Management of cardiopulmonary bypass in children with hypoplastic left heart syndrome undergoing multiple sternotomy procedures: a case report

Introduction

Hypoplastic left heart syndrome (HLHS), which was universally fatal just 40 years ago, remains one of the most challenging congenital heart defects (1). It is characterized by the underdevelopment of the left ventricle, accompanied by atresia, stenosis, or underdevelopment of the mitral and/or aortic valves, as well as incomplete development of the aortic arch and arterial duct (2). Treatment of HLHS is usually costly, and the prognosis is poor. Although heart transplantation is considered the optimal solution, the supply of heart donors is relatively limited. Over the past 30 years, a three-stage palliative surgery has been the most common surgical strategy for treating HLHS (3). This approach involves the Stage I Norwood procedure​(performed during the neonatal period), II bidirectional Glenn or hemi-Fontan procedures​, and ​Stage III Fontan procedure. The improvement of clinical outcomes depends on advances in surgical techniques and perioperative management, including cardiopulmonary bypass (CPB), anesthesia, and postoperative care. Owing to the multiple operations required for this staged surgical approach and the need for CPB, each procedure leads to distinct hemodynamic alterations, which can lead to significant perioperative complications, such as systemic inflammatory response syndrome, coagulopathy, and multiple-organ dysfunction. Therefore, CPB management must be tailored to the specific pathophysiological conditions. ​​​ver, few studies have focused on CPB management in treating children with HLHS. In the process of complex congenital heart disease (CHD) surgery, CPB is not only limited to the technical level but also an important part of the overall strategy to improve surgical prognosis. For children with complex malformations who have undergone multiple operations, what CPB catheterization strategy can be selected to ensure tissue perfusion and reduce the risk of cardiac rupture? When intraoperative blood vessels and surrounding tissue adhesions are serious and cannot be separated, how can blood flow be occluded to expose the surgical field? How should we cooperate with anesthesia during CPB weaning in patients with single ventricular physiology? The purpose of this paper is to focus on the above three aspects through case reports. This study presents a case of HLHS at our hospital that required surgical interventions​, with six procedures utilizing CPB​. We have detailed the CPB strategies implemented during the Norwood procedure​(stage I palliation) and the reoperation​ (hybrid approach, including aortic stent implantation, aortic arch reconstruction, and tricuspid valve repair). We present this article in accordance with the CARE reporting checklist (available at https://tp.amegroups.com/article/view/10.21037/tp-2025-460/rc).

Case presentation

Patient history and preoperative assessment

A 7-year-old girl who was diagnosed with HLHS at birth (December 2016) and had previously undergone a series of cardiac operations (see Table 1) was admitted to our hospital on January 10, 2024, for surgical treatment. Physical examination revealed a heart rate of 86 beats/min, a respiratory rate of 26 breaths/min, a blood pressure of 100/60 mmHg, a weight of 15 kg, a height of 106 cm, and an oxygen saturation (SpO₂) of 85%. Cardiac magnetic resonance imaging (MRI) showed tricuspid regurgitation, slight thickening of the valve leaflets, mild tortuosity and stenosis of the ascending and descending parts of the aorta and aortic arch (narrowest site diameter: 10 mm); significant enlargement of the right atrium, and significant enlargement of the inferior vena cava and three hepatic veins. The bidirectional Glenn anastomosis was intact. Echocardiography revealed the following measurements: end-diastolic volume, 144.5 mL; end-systolic volume, 37.0 mL; ejection fraction, 74%; stroke volume, 107.5 mL; and end-diastolic wall mass, 48.9 g. Both MRI and computed tomography angiography (CTA) indicated right atrial enlargement and severe adhesions between the heart and the infrasternal tissues (Figure 1). Transthoracic echocardiography revealed severe tricuspid regurgitation, tricuspid annular plane systolic excursion of 6.7 mm, tortuosity and stenosis of the ascending and descending aorta, and mild aortic valve regurgitation. Cardiac catheterization revealed a pressure of 25–27 mmHg in the superior vena cava, 16 mmHg in the inferior vena cava and atrium, and ventricular systolic/diastolic pressures of 186/17 mmHg, respectively. The pressure in the ascending aorta was 184/72 (mean arterial pressure: 118) mmHg, the pressure in the aortic arch was 162/68 mmHg, and the pressure in the descending aorta was 90/58 mmHg. A multidisciplinary consensus recommended a hybrid intervention comprising aortic arch reconstruction, tricuspid valve repair, and stent placement in the stenotic part of the aorta.

