Innovations in aortic disease management: the descending aorta.

HERE HAVE BEEN major innovations in the clinical management for pathologies of the descending thoracic aorta. The beginning of this revolution began with the gradual introduction of endovascular interventions in the past decade. This section introduces the more recent advances that are reviewed in this article. Although serum markers such as matrix metalloproteinases and D-dimer have diagnostic utility in acute aortic dissection, C-reactive protein recently has emerged as an independent indicator of prognosis in acute type-B aortic dis- section. Although thoracic endovascular aortic repair (TEVAR) has an emerging role in complicated type-B dissection, its role in acute uncomplicated type-B dissection is yet to be deter- mined. Although underpowered, a recent landmark randomized trial showed that TEVAR is equivalent to the best medical therapy in the short term for this acute type-B subtype. Further prospective evaluation of TEVAR is required to establish con- clusively whether it should replace the best medical therapy as the treatment of choice for acute uncomplicated type-B dissec- tion. Because malperfusion in acute type-B dissection confers a significant risk for an adverse outcome, urgent intervention with open or endovascular reconstruction typically is indicated. A recent study has provided long-term acceptable data in this type-B subtype after percutaneous revascularization with inti- mal fenestration and/or aortic branch-vessel stenting. This man- agement strategy deserves further attention as the optimal man- agement of malperfusion in type-B dissection is investigated in future trials. The repair of a thoracoabdominal aortic aneurysm (TAAA) is associated with a significant risk of renal dysfunc- tion caused, in part, by ischemia and also a myoglobin release from perioperative rhabdomyolysis. Recent studies have sug- gested at least 2 nephroprotective strategies. The first strategy entails intraoperative intermittent cold crystalloid renal perfu- sion during TAAA repair to decrease renal oxygen demand; the addition of cold blood in this strategy did not enhance nephro- protection. The second strategy is to ensure lower-extremity perfusion during TAAA repair; this is associated with less myoglobin release most likely caused by reduced rhabdomy- olysis. Like the kidney, the spinal cord is significantly at risk during TAAA repair. Spinal cord ischemia (SCI) remains an indepen- dent predictor of mortality and morbidity. Although somato- sensory-evoked potentials (SSEPs) have shown diagnostic and prognostic perioperative utility, the question remains whether motor-evoked potentials (MEPs) further enhance the detection of SCI associated with TAAA repair. A recent comparison between these 2 types of spinal cord monitoring has shown that motor-evoked potentials do not add significantly to the clinical management of SCI achieved by somatosensory-evoked poten- tials alone. Although the role of perioperative drainage of cerebrospinal fluid (CSF) has gained clinical acceptance for the management of SCI in TAAA repair, its safety recently has been scrutinized in 2 large series. These recent studies show that this technique is very safe and has a low incidence of neurologic complications, which have a high mortality. Both studies emphasize the importance of limited CSF drainage to minimize the risk of intracranial hemorrhage. The endovascular repair of TAAA has triggered a renewed interest in the natural history and management of patients considered too high risk for surgical repair with left-heart bypass. A recent observational series confirmed the very poor prognosis of medically managed advanced TAAA, thus under- lining the clinical necessity for an endovascular option in this high-risk subset. The first TEVAR option in TAAA repair is for a total endovascular repair with fenestrated or branched endo- vascular stent components to not only exclude the aneurysm but also to preserve aortic branch perfusion. The second TEVAR option in TAAA repair is the hybrid approach, which uses nonfenestrated endovascular stent components for aneu- rysm exclusion and surgical transposition of aortic branches to preserve their perfusion by relocating their origin away from the extent of the nonfenestrated stent (debranching procedures). Multiple recent clinical series confirm that both TEVAR op- tions are reasonable in select high-risk patients although these techniques are still in early clinical development.