This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Cottin, Y. Articles by Waksman, R. Search for Related Content PubMed PubMed Citation Articles by Cottin, Y. Articles by Waksman, R.

EXPERIMENTAL STUDY

Vascular repair after balloon overstretch injury in porcine model effects of intracoronary radiation

Yves Cottin, MD, PhD^*, Marc Kollum, MD^*, Rosanna Chan, PhD, Balram Bhargava, MD^*, Yoram Vodovotz, PhD^* and Ron Waksman, MD, FACC^*

^* Cardiovascular Research Institute, Washington Hospital Center, Washington, DC, USA
Department of Radiation Oncology, Washington Hospital Center, Washington, DC, USA

Manuscript received August 6, 1999; revised manuscript received March 27, 2000, accepted June 1, 2000.

Reprint requests and correspondence: Dr. Ron Waksman, Vascular Brachytherapy Institute, Cardiovascular Research Institute, Suite 4B-1, Washington, DC 20010
rxw8{at}mhg.edu

OBJECTIVES

The purpose of this study was to evaluate the effect of IR on thrombus formation and dissection repair following overstretch balloon injury in porcine coronary arteries.

BACKGROUND

Exposure of blood to the injured arterial wall after percutaneous transluminal coronary angioplasty (PTCA) induces thrombus formation and inflammation in the dissection plane. Neointima formation is related to smooth muscle cell (SMC) proliferation and migration into the preformed thrombus. Intracoronary radiation (IR) with doses of 10 to 25 Gy using either beta or gamma emitters can prevent neointima accumulation by reducing SMC proliferation. However, there are some indications that IR may delay the process of dissection repair after PTCA. The purpose of this study was to evaluate the effect of IR on thrombus formation and dissection repair after overstretch balloon injury in porcine coronary arteries.

METHODS

Forty porcine coronaries were injured by balloon overstretch followed by either 0 or 18 Gy of ⁹⁰Y prescribed to 1.2 mm from the balloon center. The animals were euthanized 14 days after treatment, and intimal area (IA) and IA corrected for medial fracture length (IA/FL) were quantified by digital image analysis. Dissections were quantified by tracing the length, thickness and area behind the dissection flap. The rate of dissections was calculated for each group. Thrombi were identified and designated as intraluminal thrombus or thrombus within dissection planes (mural thrombus), and area measurements were obtained.

RESULTS

The irradiated group showed a significant reduction of IA/FL (0.55 ± 0.29 vs. 0.05 ± 0.09; p < 0.001). No difference was observed in the rate of dissection between control and irradiated arteries (77% vs. 88%, respectively). The control group showed a smaller dissection area (0.19 ± 0.28 mm² vs. 0.32 ± 0.29 mm²; p < 0.05) with smaller mural thrombi (0.03 ± 0.01 mm² vs. 0.29 ± 0.30 mm²; p < 0.001). A strong correlation between dissection area and neointima area was observed only in the control group (R² = 0.474; p < 0.003; alpha_0.05 = 0.862). A positive correlation between mural thrombus and dissection area was observed only in the irradiated group (R² = 0.889; p < 0.001; alpha_0.05 = 1.00).

CONCLUSIONS

These results suggest that the dissection area may be a useful parameter by which to quantify the extent of injury and repair after IR and may indicate an incomplete healing process after IR at this time point.

Abbreviations and Acronyms   DA = dissection area   FL = fracture length   IA = intima area   IR = intracoronary radiation   PTCA = percutaneous transluminal coronary angioplasty   SMC = smooth muscle cell   TA = thrombus area