Literature searches confirmed that no guidelines or expert consensuses on RAI as a routine cardiac surgical approach have been published domestically or internationally. There is an urgent clinical need for expert consensus to standardize its application.

This consensus adopts the international Delphi process and systematically retrieves literature on surgical treatment of CHD from 1982 to 2024 in databases including CNKI, Wanfang, VIP, Chinese Biomedical Literature Database, PubMed, Embase, and the Cochrane Central Database of Evidence-Based Medicine, incorporating high-level evidence.

Chinese search terms and English search terms: “Congenital heart disease”, “right axillary incision”, “lateral incision”, “minimally invasive surgery”, “extracorporeal circulation”, “surgical approach”, “perioperative treatment”, “complications”, “prognosis”.

This consensus uses the Grade of Recommendations Assessment, Development and Evaluation (GRADE) system (Table 1) to grade the evidence-based medical evidence supporting various diagnostic and therapeutic methods, including the strength of recommendations and quality of evidence.

With continuous refinement of surgical techniques and improvements in perioperative monitoring, the suitable weight range for RAI procedures has gradually expanded. However, for centers in the early stages of adopting this approach, it is recommended to begin with children weighing 5–30 kg [12,41,42,43].

In patients with very low body weight (<5 kg), the narrow thoracic cavity and the relative obstruction caused by cannulation and surgical instruments may limit the operative field, thereby increasing the technical difficulty and operative risk [44,45]. Nonetheless, clinical studies have indicated that even in infants of low age and low body weight, RAI does not significantly increase procedure-related complications [1,46,47].

For children weighing >30 kg, the heart is positioned deeper along the right thoracic pathway, resulting in a more technically demanding exposure. In such cases, specialized instruments or thoracoscopic assistance may be required to complete the procedure [48].

Recommendation 2: (1)

Children weighing 5–30 kg are preferred candidates for RAI surgery, as this range generally provides optimal operative exposure (Evidence level: B; Recommendation strength: I).

The age range suitable for RAI is also expanding. For centers newly implementing this technique, the optimal candidates are children aged 6 months to 6 years, in whom thoracic shape, intercostal spacing, and operative exposure are most favorable.

Similar to concerns associated with low body weight, infants <6 months have smaller thoracic cavities and incisions, making intubation and exposure more challenging. However, in well-selected cases and in experienced centers, RAI can still achieve safety and clinical outcomes comparable to those of median sternotomy [49].

In older children, especially those >12 years, the heart lies deeper within the thorax, and limitations in exposure, suturing angles, and instrument maneuverability require careful evaluation of RAI suitability [12]. If exposure proves inadequate, alternative surgical approaches should be considered.

Recommendation 3: (1)

Centers initiating RAI programs should prioritize children aged 6 months to 6 years, as this age group offers optimal thoracic and intercostal conditions for exposure (Evidence level: C; Recommendation strength: I).

The patient is placed in the left lateral decubitus position. A vertical or slightly curved small incision is made in the fourth intercostal space along the right midaxillary line. After incising the skin and subcutaneous tissues, the fascia of the serratus anterior muscle is opened. The muscle fibers should be preserved as much as possible while bluntly dissecting anteriorly and posteriorly to expose the intercostal space. The choice of intercostal space may be adjusted up or down by one level depending on the specific cardiac lesion.

Key considerations include: (1) An overly anterior incision may injure breast tissue and risks dislocation of the costochondral junction during retraction. (2) An excessively posterior incision results in a deeper operative field and inferior exposure due to cardiac displacement. (3) Overly extensive dissection between the chest wall muscles and ribs should be avoided to prevent adverse effects on muscle and breast development. (4) During serratus anterior dissection, care must be taken to protect the long thoracic nerve and associated vasculature to prevent winged scapula deformity [12,50,51].

Recommendation 4:

The standard RAI incision is made through the fourth intercostal space along the right midaxillary line, with adjustments to the third or fifth intercostal space as needed to optimize exposure. During thoracic entry and retraction, the long thoracic nerve and serratus anterior fibers should be protected, and anterior extension toward breast tissue should be avoided (Evidence level: C; Recommendation strength: I).