Figure 1 Magnetic resonance imaging indicating right atrial enlargement and severe adhesions between the heart and infrasternal tissues.

Main surgical procedure and CPB management during 8th surgery

Our strategy was to establish peripheral femoral CPB first to achieve cardiac decompression and then to establish central CPB afterwards. The CPB circuit comprised an oxygenator (Pixie, Medtronic, USA), an infantile tube (Flyer, Ningbo, China), and an arterial filter (CX AF02, Terumo, Japan). A modified ultrafiltration technique and a residual volume cell saver were used. Invasive blood pressure in the right radial and left femoral arteries, mixed venous SpO₂, hematocrit (HCT), and cerebral SpO₂ were monitored continuously. After systemic heparinization (unfractionated heparin 375 U/kg), resistance was encountered during the process of inserting a 15-Fr cannula (Bio-Medicus, Medtronic) into the right femoral vein. Digital subtraction angiography (DSA) revealed tortuosity and narrowing of the inferior vena cava (Figure 2); therefore, a smaller size (14 Fr) venous cannula and a 10-Fr (DLP, Medtronic) arterial cannula were inserted, but no drainage was attained even when supported by vacuum-assisted venous drainage. After replacing the femoral vein cannula with a 12-Fr cannula, femoral CPB was initiated. The sternotomy was performed following successful cardiac decompression at a CPB flow of 0.4 L/min. Adhesiolysis was performed to free the ascending aorta, aortic trifurcation, superior vena cava, inferior vena cava, and the right atrium. Then, a 6 mm Gore-Tex artificial vessel was anastomosed to the brachiocephalic artery and used for cannulation. A 12-Fr arterial cannula (DLP; Medtronic, USA) was inserted into the artificial vessel, an 18-Fr venous cannula (Flyer) was placed in the pulmonary artery, and a 20-Fr venous cannula was placed in the inferior vena cava to establish central CPB. The schematic diagram of the CPB circuit is shown in Figure 3. Peripheral and central CPB were performed concurrently. Next, a vascular stent with a diameter of 12 mm was inserted into the stenotic part of the aorta. Cold HTK cardioplegia solution (50 mL/kg, CUSTODIOL, Germany) was infused into the aortic root after aortic endovascular occlusion, followed by regional cerebral perfusion (RCP). During RCP, the right brain and right upper limb were perfused by a brachiocephalic artery cannula; the left brain was perfused by the circle of Willis; and the region of the descending aorta was perfused by a femoral artery cannula. The calcified tissue of the ascending aorta was excised, and the ascending aorta was reconstructed with a bovine pericardial patch, while the tricuspid valve was repaired simultaneously. The lowest nasopharyngeal temperature during the operation was 28 ℃, and the CPB flow was 1.0 L/min. Ultrafiltration was initiated after the completion of HTK cardioplegia solution infusion. Blood gas, electrolyte, and activated clotting time levels were monitored hourly during CPB. After surgery, rewarming was performed to achieve a nasopharyngeal temperature of 32 ℃; the aortic clamp was released, and the cardiac rhythm returned spontaneously. Subsequently, the femoral venous and arterial cannulas were removed, and the vessels were repaired during the reperfusion time. The central CPB was successfully weaned stepwise. After CPB weaning, the blood pressure through the radial artery was 110/55 mmHg, supported by 0.3 µg/kg/min of epinephrine, 8 µg/kg/min of dopamine, 5 µg/kg/min of treprostinil, and 20 ppm of inhaled nitrous oxide. Pacemaker leads were installed to prevent arrhythmias. After neutralizing the heparin with protamine, fibrinogen, platelets, prothrombin complex, and fresh frozen plasma were sequentially infused for hemostasis. Finally, sternal closure was performed, and the patient was transferred to the Cardiac Intensive Care Unit for postoperative care. Postoperative vascular ultrasonography revealed no abnormal signs in the right femoral artery or vein. Mechanical ventilation was discontinued 48 hours after surgery. ​The patient was transferred to the general ward on the 15th postoperative day and was discharged home on the 53rd postoperative day. All procedures performed in this study were in accordance with the ethical standards of the Children’s Hospital, Zhejiang University School of Medicine Ethics Committee (No. 2025-IRB-0289-P-01), and Declaration of Helsinki and its subsequent amendments. Publication of this case report and accompanying images was waived from patient consent according to the ethics committee.

