Author + information
- Shelby A. Leonard1,
- Alex Hill2,
- Rajiv Gupta3,
- Srinivasan Varahoor4,
- William F. Pritchard1 and
- John W. Karanian1
- 1FDA Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, Laboratory of Cardiovascular and Interventional Therapeutics, Laurel, MD
- 2Medtronic Cardiovascular, Mounds View, MN
- 3Massachusettes General Hospital, Harvard Medical School, Boston, MA
- 4Medtronic Cardiovascular, Minneapolis, MN
Modeling of aortic valve safety and performance for TAVR is challenging due to a lack of understanding of aortic valve anatomy and geometry over the cardiac cycle and the limitations of preclinical animal models. The geometry and motion-induced changes of the aortic valve over the cardiac cycle in animal models was compared to human.
Gated cardiac CT angiograms from six normal adults and eight swine and sheep were segmented and the aortic valve analyzed (Mimics, Materialise, Leuven, Belgium). Measurements included aortic valve volume, length and angle, and for each valve plane, ellipticity, area and perimeter. Differences between species and over the cardiac cycle (end systole vs end diastole) are reported.
The normal human aortic valve area, volume, perimeter, and length are greater than that of the swine and sheep (p<0.05, Figure 1). Significant changes in these characteristics were generally observed for all species over the cardiac cycle with no change in area or perimeter noted in the human (Table 1). However a significant increase in ellipticity was observed for the human valve ring plane and midpoint of the valve over the cardiac cycle. The angle between the sinotubular junction and valve ring plane was greatest in the swine valve although the change in angle over the cardia cycle was significant in the human (Table 1).
The data show normal human aortic valves although larger than swine or sheep have different motion-induced geometric changes in valve size over the cardiac cycle compared to swine and sheep. These include changes in valve length, ellipticity and angle. Basic geometric differences between animal models compared to human combined with the impact of cardiac motion present modeling challenges. This data should inform the design and evaluation of aortic valve replacement technology.