Subtypes of acute aortic dissection

Spontaneous retrograde dissection of ascending aorta from descending thoracic aorta - a case review

A 56-year-old man with sudden onset chest pain, absent right lower limb pulses and ECG changes suggestive of inferior ST elevation MI underwent coronary angiogram through the right radial artery with a view to primary percutaneous coronary intervention (PCI). The left coronary angiogram demonstrated severe proximal stenotic disease in the left anterior descending and circumflex coronary arteries, but the right coronary artery could not be selectively cannulated. An ascending aortogram to visualise the right coronary artery not only failed to demonstrate it, but revealed, instead, a dissection flap in the ascending aorta, arch and descending thoracic aorta, with moderately severe aortic regurgitation. At operation, the patient was found to have an acute dissection of the ascending aorta, arch and descending aorta with an entry tear in the descending aorta below the left subclavian artery origin. Triple coronary artery bypass grafting with re-suspension of the aortic valve, supracoronary replacement of the ascending aorta and hemiarch and transaortic repair of the descending aortic tear was performed. The patient made an uncomplicated recovery, with the re-appearance of right limb pulses. A postoperative magnetic resonance (MR) scan revealed complete thrombosis of the false channel in the residual arch and a considerably shrunken false channel in the descending aorta and no aortic regurgitation.

Retrograde dissection of the ascending aorta from the descending aorta has been reported infrequently in the past. We believe the scale of the problem has been underestimated because of the failure to adopt open distal anastomosis routinely in the past and, hence, failure to inspect the arch and the descending aorta routinely, particularly when the intimal tear was not identified in the ascending aorta. Retrograde dissection of the ascending aorta from an intimal tear in the descending aorta, when identified as such, has been managed, either on the principle of exclusion of the tear in the descending aorta by various elephant trunk procedures and their variants or, alternatively, on the principle of excision of the tear by extended one-stage aortic replacement, usually combined with an elephant trunk procedure. Neither of these procedures is widely adopted, owing to procedural, institutional and outcome considerations. We describe a transaortic repair of the intimal tear in the descending aorta with supracoronary interposition graft replacement of the ascending aorta and hemiarch with excellent clinical and radiological result. We also review the diagnostic and therapeutic approaches to this incompletely understood lethal disease.

Will Stent-Graft Repair Emerge as Treatment of Choice for Acute Type B Dissection?

Endovascular stent grafts are now accepted globally and approved by the US Food and Drug Administration as an alternative to open surgical repair for patients with descending thoracic aortic aneurysm. However, as opposed to the abdominal aorta, application of this technology to manage thoracic aortic disease is not limited to degenerative aneurysms. In fact, international registries and surveys estimate that only 60% of the thoracic cases managed currently with stent-graft placement are aneurysms. The remainder of this experience includes acute dissection, chronic dissection, traumatic aortic injury, penetrating ulcer, intramural hematoma, aortic fistula, anastomotic pseudoaneurysm, and an embolizing lesion. In this regard, it is important to keep in mind that the present devices used in these nonaneurysmal applications are not designed to address the unique anatomical and pathological features that these lesions present. Consequently, in the future, it is possible that we will see stent-graft designs that focus specifically on the challenges of some of the nonaneurysmal thoracic aortic pathologies.

Elective stent-graft treatment of aortic dissections

PURPOSE

To retrospectively review 8 years' experience with stent-graft treatment of aortic dissections at a single institution.

METHODS

Forty-six patients (31 men; mean age 59 years, range 38-88) underwent stent-graft treatment for 9 Stanford type A and 37 type B aortic dissections (9 acute phase, 13 subacute, 24 chronic). Custom-designed self-expanding stainless steel Z stents covered with polytetrafluoroethylene were used (n=20) until low-profile modular stent-grafts became available for percutaneous delivery (n=26).

