Subaxillary thoracotomy pulmonary valve-sparing repair of tetralogy of Fallot using the transatrial approach: a retrospective cohort study

Introduction

As treatment strategies continue to develop rapidly, the median sternotomy method has become the standard treatment for the correction of complex congenital heart disease, generally achieving satisfactory surgical results. However, the method is associated with multiple adverse side effects, such as bleeding, broken steel wires, pectus carinatum, and psychological distress (1,2). Therefore, more attention is being paid to minimally invasive techniques, with one of these approaches, the right subaxillary mini-incision method, being utilized by an increasing number of surgeons. The right subaxillary mini-incision method involves a small incision in the subaxillary region, providing access to the heart while avoiding the sternum. This approach offers several theoretical and practical advantages. First, it minimizes surgical trauma to the chest wall, reducing postoperative pain and the risk of complications such as sternal wound infections or dehiscence. Second, the subaxillary incision is less visible, resulting in superior cosmetic outcomes, which is particularly important for young patients and their families. Third, the technique preserves the integrity of the sternum, which may be beneficial in cases requiring reoperation, a common scenario in congenital heart disease (3-5). Nonetheless, few reports exist on the use of right subaxillary mini-incision for complex congenital heart diseases, such as the case of tetralogy of Fallot (TOF) transatrial repair with pulmonary valve preservation (6,7).

Our group at the Sixth Medical Center of the Chinese People’s Liberation Army General Hospital began performing right subaxillary mini-incisions for simple congenital heart disease in 2017. As the group gained more experience, this procedure was used to correct complex congenital heart disease. TOF is a complex congenital heart defect characterized by four anatomical abnormalities, leading to cyanosis and hemodynamic instability that require timely surgical intervention. Surgical repair faces challenges such as precise anatomical correction, residual defects, and long-term complications like pulmonary regurgitation and arrhythmias, necessitating expertise and multidisciplinary collaboration. This study aims to demonstrate the safety and efficacy of the right subaxillary mini-incision approach for radical TOF treatment. We present this article in accordance with the STROCSS reporting checklist (available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-537/rc).

Methods

Patients

This research is a retrospective cohort study. Between August 2020 and February 2022, 20 child patients underwent TOF transatrial repair with pulmonary valve preservation in the Sixth Medical Center of the Chinese People’s Liberation Army General Hospital. The integrity of the pulmonary valve annulus was preserved in all 20 patients, and 19 patients avoided an incision of the right ventricular outflow tract (RVOT), with only one patient undergoing a right ventricular incision due to intraoperative difficulty. The inclusion criteria were as follows: age ≥6 months, weight ≥5 kg, and McGoon ratio ≥1.3, while the exclusion criteria included a previous history of respiratory disease, previous history of right chest surgery, severe pulmonary artery dysplasia, associated complex cardiac abnormalities, and previous history of palliative care. All patients were operated on by the same surgical team. No patient in this study received another surgical approach for the treatment of their defect during the process. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the institutional ethics board of the Sixth Medical Center of People’s Liberation Army General Hospital (No. HZKY-PJ-2025-11). Written informed consent was obtained from the [individual(s) AND/OR minor(s)’ legal guardian/next of kin] for the publication of any potentially identifiable images or data included in this article. The demographic and clinical data of the patients are presented in Table 1.

Diagnostic and radiological evaluation

All patients underwent echocardiography and cardiac computerized tomography (CT) examinations, with the results interpreted by a specialist.

American Society of Echocardiography (ASE) 2017 guidelines for the evaluation of valvular regurgitation:

• + (mild): small regurgitant jet area, vena contracta (VC) <3 mm, effective regurgitant orifice area (EROA) <0.2 cm²;
• ++ (mild to moderate): 3 mm ≤ VC ≤5 mm, 0.2 cm² ≤ EROA ≤0.3 cm²;
• +++ (moderate to severe): 5 mm < VC <7 mm, 0.3 cm² < EROA <0.6 cm²;
• ++++ (severe): VC ≥7 mm, EROA ≥0.4 cm² (mitral valve) or ≥0.3 cm² (aortic valve).

