Hemodynamic features underlying pulmonary vein stump thrombus formation after left upper lobectomy: four-dimensional flow magnetic resonance imaging study

Pulmonary vein stump thrombosis and organ infarction after lung lobectomy

Lung resection surgery, which is performed as a treatment for lung cancer and metastatic lung tumors, is currently conducted via minimally invasive techniques such as video-assisted thoracoscopic surgery and robot-assisted methods. Postoperative complications related to this surgery, such as pulmonary vein thrombosis and cerebral and other organ infarctions, have been increasingly reported. The primary cause of these complications is thrombus formation in the pulmonary vein stump. Statistical data on the site of lung lobectomy have indicated that surgeries involving the left upper lobe are most frequently associated with embolic complications. Although this issue has not received considerable attention in anesthesiology, the importance of prevention and treatment in postoperative management is growing. The role of anesthesiologists in preventing these complications is critical. These roles involve careful fluid management to avoid hypercoagulable states, consideration of early postoperative anticoagulation therapy, assessment of the suitability of epidural anesthesia for postoperative anticoagulation, and improvement of hospital-wide safety systems and monitoring of high-risk patients. Anesthesiologists need to understand the pathology and risk factors involved and play an active role in preventing and treating these complications through effective collaboration with thoracic surgeons and the in-hospital stroke team.

Proximal ligation technique prevents thrombus formation in the pulmonary vein stump after lobectomy

PURPOSE

To assess the risk factors for thrombosis in the pulmonary vein stump (PVT) and the efficacy of proximal ligation in preventing PVT after lobectomy.

METHODS

In total, 649 surgical patients with lung cancer were retrospectively reviewed. To compare the clinical effectiveness of PV proximal ligation, the simple stapler group (290 patients) and the proximal ligation group (359 patients who underwent thread ligation at the pericardial reflection with/without a stapler) were analyzed.

RESULTS

In the simple stapler group, 12 of 290 patients (4.1%) developed PVT. Among these, 9 of 58 underwent left upper lobectomy (LUL). In contrast, 5 of the 359 patients (1.4%) in the proximal ligation group developed PVT. All five patients received LUL. The incidence of PVT in the proximal ligation group was significantly lower than that in the simple stapler group (p = 0.0295) as well as in the analysis by LUL alone (p = 0.0263). A logistic regression analysis indicated that higher BMI and LUL were associated with the development of PVT (p = 0.0031, p < 0.0001), and PV proximal ligation reduced PVT (p = 0.0055).

CONCLUSION

Proximal ligation of the PV has the potential to prevent PVT, especially after LUL.

Computational study on hemodynamic effects of left superior pulmonary vein resection and associated physiological changes in the left atrium after left upper lobectomy

Left upper lobectomy (LUL) with left superior pulmonary vein (LSPV) resection alters the left atrium (LA) physiological states and LA hemodynamics associated with thrombosis, although this underlying mechanism is poorly understood. Therefore, we investigated the effects of LSPV resection and associated LA physiological changes on LA hemodynamics using four-dimensional computed tomography image-based computational simulations. Three cases were considered: the LA before and after LUL extracted from computed tomography images and artificial LSPV resection without physiological changes. Comparisons among the three cases demonstrated that physiological changes associated with LSPV resection are the possible factors that affect the LA hemodynamics after LUL.

Stagnating blood flow related to thrombus formation in pulmonary vein stump after left upper lobectomy

OBJECTIVES

A thrombus can occur in the stump of the pulmonary vein after left upper lobectomy, potentially causing postoperative cerebral infarction. This study aimed to verify the hypothesis that stagnation of blood flow inside the pulmonary vein stump causes thrombus formation.

METHODS

The three-dimensional geometry of the pulmonary vein stump after left upper lobectomy was recreated using contrast-enhanced computed tomography. Blood flow velocity and wall shear stress (WSS) inside the pulmonary vein stump were analysed using the computational fluid dynamics (CFD) method and compared between the two groups (those with or without thrombus).

RESULTS

The volumes of average flow velocity per heartbeat < 10 mm/s, 3 mm/s, 1 mm/s (p-values 0.0096, 0.0016, 0.0014, respectively) and the volumes where flow velocity was always below the three cut-off values (p-values 0.019, 0.015, 0.017, respectively) were significantly larger in patients with a thrombus than in those without thrombus. The areas of average WSS per heartbeat < 0.1 Pa, 0.03 Pa, 0.01 Pa (p-values 0.0002, < 0.0001, 0.0002, respectively), and the areas where WSS was always below the three cut-off values (p-values 0.0088, 0.0041, 0.0014, respectively) were significantly larger in patients with thrombus than in those without thrombus.

CONCLUSIONS

The area of blood flow stagnation in the stump calculated by CFD method was significantly larger in patients with than in those without thrombus. This result elucidates that stagnation of blood flow promotes thrombus formation in the pulmonary vein stump in patients who undergo left upper lobectomy.

Left atrial CT volume and CHA2DS2-VASc score predict early pulmonary vein stump thrombus after left upper lobectomy

The purpose of this study is to clarify the feasibility of left atrial (LA) volume measurement and CHA₂DS₂-VASc score for predicting the development of pulmonary vein (PV) stump thrombus after left upper lobectomy (LUL). The study population comprised 50 patients who underwent LUL for pulmonary lesions. All patients were evaluated for the development of PV stump thrombus at 7 days after LUL. LA volume was measured using preoperative CT and the CHA₂DS₂-VASc score was evaluated. LA volume and CHA₂DS₂-VASc score were compared between patients with and without the development of PV stump thrombus using the Mann-Whitney U test. Receiver-operating characteristic (ROC) curve analysis was performed to evaluate the accuracy of prediction of PV stump thrombus development. PV stump thrombus was detected in 17 (33.4%) of the 50 patients. LA volume was significantly greater in patients who developed PV stump thrombus than in those without thrombus (79.7 ± 19.4 vs. 66.6 ± 17.0 mL, p = 0.040). CHA₂DS₂-VASc score was significantly higher in patients with PV stump thrombosis than in those without thrombus (3.4 ± 1.5 vs. 2.5 ± 1.5, p = 0.039). Area under the ROC curve values for predicting PV stump thrombus were 0.679, 0.676, and 0.714 for LA volume, CHA₂DS₂-VASc score, and their combination, respectively. In conclusion, LA volume measured using preoperative CT and CHA₂DS₂-VASc score may help predict the development of PV stump thrombus after LUL.