3D Computed Tomography Reconstruction for Pre‐Operative Diagnosis of Anomalous Venous Drainage of the Right Upper Lobe

ABSTRACT

Anatomical variation of the pulmonary vessels poses challenges to thoracoscopic lung resection and may be associated with an increased risk of intraoperative bleeding and damage to pulmonary circulation. Herein, we reported a rare and dangerous variation as the partial anomalous venous drainage of the right upper lobe into the superior vena cava in a patient undergoing thoracoscopic lobectomy for management of lung cancer of right upper lobe. The preoperative identification of such variation by 3D computed tomography scan allowed to plan a safe and accurate resection, and to prepare additional strategies for overcome unexpected intraoperative bleeding. No intraoperative and/or postoperative complications were observed. Chest drainage was removed on postoperative day two and patient discharged the day after. At 3 months follow up, the patient was well without recurrence.

Operative view showed an abnormal vein originating from the right upper lobe and draining into the vena cava. 3D reconstruction CT defined the characteristics of vascular defect and allowed the safe resection. (1) vena cava; (2) anomalous venous drainage; (3) azygos vein; (4) middle lobe vein; (5) lower lobe vein.

1. Introduction

Anatomical variation of the pulmonary vessels poses challenges to thoracoscopic lung resection and may be associated with an increased risk of intraoperative bleeding and damage to pulmonary circulation.

Herein, we reported a rare and dangerous variation as the partial anomalous venous drainage (PAVD) of the right upper lobe (RUL) into the superior vena cava in a patient undergoing thoracoscopic lobectomy for management of lung cancer of right upper lobe (RUL). The preoperative identification of such variation by 3D CT scan reconstruction allowed to plan a safe and accurate resection, avoiding intraoperative unexpected bleeding.

2. Clinical Case

A 61‐year‐old man was referred to our hospital for management of lung adenocarcinoma of right upper lobe (clinical stage: T1cN0M0). His past medical history was unremarkable and standard cardio‐pulmonary functional tests were within normal. Echocardiography showed no abnormalities. Multidisciplinary oncological board scheduled patient for surgical treatment. The careful evaluation of chest computed tomographic (CT) scan clearly showed the PAVD of the RUL into the superior vena cava (Figure 1A). The following 3D reconstruction of chest CT scan (Figure 1B) confirmed such anomaly without additional pulmonary vein alterations of middle and lower lobe and of the left lung.

FIGURE 1.

Chest computed tomographic scan showed the anomalous venous drainage of the right upper lobe into the superior vena cava (A). The following 3D reconstruction of chest CT (B) confirmed such anomaly without additional pulmonary vein alterations (B). (1) = vena cava; (2) = anomalous venous drainage; (3) = azygos vein; (4) = middle lobe vein; (5) = lower lobe vein.

A standard three‐port thoracoscopic approach with anterior incision was performed. The RUL and middle lobe were mobilized downward. The vein of the middle lobe was normally situated, but the vein of the RUL was not found (Figure 2A). After dissection of pleural adhesions between apical segment of RUL and vena cava, an abnormal vein originating from the RUL and draining into the vena cava was identified and successfully resected by stapler (Figure 2B). The right upper lobectomy was then performed in a standard manner (Video S1).

FIGURE 2.

Intraoperative view showed the lack of vein of the right upper lobe (A). An abnormal vein originating from the right upper lobe and draining into the vena cava was identified (B).

No intraoperative and postoperative complications were observed. Chest drainage was removed on postoperative day two and patient discharged the day after. Pathological diagnosis confirmed pT1cN0M0 adenocarcinoma and no additional treatment was needed. At 3 months follow up, the patient was well without recurrence.

Patient had given a written informed consent for the operation and for the anonymous use of clinical data, photo, and video for scientific purpose only.