Two principal cannulation pathways may be used to establish CPB in RAI procedures: central cannulation and peripheral cannulation.

In infants and young children, the small caliber of peripheral vessels and the potential risks associated with retrograde perfusion make peripheral cannulation less suitable. Therefore, central cannulation through the operative incision remains the preferred approach in most cases. Selecting the appropriate cannulation strategy is crucial for ensuring both satisfactory exposure and reliable CPB support [46].

In RAI procedures, the ascending aorta is typically cross-clamped either directly through the primary incision or via a small parasternal incision at the second or third intercostal space. The choice of cross-clamp depends on the patient’s body size and the depth of the operative field.

In older children, the Chitwood transthoracic aortic cross-clamp is often convenient. A fine-gauge cardioplegia needle should be used for cardioplegia infusion, and the needle may be temporarily removed after infusion to reduce obstruction in the operative field. It can then be repositioned during left-heart venting before releasing the aortic cross-clamp.

In RAI surgery, the position and size of venous cannulas are inherently limited; therefore, gravity drainage alone is often insufficient. In most cases, VAVD significantly improves venous return and allows the use of shorter and smaller tubing [57,58]. Evidence indicates that, when used correctly and safely, VAVD provides more benefits than risks in pediatric congenital heart surgeries requiring CPB [50,59].

Recommendation 5: (1)

Perfusionists and surgeons should reach an agreement preoperatively regarding the size and type of venous and arterial cannulas (Evidence level: C; Recommendation strength: I).

Myocardial protection is one of the most critical components of cardiac surgery, as its effectiveness directly influences surgical outcomes and postoperative prognosis. The myocardial protection strategies used in minimally invasive cardiac procedures via RAI are the same as those used in MS. These include antegrade delivery of cardioplegia, induction of myocardial arrest, and hypothermic myocardial protection. To date, no evidence suggests that myocardial protection protocols require modification specifically for RAI procedures.

Cerebral injury is among the most serious complications following CPB. The placement of the aortic cannula is crucial in RAI procedures; improper depth or direction of cannulation may result in inadequate or excessive cerebral perfusion. If cerebral injury or suspicion of such injury occurs, cerebral protection protocols should be initiated immediately. The strategies used for cerebral protection during RAI are identical to those used in MS. Insufflation of carbon dioxide into the operative field can reduce the incidence of intracardiac air embolism by approximately 85%, and has become routine practice in many cardiac centers. A recent study indicated that, during RAI procedures, carbon dioxide insufflation at a flow rate of 5 L/min may help reduce the risk of cardiac and neurological injury in children undergoing congenital heart surgery [60]. Additionally, when VAVD is used to enhance venous return, the principle of minimal effective negative pressure should be followed, and bubble monitoring should be performed concurrently to reduce the risk of micro-gaseous emboli [61].

Because the RAI approach involves retraction and compression of the lung tissue, it can lead to mechanical lung injury, resulting in postoperative hypoxemia, blood-tinged sputum, pneumothorax, atelectasis, and delayed pulmonary recovery [39,62].

Pulmonary protection strategies during surgery include: (1) During thoracic entry, the anesthesiologist should temporarily stop ventilation and open the endotracheal tube to allow lung collapse, reducing the risk of instrument-related injury. Protective ventilation strategies should be maintained throughout the procedure. (2) Operative manipulation must be gentle to avoid excessive traction and minimize mechanical injury to the lung. (3) During CPB, ensure unobstructed pulmonary venous drainage to prevent pulmonary congestion and edema. (4) Before releasing the aortic cross-clamp, perform adequate suctioning to clear secretions and ensure bronchial patency. (5) Avoid direct contact between suction instruments and lung tissue to prevent contusion. (6) Before closing the ribs, perform lung recruitment maneuvers to re-expand collapsed lung segments and reduce postoperative atelectasis [35].

