THORACOABDOMINAL AORTIC-ANEURYSM (TAAA) - INDICATION FOR SURGERY AND OPERATIVE RESULTS

Aortic replacement for thoraco-abdominal aneurysms remains a major cha llenge in vascular surgery. Related symptoms, maximal diameter > 6 cm, progression, aneurysm sac containing none or excentric thrombi and un controllable hypertension are factors in favour of surgery, if the gen eral condition of the patient allows the operation. Patients with aneu rysms < 5 cm maximal diameter, tube-size aneurysms, heavy calcificatio n of the aortic wall, concentric thrombi within the aneurysmal sac and significant cardiopulmonary risks should be treated conservatively. P atients in good general condition with aneurysms around 5 cm maximal d iameter should be controlled by computed tomography in 6 to 12 months intervals and in the case of progression surgery can be recommended de spite missing symptoms. Crawford developed the ,graft-inclusion-techni que', which combines the ,ingraft'-technique with reattachment of rena l, visceral and segmental arteries. The ,clamp and repair' principle i s used in patients with sufficient cardiac function. Otherwise shunt o r left sided heart bypass are used to reduce cardiac afterload. Accord ing to the literature local cooling (flush perfusion), cytoprotective drugs and numerous methods to maintain or ameliorate distal aortic per fusion during clamping ischemia have been used in patients successfull y for prevention of ischemic spinal complications. In physiological se ttings these methods may prove valuable, but under pathophysiological conditions of TAAA-repair one must doubt the efficacy, because the ind ividual risk is difficult to assess. In our hands flush perfusion and cooling of the kidneys proved to be helpful. In animal experiments we have shown prolongation of Ischemia tolerance time using eicosanoides to protect the kidneys and the spinal cord. If shunt or left-sided hea rt bypass can protect the spinal cord during clamping, is unknown, bec ause the risk of paraplegia in the individual patient can be known onl y, if the function of the spinal cord is monitored. We have developed a spinal neuromonitoring system and found, that only one third of all TAAA-patients is at high risk to develop paraplegia during aortic clam ping. The surgeon is guided by continuous recording of spinal evoked s omatosensory potentials and can adapt the operative technique by early reimplantation and eventually subsequent separate reimplantation of s egmental arteries supplying blood to the spinal cord, in order to redu ce spinal ischemia time. Our results in 260 TAAA-patients are presente d. In a high-risk population of patients with aneurysms type I-III (Cr awford's classification) it was possible, to reduce the paraplegia rat e from 7 to 3.5%, the risk of paraparesis from 15 to 6%, while the ope rative mortality was only reduced from 19 to 10%.