3. Discussion

PAVD is a rare congenital anomaly with an incidence rate between 0.4%–0.7% [1]. The anomalous pulmonary veins drain directly to the right atrium or indirectly through venous connections from a pulmonary vein to a systemic vein. The presence of PAVD is not a main contraindication for lung cancer resection. In relation to the location of the tumor and the defect, PAVD is classified in three different types including Type A (PAVD and tumor are localized in the same lobe), Type B (PAVD and tumor are localized in a different lobe but in the ipsilateral lung), and Type C (PAVD and tumor are localized in different lung) [1]. Winslow et al. reported the first case of abnormal pulmonary vein drainage in the 1739 [2]. Following, other authors [2, 3, 4, 5] described several pulmonary venous anomalies, but the PAVD of the RUL into the vena cava, as the present, remained exceptional with only few cases reported in English literature [6, 7, 8]. In this case for the first time, the characteristics of PAVD were evaluated using a 3D CT scan reconstruction and it was crucial for the success of the operation.

From a technical perspective, this strategy accurately defined the course of PAVD and the connections to the systemic venous system. It allowed to plan a more accurate and safer resection than if such abnormality was not preoperatively predicted. The RUL was gently lifted and the adhesions between the lobe and the azygous were carefully resected. In this way, the PAVS was safely exposed and resected during thoracoscopy. Conversely, in previous cases the unexpected presence of PAVD of the RUL needed a conversion to thoracotomy or the use of a mini‐thoracotomy to perform the lobectomy. Additionally, in case of bleeding due to the PAVD lesion, all surgical team was ready to perform an alternative strategy as conversion to thoracotomy, clamping the vena cava to stop the bleeding and then repairing the lesion with 5–0 prolene running suture. Similarly, Galetta et al. [8] described the intraoperative bleeding due to accidental lesion of unexpected anomalous double pulmonary veins draining into the azygous vein and into the confluence between the superior vena cava and the azygous vein in a patient undergoing right upper lobectomy for management of lung cancer. The bleeding was successfully controlled by the resection of the azygos and the partial resection of superior vena cava. Lobectomy was then completed without additional complications.

From a physiological perspective, in our case the 3D CT scan reconstruction confirmed a Type A PAVD as the tumor and the defect involved the same lobe while there were no other vein alterations. Thus, our patient was scheduled for lobectomy without needing additional cardiologic exams. Generally, the single PAVD did not cause hemodynamically significant shunt, but in patients with type B PAVD and type C PAVC undergoing lobectomy, the venous return from the nonresected lobes flowed into the systemic circulation instead of the left atrium and it could result in abnormal oxygenation or circulatory dynamics. Thus, these subsets of patients should receive an accurate cardiologic evaluation before and after lobectomy to define the surgical risk. In addition to standard diagnostic exams as ECG and echocardiography, some authors proposed the use of cardiac magnetic resonance to quantify the shunt, and the right ventriculum volume and to exclude associated heart diseases [9, 10].

Despite in this case we used a free software 3D‐slicer (Brigham and Women's Hospital, Boston) to perform the 3D reconstruction, 3D CT scan reconstruction remained a timing consuming procedure. In our clincial practice, we did not routinely used it, but only in selected case as to define vascular defects and/or to identify small nodules and intersegmental scissures during thoracoscopic segmentectomy [11].

In conclusion, our case confirmed that the presence of PAVD of RUL did not represent a major contraindication for thoracoscopic lobectomy. The preoperative definition of such alteration by 3D CT scan recontruction allowed to plan lung resection via thoracoscopy and to prepare additional strategies for safely overcoming unexpected intraoperative bleeding. Starting a surgical case well prepared is crucial, as “failure to prepare is preparing to fail.”

Author Contributions

M.A.P.: writing paper. A.M.: writing paper. M.M: photo collection. A.R.: data collection. F.C.: data collection. V.D.F.: data collection. G.M.: data collection. A.F.: review paper.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Video S1. The video edited the main steps of right upper lobectomy.

Data Availability Statement

Patient had given a written informed consent for the operation and for the anonymous use of clinical data, photo and video for scientific purpose only.