Left Upper Lobectomy for Lung Cancer as a Risk Factor for Cerebral Infarction: A Systematic Review and Meta-Analysis

Do blood flow patterns in the left atriums differ between left upper lobectomy and other lobectomies? A computational study

Background

Left atrial (LA) hemodynamics after lung lobectomies with pulmonary vein (PV) resection is widely understood to be a risk factor for LA thrombosis. A recent magnetic resonance imaging study showed that left upper lobectomy (LUL) with left superior pulmonary vein resection tended to cause LA flow patterns distinct from those of other lobectomies, with flow disturbances seen near the PV stump. However, little is known about this flow pattern because of severe image resolution limitations. The present study compared flow patterns in the LA after LUL with the flow patterns of other lobectomies using computational simulations.

Methods

The computational simulations of LA blood flow were conducted on the basis of four-dimensional computed tomography images of four lung cancer patients prior to lobectomies. Four kinds of PV resection cases were constructed by cutting each one of the PVs from the LA of each patient. We performed a total of five cases (pre-resection case and four PV resection cases) in each patient and evaluated global flow patterns formed by the remaining PV inflow, especially in the upper LA region.

Results

LUL tended to enhance the remaining left inferior PV inflow, with impingements seen in the right PV inflows in the upper LA region near the PV stump. These flow alterations induced viscous dissipation and the LUL cases had the highest values compared to other PV resection cases, especially in the LV systole in three patients, and reached three to four times higher than those in pre-resection cases. However, in another patient, these tendencies were weaker when PV inflow was stronger from the right side than from the left side, and the degree of flow dissipation was lower than those in other PV resection cases.

Conclusion

These findings suggest marked variations in LA flow patterns among patients after lobectomies and highlights the importance of patient-specific assessment of LA hemodynamics after lobectomies.

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.

Postoperative cerebral infarction and arrhythmia after pulmonary lobectomy in Japan: a retrospective analysis of 77,060 cases in a national clinical database

PURPOSE

To investigate the incidence of postoperative cerebral infarction after curative lobectomy, its association with the type of lobectomy, and how postoperative new-onset arrhythmia contributes to postoperative cerebral infarction.

METHODS

The subjects of this analysis were 77,060 patients who underwent curative lobectomy for lung cancer between 2016 and 2018 according to the National Clinical Database. Incidences of postoperative cerebral infarction and postoperative new-onset arrhythmia were analyzed. Moreover, mediation analysis was performed to evaluate the causal pathway between postoperative new-onset arrhythmia and postoperative cerebral infarction.

RESULTS

Postoperative cerebral infarction occurred in 110 (0.7%) patients after left upper lobectomy and in 85 (0.7%) patients after left lower lobectomy. Left upper lobectomy and left lower lobectomy were associated with a higher likelihood of postoperative cerebral infarction than right lower lobectomy. Left upper lobectomy was the strongest independent predictor of postoperative new-onset arrhythmia. However, in the mediation analysis, the odds ratio for cerebral infarction did not change after the addition of the factor of postoperative new-onset arrhythmia.

CONCLUSION

Cerebral infarction occurred significantly more often not only after left upper lobectomy, but also after left lower lobectomy. Postoperative new-onset arrhythmia was less likely to be related to cerebral infarction after left upper lobectomy.

Lung Lobectomy Is an Embolic Risk Factor for Cerebral Infarction, Even in the Long-term Postoperative Phase

The vein stump created after lung lobectomy has been reported to cause thrombus and subsequently cerebral infarction. However, its assessment after a long-term postoperative course remains unreported. The pulmonary vein stump is a structure near the left atrial appendage; therefore, such patients may be at a constant risk of thrombus formation. We herein report two cases of cerebral infarction associated with lung lobectomy. Transesophageal echocardiography revealed mobile thrombi in the pulmonary vein stump. Both patients had cancer recurrence, and hypercoagulability may have contributed to thrombus formation. This vein stump should be investigated as an embolic source, even after a long postoperative duration.

A case of cerebral infarction due to aplastic or twig-like middle cerebral artery after lung cancer surgery

Aplastic/twig-like middle cerebral artery is a rare vascular abnormality. We report a case of postoperative cerebral infarction caused by this disease. The patient is a male in his 40s. A 9-cm tumour was revealed to have invaded the superior vena cava from his right lung. He underwent right upper and middle bilobectomy. Due to the vascular invasion, the intraoperative bleeding exceeded 2 litres. Mechanical ventilation was required for postoperative pneumonia. After extubation, he was unable to write and was found to have cerebral infiltration in the left middle cerebral artery region. The cause of the cerebral infarction was investigated, but no thrombus in the left atrium or arteriosclerosis was found. No atrial fibrillation was observed during or after the surgery. Magnetic resonance angiography of the brain revealed an aplastic/twig-like middle cerebral artery.

4D Flow MR Imaging of the Left Atrium: What is Non-physiological Blood Flow in the Cardiac System?

Most cardiac diseases cause a non-physiological blood flow pattern known as turbulence around the heart and great vessels, which further worsen the disease itself. However, there is no consensus on how blood flow can be defined in disease conditions. Especially, in the left atrium, the fact that vortex flow already exists makes this debate more complicated. 3D time-resolved phase-contrast (4D flow) MRI is expected to be able to capture blood flow patterns from multiple aspects, such as blood flow velocity, stasis, and vortex quantification. Previous studies have confirmed that physiological vortex flow is predominantly induced by the higher-volume flow from the superior left pulmonary vein. In atrial fibrillation, 4D flow MRI reveals a non-physiological blood flow pattern, which information may add value to well-established clinical risk factors. Currently, the research target of LA analysis has also widened to lung surgeons, pulmonary vein stump thrombosis after left upper lobectomy. 4D flow MRI is expected to be utilized for many more variable diseases that are currently unimaginable.