Surgical technique

The patients were placed in the left lateral decubitus position. A thin cotton pad was placed under the left lateral underarm, and the fully extended right forearm was placed on the right ear and fully fixed with medical adhesive tape (Figure 1). A 3–5-cm arc incision was made from the third to the fourth intercostal space along the right midaxillary line on the skin. Following muscle sparing, an entrance to the thoracic cavity was obtained through the third intercostal space, and the lung was retracted posteriorly with a wet sponge to expose the pericardium. The pericardium was opened more than 2 cm anterior to the phrenic nerve to avoid injury to the nerve trunk and branch, while the thymus gland was preserved to avoid bleeding due to injury. Three pericardial traction sutures were placed at the superior, middle, and inferior aspects of the incision to expose the right atria and the superior and inferior vena cava, while two or three traction sutures were positioned at the cephalic side of the pericardium to expose the aorta. The disposable flexible annular rib retractor used in this procedure improved the exposure of the operative field and protected the incision.

Figure 1 Surgical body position and intercostal choice. (A) Position and approach of the axillary incision; (B) establishment of extracorporeal circulation through the axillary incision; (C) length of the underarm incision (3.5–5 cm); (D) anterior exposure after the subaxillary incision.

Following heparinization, the ascending aorta was first cannulated before the superior vena cava was cannulated with a right-angled cannula. The inferior vena cava was then cannulated, and to achieve better exposure, the cannula was pulled out from the sixth intercostal space, from which the chest drainage tube could be placed following the operation. The ascending aorta was cross-clamped using a belt with a 16-Fr silicone tube, and cardioplegia was administered via antegrade infusion of histidine-tryptophan-ketoglutarate (HTK) cardioplegic solution. At the same time, a right atriotomy was performed and the interatrial septum was opened in the fossa ovalis to insert a left ventricular vent. If there emerged a patent ductus arteriosus, it was closed by opening the pulmonary artery, and a 6-0 propylene suture with pads was used to seal the ductus arteriosus directly from the inside out. A drag hook was placed into the RVOT to expose the size and location of the ventricular septal defect, with the defect repaired with Dacron or a biomaterial patch through the tricuspid orifice. Interrupted suture 3–4 stitching was used to secure the patch where the tricuspid chordae implants were located in the ventricle, while the remainder were sutured continuously using 6-0 propylene. The RVOT hyperplastic myocardium was sufficiently resected through the tricuspid orifice and the pulmonary orifice.

Following this, the inferior, horizontal, and suprapulmonary valve stenoses were fully released. The key intraoperative techniques included completely relieving the obstruction above and below the valve, as well as relieving the adhesion and fusion of the valve. The pulmonary artery and pulmonary sinus were widened using a biomaterial patch, which was deemed appropriate for the situation. After eliminating the air in the heart, the cross-clamp was removed, and the right atrial incision was sutured continuously with 5-0 propylene following cardiac re-beating. The cardiopulmonary bypass (CPB) was withdrawn gradually, and a right pleural drain was inserted into the right thoracic cavity through the hole in the sixth intercostal space. Before closing the chest, the lung was inflated adequately to eliminate the residual air in the thoracic cavity (Figure 1).

Follow-up and outcomes

The relevant data were acquired mainly through postoperative re-examinations and follow-up telephone calls. In the routine re-examinations (echocardiography andcardiac CT), which were performed postoperatively at 1 week, 3 months, 6 months, and 1 year, the following data were collected: perioperative death (death within 1 month postoperative), reintervention rate (re-operative surgical treatment due to residual right ventricle outflow tract stenosis, residual pulmonary valve stenosis or regurgitation), pulmonary valve regurgitation, the pressure gradient of the RVOT, the pulmonary valve pressure gradient, residual shunt, cardiac arrhythmias (atrial or ventricular arrhythmias), heart failure, McGoon ratio, Nakata index, ejection fraction (EF), and tricuspid valve regurgitation. The above evaluation indicators were measured by senior ultrasound doctors using transthoracic or transesophageal echocardiography equipment (Philips iU Elite, Shanghai, China). Here, heart failure was defined in accordance with the European Society of Cardiology guidelines on acute and chronic heart failure (8). Events such as perioperative death, reintervention rate, and pulmonary valve regurgitation were considered to be primary outcomes.

Statistical analysis

All the original data were double-checked and analyzed using SPSS 19.0 statistical software, and were expressed in terms of median and range or interquartile range. T-tests were used, with a one-tailed P value of <0.05 considered to be statistically significant. The Z scores of the pulmonary valve annulus, upper valve, and lower valve were converted, the Z table was drawn, and the corresponding Z scores were defined (9). Stratification was performed using −1≤ Z score ≤1, −2≤ Z score <−1, Z score <−2, and Z score >1. The Z scores of the patients before and after the operation were compared. All data were recorded in the department database.

