Thorac Cardiovasc Surg 2014; 62 - OP86
DOI: 10.1055/s-0034-1367161

Bicuspidalization of the native tricuspid Aortic Valve: A new experimental model to isolate the effect of altered 'Flow-Architecture' on Ascending/Root Disease

C.D. Etz 1, J. Haunschild 1, M. Luehr 1, A. Hoyer 1, F.F. Girrbach 1, K. von Aspern 1, M. Grothoff 2, M. Gutberlet 2, M. Misfeld 1, F.-W. Mohr 1
  • 1Herzzentrum Leipzig - Universitätsklinik, Klinik für Herzchirurgie, Leipzig, Germany
  • 2Herzzentrum Leipzig - Universitätsklinik, Abteilung für Radiologie, Leipzig, Germany

Objectives: Bicuspid Aortic Valve (BAV) is associated with a significantly higher risk of ascending aortic/root pathologies at a young age. Previously, associated aortic wall alterations were thought to be of genetic origin but more recently altered flow architecture has been suggested the major culprit. We present the first large animal model to experimentally isolate the effect of flow phenomena through the BAV from possible genetic factors.

Methods: Six juvenile pigs underwent CPB and open aortic valve (AV) surgery for cusp fusion (5-7 Prolene (7 x 0) stiches) to bicuspidalize the native tricuspid aortic valve. The two most common Sievers types-1L-R (∼75% of the general BAV population) and Sievers type I R-N (∼20%) were generated for further flow simulation (Fig.1). All pigs underwent a pre- and postoperative 4D-MRI to gather raw data for visualization of changes in flow architecture and dynamics and altered pressure profiles within the wall of the ascending aorta/root.

Results: After bicuspidalization of the AV typical vortex formation and changed wall pressure profiles could be seen in the ascending aorta/aortic root. No severe artificial stenosis was created by this procedure with invasively measured transvalvular gradients over the AV in both SIEVERS types of 15 ± 5 mmHg. No significant flow alteration but normalized laminar flow was present again downstream, in the distal aortic arch /proximal descending (Fig.1).

Conclusions: We present the first large animal model that allows for the systematic analysis of the primary effects of altered flow architecture-isolated from possible genetic factors-caused by BAV of separate Sievers types. With low transvalvular gradients and negligible degree of stenosis, long-term evaluation of various helical flow patterns on changes in wall enzyme activity, smooth muscle cell function and structural transformation of the extracellular matrix possibly resulting in aneurysm formation or triggering acute dissection will be feasible.

Fig. 1