Abstract
Early recovery from surgery for congenital heart disease (CHD) is becoming a trend. Tetralogy of Fallot/pulmonary stenosis (TOF/PS) is the most common cyanotic CHD with excellent long-term outcomes. We examined potential factors associated with early extubation in 249 patients who underwent TOF/PS complete repair in a tertiary pediatric medical center from January 2015 to December 2022. Patient demographics, preoperative characteristics, intraoperative variables, postoperative outcomes, surgical type, surgical duration, cardiopulmonary bypass (CPB) time, cross-clamp time, and blood product volumes were acquired from the electronic medical records. Valve sparing repair (VSR) tends to demonstrate earlier recovery profiles than transannular patch repair (TAP) irrelevant of the presence of monocusp valve (P< 0.0001) and the degree of right ventricular outflow pressure drop was significantly correlated with post-operative recovery profile (p=0.0204). Because of intracardiac shunts and PaO2/FiO2 ratios being poor indicators of lung injury, Brixia scores were also used. Our data suggested that Brixia score could be an excellent alternative to evaluate post-operative lung status.
Keywords: Tetralogy of Fallot, Transannular patch repair, pulmonary valve sparing repair, mechanical ventilation, Brixia score
Introduction
Tetralogy of Fallot (TOF)/Pulmonary stenosis (PS) is the most common form of cyanotic congenital heart diseases (CHDs) requiring surgical intervention and accounts for 7% to 10% of all CHD 1. Historically Blalock-Taussig shunt (BT shunt) was first placed to palliate children in 19442. Complete repair was introduced by Lillhei in 1954 3,4. Currently one-step complete repair is performed in most cases with low mortality. TOF surgery may involve transannular patch (TAP) repair, pulmonary valve-sparing repair (VSR), or in some cases repair without right ventriculotomy. Overall long-term outcomes following TOF repair is excellent5.
As the outcome of CHDs has improved, post-surgical management of these cohorts also demonstrated \ change. Early extubation after pediatric cardiac surgery has become increasingly prevalent. The report based on Society of Thoracic Surgeons (STS) database showed approximately 1/3 of patients were extubated within 6 hours after TOF repair although there was a significant variation in institutional practice6. From a hemodynamic standpoint, 1/3 of patients develop low cardiac output (LCO) due to right ventricular (RV) failure following TOF repair. Bronicki et al. showed that the conversion from positive ventilation to spontaneous ventilation provided hemodynamic benefit, appreciated as an increased blood pressure (BP) and cerebral oxygen saturation7,8. In these studies, the authors did not examine the impact of the type of surgical repair. However, we expect that the type of repair affects postoperative recovery. For example, TAP can immediately resolve right ventricular hypertension, but cause significant pulmonary regurgitation (PR). In one study, monocusp valve placement along with TAP significantly decreased postoperative PR and shortened ICU length of stay without perioperative mortality compared to TAP alone9. To stratify the selection of early extubation candidates, it would be critical to understand perioperative factors associated with early extubation.
This study aimed to identify perioperative factors linked to extubation within 12 hours following corrective surgery for Tetralogy of Fallot in infants in a single tertiary center with high surgical volume. To allow early extubation, adequate hemodynamic profiles and pulmonary function are requisites. We frequently use PaO2/FiO2 (P/F) ratio to examine the efficiency of oxygenation in patients with normal biventricular circulation, but it might not be accurately reflective of lung function in the presence of significant intracardiac shunts. Thus, we also included Brixia scores, a simple radiographic severity scoring system that was previously introduced during the pandemic10 to provide an additional tool to evaluate the feasibility of early extubation.
Methods
Study design and cohort
The Institutional Review Board (IRB) at Boston Children’s Hospital approved this retrospective cohort study. We included 249 infants who underwent corrective surgery for TOF/PS between January 2015 to December 2022. The study referred to the SQUIRE 2.0 (Standards for Quality Improvement Reporting Excellence) guidelines of the Enhancing the Quality and Transparency of Health Research (EQUATOR) network11. Patient demographics, preoperative characteristics, intraoperative variables, postoperative outcomes, surgical type, surgical duration, cardiopulmonary bypass (CPB) time, cross-clamp time, and blood product volumes were acquired from the electronic medical records. P/F ratio was calculated as PaO2/FiO2. Oxygen index (OI) was calculated as mean airway pressure x FiO2 × 100/PaO2. All patients underwent surgical repair under general anesthesia. Briefly, patients were intubated with cuffed endotracheal tubes, received arterial and central venous lines and were maintained with a combination of volatile and intravenous anesthetics. Doses and combination of different anesthetics were at the discretion of the attending cardiac anesthesiologists. Cardiopulmonary bypass (CPB) was used in all patients, the circuit primed with reconstituted whole blood to maintain hematocrit ≥30 and methylprednisolone (30 mg/kg) was added to attenuate inflammation.
