Cardiopulmonary Bypass for Extended Thoracic Resections




Introduction



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Bronchogenic carcinoma remains the most common cause of cancer death in both men and women in the United States. These tumors can exhibit local progression and invasion before metastatic spread has occurred, which does not preclude resection with curative intent. Any contiguous structure within the chest may be involved, with chest wall involvement being the most common. Other potential sites of local invasion include the left atrium, aorta, superior vena cava, vertebral bodies, diaphragm, and esophagus. The increased potential for morbidity and mortality are well documented for these complex extended resections, making appropriate patient selection crucial. Long-term prognosis depends on accurate pretreatment staging to assist in selection of therapy and complete resection. Cardiopulmonary bypass (CPB) may be necessary to allow surgical resection of central, locally advanced malignancies because they involve, or are close to, the heart and/or the great vessels. CPB serves as an alternative to conventional ventilation during extended resections providing oxygenation and hemodynamic support. This chapter will review the role of CPB for the extended resection of lung cancer, as well as the clinical and technical considerations and expected surgical outcomes.




General Principles



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For those patients presenting with locally advanced lung cancers, long-term outcome is primarily dependent on the ability to obtain a complete (R0) resection. For non–small-cell lung cancers (NSCLCs) with direct invasion into the mediastinum, Martini et al.1 found a survival rate of 30% if an R0 resection was obtained in contrast to 14% if the resection was incomplete. Likewise, for tumors invading the heart or the great vessels, 5-year survival rate ranges between 23% and 40% with complete resection versus 0% with incomplete resection.2,3



The operative approach is ultimately based on the tumor anatomy, the need for vascular reconstruction, and the urgency with which circulatory support is initiated. To optimize outcomes, one must maintain a flexible strategy with regard to arterial and venous cannulation sites, need for aortic clamping, cardioplegia requirements, and deairing options.



When an injury to a major vascular structure (i.e., pulmonary artery, superior vena cava) occurs during a thoracotomy, CPB support may be required. In the setting of a right thoracotomy approach, cannulation can be achieved via the ascending aorta and the right atrium. In the setting of a left thoracotomy approach, cannulation can be obtained via the descending thoracic aorta and main pulmonary artery.4



If the groin is accessible, systemic venous drainage can be achieved by placing a long venous cannula into the right atrium through the femoral vein. In the emergent setting, decompression of the heart with the ability to control blood loss and return shed blood is usually all that is required to enable primary or patch repair of the injury to the central vascular structure.



In the elective setting, standard median sternotomy is the surgical approach used to address lesions involving the central pulmonary arterial system. Standard ascending aorta and right atrial cannulation are used for CPB institution. Reconstruction with pulmonary homograft or autologous pericardium can be readily achieved. In lesions involving the left atrium, median sternotomy is usually satisfactory; however, one must be alert to the issues of deairing and ensure appropriate means of preventing systemic air emboli. Additionally, tumor emboli can occur, and care must be taken to limit tumor manipulation before cardiac decompression and adequate circulation control.5 If the left thoracotomy is the surgical approach used, it is useful to access the left femoral vein with a small caliber catheter prior to turning the patient to the side.




Effect of Cardiopulmonary Bypass on Cancer Biology



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Cancer progression is a multistep process including proliferation, migration, vascular invasion, and angiogenesis. The effects of operative stress on cancer cell proliferation have been shown in several in vitro models.68 One such study demonstrated that lung cancer cell proliferation was better in human serum obtained immediately following lung resection when compared with serum drawn preoperatively.8



The immunosuppressive effects of extracorporeal circulation have been clearly elucidated. The physiologic stress of CPB has been shown to alter the circulating levels of certain cytokines and growth factors.911 There are also inhibitory effects to both cell-mediated and humoral immunity.12,13 In a study performed in patients undergoing cardiac surgery with and without CPB, those undergoing CPB had a significantly decreased inhibitory capacity of serum for cancer cell proliferation.14 Previous series of extended resections have demonstrated an earlier recurrence rate after resection with CPB.3,15



Centrally Advanced Tumors


Locally advanced tumors that involve the central pulmonary vasculature or the heart (T4 lesions) are classically considered to be unresectable. Achieving a tumor-free proximal margin or satisfactory proximal vascular control may not be possible with standard (non-CBP) techniques. A small but definable subset of such patients will benefit from surgery if CPB is used to facilitate these complex resections. Accurate preoperative evaluation, including aggressive staging, must be performed to exclude the presence of occult metastatic disease, determine the patient’s physiologic fitness, and establish the limits of resection to achieve the optimal long-term survival for each individual patient. Since these tumors are often larger and more centrally located, preoperative imaging should include PET and CT scanning. There should be consideration for magnetic resonance imaging (MRI) of the brain to rule out occult disease. Mediastinoscopy must be performed not only for identifying nodal disease, but also as an assessment of the extent of airway and pulmonary artery involvement.