RESULTS

Endovascular stent-graft deployment was technically successful in 44 (96%) patients; the 2 failed cases owing to intraprocedural migration and graft torsion were converted to surgery. There were 5 type I endoleaks for a clinical success (entry tear exclusion) of 85% (39/46). Complications included 3 cases of transient renal failure, 2 puncture site pseudoaneurysms, 1 guidewire-induced new intimal tear (converted), and 2 cases of stent-induced saccular aneurysms (1 converted). Follow-up at a mean 34 months (range 12-96) showed complete resolution of the thoracic false lumen in 14 (74%) of 19 acute/subacute patients treated successfully; 3 (16%) showed a reduced thoracic false lumen diameter. In the 23 chronic-phase patients treated successfully, 8 (35%) had complete resolution of the thoracic false lumen, and 11 (48%) showed size reduction. Enlargement of the abdominal aortic false lumen due to persistent flow into re-entry tear(s) occurred in 3 (13%).

CONCLUSIONS

Stent-graft treatment is a feasible and effective treatment modality in aortic dissection. However, close follow-up is mandatory to monitor new intimal tear, saccular aneurysms, or enlargement of the abdominal aortic false lumen.

Transluminal placement of endovascular stent-grafts for the treatment of type A aortic dissection with an entry tear in the descending thoracic aorta

PURPOSE

The current therapy for type A aortic dissection is ascending aortic replacement. Operative mortality and morbidity rates have been markedly improved because of recent advances in surgical techniques and anesthesiology. However, type A aortic dissection with an entry tear in the descending thoracic aorta is still a surgical challenge because of the need for extensive aortic replacement.

METHODS

Ten patients with type A aortic dissection were treated with endovascular stent-grafts. The false lumen of the ascending aorta was patent in five patients, and it was thrombosed in the other five patients. The entry tears were located in the descending thoracic aorta in all cases. Seven patients had acute dissection, and three patients had subacute dissection. Four patients had pericardial effusion. Stent-grafts were fabricated from expanded polytetrafluoroethylene and Z-stents.

RESULTS

Entry closure was achieved in all patients. Complete thrombosis of the false lumen of the ascending aorta was observed after stent-grafting in all patients. A second stent-graft was required in two patients to obtain complete thrombosis of the false lumen of the descending thoracic aorta. No procedure-related complications were observed, with the exception of a minor stroke in one patient. During a mean follow-up period of 20 months, no aortic rupture or aneurysm formation was noted in either the ascending or descending thoracic aorta, and all patients were alive and doing well. The abdominal aortic aneurysm enlarged after stent-grafting in one patient, and this was treated by closing the fenestrations of the abdominal aorta with stent-grafts.

CONCLUSION

Stent-graft repair of aortic dissection with an entry tear in the descending thoracic aorta is a safe and effective method and may be an alternative to surgical graft replacement in highly selected patients.

Extended aortic replacement for acute type A dissection with the tear in the descending aorta

OBJECTIVE

There has been controversy as to the selection of surgical treatments for acute type A dissection with the tear in the descending thoracic aorta, a subtype of acute aortic dissection in which the limited tear is located distal to the left subclavian artery but the dissection extends retrogradely to the ascending aorta.

METHODS

Total replacement of the ascending aorta and aortic arch was performed in 12 patients with acute type A dissection with the tear in the descending thoracic aorta between March 1991 and the end of September 1995. The indications for total replacement of the ascending aorta and aortic arch were cardiac tamponade, acute aortic regurgitation, cerebral ischemia, and dilatation of the ascending aorta. The operation was performed with the aid of extracorporeal circulation, blood cardioplegia, selective cerebral perfusion, and open distal anastomosis. The surgical procedure used was total replacement of the ascending aorta and aortic arch with a graft provided with three limbs accompanied by resection of the intimal tear in the descending thoracic aorta.

RESULTS

Hospital death occurred in two patients (16.7%). In both, death was due to dissection/related complications of renal/mesenteric ischemia. The other 10 patients have had uneventful postoperative courses over a mean period of 24 months.

CONCLUSIONS

Total replacement of the ascending aorta and aortic arch accompanied by resection of an intimal tear distal to the left subclavian artery seems to be justified in selected patients with acute type A dissection with the tear in the descending thoracic aorta.