Predictive Value of Right Ventricular Pressure Measurement for Residual Pulmonary Stenosis in Tetralogy Repair

Objective: The long-term outcome of tetralogy of Fallot repair depends on an adequate relief of right ventricular outflow tract obstruction and preservation of the pulmonary valve function. Since intraoperative transesophageal echocardiography is not routinely performed in small patients, we postulated that the post-bypass right ventricular pressure measured intraoperatively could predict residual pulmonary stenosis when evaluated by transthoracic echocardiography.Materials and Methods: Of the 187 patients who underwent tetralogy repair between 2012 and 2019 at Siriraj Hospital, Thailand, 95 with right ventricular pressure measurements and pre-discharge echocardiography were included in the study. Their intraoperative parameters, and postoperative outcomes were analyzed. The tolerable pressure cutoff was determined.Results: The median patient age was 3.9 years old (interquartile range 2.75–6). Fifty-three patients (54.6%) required the use of the transannular patch. Ten patients (10.3%) had significant residual pulmonary stenosis with a mean right ventricular systolic pressure of 64.0±10.6 mmHg compared with 48.7±14.4 mmHg for the other patients. There was an association between the pressure figure and the degree of residual pulmonary stenosis (rho=0.391, p=0.01). A systolic pressure above 49 mmHg predicted pulmonary stenosis with a likelihood ratio of 2.18 (1.94-2.80, 95%CI). The likelihood rose to 2.93 (2.44-4.01, 95%CI) if the pressure resulted in a right to left ventricular pressure ratio above 0.62. The patients whose figures did not exceed 49 mmHg experienced no significant residual obstruction, regardless of the pressure ratio.Conclusion: Intraoperative measurement of the right ventricular pressure can predict residual pulmonary stenosis after tetralogy repair with a reassuring cutoff of 49 mmHg