Invited commentary
Article Outline
Patients presenting with complicated type B aortic dissection represent the highest risk group of all patients with acute type B dissection. Medical management remains the preferred method of treatment for patients without complications such as intractable pain, malperfusion, or rupture. Surgical treatment of complicated type B aortic dissection improves the outcome compared with medical therapy but is still associated with significant mortality (15% to >30%).1
The authors have presented a relatively large, well-analyzed experience on the management of patients with complicated type B aortic dissection primarily treated with an endovascular approach. Additional surgical or endovascular procedures were required in almost 50% of patients (hybrid procedure). This included six aortic bandings; it remains to be seen whether this particular combination is an effective treatment on long-term follow-up.
All deaths occurred in patients with either rupture or malperfusion, underscoring the high risk in this cohort. These results suggest that a primary endovascular approach is a promising alternative to manage acute type B dissection in the absence of malperfusion or rupture. The morbidity and mortality reported in this series is comparable with contemporary results with the standard surgical approach. Survival for the endovascular approach, however, was only 61% at 5.5 months. Persistent endoleaks (35%) and false lumen patency (25%) threaten long-term results. The authors have appropriately concluded that the overall role of endovascular treatment for complicated acute type B aortic dissection remains to be better defined.
Most reports of endovascular treatment of thoracoabdominal aortic pathology identify two elements that are associated with spinal cord ischemia: hypotension and lack of spinal catheter drainage. Spinal cord ischemia did not develop in any patients in this series with preoperative spinal catheter drainage (SCD), but it did occur in 24% of patients without preoperative SCD. The method used by the authors for SCD was based on volume, not pressure. In 1994 Safi and associates concluded that maintaining intraspinal pressure <15 mm Hg was key in their improved results compared with the previous experience when SCD was limited to a certain volume (50 ml).2 Thus, a preferred approach for SCD is to continuously monitor intraspinal pressure, keeping it <15 mm Hg (10 mm Hg at our institution) at all times. The authors now recommend that SCD be used in patients who require >15 cm of thoracic aortic coverage and in those who will have coverage of ≥5 cm of the distal thoracic aorta. This essentially represents all patients with type B aortic dissection.
As more experience is gained, a primary endovascular approach to acute type B aortic dissection is likely to improve results. In a significant number of cases, a hybrid procedure where focused surgical intervention complements the endovascular repair will be necessary. Guidelines for patient selection and development of endovascular devices specifically designed for the treatment of this condition will help in the evolution of our current approach.
References
- The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease. JAMA. 2000;283:897–903
- Neurologic deficit in patients at high risk with thoracoabdominal aortic aneurysms: the role of cerebral spinal fluid drainage and distal aortic perfusion. J Vasc Surg. 1994;20:434–444
PII: S0741-5214(08)01798-9
doi:10.1016/j.jvs.2008.10.027
© 2009 Published by Elsevier Inc.
Refers to article:
- Early outcomes after endovascular management of acute, complicated type B aortic dissection
