B. L. Rademacher1, P. D. DiMusto2, J. L. Philip1, C. B. Goodavish3, N. C. De Oliveira3, P. C. Tang3 1University Of Wiscosin,Department Of Surgery, Division Of General Surgery,Madison, WISCONSIN, USA 2University Of Wisconsin,Department Of Surgery, Division Of Vascular Surgery,Madison, WISCONSIN, USA 3University Of Wiscosin,Department Of Surgery, Division Of Cardiothoracic Surgery,Madison, WISCONSIN, USA
Introduction: Numerous studies have described thoracic stent graft induced retrograde type A dissections (rTAD), however, much less is known about acute spontaneous rTAD with tears originating past the left subclavian without prior aortic instrumentation. This study compares the morphology of acute rTAD with both acute antegrade type A dissection (aTAD) with primary tears in the ascending aorta and acute type B dissection.
Methods: From 2000 to 2016, there were 12 acute rTAD, 96 aTAD, and 92 acute type B dissections with available imaging that underwent operative intervention at our institution. Dissection morphology along the length of the aorta was characterized using 3-dimensional reconstruction based on computerized tomography angiography (CTA) images. We examined primary and secondary tear characteristics, true lumen area as a fraction of the total lumen area, and false lumen contrast intensity as a fraction of the true lumen contrast intensity. Features of presentation and operative parameters were compared between rTAD and aTAD.
Results: Compared with acute type B dissections, primary rTAD tears were more common in the distal arch (75% vs 43%, p=0.04), and the false lumen to true lumen contrast intensity ratio at the mid-descending thoracic aortic level was lower (0.46 vs 0.71, P=0.02) indicating more sluggish blood flow or thrombosis in the false lumen. rTAD cases had less decompression of the false lumen compared with acute type B dissections such that there were fewer aortic branch vessels distal to the subclavian that were either exclusively perfused through the false lumen or through both the false and true lumen (0.40 vs 2.19, P<0.001). Compared with aTAD, rTAD had a tendency for less root involvement where true lumen as a fraction of total lumen area at the root level was higher (0.88 vs 0.76, P=0.081). rTAD had a lower false lumen to true lumen contrast intensity ratio compared to aTAD at the root (0.25 vs 0.57, P<0.05), ascending aorta (0.25 vs 0.72, P<0.001), and proximal arch (0.39 vs 0.67, P<0.05) indicating more sluggish flow or greater tendency to thrombose. rTAD patients were more likely to undergo aortic valve resuspension (100% vs 74%, P=0.044) than aortic valve replacement, and tend to have lower aortic cross-clamp times (83 vs 108 min, P=0.066) (Table 1).
Conclusion: This study suggests that retrograde propagation of the false lumen to the arch and ascending aorta tends to occur when the primary tears that occur distal to the left subclavian are in close proximity to the aortic arch and when false lumen decompression through the distal aortic branches are less effective. Compared to aTAD, rTAD tends to have less root involvement and successful aortic valve resuspension is more likely.
