Implantation and recovery of temporary metallic stents in canine coronary arteries.
OBJECTIVE
The purpose of this study was to test the feasibility of implanting and retrieving a heat-activated recoverable temporary stent and to determine its effect on the angiographic, gross and histologic appearance of a normal coronary artery wall.


BACKGROUND
Permanent coronary stenting is associated with a significant incidence of thrombosis, bleeding and vascular complications. These may be avoided by temporarily stenting for a period of hours to several days.


METHODS
Seventy-eight stents constructed from the shape-memory nickel-titanium alloy nitinol were deployed by balloon expansion in the coronary arteries of 28 dogs and left in place for up to 6 months. Thirty minutes to 1 week after implantation, 70 stents were recovered by flushing the coronary arteries with 3 to 5 ml of 75 degrees C lactated Ringer solution, with collapse of the stent over a recovery catheter and subsequent withdrawal.


RESULTS
All stents were successfully recovered and removed percutaneously. Mean vessel diameter after stenting was 12 +/- 6% (p < 0.05) greater than baseline diameter. Mean vessel diameter after stent removal remained enlarged (6 +/- 3%, p < 0.05). No angiographic or gross evidence of thrombosis, dissection, embolization, migration or spasm was associated with implantation or recovery. Microscopic examination revealed minor intimal injury in 40 segments (51%). Microscopic focal medial necrosis was associated with mural platelet-fibrin thrombus in 23 stented segments (29%) and media was interrupted in 7 (9%).


CONCLUSIONS
This study demonstrates the feasibility of a new method of temporary stenting that uses the thermoelastic properties of nitinol to permit reliable recovery of the stent in normal canine coronary arteries.
Eigler
N L
NL
Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California 90048.
Khorsandi
M J
MJ
Forrester
J S
JS
Fishbein
M C
MC
Litvack
F
F
D000497:Alloys / Q000009:adverse effects / Q000737:chemistry / Q000592:standards*; D000818:Animals; D001706:Biopsy; D017023:Coronary Angiography; D003328:Coronary Thrombosis / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology / Q000473:pathology; D003331:Coronary Vessels / Q000293:injuries*; D004285:Dogs; D004867:Equipment Design; D005240:Feasibility Studies; D006358:Hot Temperature; D015994:Incidence; D008422:Materials Testing; D009336:Necrosis; D015607:Stents / Q000009:adverse effects / Q000592:standards*; D013816:Thermodynamics; D013997:Time Factors; D014947:Wounds and Injuries / Q000145:classification / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology
D000497:Alloys; C013616:nitinol