Stephens EH, Wolfe BL, Talwar AA, Patel A, Camarda JA, Eltayeb O, Monge MC, Forbess JM.World J Pediatr Congenit Heart Surg. 2021 Sep;12(5):628-634. doi: 10.1177/21501351211031242.PMID: 34597206
Take Home Points:
- The ideal repair of TOF is defined as the repair that results in the lowest RVOT gradient and the maximal pulmonary valve competence.
- Two strategies are available to manage the right ventricular outflow tract (RVO) during TOF repair: transannular patch and valve-sparing.
- Several factors affect the decision to chose one strategy versus the other. Some of these factors are based on preoperative echocardiographic data, and some from intraoperative RVOT assessment.
- Pulmonary valve annular Z score, while helpful, is just one factor among many that affects the decision to choose a transannular patch or valve-sparing approach.
- Surgeon’s judgement and experience remain of paramount importance in this decision-making process.
Commentary from Dr. Sameh Said (Minneapolis, MN, USA), Guest Editor of Congenital Heart Surgery Journal Watch:
In this article by Stephens et al, the authors asked an important clinical and practical question. When it comes to managing the right ventricular outflow tract (RVOT) during repair of tetralogy of Fallot (TOF), which technique should be used? Transannular patch (TAP) versus Valve-sparing (VS)? And how to select the right technique for the right patient? and on what basis this selection should be done, preoperative data and/or intraoperative decision?
Their retrospective review included 67 patients (17 underwent TAP and 50 underwent VS) with a mean age of 4.5 months and a mean weight of 5.8 Kg. The authors described their management algorithm which highlights that the final decision is made based on intraoperative assessment of the pulmonary valve (PV) cusps mobility, and quality in addition to the z score of the annulus. They used a cut off limit of -2 to predict the need for TAP. They also use right ventricular (RV) pressure >70% of systemic pressure after coming off cardiopulmonary bypass to determine the need for a TAP despite an initial adequate repair.
As expected, those who needed a TAP had much smaller preoperative echocardiographic Z score compared to those underwent a VS approach. Interesting enough that 34% of those who had VS repair, had a z score < -2.5 (14% with z score <-3 and 20% with a z score between -2.5 to -3). Overall, 52% of those with preoperative Z score < -2.5 underwent VS repair.
At discharge, the VS group had higher peak gradient with less regurgitation compared to the TAP group. This peak gradient and degree of regurgitation remained stable in the VS group during a median follow-up of 58 months, while those with TAP remained with free regurgitation. Both groups, however, had similar PV z scores indicative of annular growth over time.
The authors defined an “ideal” long-term repair as peak gradient < 25 mmHg and no more than mild PR on most recent echocardiogram.
I would like, however, to point out few important points:
- The authors did not describe their TAP technique and how they manage the native pulmonary valve? And if there are any technical points they consider when designing the patch such as its width and/or the orientation of the commissures of the PV cusps.
- Overall, 15% of these patients had residual atrial level shunt. Was that left intentionally? Most of the patients in the series are in the typical age and weight for TOF repair and we usually leave a residual atrial level shunt mainly in neonates or those with anticipated post-repair right ventricular diastolic dysfunction or persistent elevated RV pressure.
- Despite the authors mentioned post-repair RV/systemic pressure ratio <70% as one of their goals for VS, no data is provided about the post-repair RV pressure among the current cohort.
- The goal of having RV pressure post-repair that is < 70% of the systemic pressure seems to be based on old data. If the post-repair RV pressure under anesthesia close to 70% that may result in systemic RV pressure at time of discharge and could result in earlier reintervention. This in my opinion an important variable that may be superior to the PV annular z score itself due to the obvious limitations of the Z score.
- It would have been quite helpful to see a correlation between the post-repair RV/systemic pressure ratios and the PV annular z score and to see if this can correlate/predict reintervention later.
- It is unclear which system the authors used or followed in regard to the use of the PV annular z score.
- The authors proposed a cut-off z score of -2 to define a durable and successful VS repair. I do not believe such conclusion can be made with certainty from the current study due to the lack of details of other factors that may affect the durability and reinterventions after TOF repair such as PV cusps analysis, and the lack of long-term data.
- While the follow-up echocardiographic data demonstrated higher peak gradient in the VS group and more PR in the TAP group, this did not translate into a significant difference in the reintervention rate between the two groups.
Finally, I would agree with the authors that PV annular z score is only one factor in the decision-making algorithm to chose VS versus TAP for those undergoing TOF repair. While the goal is to preserve valvular competence and lower post-repair RV pressures, this is not always easy to achieve and a longer-term data with larger group of patients are needed to determine the superiority of one approach versus the other.