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. Mediastinoscopy also must be performed (see Chap. 61).
Most thoracic surgeons are reluctant to perform pulmonary resections with patients on CPB. Several authors1–4 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. Others5–7 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 and colleagues reviewed a decade of experience at Brigham and Women's Hospital and Massachusetts General Hospital in Boston.5 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 6 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 and others reported the University of Texas M. D. Anderson Cancer Center experience from January 1995 to July 2000 using CPB for resection of metastatic or noncardiac primary malignancies that extended directly into the heart.6 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.
Technical Considerations for CPB and Resection of Thoracic Tumors
The operative approach is based on 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 selection of arterial and venous cannulation sites, need for aortic clamping, cardioplegia requirements, and deairing options. When CPB is required in an emergent setting, a thoracotomy is performed, and CPB support may be required to address central injury to a major vascular structure. Byrne and colleagues reported that cannulation after right thoracotomy was consistently achieved via the ascending aorta and right atrium. On the left, cannulation was achieved via the descending thoracic aorta and main pulmonary artery.5
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, surgical approaches often require the combined expertise of a thoracic surgical oncologist and a cardiac surgeon who is experienced at central vascular reconstruction. Standard ascending aorta and right atrial cannulation is satisfactory to address lesions involving the central pulmonary arterial system. 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. A well-coordinated combined effort by the general thoracic surgeon, the cardiac surgeon, the anesthesiologist, and the perfusionist is needed to achieve a satisfactory outcome when addressing these complex lesions.
Lung Tumors with Infiltration of the Thoracic Aorta
Left-sided lung cancers may involve the descending thoracic aorta. It is often difficult to determine the presence and extent of aortic invasion on imaging studies (Fig. 70-1). If the fat plane between the aorta and the tumor is absent or there is abutment of the tumor involving greater than 90 degrees of the aortic circumference, invasion should be suspected. However, ultimate determination of involvement of the aorta generally is made at exploration. As with lesions involving the central pulmonary vasculature, these T4 tumors with full-thickness involvement of the thoracic aorta are classically deemed unresectable. Experience with combined pulmonary and aortic resection is limited and often anecdotal. However, some authors8–10 have described their experiences with these combined resections. These reviews suggest a favorable impact on survival in highly selected patients; however, the few available reports in the literature make it difficult to draw more generalized conclusions.
Left lower lobe mass abutting the descending thoracic aorta. Aortic adventitial invasion identified at exploration. Tangential resection of the aorta was required.
Technical Considerations for Aortic Resection and Reconstruction
Different technical methods are needed to manage the aorta that is locally invaded with lung cancer. The options include resection of the tumor in a subadventitial plane, partial resection with patch reconstruction, and complete segmental aortic resection with tube graft reconstruction. Nakahara and colleagues reported their results in three patients in whom the aorta was resected at the time of pulmonary resection.10 One patient was a midterm survivor; however, the other two succumbed to metastatic disease within 1 year. In 1994, Tsuchiya and colleagues reported their experience in 28 patients at the National Cancer Hospital in Tokyo.9 Resection in a subadventitial plane was used in 75% of patients. In these 21 patients, 10 had complete resections, and all patients with incomplete resections did poorly. The authors comment that peeling the adventitia off the aorta is inadequate for lung cancer invading the aorta. Of the 7 patients who had a complete aortic resection with tube graft reconstruction, 4 developed recurrent disease. Only 1 of the 7 patients who were managed with complete aortic resection was a long-term survivor. Klepetko and colleagues reported similar observations in their experience in 7 patients undergoing full-thickness aortic resection with patch or tube graft reconstruction.8 Perfusion was supported with CPB in 6 of the operations without apparent untoward events. Long-term survival was achieved in 2 of the 7 patients. These observations regarding pulmonary malignancies with direct aortic invasion support the observation that complete resection and long-term cures are rare, but possible, in appropriately selected patients.