Results

Baseline characteristics of the patients

See Table 1 for baseline characteristics of the patients. The RVOT stenosis was at varying degrees among the patients, with the pressure gradient of the RVOT ranging from 45.6±33.4 mmHg. The McGoon ratio via cardiac CT ranged from 1.9±0.3, and the Nakata index via cardiac CT ranged from 189.1±65.6 mm²/m².

Early results of surgery

All the early results are presented in Table 2. Here, all 20 patients underwent a total repair of TOF with preservation of the pulmonary artery valve via a right subaxillary mini-incision, with an incision length of 3.5–5 cm (median =4). Median CPB time is 139 minutes (range, 77–334 minutes), and median aortic clamp time is 105 minutes (range, 44–242 minutes). A total of 19 cases were successfully treated without right ventriculotomy, and the pulmonary valve was preserved in all patients. Non-transannular patches and the leaflet commissure area relieving method were used with all patients, with five patients receiving leaflet thinning and two receiving leaflet shifts. Only one case received a right ventricle incision due to the difficulty in exposure during the operation. There was no postoperative low cardiac output syndrome, malignant arrhythmia, pericardial tamponade, reoperation, reintubation, lung infection, lung injury, atelectasis, pneumothorax, pleural effusion, pericardial effusion, or poor wound healing. All patients retained the moderator band; however, 17 patients developed postoperative right bundle branch block. Among them, 13 cases were complete and four were incomplete, 10 patients returned to normal cardiac rhythm after 3 months. No deaths occurred during hospitalization, and all patients were discharged without serious complications (e.g., severe pulmonary stenosis or insufficiency, complete atrioventricular block, or aortic valve injury). As shown in Table 2, postoperative pulmonary and tricuspid valve insufficiency was mild.

None of the patients had a residual shunt. All 20 patients underwent an immediate pressure measurement via transesophageal echocardiography during the operation, and the results revealed that the pressure gradient of the RVOT decreased significantly immediately after the operation (7.6±2.5 vs. 45.6±33.4 mmHg, P<0.05). In addition, the postoperative cross-valve pressure gradient decreased significantly (21.5±10.6 vs. 59.4±27.7 mmHg, P<0.05). The results of the postoperative echocardiography and CT scans indicated the following: the subvalvular diameter of the pulmonary artery was significantly wider (13.0±2.7 vs. 5.5±3.6 mm, P<0.05). The subvalvular Z scores of all the patients were less than −2 before the operation and between −2 and 1 following the operation (Figure 2). There was no significant difference between the preoperative and postoperative EF [66% (52%, 77%) vs. 66% (56%, 75%), P>0.05]. The right ventricular function was normal, and the chest radiographs indicated normal cardiopulmonary images.

Figure 2 Comparison of pulmonary artery subvalvular diameter and RVOT pressure gradient before and after TOF repair via subaxillary incision. (A,B) Comparison of the subvalvular diameter of the pulmonary artery before and after total TOF repair via subaxillary incision; (C,D) comparison of the RVOT pressure gradient before and after the total repair of TOF via subaxillary incision. CF, color flow; CW, continuous wave Doppler; PG, pulmonary gradient; PW, pulsed wave Doppler; RVOT, right ventricular outflow tract; TOF, tetralogy of Fallot; Vel, velocity; WF, wall flow.

Surgical follow-up results

The follow-up period was from 3.1 to 20.8 months (median =11.6), and at the end of the follow-up period, two patients were at less than 6 months and five at less than 1 year; the follow-up rate was 100% (Table 3). No ventricular residual shunt, third-degree atrioventricular block, severe pulmonary stenosis, severe pulmonary regurgitation, tricuspid regurgitation, secondary operation or other complications were found during the follow-up. All 20 patients presented thoracic cage integrity without pectus carinatum, and the cardiac function was New York Heart Association (NYHA) class I or II across all the patients. The patients were all able to engage in activities like healthy children 2 weeks after surgery.

The routine test results

The echocardiography and cardiac CT re-examinations conducted 1 week postoperatively indicated that the cross-valve pressure gradient was significantly decreased (19.0±12.3 vs. 59.4±27.7 mmHg, P<0.05). One patient had a pressure gradient of 54 mmHg at 6 months postoperatively, which decreased to 37 mmHg at 1 year postoperatively. The pressure gradient of the RVOT also decreased significantly after the operation (6.1±3.2 vs. 45.6±33.4 mmHg, P<0.05) (Figure 3).