Brixia score
The Brixia score was adopted to quantitate lung abnormality as previously described10. In this scoring system, the lungs were divided into six zones, and the degree of opacification was scored based on its location as follows; interstitial opacities, both interstitial and alveolar opacities with interstitial dominance, and both interstitial and alveolar opacities with alveolar dominance were given the score of 1, 2, and 3, respectively. The sum of the scores from the six lung zones was reported as each radiograph’s Brixia score (minimum 0, maximum 18). Brixia scores were evaluated by three assessors (PL, KY, and WM) who were all blinded to the patients perioperative and outcome data during scoring process. An experienced radiologist trained these three reading physicians to standardize the interpretation of the chest radiographs12. Inter-observer variability was determined with the intraclass correlation coefficient (ICC). All assessors agreed to the final consensus scores.
Statistical analysis
Factors associated with extubation within 12 hours postoperatively were identified with univariate analysis. Continuous variables with a normal distribution were summarized as means with standard deviation and those with a non-normal distribution as medians and interquartile ranges. Normality was tested using Shapiro-Wilk test. Categorical variables were reported using frequencies and percentages. A student t-test or Mann-Whitney U test was used to compared means or medians for continuous variables. For categorical variables, chi square test was used. For multiple comparison, we used Dunn’s test. P value < 0.05 was considered statistically significant. Analysis was performed on commercial software (STATA15; StataCorp; College Station, TX).
Results
Postoperative ventilatory support profiles of patients undergoing corrective surgery for TOF.
A total of 249 infants undergoing corrective surgery for TOF/PS between January 2015 and December 2022 were included (Table 1). The cohort had a median age of 95 days (interquartile range, 57–132) and a median weight of 5.0 kg (interquartile range, 4–6). Types of repair included: VSR (61%), TAP (36.6%) and non-ventriculotomy repair (2.4%). The cohort distribution based on extubation time was shown in Fig. 1. Median duration of mechanical ventilation in all patients was 23 hours (interquartile range, 14–46). Extubation occurred within 6 hours after surgery in 0.8% patients (n=2), between 6–12 hours after surgery in 21% patients (n=51) and greater than 12 hours in 79.5% patients (n=198).
Table 1.
Characteristics of patients with TOF/PS.
| Age (days) | 95 (57, 132) |
| Weight (kg) | 5 (4, 6) |
| Gender | Male 149 (59.8%) |
| Female 100 (40.2%) | |
| Postoperative ventilation (hours) | 23 (14, 46) |
| Surgical type | Valve sparing 152 (61.0%) |
| Transannular 65 (26.1%) | |
| Transannular w/ monocusp 26 (10.5%) |
Figure 1.
Distribution of patient number based on postoperative extubation time.
Factors associated with early extubation.
We dichotomized the cohort based on post-operative ventilation, using 12 hours as a cutoff. To determine factors associated with early extubation, we performed univariate analysis (Table 2). Older age, term birth, non-TAP repair, less reduction of RVOT gradient (45 mmHg or less highly predictive of extubation within 12 hours, Table 3), less incidence of PFO left, higher P/F ratio at ICU admission, and lower Brixia scores at ICU admission and on post-operative day 1. Interestingly, P/F ratio at the time of anesthesia induction (P/F baseline) was comparable between the two cohorts, suggesting that the degree of preoperative cyanosis was not statistically different. Although Brixia scores at ICU admission and on postoperative day 1 were significantly worse in patients who were ventilated longer than 12 hours postoperatively, P/F ratio at 12 hours post-operatively was not statistically different. This discrepancy may be explained by presence of right to left shunts at the atrial level. 486 postoperative radiographs were assessed for Brixia scores, and satisfactory, interobserver agreement was observed (ICC = 0.87, (95%CI 0.85–0.89)).
Table 2.
