Comparison of right ventricular outflow tract gradient under anesthesia with post-operative gradient in patients undergoing tetralogy of Fallot repair

BACKGROUND: Intra-cardiac repair for tetralogy of Fallot has some degree of residual right ventricular outflow tract (RVOT) obstruction. However, the measurement of this gradient intra-operatively might get affected by the depth of anesthesia which is important for the long-term outcome. AIMS: The primary aim was to compare intraoperative RVOT gradient post repair under two different anesthetic depths of 1% and 2% end-tidal sevoflurane. The secondary objective was to follow up the changes in RVOT gradient till 1 month postoperatively. Design: Observational study. Setting : Advanced Cardiac Centre of PGIMER, Chandigarh. METHODS: Following intracardiac repair, RVOT gradient was measured directly by placing needle into the right ventricle and pulmonary artery at sevoflurane 1%, and subsequently, at 2% end.tidal concentration while maintaining hemodynamic stability. These gradients were also measured using transesophageal echocardiography (TEE) (ClinicalTrials.gov NCT03234582). RESULTS: Twenty-one patients were included in this study that had intra-cardiac repair, of which pulmonary annulus was preserved for 15 cases. Mean RVOT gradients measured invasively and by TEE at end-tidal sevoflurane concentration of 1% and 2% were not significantly different (6.67 ± 4.16 mmHg vs. 6.76 ± 3.82 mmHg, P > 0.05 invasively and 13.01 ± 7.40 mmHg vs. 12.53 ± 7.11 mmHg, P > 0.05 by TEE, respectively). RVOT gradient measured by trans-thoracic echocardiography (TTE) postoperatively at the time of extubation and during follow-up at 1 month showed significant reduction (11.37 ± 6.00 mmHg, P < 0.05 and 9.23 ± 4.92 mmHg, P < 0.01 respectively). Six patients who underwent repair with transannular patch had significant pulmonary regurgitation (PR) following surgery, with no significant change in PR severity or RVOT gradient on increasing anesthetic depth. CONCLUSIONS: Postoperative RVOT gradient was not altered by changing depth of anesthesia provided systemic blood pressure was maintained. One month postrepair RVOT gradients were significantly reduced as compared to the intraoperative values.