Figure 3 Postoperative changes in PTG and RVOTG. (A) Changes in the PTG after the operation; (B) changes in the RVOTG after the operation. Error bars represent 25^th–75^th percentile. *, P<0.05 vs. pre-operative. PTG, cross-valve pressure gradient of the pulmonary artery valve; RVOTG, pressure gradient of the right ventricular outflow tract.

Subvalvular Z scores

The subvalvular Z scores of the pulmonary artery were significantly improved following the operation, and the re-examination results at 3 months, 6 months, and 1 year post-surgery were consistent with those obtained at 1 week post-surgery (Figure 4).

Figure 4 Changes in subvalvular Z-score for the pulmonary artery pulmonary valve annulus in patients following subaxillary thoracotomy with TOF. TOF, tetralogy of Fallot.

Postoperative Z scores

The postoperative Z scores of the pulmonary valve annulus improved compared with those pre-surgery, and they remained the same at 1 week, 3 months, 6 months, and 1 year post-surgery (Figure 5).

Figure 5 Changes in the Z-score of the pulmonary valve annulus in patients following subaxillary thoracotomy with TOF. TOF, tetralogy of Fallot.

Postoperative insufficiency

In terms of postoperative insufficiency of the pulmonary valve, one case of insufficiency changed from mild to moderate following the surgery; however, the degree of insufficiency did not increase during the follow-up period (Figure 6).

Figure 6 Postoperative insufficiency of the pulmonary valve. − (no): no regurgitation; + (mild): small regurgitant jet area, VC <3 mm, EROA <0.2 cm²; ++ (mild to moderate): 3 mm ≤ VC ≤5 mm, 0.2 cm² ≤ EROA ≤0.3 cm². EROA, effective regurgitant orifice area; VC, vena contracta.

Discussion

This study demonstrates that transatrial repair of TOF with pulmonary valve preservation can be achieved using a mini right axillary approach with good safety. There were no postoperative low cardiac output syndrome (LOCS) or other serious complications in this study. The survival rate and the freedom from reintervention at 1 year were both 100%.

Furthermore, the effects of the operation were acceptable. All patients retained the integrity of the pulmonary valve and right chamber, except for one with right ventriculotomy, while only 1 (5%) patient had a pressure gradient of 54 mmHg at the 6-month follow-up, which decreased to 37 mmHg at the 1-year follow-up, while all other patients had good results at the follow-up visit. One (5%) patient developed moderate pulmonary valve insufficiency and exhibited no increasing trend during the follow-up period. A study reported 47 cases of TOF with subaxillary thoracotomy, with 30 patients receiving a right ventriculotomy and 20 receiving transannular patches during the operation, while 2 (4.3%) patients had mild residual RVOT obstruction and 3 (6.4%) had moderate pulmonary valve regurgitation at the follow-up visit (10). While the present study’s data are similar to those reported in the existing literature, the integrity of the pulmonary valve and the right chamber was better preserved in this study, which was likely due to the use of our special small-incision exposure method and a variety of pulmonary valve preservation techniques.

The total repair of TOF via median sternotomy has been widely accepted and has largely obtained satisfactory results (11,12). The minimally invasive transatrial-transpulmonary approach with pulmonary valve preservation for TOF repair can reduce postoperative pulmonary regurgitation and right ventricular dysfunction, improving long-term outcomes (9,13). With advancements in cardiac surgery, achieving optimal correction with minimal scarring has become increasingly important, particularly for children, adolescents, and young women (14). Mini-incision alternatives to median sternotomy, such as the right subaxillary approach, offer cosmetic benefits and are feasible due to children’s anatomical features, while maintaining familiarity for surgeons and reducing the learning curve. Although a right subaxillary mini-incision has been used for various cardiac repairs, few reports exist on total TOF repair with pulmonary valve preservation using this approach (15).

In 2017, our group initiated simple congenital heart disease corrections using a subaxillary mini-incision, refining techniques such as intercostal pathways and aortic clamping as experience grew. This approach was gradually expanded, successfully completing 20 cases of TOF correction with pulmonary valve preservation via subaxillary mini-thoracotomy.