Comparison based on postoperative extubation time
| Vent =<12h (n=51) | Vent > 12h (n=198) | P value | |
|---|---|---|---|
| Age (day) | 133 (99, 170) | 84.5 (52, 116) | < 0.0001* |
| Gestation (week) | 39 (37.75, 40) | 38 (37, 40) | 0.0444* |
| Weight (kg) | 6 (5, 7) | 5 (4, 6) | < 0.0001* |
| Gender | male 31, female 20 | Male 118, female 80 | 0.635 |
| Vent (h) | 10 (8, 11) | 26.5 (19, 52.25) | < 0.0001* |
| ICU (h) | 28 (11, 37) | 67 (34, 131) | < 0.0001* |
| Hospital (h) | 132 (108, 156) | 202.5 (151, 364.3) | < 0.0001* |
| CPB time (min) | 117 (101, 141) | 130 (99.75, 152.5) | 0.0951 |
| X clamp time (min) | 88 (73, 103) | 94 (71.75, 117.5) | 0.111 |
| PRBC (mL) | 0 (0, 0) | 0 (0, 0) | 0.4907 |
| Cell savor (mL) | 60 (30, 90) | 60 (30, 90) | 0.675 |
| cryoprecipitate (mL) | 0 (0, 0) | 0 (0, 0) | 0.8039 |
| Platelet (mL) | 30 (0, 60) | 45 (0, 80) | 0.3118 |
| OI ICU admission | 3 (2, 4) | 5 (3, 7) | < 0.0001* |
| OI 12h | 2 (1.5, 2.5) | 3 (2, 5) | 0.0211* |
| P/F baseline | 143 (81, 149) | 108 (75.5, 208.5) | 0.098 |
| P/F post CPB | 224 (137.5, 346) | 176 (83, 297.5) | 0.0484* |
| P/F ICU admission | 361.5 (247.3, 395.5) | 218 (140.5, 319) | < 0.0001* |
| P/F 12 h | 344 (240.5, 415.8) | 268 (194, 354) | 0.241 |
| Brixia ICU | 7 (6, 10.75) | 12 (9, 12) | < 0.0001* |
| Brixia POD#1 | 9 (6, 12) | 12 (9, 12) | < 0.0001* |
| Reintubation | 1 (2.0%) | 4 (2.0%) | 0.683 |
| Mortality | 0 (0%) | 3 (1.5%) | n/a |
| Volume balance day 0 (mL) | 0 (−7, 6) | 1.5 (−8, 9) | 0.5066 |
| Volume balance day 1 (mL) | 0.5 (−4.5, 3) | −4 (−22, 6) | 0.1922 |
| Preop RVOT gradient (mmHg) | 53.66+/− 16.89 | 62.2+/− 24.7 | 0.0736 |
| Postop RVOT gradient (mmHg) | 15 (10.75, 20.75) | 15 (8, 20) | 0.3691 |
| d (RVOT gradient) (mmHg) | 37.82+/− 21.26 | 47.48+/−27.49 | 0.0204* |
| Type of surgery | TAP 4 (7.8%) | TAP 61 (30.8%) | 0.041* |
| TAP + monocusp 3 (5.8%) | TAP + monocusp 23 (11.6%) | ||
| VSR 41 (80.4%) | VSR 111 (56%) | ||
| no ventriculotony 3 (5.8%) | no ventriculotomy 3 (1.5%) | ||
| PFO Post-repair | 28 (54.9%) | 134 (67.7%) | <0.001* |
p<0.05.
Table 3.
Area under the curve predicting extubation within 12 hours based on the degree of RVOT gradient reduction.
| RVOT gradient reduction | AUC |
|---|---|
| 40 mmHg | 0.6092 |
| 45 mmHg | 0.6257 |
| 50 mmHg | 0.6102 |
| 55 mmHg | 0.6018 |
| 60 mmHg | 0.5835 |
| 65 mmHg | 0.5677 |
AUC, area under the curve
Lung injury per surgical type.
Because non-TAP repair was associated with shorter ventilatory support post-operatively, we first compared the characteristics of patients who underwent TAP with monocusp valve, TAP alone, and VSR. We excluded non-ventriculotomy cohort due to its small number. Overall, TAP showed very similar profiles with and without monocusp valve placement (Table 4). In contrast, VSR showed shorter ventilatory support, higher P/F ratio at ICU admission and at 12 hours post-operatively compared to patients with TAP alone or TAP with monocusp valve (Table 4). Based on this result, next we compared VSR with all TAP (Table 5). We found that VSR was associated with older age, slightly shorted CPB time, higher P/F ratio at ICU admission and 12 hours post-operatively, less PFO, smaller reduction of RVOT gradient, better Brixia scores at ICU admission and on post-operative day 1. VSR patients had shorter ICU and hospital stays. Overall 41 out 152 VSR patients were extubated within 12 hours, and 109 out of 152 patients were extubated within 24 hours. One patient was extubated in the OR.