Recommendation 6: (1)

Myocardial and cerebral protection strategies during RAI should follow the same protocols used for MS (Evidence level: C; Recommendation strength: I).

The treatment of PDA through RAI surgery is relatively challenging, but feasible [63,64], especially in cardiac centers with large surgical volumes. During the surgery, it is necessary to clarify the anatomical position of the left pulmonary artery and aortic arch to avoid accidental ligation; When dissecting PDA, attention must be paid to protecting the recurrent laryngeal nerve. If dissection is difficult, it is recommended to establish extracorporeal circulation (CPB) with partial support to complete the separation, ligation, or suturing of PDA. For PDA that is still particularly difficult to expose during surgery, the PDA problem can be solved by opening the main pulmonary artery, extending the incision to within 3–4 mm from the starting point of PDA, reducing flow, and suturing the PDA opening after starting extracorporeal circulation.

Subcapillary or intracapillary ventricular septal defect is located deep in the outflow tract. Traditionally, repair is performed through the main pulmonary artery or right atrium tricuspid valve pathway. In recent years, some centers have started using RAI to repair subarterial ventricular septal defect through tricuspid valve approach, achieving good results [65]. However, for young infants, the narrow surgical space can pose challenges for exposure and manipulation. Therefore, using a tricuspid valve approach to repair subarterial ventricular septal defect requires a high level of technical expertise. If the field of view through the tricuspid valve is poor, repair can be performed through an incision in the main pulmonary artery [23,39,66,67].

Recommendation 7: (1)

For RAI surgery with PDA, if dissection is difficult, separation and ligation/suturing should be performed after establishing extracorporeal circulation with partial circulatory support. It is only recommended to use RAI for PDA surgical treatment in cardiac centers with high surgical volume (Evidence Level: B; Recommendation Strength: II).

For children who have previously undergone cardiac surgery, the decision to use RAI for reoperation requires careful risk–benefit assessment. Compared with resternotomy, RAI reoperations avoid dense retrosternal adhesions and typically encounter only mild pericardial adhesions. However, the previous operation disrupts the pericardium and mediastinal pleura, potentially causing extensive adhesions between the lung, heart, and chest wall. Therefore, re-entering the thoracic cavity via RAI may require precise adhesiolysis.

When performing reoperations via RAI, the following key points must be noted to ensure safety and optimal recovery: 1.

Imaging evaluation: Use cardiac CT/MRI or three-dimensional reconstruction to clarify changes in cardiac anatomy, adhesion extent, and the location of abnormal vessels or scar tissue.

Recommendation 8:

For patients who previously underwent RAI for CHD, reoperations may be performed either through the original axillary incision or via an MS. Compared with traditional resternotomy, patients who previously had RAI typically have less pericardial and retrosternal adhesion, although lung-to-heart and lung-to-chest wall adhesions may be significant. When re-entering through the original incision, careful dissection is required to avoid injury to vital structures (Evidence level: B; Recommendation strength: II).

For patients undergoing RAI who require ECMO support: (1) Cannulation can still be performed via the original axillary approach. If left heart drainage is needed, the cannula may be inserted via the right upper pulmonary vein. Ensure the drainage tube is of sufficient length within the thoracic cavity and is securely fixed to the chest wall to avoid lung compression. (2) With secure cannulation fixation: The patient may be placed in a supine or slightly left lateral decubitus position to avoid skin pressure ulcers. Other management measures are identical to those for MS.

Recommendation 9:

When ECMO support is required in patients treated with RAI, cannulation can still be performed through the original axillary pathway. However, careful attention must be given to securing the drainage cannula and adjusting patient positioning (Evidence level: C; Recommendation strength: I).

Residual shunts after VSD repair are among the most common postoperative complications. They most frequently occur at the anterosuperior and posteroinferior margins of the defect. Residual shunts at the anterosuperior margin involve high-pressure areas and are prone to tearing, making spontaneous closure unlikely.

