Endovascular Cryotherapy Accentuates the Accumulation of the Fibrillar Collagen Types I and III after Percutaneous Transluminal Angioplasty in Pigs

Abstract

Purpose:

To investigate the effect of endovascular cryotherapy (Cryo) on the density of collagen types I (CI) and III (CIII), which are involved in the dynamic modulation of extracellular matrix (ECM) after percutaneous transluminal angioplasty (PTA).

Methods:

Twenty-one juvenile farm swine and 10 miniswine underwent PTA of the femoral arteries with and without Cryo (–50°C for 2 minutes). Quantitative angiography, histomorphometry, and quantification of CI and CIII were performed at 1 week (n=7), 1 month (n=7), 3 months (n=7), and 6 months (n=10).

Results:

PTA decreased the minimal luminal diameter (MLD) (range 3.48±0.18 to 4.2±0.39 mm) compared to baseline values (range 3.67±0.15 to 4.59±0.23 mm), but the application of Cryo maintained the MLDs at preprocedural levels (range 3.88±0.31 to 4.58±0.21 mm). At the time of sacrifice, the MLDs were similar in PTA and Cryo-treated arteries, but the external elastic lamina was significantly greater after Cryo application (range 10.17±0.54 to 14.34±0.76 mm²) than after PTA (range 8.69±0.70 to 11.77±0.73 mm², p<0.05). Cryo did not alter the luminal area or prevent neointimal growth. A time-dependent increase of both CI and CIII was observed as early as 1 week after PTA, peaking at 3 months, and declining thereafter. Cryo accentuated this increase at all time points.

Conclusion:

The application of Cryo accentuates the accumulation of CI and CIII in PTA-treated femoral arteries. This effect may be of clinical relevance in the stabilization of peripheral atherosclerotic plaque.