Figure 2 Digital subtraction angiography revealing tortuosity and narrowing of the inferior vena cava.

Figure 3 Cardiopulmonary bypass circuit schematic diagram.

Discussion

Building on the clinical details presented above, the subsequent discussion explores the key aspects of CPB management and the challenges encountered during the multistage surgical process.

Cannulation strategy and vascular access

Cannula site and size selection in pediatric patients with complex CHD are critical, particularly in those with HLHS who require multiple sternotomy procedures. In the pediatric population, the posterior structures of the sternum are strongly adherent, posing a high risk of vascular and/or cardiac injury during sternotomy. To ensure safe thoracotomy, peripheral CPB is usually initiated before thoracotomy to achieve cardiac decompression (4,5). In this report, CTA showed adhesions of the ascending aorta and right ventricular outflow tract, especially between the right ventricular outflow tract, the pulmonary artery duct, the right ventricle, and the sternum. Therefore, femoral vascular cannulation was used to establish peripheral CPB to reduce the risk of uncontrolled bleeding and maintain stable hemodynamics (6). Despite comprehensive preoperative vascular ultrasonography evaluation of femoral vascular dimensions, luminal irregularities, thrombotic burden, and hemodynamic profiles, persistent challenges in venous cannulation still exist. Fortunately, DSA was performed during the hybrid surgery, which helped in diagnosing the vascular tortuosity. When the tip of the venous cannula failed to attain proper positioning within the right atrium, downsized cannula was selected​, thereby creating a gap between the cannula and the vessel to optimize ​side-hole drainage. If femoral cannulation is completely limited, cervical vessels can be chosen as an alternative peripheral cannulation site.

The femoral vessels in children are usually much smaller; therefore, perfusion of the distal limbs should be evaluated closely after cannulas are removed. Because the ascending aortic wall was a calcified bovine pericardium patch placed in the stage I Norwood procedure, a Gore-Tex artificial vessel was anastomosed to the brachiocephalic artery and used as the central cannulation site. Following the establishment of central cannulation, the CPB arterial circuit bifurcated into dual pathways connecting the brachiocephalic artery and femoral artery, and the blood flow in the brachiocephalic and femoral arteries was not monitored. The adequacy of perfusion to meet the body’s oxygen consumption was assessed by continuously monitoring invasive blood pressure in the right radial and left femoral arteries, cerebral SpO₂ using near-infrared spectroscopy, mixed venous SpO₂, and hourly monitoring of blood gas and lactate levels.

In summary, careful evaluation of vascular anatomy and appropriate cannula selection are essential to ensure optimal CPB flow and minimize complications. PubMed was searched for keywords such as ‘cardiopulmonary bypass’ and ‘hypoplastic left heart syndrome’. Three articles (7-9) that met the criteria were selected, involving 3 children with HLHS, all of whom were male (see Table 2).

