The immediate result of coronary balloon angioplasty was influenced by plastic and elastic changes of the vessel wall. After successful coronary angioplasty, the minimal luminal diameter of the dilated coronary artery segment was generally smaller than the diameter of the largest balloon catheter at the maximal inflation pressure. Several mechanisms could explain this phenomenon, including vasoconstriction, subintimal or intraplaque bleeding or edema and platelet or thrombus deposition. In addition, whenever balloon inflation results in overdistension of elastic components of the arterial wall, some degree of elastic recoil may occur.

To evaluate magnitude of elastic recoil after percutaneous transluminal coronary angioplasty in relation to lesion morphology and other procedure-related variables, 141 coronary lesions were selected from patients with acute myocardial infarction, stable angina, unstable angina and post myocardial infarction angina undergoing successful coronary angioplasty. Coronary angiograms were recorded before and after angioplasty, and during dilatation of balloon. The computer measuring program was used for the assessment of balloon diameters and coronary luminal diameters.

1) Of all 141 coronary lesions, percent diameter stenosis before angioplasty averaged 74.2% and after angioplasty averaged 22.5%.

2) Residual diameter stenosis was directly related to the degree of elastic recoil, the greater the elastic recoil the more severe the residual lesion immediately after angioplasty. The increase in elastic recoil corresponded to a increase in the balloon/artery ratio(p<0.05).

3) The residual diameter stenosis tended to decrease in segments dilated with an oversized balloon than with an undersized balloon(p<0.05).

4) The elastic recoil increased significantly in the subgroups of coronary segments dilated with an oversized balloon, of eccentric lesion, and type C lesion(p<0.05).

5) Percent residual stenosis was more sever in eccentric stenosis dilated with undersized balloon than in concentric stenosis.

6) Elastic recoil was greater in type C coronary segment dilated with an oversized balloon than with an undersized balloon(<0.05).

7) The lesion dilated with oversize non-compliant balloon showed more elastic recoil than with oversize compliant balloon(p<0.05).

Factors such as oversized balloon, eccentric lesion, type C lesion, and non-compliant balloon significantly affected increase of the elastic recoil.