Stenting in Unusual Settings: Compression of a Subintimal or False Lumen Stent by Stenting in the True Lumen

Since stents were first approved in the United States for clinical use in the fourth quarter of 1993, their use has skyrocketed with 890,000 stents implanted in coronary arteries in 550,000 interventions in the United States in 1999.1 A variety of complications have been described in association with stent deployment, including coronary artery aneurysm,2–4 stent embolization,5 dissection,6 subacute thrombosis,7–9 sidebranch closure10 and in-stent restenosis.7,11 A rare complication of intravascular stenting, subintimal or false lumen deployment, has been reported in 2 patients undergoing peripheral vascular stenting12 and 4 patients during percutaneous coronary stenting.13,14 This is the first case report of subintimal or false lumen stent deployment with subsequent (successful) stenting of the true lumen with (intentional) compression of the subintimal stent. Case Report. A 75-year-old woman with treated hypercholesterolemia, hypertension, and advanced osteoporosis sustained a diaphragmatic wall myocardial infarction in 1993 and subsequently underwent bypass graft surgery that year with a left internal mammary artery (LIMA) graft to the left anterior descending coronary artery (LAD) and a saphenous vein graft to the posterior descending branch of the right coronary artery (RCA). The RCA was totally occluded prior to bypass graft surgery. In March 2000, Sestamibi exercise stress testing was done for evaluation of chest pain, revealing inferior wall ischemia; catheterization revealed an occluded saphenous vein graft to the RCA, a tortuous and severely stenotic recanalized channel in the native RCA and a patent LIMA graft to the LAD. The circumflex and left main coronary arteries had no significant disease. On March 16, 2000, she underwent angioplasty of the recanalized native RCA. This was done through an 8 French (Fr) 3.5 Zuma II guiding catheter (Medtronic AVE, Minneapolis, Minnesota). A Hyperflex 0.014´´ wire (MedtronicAVE) would not cross the lesion, nor would a choice PT wire (Boston Scientific/Scimed, Inc., Maple Grove, Minnesota). Crossit XT 100 and 300 wires (Guidant Corporation, Temecula, California) were used and were also unable to cross the lesion. The guiding catheter was then exchanged for an 8 Fr AL1 (Cordis Corporation, Miami Lakes, Florida) and a 2.5 x 13 mm Maxxum balloon (Boston Scientific/Scimed, Inc.) was brought down to the tip of the wire, which was positioned just proximal to the stenosis. The wire was then successfully passed into the distal RCA with a linear tear seen at the site of the lesion consistent with intimal dissection. A 2.5 x 18 mm Tristar stent (Guidant Corporation) was deployed at 10 atmospheres (atm) for 40 seconds in the proximal RCA with subsequent no reflow. A 2.5 x 23 mm Tristar stent was then deployed just distal to the first stent at 10 atm for 55 seconds. Normal flow appeared down to and including the right ventricular branch and the posterolateral branch, but with the dye stopping in the proximal posterior descending branch of the RCA. At this point, it was unclear whether there was a dissection extending down and shutting off the posterior descending branch or whether distal embolization had caused this occlusion. A 0.014´´ Hyperflex wire (MedtronicAVE) was advanced to the proximal RCA in an attempt to enter and open the posterior descending branch, but it appeared to stop in a dissection plane just proximal to the stent. By selective left coronary injection, there were now collaterals from the left circumflex to the posterior descending branch. Because of this and since the patient experienced no discomfort at this point and as the procedure had been a long one, it was elected to leave the posterior descending occluded. She had had discomfort when there was no reflow in the main RCA, which was a pressure discomfort in the mid-chest without associated ST-segment changes. This pain had resolved upon re-establishing TIMI III flow to the posterolateral branch. There were no subsequent complications and she was discharged the following day (Figure 1). It was elected to bring her back for re-angiography of the RCA in 2 months given the proximal intimal tear, transient no-reflow, difficulty with guidewire readvancement after stent deployment, and occlusion of the posterior descending branch. The follow-up catheterization was performed 2 months later on May 26, 2000. In the interim, the patient had no chest discomfort or other symptoms and had taken clopidogrel 75 mg with 1 adult aspirin daily for 1-month post-procedure, and then continued taking one aspirin daily. Repeat angiography revealed severe stenosis in the area of the previous lesion (Figures 2A and 2C), and it was only when a guidewire was successfully passed through the narrow channel that it was noted that the wire appeared to be clearly outside the previously deployed, fluoroscopically visible stent. A 2.5 x 15 mm Gemini balloon (Guidant Corporation) was advanced over the guidewire, but would not go through the severely stenotic area in the proximal RCA. It was exchanged for a 1.5 x 20 mm Photon balloon (Guidant Corporation), which did cross the lesion and was dilated to 17 atm for 45 seconds. Slight improvement in the lumen was seen on repeat angiography. A 2.5 x 15 mm Gemini balloon was then advanced through this area and dilated