Usefulness of Transesophageal Echocardiography in the Evaluation of Celiac Trunk and Superior Mesenteric Artery Involvement in Acute Aortic Dissection

Mesenteric ischemia is a serious complication of acute aortic dissection (AAD), and its early diagnosis is vital for prognosis and appropriate treatment indication. Arteries affected by this complication are the celiac trunk and superior mesenteric artery, and their evaluation is usually based on computed tomographic angiography. Transesophageal echocardiography is also a useful technique for diagnosing AAD and is essential in monitoring surgical or endovascular treatment when computed tomographic angiography is not available. However, the usefulness of transesophageal echocardiography for evaluating celiac trunk and superior mesenteric artery involvement and mesenteric ischemia mechanisms in AAD is not well established. Real-time information on mesenteric malperfusion is needed at the bedside, in primary care facilities, and in the operating room to achieve prompt diagnosis and better therapeutic management. The aims of this review are to assess the role of TEE to diagnose celiac trunk and superior mesenteric artery involvement in AAD, determine the mechanisms that can cause flow obstruction in patients with mesenteric ischemia, and analyze possible implications in the treatment of this complication.

Branch Vessel Patency after Thoracic Endovascular Aortic Repair for Type B Aortic Dissection

BACKGROUND

Thoracic endovascular aortic repair (TEVAR) for type B aortic dissections is used to promote false lumen (FL) thrombosis and favorable aortic remodeling, but its impact on occlusion of FL origin branch vessels has not been widely described. We compare FL versus true lumen (TL) branch vessel patency after TEVAR.

METHODS

Patients treated by TEVAR for type B aortic dissection in zones 2-5 in the Vascular Quality Initiative from 2009 to 2018 were evaluated. The primary outcome was postoperative branch patency. Secondary outcomes were need for branch vessel intervention, preoperative origin, and postoperative patency of individual branch vessels (celiac, superior mesenteric artery, renal arteries, and iliac arteries). A subset analysis was performed comparing acute and chronic dissections.

RESULTS

Of 11,774 patients, 1,484 met criteria for analysis. The left renal was the most common to have FL origin (21.6%), whereas right and left common iliac arteries were the most likely to originate off both lumens (BLs; 22% and 24%). Branch vessels that originated from the TL, FL, BLs, or were obstructed had postoperative patency rates of 99%, 99%, 99%, and 87% (P < 0.0001). Branch vessel treatment was performed in 5% of patients. The right (2.5%) and left (2.8%) renal arteries were the most frequently obstructed branches postoperatively. On multivariate analysis, preoperatively obstructed branches (odds ratio 0.03, P < 0.0001) were negatively associated with postoperative branch patency and branch vessel treatment (odds ratio 3.8, P = 0.004) was positively associated with postoperative patency. FL or BL origin, number of zones covered by TEVAR, urgency, dissection chronicity (acute versus chronic), and demographics were not independently associated with patency. These findings remained unchanged in the subset analysis of only acute dissections.

CONCLUSIONS

Branch vessel patency rates after TEVAR for a type B aortic dissection are high and are not significantly different for FL or BL origin vessels compared with TL vessels. Branches that are patent before TEVAR almost always remain patent after TEVAR, but branch vessel stenting may be required in less than 5%.

Debate: Whether level I evidence comparing thoracic endovascular repair and medical management is necessary for uncomplicated type B aortic dissections

Type B aortic dissections continue to be one of the most challenging clinical scenarios confronting vascular surgeons. In the era of open surgery, the therapeutic options were limited to medical management of hypertension and large open thoracoabdominal operations. In the current endovascular era, the operative strategies have become less invasive but the questions regarding therapeutic approaches have become more numerous and complex. In patients with acute uncomplicated type B aortic dissections, we are still unsure as to which patients are best treated with medical therapy alone or with the addition of early endovascular repair. Data from single centers and registries have provided some guidance; however, questions remain. Perhaps level 1 evidence from well-designed randomized controlled trials will answer all of our questions. This is the topic of the current debate.

Human ex-vivo model of Stanford type B aortic dissection

OBJECTIVE

To report a new human ex vivo model of type B aortic dissection (TBAD) and to assess if the locations of the primary entry tear determine the patterns of dissection propagation.

METHODS

Twenty fresh human aortas were harvested. TBADs were surgically initiated 2 cm below the left subclavian artery at four different locations (lateral, n = 5; medial, n = 5; anterior, n = 5; posterior, n = 5). Aortas were thereafter connected to a bench-top pulsatile flow model to induce antegrade propagation of the dissection.

RESULTS

Antegrade propagation of the dissection was achieved and reached at least the celiac trunk (CT) in all the cases. Dissection was propagated to the renal aorta in 16 (80%) and infrarenal aorta in seven cases (35%). Left renal artery with or without the CT originated more often from the false channel when primary entry tear was lateral. Right renal artery and the CT most often originated from the false channel when primary entry tear was medial. When the CT was the only one originating from the false channel, primary entry tear was more often anterior, whereas when it originated from the true channel, it was more often posterior.

CONCLUSIONS

This human ex vivo model of TBAD is reproducible, since, in all the aortas, extended dissection was achieved and provides the first model of human aortic dissection with infrarenal aorta extension allowing future assessment of endovascular devices developed for human use. Furthermore, it allows clarification of the patterns of aortic dissection propagation and visceral and renal artery involvement according to the site of the primary entry tear.