The role of induction chemotherapy prior to resection of T4 malignancies remains undefined. There are some small series in which preoperative chemotherapy improved resectability.1618 In one series, induction chemotherapy prevented 20% of patients from proceeding on to resection due to toxic side effects.19 Furthermore, there is evidence that induction therapy increases surgical morbidity and mortality.2022 In patients undergoing extended surgical resection, induction therapy followed by surgery is associated with an increase in morbidity and mortality when compared to surgery alone.20 Therefore, decisions for preoperative chemotherapy should be tailored on a case-by-case basis.



Most thoracic surgeons are reluctant to perform pulmonary resections with patients on CPB. Several authors2326 have reviewed the results and safety of combined cardiac and pulmonary procedures requiring CPB. Their opinions are varied, and several authors have expressed concerns for the adverse effects of CPB on hemostasis and pulmonary function. Others4,27,28 with significant institutional experience have written more extensively on the subject, describing the advantages, disadvantages, and parameters for patient selection when CPB is used as an adjunct to conventional thoracic surgical techniques.



Byrne et al.4 reviewed a decade of experience at Brigham and Women’s Hospital and Massachusetts General Hospital in Boston. Between January 1992 and September 2002, CPB was used in 14 patients during planned curative resection of locally advanced thoracic malignancies. In 8 of the 14 patients, CPB use was planned to facilitate resection. In the remaining six patients, CPB was required as an emergent therapy to manage central vascular injury. Indications for planned CPB included tumor involvement of the left atrium, pulmonary artery, and superior vena cava. Complete resection was achieved in 12 patients (86%). There was one operative death from pulmonary embolism. Complications included low cardiac output state (5), stroke (1), pulmonary edema (1), and reoperation for bleeding (3). The overall 1-, 3-, and 5-year survival rates were 57%, 36%, and 21%, respectively. The authors concluded that although CPB is rarely required for thoracic malignancy resection, in appropriate circumstances, it can be used with low morbidity and mortality and may be lifesaving if the surgery is complicated by a central vascular injury. They also concluded that the ability to perform a complete resection influences ultimate survival. In addition, optimal outcome depends on careful patient selection with use of radiographic imaging and thorough intraoperative inspection.



Vaporciyan et al.28 reported the University of Texas MD Anderson Cancer Center’s experience from January 1995 to July 2000 using CPB for resection of metastatic or noncardiac primary malignancies that extended directly into the heart. This series included 19 patients, 11 of whom underwent surgery for curative intent. Complete resection was achieved in 10 of these patients. There were two deaths in the group operated on for palliation. Major complications occurred in the majority of patients (58%) and included acute respiratory distress syndrome, mediastinal hematoma, and pneumonia. The overall 1- and 2-year survival rates were 65% and 45%, respectively. The authors concluded that the use of CPB has a role in selected patients with these central thoracic malignancies if there is confidence that complete resection can be achieved.




Vena Cava Involvement with Bronchogenic Carcinoma



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Bronchogenic carcinoma of the right upper lobe can invade the mediastinal pleura and on rare occasions invade the superior vena cava (Fig. 81-1). Involvement of the superior vena cava may also occur as a consequence of metastatic nodal disease, which, when present, is a uniformly poor prognostic indicator. There is an increasing experience in extended resections of pulmonary malignancy with en bloc resection of the superior vena cava. Several authors2,15,2931 have suggested a benefit in selected patients, but there is still uncertainty regarding a consistent benefit.




Figure 81-1


Right upper lobe mass abutting superior vena cava. Caval invasion was identified at right thoracotomy. Tangential resection of the superior vena cava with autologous pericardial patch reconstruction was performed.



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Dec 30, 2018 | Posted by in VASCULAR SURGERY | Comments Off on Cardiopulmonary Bypass for Extended Thoracic Resections
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