Pathophysiologic Consequences of Early Coarctation Stenting in a Longitudinal Porcine Model.

BACKGROUND

Novel stent technologies offer early intravascular treatment options for coarctation (COA). Mid-to-long-term cardiovascular responses to early COA stent interventions are undefined.

AIMS: We studied a porcine model of COA, with and without early stent implantation with serial dilation to adult aortic diameters, aiming to define longitudinal cardiovascular changes.

METHODS

In total, 18 swine were studied: 6 shams, 6 COA controls (CC), and 6 COA stents (CS). Surgical COA was induced at 2 weeks (4.5 kg) followed by stent implant at 6 weeks, with serial dilations at 12 and 20 weeks (80 kg). All animals were terminally studied at 20 weeks.

RESULTS

Successful stent implantation with serial dilation matching somatic growth occurred in all CS animals with predictable stent performance and elimination of COA. No in-stent stenosis observed. Final stent dimensions equaled the proximal descending aorta (DAo) of shams (16.8 ± 1.5 vs. 17.5 ± 0.8, p = 0.3); however, DAo narrowing (13.3 ± 1.1 mm) just distal to the stent without gradient was created because of stent shortening, and this DAo segment demonstrated decreased vessel wall collagen content. Four of 6 animals developed peri-stent aneurysms treated with covered stents. CS prevented post stenotic dilation and collateralization and resulted in near normalization of catheter-derived hemodynamics. Cardiac MRI documented similar ventricular function, cardiac index, and myocardial tissue characterization between groups. Early COA stenting was associated with increased systemic arterial elastin content.

CONCLUSION

In this swine COA model, early stent implants effectively dilated to adult aortic dimensions, prevented blood pressure gradients, collateralization, and adverse myocardial remodeling. Early stenting with serial dilations altered systemic arterial elastin content, and additional stents may be necessary to enlarge the adjacent DAo. Aneurysm formation frequently occurred.