Right S3 segmentectomy for lung cancer with partial anomalous pulmonary venous return in the right upper pulmonary vein: A case report

Abstract Partial anomalous pulmonary venous return (PAPVR) is a rare congenital malformation where the pulmonary vein partially refluxes into the venous system. Here, we present the first robotic‐assisted right S3 segmentectomy in a 70‐year‐old male with early‐stage lung cancer and PAPVR in the right upper pulmonary vein. The patient, with suspected primary lung cancer (11 mm diameter, pure solid appearance in right S3 segment), exhibited clinical stage T1bN0M0 stage IA2. Preoperative computed tomography revealed severe lung emphysema, and right V1–3 returned directly to the superior vena cava. However, no signs of right‐sided heart failure were observed, and echocardiogram was normal with a pulmonary‐to‐systemic blood flow ratio of 1.4. Successful robot‐assisted right S3 segmentectomy with hilar nodal dissection was performed, and the patient was discharged on the sixth postoperative day without complications. One year postoperatively, there has been no recurrence of lung cancer or respiratory/right‐sided heart failure symptoms.


INTRODUCTION
Partial anomalous pulmonary venous return (PAPVR) is a congenital malformation where a portion of the pulmonary vein returns abnormally into the venous system.Its incidence has been reported to be approximately 0.1% in the adult population based on computed tomography (CT). 1,2atients are typically asymptomatic and it is incidentally detected during the investigation of other diseases. 3However, symptoms of right-sided heart failure, such as dyspnea and palpitations, may arise as the right and left shunts enlarge. 3A pulmonary-to-systemic blood flow ratio (Qp/Qs) of 1.5-2.0 or higher is considered an indication for revascularization. 4Here, we report the first case of robot-assisted right S3 segmentectomy for a patient with early lung cancer with PAPVR in the right upper pulmonary vein.

CASE REPORT
A 70-year-old male presented with suspected primary lung cancer (clinical stage T1bN0M0, stage IA2) based on a chest radiograph during physical examination.He was undergoing inhalation therapy for emphysema.Chest x-ray revealed a nodule in the right upper lung field, without cardiac enlargement (Figure 1a).Chest CT revealed severe lung emphysema and an 11 mm pure solid tumor in the right S3 segment (Figure 1b,c).Preoperative contrast CT revealed abnormal return of the right V1-3 directly into the superior vena cava (SVC), with V4 + 5 and the inferior pulmonary vein returning normally to the left atrium (Figures 1d,e and 2a,c).The bronchial and pulmonary artery branches of the right upper lobe were normal (Figure 2b,c).His preoperative forced expiratory volume in 1 s/forced vital capacity ratio was 58.7%.There were no signs of heart failure, and echocardiogram was normal, with a pulmonary-to-systemic blood flow ratio (Qp/Qs) of 1.4 and a tricuspid regurgitation pressure gradient of 35 mmHg, without an atrial septal defect.Robot-assisted right S3 segmentectomy was performed with five ports and CO 2 insufflation pressure under 8 mmHg (Figure 3a-c).The operation took 149 min with a blood loss of 3 mL.The chest drain was removed on postoperative day 3, and the patient was discharged on postoperative day 6 without any complications.Postoperative chest x-ray revealed that the remaining right upper lobe was wellinflated, and no enlargement of the cardiac shadow was observed (Figure 1f).The pathological findings indicated invasive papillary adenocarcinoma (pT1bN0M0, stage IA2) with a 15-mm margin.One year following surgery, no lung cancer recurrence or any respiratory or right-sided heart failure symptoms were observed with a Qp/Qs of 1.3 in the echocardiogram.
This case showed no symptoms of right heart failure, and echocardiographic findings were normal, suggesting a small left-right shunt volume.Most patients had no symptoms associated with PAPVR, and echocardiography of 11 of 13 patients was normal (Table 1).In patients with low shunt volume and low risk of right heart failure, a limited resection, including segmentectomy may preserve respiratory function and is considered a less invasive technique than lobectomy, especially in patients with low pulmonary function.If the shunt volume is large, lobectomy is necessary to reduce the right cardiac load.Given the patient's low pulmonary function due to emphysema and the early-stage nature of the lung cancer, segmentectomy was chosen over right upper lobectomy, prioritizing the preservation of pulfunction over shunt improvement.Thoracotomy is a common approach for lung cancer resection in patients with PAPVR on the same lobe (Table 1).Robot-assisted thoracic surgery is a feasible approach in segmentectomy requiring vascular and bronchial processing in the restricted space because the surgical field is extended under CO 2 insufflation, and multiple  articulations of robotic arms enable thoracic surgeons to achieve fine manipulation.This case report presents a rare case of early-stage lung cancer along with PAPVR with a small left-to-right shunt.Robot-assisted right S3 segmentectomy was performed safely without postoperative cardiac and respiratory complications in low respiratory patients with PAPVR in the same lobe.

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I G U R E 1 (a) Chest x-ray revealed a nodule in the right upper lung field (red arrow) without cardiac enlargement.(b) Contrast-enhanced computed tomography revealed severe emphysematous lung changes with diffuse low attenuation areas in the lung fields.(c) A pure solid tumor with 11 mm diameter in the S3 of the right upper lobe.(d, e) V1-3 refluxed through the right upper lobe and returned directly into the superior vena cava.(f) After 4 months following surgery, a chest x-ray revealed that the remaining right upper lobe was well-inflated, and no cardiac enlargement was observed.SVC, superior vena cava.

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I G U R E 2 (a) Three-dimensional images of the bronchial and vascular structures of the patient revealed that an abnormal V1-3 returning into the superior vena cava consisted of V1a, V1b, V2, and V3.(b) The bifurcation of pulmonary arteries was normal; the right main pulmonary artery branched into the right truncus superior and A2a, whereas the truncus superior pulmonary artery branched into A1, A2a, A3a, and A3b.(c) The right upper bronchus branched into B1, B2, and B3 as per normal branching.The A3a, A3b, V3, and B3 were dissected during S3 segmentectomy, located caudal to V2. LA, left atrium; SVC, superior vena cava.F I G U R E 3 (a) Intraoperative findings showing that an abnormal V1-3 returned directly into the superior vena cava.The caudal side of abnormal V1-3 demonstrated A3b branching from the right truncus superior.(b) A3a was identified just behind the A3b after A3b was divided with a stapler.B3 was located on the caudal side of abnormal V1-3 within the space between A3 and A2b.(c) V2 was located just behind V3 and V1b after V3 and V1b were clipped and divided.After dividing V1b, V3, A3a, A3b, and B3, the lung parenchyma of the S3 segment was dissected using a stapler.RML, right middle lobe; SVC, superior vena cava.T A B L E 1 Previous and present cases of lung cancers with partial anomalous pulmonary venous return (PAPVR) at the same resected lung lobe.