries (e.g., subclavian approach), or lung injury and cardiac tamponade (e.g., transapical). [2]
When using a transcarotid approach, thorough carotid artery assessment prior to the procedure is required to ensure that there is no evidence of significant stenosis, plaque burden or anatomical variation. Anaesthetists must be wary of the risk of cerebral hypoperfusion and embolus formation during the procedure, which can be minimised using transcranial doppler and magnetic resonance angiography. Debry et al studied the outcomes of those who received transcarotid TAVI with the use of lidocaine as LA along with an infusion of remifentanyl as CS. Cerebral perfusion was monitored with cerebral oximetry. A total of 174 patients were included with 52 in the CS group and 122 in the GA group. Mean age was 80.5+/-7.9 years with patients in the CS group more likely to have a history of coronary artery disease and revascularisation. 7.6% were converted to GA due to discomfort and respiratory distress. Successful carotid vascular access was gained in all cases and device success was achieved in 88% of the CS group and 93% of the GA group. There were no cerebrovascular (CVA) or adverse events. There were 3 procedural deaths, and 30-day mortality was 7%. There was no difference in mortality according to the anaesthetic strategy. Post procedural AR was noted in 8.6% but was not significantly different between the groups. 5.7% developed CVA during 30 days with all events occurring in the GA group. [4]
A transapical (TA) approach can also be considered in those who have difficult peripheral vascular access or those who have significant plaque burden making a transcarotid approach difficult. Gauthier et al compared the outcomes of patients undergoing TAVI either via TF or TA under GA or LA+/-Sedation. The choice of agents for GA was left at the anaesthetist’s discretion. Propofol infusion or sevoflurane were used for maintenance of anaesthesia. LA was performed by the interventionalist with sedation only used if required. Patients in the TA group had a higher logEuroSCORE, they also stayed significantly longer in ICU and hospital compared to the TF group. Patients who had TF TAVI with sedation had shorter stays than those who had GA. Intrahospital and 30-day mortality was statistically significantly higher in the TA group. 30-day mortality was 17% in the TA group, 2% in the TF group under GA and 5% in the TF group under sedation. Major cardiac complications occurred more frequently in the TA group. One year mortality was calculated to be 24%, 11%, and 16% in the TF GA, TF Sedation, and TA group respectively. Overall estimated survival at maximal follow up was 26% for the TF GA group (46 months), 63% for the TF Sedation group (29 months), and 0% for the TA group (55 months). [5]