Coronary Artery Radial Deformation and Velocity in Native and Stented Arteries

Abstract

Introduction: Coronary arteries are exposed to a variety of complex biomechanical forces during a normal cardiac cycle. These forces have the potential to contribute to coronary stent failure. Recent advances in stent design allow for the transmission of native pulsatile biomechanical forces in the stented vessel. However, there is a significant lack of evidence in a human model to measure vessel motion in native coronary arteries and stent conformability. Thus, we aimed to characterize and define coronary artery radial deformation and the effect of stent implantation on arterial deformation.

Materials and methods: Intravascular ultrasound (IVUS) pullback DICOM images were obtained from human coronary arteries using a coronary ultrasound catheter. Using two-dimensional speckle tracking, coronary artery radial deformation was defined as the inward and outward displacement (mm) and velocity (cm/s) of the arterial wall during the cardiac cycle. These deformation values were obtained in native and third-generation drug-eluting stented artery segments.

Results: A total of 20 coronary artery segments were independently analyzed pre and poststent implantation for a total of 40 IVUS runs. Stent implantation impacted the degree of radial deformation and velocity. Mean radial deformation in native coronary arteries was 0.1230 mm ± 0.0522 mm compared to 0.0775 mm ± 0.0376 mm in stented vessels (p=0.0031). Mean radial velocity in native coronary arteries was 0.1194 cm/s ± 0.0535 cm/s compared to 0.0840 cm/s ± 0.0399 cm/s in stented vessels (p=0.0228).

Conclusion: In this in vivo analysis of third-generation stents, stent implantation attenuates normal human coronary deformation during the cardiac cycle. The implications of these findings on stent failure and improved clinical outcomes require further investigation.

Figure 1

Representative image of the IVUS prestent implantation cross section. Representative image of the IVUS prestent implantation cross section that was measured using strain speckle tracking software. The left anterior descending vessel wall was divided into six 60-degree colored segments. The average of the six segments was calculated for total coronary vessel motion. The orange lines represent inward and outward motion (radial deformation) and radial velocity that was measured for each of the six vessel wall segments.

Figure 2

Poststent coronary artery vessel wall radial deformation. Example of syngo® software output for radial deformation (displacement) values over three full cardiac cycles. The colored curves represent regional deformation in a six-segment model of the coronary vessel. The black curve represents the averaged deformation of all of the individual segments.

Figure 3

Pre and poststent coronary artery vessel wall radial deformation: (a) Prestent and (b) Poststent. Representative example of radial deformation over time in (a) prestent and after (b) poststent implantation. Poststent delivery, total coronary vessel radial deformation is attenuated compared to prestent delivery.