AN EXTERNAL AORTIC ROOT DEVICE FOR DECREASING AORTIC REGURGITATION - IN-VITRO AND IN-VIVO ANIMAL STUDIES

Objectives: The purpose of this study was to determine if a device pla ced externally around the aortic root decreases regurgitant flow in ac ute aortic regurgitation. Background: Aortic regurgitant flow is depen dent on central aortic pressure and the aortic root and leaflet geomet ry. It may be possible to decrease aortic regurgitant severity by redu cing aortic root size or dimension changes. Methods: Aortic regurgitat ion was created in eight calf heart specimens suspended in a continuou s flow system. Retrograde and antegrade aortic flow and distending aor tic pressure were measured at baseline and after placement of an exter nal aortic device at the level of the aortic annulus. In two additiona l specimens, the incompetent aortic valve was visualized fiberopticall y before and after placement of the external device. Acute aortic regu rgitation was created surgically in four live calves by excising a por tion of the aortic leaflets. Antegrade and retrograde flow, left ventr icular pressure, and central aortic pressure were measured at baseline , after creation of aortic regurgitation, and after placement of the e xternal device. Results: In the in vitro calf specimens, regurgitant f low decreased from 46.9 cc/sec to 15.1 cc/sec (66.0% +/- 21.8% decreas e) after placement of the external device (p < 0.001). The regurgitant orifice area decreased from 0.13 +/- 0.04 cm2 to 0.04 +/- 0.02 cm2 af ter device placement (p < 0.001). Antegrade flow was reduced to a smal ler extent (20.0% +/- 19.2% decrease) by the device (p < 0.05). Placem ent of the device around the aorta resulted in improved coaptation of the leaflets with a marked reduction in defect size by endoscopic visu alization. Use of the external aortic device was associated with impro vement in aortic regurgitant severity in three of four calves with sur gically created aortic regurgitation. Conclusions: In these preliminar y studies, acute experimental aortic regurgitant severity is decreased by the use of an external aortic device, probably due to reduction in aortic annular dimension changes and improved aortic leaflet appositi on. Further studies are needed to determine the effectiveness of this device in chronic aortic regurgitation.