Table 4.
Comparison among TOF/PS surgical procedure types
| Transannular/Monocusp (Group A, n=26) | Transannular (Group B, n=65) | Valve-sparing (Group C, n=152) | A vs B | A vs C | B vs C | |
|---|---|---|---|---|---|---|
| Age (day) | 86.5 (40.5, 116.8) | 66.0 (48.5, 103.5) | 102.0 (68.8, 145.5) | >0.9999 | 0.1865 | 0.0001* |
| Gestation (week) | 38 (37, 39) | 39 (36.75, 40) | 38 (27, 40) | > 0.9999 | > 0.9999 | > 0.9999 |
| Weight (kg) | 5.0 (4.0, 6.0) | 4.0 (4.0, 6.0) | 5.0 (4.0, 6.0) | >0.9999 | 0.5388 | 0.0332* |
| Gender | male 15, female 11 | male 41, female 24 | male 90, female 62 | > 0.9999 | > 0.9999 | > 0.9999 |
| Vent (h) | 27.0 (18.8, 76.0) | 45.0 (21.0, 107.0) | 18.5 (12.0, 27.0) | 0.6841 | 0.0164* | < 0.0001* |
| ICU (h) | 100.5 (52.5, 182.8) | 78 (34.5, 211) | 50.5 (28, 80) | > 0.9999 | 0.0051* | 0.0006* |
| Hospital (h) | 236 (154.3, 365.8) | 298 (172.5, 414.5) | 155.5 (128.0, 248.3) | > 0.9999 | 0.0052* | < 0.0001* |
| CPB time (min) | 145.5 (98, 169.3) | 131 (105, 160.5) | 123 (99, 145) | > 0.9999 | 0.1637 | 0.2441 |
| X clamp time (min) | 111 (71.75, 131.8) | 90 (72.5, 117) | 93.5 (71, 108) | 0.5706 | 0.1451 | > 0.9999 |
| PRBC (mL) | 0 (0, 0) | 0 (0, 0) | 0 (0, 0) | 0.7218 | 0.3388 | > 0.9999 |
| Cell savor (mL) | 57.88+/− 41.42 | 60 (32.5, 90) | 60 (30, 90) | > 0.9999 | > 0.9999 | > 0.9999 |
| cryoprecipirate (mL) | 0 (0, 0) | 0 (0, 0) | 0 (0, 0) | > 0.9999 | > 0.9999 | 0.6003 |
| Platelet (mL) | 60 (37.5, 60) | 30 (0, 80) | 40 (0, 78.75) | > 0.9999 | 0.6948 | > 0.9999 |
| OI ICU admission | 5 (3, 10) | 6 (3, 9) | 4 (2.75, 5) | > 0.9999 | 0.0346* | 0.0019* |
| OI 12h | 4 (3, 8) | 4 (3, 5) | 3 (2, 4) | >0.9999 | 0.0233* | 0.001* |
| OI POD#1 | 5 (3.25, 7.75) | 3 (3, 5.75) | 3 (2, 5) | 0.1572 | 0.0698 | > 0.9999 |
| P/F baseline | 82.5 (69.75, 136.3) | 83 (66, 136.5) | 151.5 (87.5, 246) | > 0.9999 | 0.0069* | 0.0001* |
| P/F post CPB | 178 (81.25, 290.3) | 163 (71.5, 257) | 192.5 (104.5, 329) | 0.7641 | 0.7641 | 0.1617 |
| P/F ICU admission | 175.5 (115, 286.3) | 167.5 (116.8, 303.5) | 275 (191, 371) | > 0.9999 | 0.0143* | 0.001* |
| P/F 12h | 170 (107, 358) | 247 +/− 107 | 303 +/− 110.3 | > 0.9999 | 0.04* | 0.0106* |
| P/F POD#1 | 211.8+/− 107.2 | 259.7 +/− 103.9 | 260.2+/− 112 | 0.392 | 0.4035 | > 0.9999 |
| Brixia ICU | 12 (12, 12) | 12 (12, 12) | 8.5 (6, 12) | > 0.9999 | < 0.0001* | < 0.0001* |
| Brixia POD#1 | 12 (12, 12) | 12 (12, 12) | 10 (6.25, 12) | > 0.9999 | 0.0005* | < 0.0001* |
| Reintubation | 3 (11.5%) | 2 (3.1%) | 2 (1.3%) | |||
| Mortality | 1 (3.8%) | 0 (0%) | 2 (1.3%) | |||
| Volume balance day 0 (mL) | −2 (−13.5, 4.25) | 5 (−2.5, 20) | −3.5 (−16.75, 5) | 0.0523 | >0.9999 | <0.0001* |
| Volume balance day 1 (mL) | 1 (−27, 19) | −4 (−23.75, 4.5) | −3.5 (−16.75, 5) | >0.9999 | >0.9999 | >0.9999 |
| Preop RVOT gradient (mmHg) | 70.83+/− 22.81 | 66.53+/−25.24 | 57.45+/−22.44 | 0.4888 | 0.03* | 0.03* |
| Postop RVOT gradient (mmHg) | 0 (0, 13.75) | 15 (0, 20) | 16 (12, 25) | 0.1978 | <0.0001* | 0.009* |