Considerations during CPB weaning

Reasonable anatomical correction is a prerequisite for successful CPB weaning in patients with complex CHD. An individualized strategy must be considered based on specific cardiac structures and hemodynamic characteristics during CPB weaning. In this report, the patient underwent six CPB surgeries, two of which showed significant changes in hemodynamics. After the stage I Norwood procedure, a single ventricle supplied blood to both the systemic and pulmonary circulation simultaneously; therefore, a combination of active reduction of afterload, myocardial contractile support, and reduction of pulmonary overcirculation was required during the CPB weaning and subsequent recovery phases to achieve balanced circulation and adequate peripheral perfusion (10). Despite technical improvements in both surgical and CPB techniques, 10–15% of patients still require extracorporeal membrane oxygenation (ECMO) support during the Norwood procedure to avoid failure in CPB weaning or low cardiac output syndrome (11). In this case, although we attempted to achieve appropriate QP/QS values by reducing the systemic afterload and enhancing myocardial contractility during the weaning process, we failed to wean off the CPB and eventually transferred the patient to veno-arterial ECMO support.

After the 8th surgery, the blood from the superior vena cava flowed directly into the pulmonary artery and returned to the single atrium, whereas the blood from the inferior vena cava returned to the single atrium. The afterload of the systemic circulation decreased after ascending aortic reconstruction and descending aortic stenosis correction. Therefore, oxygenation was the priority during CPB weaning and the subsequent phases, since gas exchange in the body depends on pulmonary blood flow through the superior vena cava, after weaning from CPB. Oxygenation can be improved by considering the following: (I) reducing pulmonary vascular resistance; (II) titrating the positive end-expiratory pressure of the ventilator; (III) maintaining a relatively high HCT; and (IV) titrating appropriate positive inotropic and vasoactive drugs to maintain appropriate systemic blood pressure.

CPB can cause lung injury and even acute respiratory distress syndrome by triggering a systemic inflammatory response. A longer CPB time (with a cutoff value of 160.5 min) may lead to a worse clinical prognosis after cardiac surgery (12). Stopping ventilation during CPB may cause partial consolidation of the lung alveoli. Repeated lung volume maneuvers at the end of the bypass can improve alveolar recovery (13). Continuous positive airway pressure or vital capacity maneuvers during CPB can directly improve oxygenation variables in adult cardiac surgery (14). If high doses of inotropic drugs and/or vasopressors are required or if severe hypoxia or arrhythmia occurs during CPB weaning, ECMO should be started as soon as possible (15).

In conclusion, individualized weaning strategies addressing both myocardial and pulmonary factors are critical for the successful discontinuation of CPB, and the implementation of lung-protective strategies during CPB can significantly reduce postoperative pulmonary complications.

Conclusions

During high-risk repeated complex CHD operations, initiation of peripheral CPB plays a vital role in reducing cardiac compression and preventing cardiac rupture or bleeding. Thorough preoperative evaluation of the inner diameter and morphology of the femoral vessels is essential for optimal cannulation. When the venous cannula tip fails to reach the atria, selecting a smaller cannula facilitates better side hole drainage. Furthermore, appropriate anatomical correction is fundamental for successful CPB weaning, emphasizing that CPB management must be individualized, according to the unique cardiac structure and hemodynamic characteristics of each patient. Overall, our experience highlights the critical importance of tailored CPB strategies in improving surgical outcomes, and future studies should focus on refining these techniques to further enhance their clinical efficacy.

Acknowledgments

We would like to thank Editage (www.editage.cn) for the English language editing.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://tp.amegroups.com/article/view/10.21037/tp-2025-460/rc

Peer Review File: Available at https://tp.amegroups.com/article/view/10.21037/tp-2025-460/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-2025-460/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. All procedures performed in this study were in accordance with the ethical standards of the Children’s Hospital, Zhejiang University School of Medicine Ethics Committee (No. 2025-IRB-0289-P-01), and Declaration of Helsinki and its subsequent amendments. Publication of this case report and accompanying images was waived from patient consent according to the ethics committee.

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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