Tumor lesions are relatively more common, observed in the upper aorta, in the “aortic window” and on the border of the aortic arch and the beginning of its descending part, in the region adjacent to the back surface of the left main bronchus. The location of areas of tumor lesions of the thoracic aorta is depicted in Figure 44.
The germination of all layers of the aorta wall by a lung tumor is considered evidence of a far-reaching blastomatous process and the maximum expansion of the intervention does not prolong the life of the patient. With this statement it is difficult to disagree. We add that, in addition to considerations of oncological expediency, the issue of the safety of surgical intervention is also urgent on the agenda. Opening the lumen of the aorta during attempts to separate a tumor from it is an extremely serious complication, accompanied by significant blood loss, with unpredictable consequences. Performing resection of the aortic wall with its subsequent plasty or prosthesis requires special equipment and organization of surgical intervention. Under normal conditions, in the presence of complete germination by the tumor of all layers of the aortic wall, it is advisable to refuse the operation.
However, as experience shows, it is not always easy to establish the presence of such a lesion, even during an intraoperative revision. The aortic wall is extremely tolerant to tumor lesion and often remains intact even with very
significant blastomatous changes in para-aortic tissues. In some cases, the tumor, germinating the adventitious membrane of the aortic wall, for a long time does not affect its middle and the inner lining, which, in contrast to the outer, does not have in its composition small blood vessels and lymphatic capillaries. This circumstance, apparently, can explain the fact that the tumor initially grows predominantly along the aorta through its adventitia, without affecting the deeper layers. The mechanical strength of the vessels of the elastic type, to which the aorta belongs, is mainly provided by the inner and, especially, the middle shells. The outer shell is thin. It is formed by unformed connective tissue containing collagen and elastic fibers. The adventitia is delimited from the middle aortic membrane by an outer elastic membrane, from which it can be separated for a considerable distance.
The presence and extent of true tumor lesion of the aortic wall can be most fully assessed only during the operation, with careful preparation of the vessel. The main rule for isolating the aorta involved in the blastomatous process is the beginning of its preparation by the unchanged sections. The preparation is carried out sequentially in different layers — first, after opening the perivascular connective tissue sheath and, if they are convinced that the tumor grows into the aortic wall, the adventitious membrane is opened and separated. In the absence of tumor invasion into the deeper layers of the vessel, it is possible to determine a certain mobility of the tumor conglomerate with respect to the aorta. The size of the resected outer wall can be different: from 2×3 cm 2 up to 7 cm in length and 1/3 of the circumference of the vessel. If we are convinced that there is germination of the tumor in the deep layers of the vessel, then it is better to refuse to perform the resection. The exception, from our point of view, can only be cases where there is limited tumor invasion by the tumor of the descending part of the thoracic aorta and it is possible to impose an aortic clamp and perform marginal resection without significant narrowing of the vessel lumen.
Of the 34 patients operated in the clinic, 24 had resection of the aortic adventitious membrane at different lengths without opening the vessel lumen. In 10 patients, resection of the aortic wall was accompanied by the opening of its lumen. In 6 cases, the planned regional resection of the descending aorta was performed, followed by closure of the defect with a vascular suture. In 4 patients, the opening of the vessel lumen occurred during its isolation from the tumor conglomerate. A resection was performed, except for the adventitia, and the deeper layers, successively taking in the resulting defect in the aortic wall. Such operations are always highly traumatic, accompanied by significant blood loss. One of these patients died during the operation from massive blood loss resulting from damage to the aortic wall.
After performing resections, especially extensive, adventitious membrane, it is advisable to strengthen the aortic wall with its own surrounding tissues or alloplastic materials. The clinic uses for this purpose the anti-bacterial polycapromide mesh “Ampoxen” or a portion of the aortic vascular prosthesis, which are stitched to the edge of the adventitia or para-aortic tissues.