to 12 atm for 45 seconds. Repeat angiography revealed a larger lumen but a small intimal tear on the lateral margin of the area just dilated (Figure 3). Intravascular ultrasound (IVUS) was performed using a Jomed catheter (Rancho Cordova, California), which confirmed the suspicion that the wire was in the true lumen and that the stent had been placed subintimally in a spiral dissection plane (Figures 3–5). It was elected to stent the narrowed, true lumen of the right coronary artery, and hopefully in doing so, to compress the stent in the subintimal space. Next, a 3.0 x 18 mm Tristar stent was advanced partially through the lesion but would not cross completely and was therefore removed; a 3.0 x 12 mm S670 stent (MedtronicAVE) was then deployed in the lesion to 14 atm for 45 seconds. The balloon was deflated, pulled back, and repeat pictures made, which revealed a small segment of dissection distal to the stent. A 2.5 x 12 mm S540 stent (Medtronic/AVE) was advanced through the first stent and deployed to 16 atm for 45 seconds. The balloon was deflated, pulled back, and repeat pictures were again made, showing excellent patency throughout the right coronary artery (Figures 2B and 2D). It was noted at the beginning of the procedure that the posterior descending branch had recanalized since its initial closure at the time of the first procedure. Repeat IVUS revealed that there had been partial compression of the previously deployed stent in the subintimal space by the new stents. The minimum lumen diameter (MLD) was 2.7 x 2.9 mm inside the stented true lumen with full strut apposition to the vessel wall, and the angiographic appearance was excellent (Figures 6 and 7). The balloon and wire were then removed, final diagnostic pictures were made, and the patient was returned to her room without symptoms or electrocardiographic changes. There were no complications and she was discharged on aspirin and clopidogrel the next day. Discussion. The unique aspect of this case report is that stenting was successfully performed in the true lumen alongside a previously deployed subintimal or false lumen stent. One concern was that perforation or vessel rupture might occur upon balloon expansion inside the second stent, especially since a 3.0 mm diameter stent was parallel to a 2.5 mm diameter stent in a 3.5 mm diameter coronary artery. Instead, adequate expansion of the true lumen with partial compression of the subintimal stent occurred, facilitating a good final angiographic and sonographic result. The final MLD inside the false lumen stent was 0.8 x 2.5 mm and inside the true lumen stent was 2.6 x 2.5 mm. There have been no previous reports of true lumen coronary stent deployment alongside a subintimal or false lumen stent. Subintimal coronary stent deployment has been previously reported in 4 patients, all of whom had totally occluded vessels before the procedure. Three of these were in the RCA14 and 1 was in the LAD.13 Reimers reported deployment of 3 coronary stents in the LAD with good procedural and 4-month angiographic and 6-month clinical results.13 Werner reported 3 cases of RCA subintimal stenting using 3–4 stents in each case with successful procedural and 6–7 month clinical follow-up (1 of 3 cases also had angiographic follow-up at 6 months).14 In the current case report, while subintimal stenting was initially successful, the stented subintimal lumen closed within 2 months and the stenotic true lumen remained patent. Since late angiographic follow-up was obtained in only 2 of the previously reported cases, it is not clear if all of the vessels remained open following subintimal stenting. It is interesting to note that the 4 previous cases of subintimal stenting were in totally occluded vessels and this case was a previously totally occluded vessel that had subsequently recanalized. Guidewire complications (usually subintimal passage) have been reported to be particularly high (10–20%)15–17 in total occlusions. Although no reference could be found for guidewire complications in recanalized vessels, in the authors’ experience such vessels are also more likely to result in guidewire complications, especially when the channel is tortuous, severely stenotic and the occlusion is old. In this case recanalization probably occurred 6–7 years before intervention. Moreover, this issue may become particularly important in the era of coated stents, since a drug eluted from a subintimal stent might not reach the necessary vessel wall(s). The RCA has been mentioned as being more prone to intimal dissection then the other coronary vessels18 and was the culprit vessel in 4 of these 5 cases of subintimal stenting, including this report. The reasons for this are unclear. Ultrasound was particularly useful in confirming the subintimal stent placement as well as the guidewire placement in the true lumen and in confirming the satisfactory result after deployment of the stent in the true lumen. Coronary angiography demonstrated 1 atrial sidebranch arising from the true lumen. Conclusion. This report describes an unusual case of subintimal or false lumen stent deployment with subsequent closure of this stented channel, but preservation of patency in the narrowed true lumen with subsequent deployment of additional stents in the true lumen, compressing the initial stent with a good procedural and clinical result.

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