Clinically, residual shunts <3 mm without symptoms may be followed conservatively. Shunts <2 mm often close spontaneously. Shunts 2–3 mm require periodic evaluation of hemodynamic significance. Shunts >3 mm typically require intervention [68,69,70]. If intraoperative echocardiography reveals a residual shunt ≥3 mm, immediate re-repair should be considered. If postoperative echocardiography identifies a residual shunt ≥3 mm, treatment options include: Transthoracic echo-guided closure, catheter-based transcatheter closure, or reoperation with CPB through the original incision, each providing good clinical results [69,71,72,73].

Arrhythmias are common after open-heart surgery. Because the RAI incision is small, placement of internal defibrillation paddles may be challenging; therefore, preoperative placement of external defibrillation pads is essential.

For temporary pacing: A pacing lead can be sutured onto the right ventricular outflow tract, brought out through the fourth intercostal space, and connected to an external pacing device. The lead must remain sufficiently long to avoid tension or dislodgement during postoperative lung expansion or pericardial suspension.

Common arrhythmia types and management include: (1) Focal atrial tachycardia. (2) Intra-atrial reentrant tachycardia/Atrial fibrillation: Acute episodes may be terminated via cardioversion or medications. Unstable hemodynamics require immediate electrical cardioversion. (3) Complete atrioventricular block: If it occurs during surgery, it is usually recommended to perform another surgery immediately to rule out conduction block caused by suture or patch traction. If postoperative atrioventricular block persists for 7–10 days, permanent pacemaker implantation should be considered [74]. (4) Bundle branch block: Right bundle branch block typically requires no special treatment. Surgery-related left bundle branch block may partially recover. If left ventricular ejection fraction (LVEF) remains <35% after three months of optimized medical therapy, cardiac resynchronization therapy (CRT) should be considered.

Mechanisms of atelectasis after RAI include: Factors similar to those in the MS (anesthesia effects and CPB) [75,76]. Surgical positioning, excessive intraoperative lung compression, postoperative edema, exudation, and fibrous scar formation.

Intraoperative and Postoperative Recommended Strategies include: (1) After releasing the aortic cross-clamp, perform intermittent lung recruitment to prevent postoperative atelectasis. (2) Because RAI requires posterior and lateral displacement of the right lung, care must be taken to minimize friction and mechanical injury to lung tissues from instruments. (3) In the ICU, timely suctioning and appropriate use of positive end-expiratory pressure (PEEP) are essential. (4) Routine and timely bronchoscopy with lavage helps prevent and treat atelectasis. Recent reports also suggest that single-lung ventilation during RAI may reduce the incidence of atelectasis, though further multicenter studies are necessary to confirm this [77].

Surgery-induced phrenic nerve injury may result in diaphragmatic paralysis. Studies have shown that RAI does not increase the incidence of diaphragmatic paralysis compared with the MS approach [41]. Most cases of diaphragmatic elevation after cardiac surgery are associated with excessive phrenic nerve traction. Therefore, during RAI procedures, pericardiotomy and suspension should be performed 2 cm anterior to the phrenic nerve to avoid overstretching [78]. Using ice slush in the mediastinum for myocardial protection may increase the risk of diaphragmatic elevation. Thus, care should be taken to protect the phrenic nerve when using ice slush [79].

There is still controversy over the optimal timing for diaphragmatic folding surgery regarding postoperative management [80,81]. Follow up studies have shown that most postoperative diaphragmatic elevation can spontaneously alleviate over time [82,83]; However, for children who cannot escape mechanical ventilation due to diaphragmatic paralysis or have obvious respiratory distress, early surgical intervention often achieves good results [84].

Recommendation 10: (1)

Residual VSD shunt: (1) Residual shunt ≤2 mm: Follow-up observation; (2) Intraoperative residual shunt ≥3 mm: Immediate re-repair; (3) Postoperative residual shunt ≥3 mm: closure via transthoracic echo guidance, catheter intervention, or reoperation via original incision (Evidence level: B; Recommendation strength: I).