Indications and candidates

The right subaxillary mini-incision operation is a challenge for both the surgeon and the surgical team, requiring sufficient experience in simple congenital disease correction via subaxillary mini-thoracotomy and in total TOF correction via traditional median sternotomy. In addition, adequate preoperative evaluations and precise case selection are key factors for a successful operation. The preoperative diagnosis should be confirmed via echocardiography and CT angiography examinations, and, if necessary, via cardiac catheterization, to further clarify the pulmonary valve anatomy and rule out other complex cardiac abnormalities. In 1983, Villani et al. proposed the following criteria for total TOF correction procedures (16): (I) a left ventricular end-diastolic volume index (LVDI) of >30 mL/m²; and (II) a McGoon ratio of >1.2. More recent studies have demonstrated that age, LVDI, McGoon ratio, and Nakata index are risk factors for prolonged postoperative mechanical ventilation (17-21). The preoperative development degree of the pulmonary valve annulus determines whether the pulmonary valve should be preserved or not. At present, there exist few reports on the selection criteria of small axillary incisions with right ventricle and pulmonary valve preservation. Based on our group’s experience, the operative approach and right ventricle incision are secondary to the preservation of the pulmonary valve. We believe that TOF correction operations can be performed using right subaxillary mini-incision without right ventriculotomy and with preservation of the pulmonary valve in candidates with a McGoon ratio of >1.3, an age of >3 months, a weight ranging from 5–30 kg, and a pulmonary valve annulus Z score of over −3 (according to the CT standard). The exclusion criteria include a history of pleurisy or thoracic surgery on the right and other complicated congenital heart defects.

Key points of right subaxillary mini-incision

The surgical exposure of the right subaxillary mini-incision is closely related to the position of the patient and the choice of intercostal space. Attention should be paid to all of the following factors during the procedure: reasonable surgical body position and intercostal choice (Figure 1), protection of the thymus gland, position of the inferior vena cava cannula, and the lung protection technique.

The experience of TOF transatrial repair with pulmonary valve preservation

The key intraoperative techniques include completely relieving the obstruction above and below the valve, as well as relieving the adhesion and fusion of the valve. Due to the improvement of key techniques (i.e., the intercostal approach, aorta clamping, and the exposure method), widening the RVOT through the tricuspid and pulmonary valve orifices and preserving the pulmonary valve can be achieved.

Surgical techniques for preserving the pulmonary valve annulus are varied and include dilatation of the pulmonary valve commissure, balloon dilatation of the valve commissure under direct vision, the “double-hole” method of the pulmonary valve annulus, and pulmonary valve commissure incision and release (22-26). The cases examined in the present study included almost all of the above methods of pulmonary valve preservation, which ensured that the stenoses of the inferior, horizontal, and suprapulmonary valves were relieved.

In their study on postoperative pressure measurements, right/left ventricular pressure differences, and valve structures, Vida et al. (27) found that the Z score increased with time when the residual obstruction occurred in the valve annulus alone. However, if the residual obstruction occurred under, on, or above the annulus, the annulus did not grow over time and would possibly require reoperation. The early postoperative period and follow-up results of this group indicated that only one patient had mild residual stenosis and that the stenosis site was mainly concentrated at the level of the pulmonary valve ring, and its long-term effect needs to be confirmed using a long-term follow-up period.

The cosmetic effect of the right subaxillary mini-incision method is evident. Given that the incision is made in a muscle-free area, thus preserving the pectoral muscles and normal intercostal space, normal development of the breasts is unaffected. The location of the incision provides the best cosmetic effect since it does not cross the axilla front line and the incision remains invisible under the armpit.

Study limitations

This was a single-center retrospective study, involving only short-term follow-up results for a small number of patients. It is therefore necessary to expand the number of cases and to extend the follow-up time to provide a more reliable assessment of the safety and effectiveness of this technique.

Conclusions

Transatrial TOF repair with pulmonary valve preservation can be safely achieved using a mini right axillary approach, with excellent results. The operation’s success is related to surgical team experience but, more importantly, to patient selection since non-TOF patients are candidates for such an operation.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROCSS reporting checklist. Available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-537/rc

Data Sharing Statement: Available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-537/dss

Peer Review File: Available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-537/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-537/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the institutional ethics board of the Sixth Medical Center of People’s Liberation Army General Hospital (No. HZKY-PJ-2025-11). Written informed consent was obtained from the [individual(s) AND/OR minor(s)’ legal guardian/next of kin] for the publication of any potentially identifiable images or data included in this article.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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