| d (RVOT gradient) (mmHg) | 57.08+/−32.12 | 57.02+/− 27.53 | 38.91 +/− 23.13 | 0.9917 | 0.0018* | < 0.0001* |
| PFO Post-repair | 21 (80.8%) | 53 (81.5%) | 86 (56.6%) | >0.9999 | 0.0494* | 0.0012* |
A vs B, B vs C, A vs C was performed using Dunn’s test.
Table 5.
Comparison between transannular patch repair and valve-sparing repair cohorts
| Transannular patch (n=91) | Valve-sparing (n=152) | P value | |
|---|---|---|---|
| Age (day) | 70 (47, 106) | 102 (68.75, 145.5) | < 0.0001* |
| Gestation (week) | 39 (37, 39.5) | 38 (37, 40) | 0.4999 |
| Weight (kg) | 5 (4, 6) | 5 (4, 6) | 0.0081* |
| Gender | Male 56, female 35 | Male 90, female 62 | 0.529 |
| Vent (h) | 43 (21, 91) | 18.5 (12, 27) | < 0.0001* |
| ICU (h) | 78 (36, 203) | 50.5 (28, 80) | < 0.0001* |
| Hospital (h) | 267 (171, 392) | 155.5 (128, 248.3) | < 0.0001* |
| CPB time (min) | 133 (101, 166) | 123 (99, 145) | 0.023* |
| X clamp time (min) | 96 (72, 125) | 93.5 (71, 108) | 0.1281 |
| PRBC (mL) | 0 (0, 0) | 0 (0, 0) | 0.4154 |
| Cell savor (mL) | 83.07 (41.71, 123.4) | 112.6 (70.08, 154) | 0.6338 |
| Cryoprecipitate (mL) | 0 (0, 0) | 0 (0, 0) | 0.1749 |
| Platelet (mL) | 50 (0, 72) | 40 (0, 78.75) | 0.4515 |
| OI ICU admission | 6 (3, 9) | 4 (2.75, 5) | < 0.0001* |
| OI 12h | 4 (3, 6.5) | 3 (2, 4) | < 0.0001* |
| OI POD#1 | 3 (3, 6) | 3 (2, 5) | 0.2117 |
| P/F baseline | 83 (69, 129) | 151.5 (87.5, 246) | < 0.0001* |
| P/F post CPB | 165 (73, 260) | 192.5 (104.5, 329) | 0.029* |
| P/F ICU admission | 171 (116, 295.3) | 275 (191, 371) | < 0.0001* |
| P/F 12 h | 248 (145.5, 313.8) | 290 (226, 382.5) | 0.0006* |
| P/F POD#1 | 259.5 (161, 314) | 259 (157.3, 336) | 0.6152 |
| Brixia ICU | 12 (12, 12) | 8.5 (6, 12) | < 0.0001* |
| Reintubation | 5 (5.5%) | 2 (1.3%) | 0.082 |
| Mortality | 1 (1.1&) | 2 (1.3%) | 0.882 |
| Volume balance day 0 (mL) | 3 (−8, 16) | −3.5 (−16.75, 5) | 0.0003* |
| Volume balance day 1 (mL) | −2 (−23.5, 10) | −3.5 (−16.75, 5) | 0.804 |
| Preop RVOT gradient (mmHg) | 65 (50, 85) | 56 (45, 70) | 0.0025* |
| Postop RVOT gradient (mmHg) | 10 (0, 17.25) | 16 (12, 25) | < 0.0001* |
| d (RVOT gradient) (mmHg) | 60 (35, 80) | 37.5 (25, 55) | < 0.0001* |
| PFO Post-repair | 74 (81.3%) | 86 (56.6%) | <0.001* |
p< 0.05
Discussion
The postoperative recovery profiles of patients who underwent TOF/PS complete repair were compared. In our cohort, VSR was associated with shorter duration of post-operative mechanical ventilation, shorter ICU and hospital stays. In support of these findings, lung injury scores were significantly lower in VSR cohort at ICU admission and on post-operative 1, suggesting that their lungs were subjected to less injury. Similar to Brixia score, VSR group was associated with higher P/F ratio at ICU admission and at 12 hours postoperatively compared to TAP. However, P/F ratio at post-operative day 1 was comparable between VSR and TAP cohorts. This difference between Brixia score and P/F ratio on post-operative day 1 suggested the potential usefulness of Brixia score to assess lung status in this cohort.
