CRT-200.66 Biomechanical and Geometric Analysis of Left Coronary Artery Bifurcation Motion and Compliance: Implications for Stent Development and Evaluation

¹FDA Center for Devices and Radiological Health, Office of Science and Engineering Laboratories, Laboratory of Cardiovascular and Interventional Therapeutics, Laurel, MD
²Medtronic, Mountain View, MN
³Massachusetts General Hospital, Harvard Medical School, Boston, MA
⁴Medtronic, Minneapolis, MN

Background

Coronary bifurcation stenting is associated with an increased risk of adverse coronary events compared to other regions stented. The purpose of this study was to quantify the motion of the left coronary artery bifurcations over the cardiac cycle and determine differences in vascular geometry, motion and compliance between swine and humans.

Methods

Gated-CT angiograms of left coronary arteries of swine and adult males were segmented across the cardiac cycle (end systole vs. end diastole) (Mimics, Materialise, Leuven, Belgium). The cross sectional area, angle, tortuosity and ellipticity were measured at three bifurcations: B1=LCX/LAD; B2=LAD/D1; and B3=LCX/M1 (Figure 1A). Pulse pressures used to calculate vascular compliance were based on literature reports of average pressures.

Results

A significant change in human and swine cross sectional area was noted in all bifurcations over the cardiac cycle. A compliance difference was observed at B2 in humans with the D1 having 50% lower compliance compared to the proximal LAD. Figure 1 presents the bifurcation angles in each species over the cardiac cycle. The bifurcation angles significantly increased from end systole to end diastole at B1 and B3 in humans (14.3%; 9.6%) and swine (11.3%; 28.9%). The bifurcation angle at B2 was significantly greater in swine compared to humans in end systole and end diastole (32.8%; 39.5%).

Conclusion

A significant change in bifurcation angle and cross sectional area was observed over the cardiac cycle, however few compliance differences were noted across each bifurcation. These data illustrate that the coronary artery bifurcations are a dynamic environment in both humans and swine, which presents a challenge in pre-clinical modeling and stent design.