RIGHT MIDDLE LOBE TORSION IN THE SETTING OF ABERRANT BRONCHIAL ANATOMY

Abstract

SESSION TITLE: Medical Student/Resident Cardiothoracic Surgery Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Pulmonary torsion (PT) is defined as twisting of the entire lung or lobe around its bronchovascular pedicle. This disorder most commonly involves the right middle lobe (RML) following right upper lobe (RUL) lobectomy. The objective of this report is to describe a case of RML torsion following RUL lobectomy, in the setting of aberrant bronchial anatomy, which potentially led to this problem. CASE PRESENTATION: A 61-year-old African American woman with a RUL nodule, suspected to be cancerous, presented for RUL lobectomy. Flexible bronchoscopy revealed a right mainstem bronchus (RMB), which ended in a trifurcation of the upper, middle, and lower lobe bronchi. During thoracotomy, the inferior pulmonary ligament (IPL) was divided and RUL lobectomy was completed. Her major and minor fissures were noted to be partially complete and she had a short pedicle to the RML. As her risk of developing RML torsion was deemed to be low, no prophylactic fixation was done. Pathology confirmed the nodule to be a T1a N0M0 stage I adenocarcinoma. Post-operatively she complained of chest pain and hemoptysis. CT scan of the chest showed opacification of the right upper hemithorax, and RML torsion was suspected. Subsequent bronchoscopy showed that the RML bronchi were extrinsically compressed. Thoracoscopy demonstrated that the RML was torsed and engorged with venous blood (Figure 1). A thoracotomy and RML lobectomy were performed. Final pathology showed ischemic necrosis and hemorrhage. DISCUSSION: Ordinarily, the RMB gives rise to the RUL bronchus and the bronchus intermedius, which then bifurcates into the RML and right lower lobe (RLL) bronchi. The bronchus intermedius was absent in this patient and, instead, the RMB ended in a trifurcation of the RUL, RML, and RLL bronchi. The risk of RML torsion increases with division of the IPL in patients with complete pulmonary fissures and a lack of parenchymal bridges between the lobes prior to surgery. These factors increase the mobility of the RML, while the presence of a long pedicle predisposes to additional rotation along the bronchovascular pedicle.(1-3) This patient, despite lacking these risk factors, still developed RML torsion after RUL lobectomy. We speculate that the aberrantly located RUL takeoff, once resected, increased the range of rotational motion of the RML relative to the RLL, resulting in torsion of the RML. CONCLUSIONS: In patients at risk for RML torsion after RUL lobectomy, incomplete severing of the IPL and prophylactic inter-lobar fixation (or fixation to the thoracic wall or cardiac fat pad) are suggested. (2,3) Such measures may need to be considered in patients with a trifurcate RMB. Reference #1: Felson B. Lung torsion: Radiographic findings in 9 cases. Thoracic Radiology 1987 March; 162(3): 631-8. Reference #2: Moser E, Proto A. Lung torsion: Case report and literature review. Thoracic Radiology 1987 March; 162(3): 639-43. Reference #3: Kanemitsu S, Tenaka K, Suzuki H et al. Pulmonary torsion following right upper lobectomy. Ann Thorac Cardiovasc Surg 2006; 12: 417-9. DISCLOSURES: No relevant relationships by Batool Abuhalimeh, source=Web Response No relevant relationships by Joseph Lahorra, source=Web Response No relevant relationships by Tanya Marshall, source=Web Response No relevant relationships by Sanjiv Tewari, source=Web Response