More lung injury in the TAP cohort could be attributed to several possibilities. CPB driven lung injury has been a well-recognized problem13. CPB duration for TAP cohort was longer by 10 min. However, 10 min occupies only 7% of the total CPB time and is unlikely responsible for the injury. TAP cohorts received more volume during the first day in ICU, which may be in part responsible. If central venous pressure (CVP) is higher in TAP cohort, this could impede lymphatic drainage, leading to lung edema14. Although we routinely placed central monitoring lines for cardiac surgery and monitored the CVP in the early postoperative phase, we noted significant outliners in the recording, which hindered our analysis of CVP. Further work would address this possibility. Lastly, RVOT gradient reduction was more significant, which may induce more reperfusion injury. However, not all TAP patients required longer intubation. When we compared patients who required more than 12 hours of mechanical ventilation with ones who required less, CPB time and post-operative volume requirement did not show any difference. However, RVOT gradient reduction was less in groups with extubation within 12 hours. This could support the idea that patients extubated within 12 hours after the surgery experienced less reperfusion injury. Clinically reperfusion injury is presented as nonspecific alveolar damage, lung edema and hypoxemia15. Once patients succumb to reperfusion lung injury, ventilation and oxygenation will be impaired. An increase in PaCO2 will raise PVR and will facilitate R to L shunt at the atrial level if a PFO is present. We did not include TOF with pulmonary atresia (PA) and major aortopulmonary collateral arteries (MAPCAs) in this study. However, it is worth noting that reperfusion injury has been a well-recognized problem in patients with TOF/PA/MAPCAs 16.
Ideal surgery for TOF/PS will be the one to minimize the need for any re-intervention. If not symptomatic, complete surgical repair is recommended between 3 and 6 months of age as repair at this age carries the lowest operative risk and there is no evidence to support delaying repair to a later age17. Historically, TAP has been the dominant operative approach providing an unobstructed RVOT with free PR. Patients often experience restrictive physiology with low cardiac output17. Monocusp valve placement has been attempted in adjunct with TAP, which if functionally properly will alleviate PR improving cardiac output, but outcomes have been inconsistent likely related to different techniques and materials used18,19. With the introduction of 3D printing technology and newer simulated modeling methods20 more reliable methods for monocusp valve creation are becoming available. VSR technique was introduced in 1990s and has become increasingly popular21. In the most recent era (2015–2022), 61% of patients received VSR while in the earlier era (2005–2015), only 44% received VSR (56% received TAP)22. Currently, there continues to be equipoise between selecting between TAP and VSR among surgeons. It generally depends on the perceived morphology of RVOT and institutional preference, although TAP is often employed in infants with severe annular hypoplasia. In our institution, the operative approach is based on annular adequacy, leaflet quality, and balancing the ability to establish a competent outflow tract with less than 2/3 systemic right ventricular pressures.
Our study suggests that not only the type of repair affects post-operative recovery but also the degree of RVOT gradient reduction may be an important factor impacting post-operative lung status, therefore the timing of extubation. Also it is important to note that P/F ratio may not be necessarily reflective of lung status alone in this cohort and Brixia scoring may be a useful addition to evaluate post-operative recovery profiles in post-operative TOF patients.
Acknowledgement
This study was in part supported by NICHD HD109119 (K.Y.).
Footnotes
Declaration of competing interest
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Koichi Yuki reports financial support was provided by NICHD. Koichi Yuki reports a relationship with National Institute of Child Health and Human Development that includes: funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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