Complications, and Drawbacks
When using LA; routine monitoring is required, though the need for invasive monitoring is at anaesthetist’s discretion. Sedation with similar agents as in GA such as propofol, midazolam can even at lower doses result in the side effects such as respiratory depression, loss of airway reflexes and haemodynamic compromise especially in the elderly who are more sensitive to these agents. Patients can vary in their depth of anaesthesia which can be challenging given a lack of definitive airway and require constant monitoring and observation by the anaesthetists. Risk of LA can include LA toxicity, due to accidental intravascular infiltration of LA. Though this is uncommon due to ultrasound use, good technique, and operator experience. [21] Mayr et al suggest the presence of anaesthetic support in use of CS in TAVI. 2009 patients underwent transfemoral TAVI between 2011 and 2016. 30% had CS with critical adverse events noted in 9%. CPR was performed in 2% and defibrillation in 1.6%. Conversion to GA occurred in 24 patients with 2% due to respiratory distress and 1% due to pain. Catecholaminergic support was required in 45% with 41% receiving vasopressors. [22]
Goldfuss et al studied the anaesthetic related complications during TAVI. 853 underwent GA with appropriate invasive monitoring, pre oxygenation and induction of etomidate, rocuronium and an infusion of remifentanyl. Inhalational anaesthetic agents such as sevoflurane were for maintenance. Mean age was 79+/-6 years with mean BMI 27+/-5 kg/m2. Most patients had an American Society of Anaesthesiologists (ASA) score of 3. Transfemoral (TF) access was used in 59.3% and transapical (TA) in 40.7%. Common complications included difficult intubations (0.7%), airway damage (0.9%), Dental damage (0.4%), laryngospasm (0.2%) and allergic reactions (0.4%). Despite 17.5% receiving prophylaxis against postoperative nausea and vomiting; 232 patients still developed symptoms. Delirium occurred in 74 patients with factors such as male gender, and pre-existing dementia influencing delirium rate. 44% were hypothermic by 0.8+/- 1.1 degrees though postoperative complicate rate nor mortality rate were significantly increased in this group. 75 patients were noted to be hypoxaemic during the start of anaesthesia with 22 patients with severe hypoxaemia. 61.3% of these patients received midazolam as premedication. [23]
Cerebral perfusion can be compromised at two points during TAVI: on induced cardiac arrest for balloon valvuloplasty and hypotension during valve release. Which in turn can affect post-operative morbidity and mortality as well as neurocognitive function. Anaesthetic agents can also affect haemodynamics and impair cerebral circulation. Mayr et al compared cerebral oxygen saturation and neurocognitive outcomes in patients receiving GA and sedation in the INSERT trial. Cerebral oximetry was monitored by near infrared spectroscopy. In 66 patients (31 in GA and sedation groups each) with sedation being carried out with an infusion of propofol 1 mg/kg/hr and remifentanyl 0.03 mcg/kg/hr with 10 ml of 1% Mepivacaine infiltrated to skin aiming for moderate to DS. 39% experienced peri-operative cerebral desaturation below the desaturation threshold, though there was no significant difference between groups. Neurocognition was assessed by memory, speech fluency and executive function which revealed no significant difference pre- or post-operative between groups. Procedure time, induction time, time taken to transport to ICU were comparable between groups. ICU stay was shorter in the GA group. Patients in the sedation group had a higher rate of respiratory events and need for bag valve mask ventilation (19%). Unrest and pain (61%) were also noted in the sedation group. 94% of sedation patients developed adverse events as oppose to 13% in the GA group with one patient (sedation group) developing a peri-operative stroke without signs of cerebral desaturation. Type of anaesthesia used did not affect implant outcome. [24]
Delirium is a common disturbance of cerebral function which can be seen in the elderly, frail, and patients with multiple co-morbidities. Postoperative delirium (POD) can be because of one or more pathophysiological stressors such as major surgery, sepsis, hypotension, GA and can increase the risk of mortality in these patients. Van der Wulp et al in a single centre study observed the outcomes of patients who underwent GA for a TAVI and the occurrence of POD. Of 703 TAVI patients with POD observed in 16.5%. POD occurred a median of 1 day after TAVI and continued for a median of 3 days. Mean age was 82 years in the POD groups and 49.5% were male. 25.9% of patients who developed POD had a history of delirium. 30-day survival was significantly lower in patients with POD. Long term follow up showed impaired 1 year, 3 year and 5 year survival in patients with POD. Complications such as CVA, infection, and atrial fibrillation were more frequently observed in patients with POD and longer hospital stays were noted. Patients with POD were older, had less body mass index, and a smaller aortic valve area. Device success was seen in 93.6%. There was also no difference in procedural duration between groups.[25] Goudzwaard et al studied the indicators and outcomes of TAVI patients with POD. 543 patients were enrolled with 43% having GA. Mean age was 70.1+/-8 years and 55% were men. There were no patients with a diagnosis of dementia. Incidence of delirium was 14% and patients who developed POD tended to be older, had a high prevalence of renal failure and stroke, and were considered frail. 59% of POD patients had GA with GA, non-transfemoral access and longer procedure time being associated with POD. [26]