Abstract
Subclavian artery steal (SAS) after coronary artery bypass graft (CABG) has been reported to be as high as 3.4%. These patients with patent left internal mammary artery (LIMA) anastomosis will also have coronary–subclavian steal syndrome (CSSS). Percutaneous intervention (PCI) by balloon angioplasty (BA) and stenting has been done successfully for subclavian artery (SA) stenosis. The visibility of the vertebral artery (VA) and LIMA during BA and stent positioning is extremely important. Debulking total occlusions by orbital atherectomy (OA) and avoiding unnecessary BA, stenting across side branches may decrease the chance of plaque shifting and subsequent loss of flow especially if they have ostial disease. Herein we report successful OA, BA and stenting of chronic total occlusion (CTO) of proximal left subclavian artery in a patient with coronary–subclavian steal syndrome with preservation of LIMA and diseased left vertebral artery (VA).
1
Introduction
The left internal mammary artery (LIMA) is a commonly used conduit in patients having CABG surgery due to highest long-term patency rate and shown mortality benefit. Left SA stenosis proximal to the LIMA origin can cause a steal syndrome leading to myocardial ischemia or LIMA failure . SAS after CABG has been reported to be as high as 3.4% . Significant left SA stenosis was found in about 2.7% of 226 patients during coronary angiogram even at the time of CABG referral . Patients with peripheral arterial disease (PAD) have higher percentage of left SA stenosis up to 18.7% . In a study by Shadman et al. history of PAD was the strongest predictor of SA stenosis.
CSSS is defined by retrograde flow in LIMA to left subclavian artery in the presence of SA stenosis and is associated with symptoms of myocardial ischemia, upper extremity claudication and cerebrovascular insufficiency . BA and stenting are effective treatments for proximal left SA stenosis in patients with CSSS , or before a planned CABG with a LIMA. OA device has been used in peripheral interventions to decrease the plaque burden and for improved balloon/stent expansion especially in calcified occlusions. Creation of a visible lumen after atherectomy also facilitates precise positioning of the balloon/stent and decreases the chance of plaque shifting during the procedure especially if there is an involvement of left VA and LIMA. In the literature there is no reported clinical experience in use of OA for CTO of left SA. Herein we report our experience with successful usage of OA, BA and stenting in a patient with CTO of left proximal SA with high grade ostial left VA stenosis.
2
Case report
A 56 year old white female with history of hypertension, hyperlipidemia and coronary artery disease was admitted to the hospital with non-ST elevation myocardial infarction. She had three-vessel CABG 6 years ago. Her peak troponin was 2.6 ng/ml and admission EKG showed new anterior T-wave inversions in the precordial leads. The patient has also reported non-specific cramps and tiredness in her left arm but she denied angina, vertigo or dizziness with left arm use. In the physical exam there was about 40 mm pressure difference between the right and left arm and her left radial, ulnar pulses were weaker compared to right arm. She underwent left heart catheterization which showed severe native three-vessel coronary artery disease with left anterior descending artery (LAD) mid 70% lesion before the LIMA anastomosis, there was antegrade flow present in LAD but LIMA was filling the left subclavian artery in retrograde fashion with proximal total occlusion of left subclavian artery ( Fig. 2 ). The contrast would not fill beyond proximal left VA suggestive of antegrade flow in left VA consistent with SAS. Saphenous vein graft (SVG) to right coronary artery was occluded and SVG to obtuse marginal (OM) had proximal about 95% disease. She initially had percutaneous intervention (PCI) to LAD lesion proximal to the LIMA anastomosis by drug eluting stent because of the new anterior ST/T changes and the next day she underwent PCI to OM vein graft lesion due to continued chest pain. Her symptoms were resolved after the second procedure. She was scheduled for PCI of left subclavian artery in an outpatient setting. After discharge, she had one short episode of chest pain without any relation to activity. When the patient returned for the SA intervention, recently treated vessels were reimaged and found to be patent.
During the procedure to left SA, a 6 French 80 cm long sheath was advanced over the 6F Judkins Right catheter to the stump of left subclavian artery. Patient received 7000 units of IV heparin and ACT was 250. The CTO was mildly calcified and it was ending just before the left VA and LIMA ( Figs. 1 and 2 ), the left VA has also significant ostial lesion. We were concerned about significant chance of plaque shifting with high risk of occlusion and embolization of these vessels with traditional BA/stenting, there was also additional concern for unnecessary balloon inflations across these arteries due to poor visualization of the branch vessels after the CTO. Because of these concerns, we decided to use OA to minimize risks in this patient ( Fig. 6 ).
Then a Confianza Pro 12 ( Asahi Intecc Co., Nagoya, Japan ) wire was used to cross the CTO and placed into the distal axillary artery ( Fig. 3 ) and a 1.5 mm over the wire (OTW) apex coronary balloon (Boston Scientific, Natick, Mass.) was advanced distal to the occlusion and used for exchange to viper wire ( ViperWire, Cardiovascular Systems, Inc .). A diamondback atherectomy 1.5 mm burr ( Diamondback 360 ° Orbital Atherectomy System (OAS), Cardiovascular Systems, Inc., St. Paul, Minnesota) was used at low, medium and high speeds with establishment of flow in the CTO. Margins of CTO were clearly seen ( Fig. 4 ).There was a consideration of wiring and subsequent stenting of left VA at that time, but patient had a patent right VA supplying retrograde flow to the left VA and SA with no vertebral insufficiency symptoms suggesting adequacy of flow to brain stem by the right VA. Our goal in this patient was more about preserving the patency and flow of the left VA in case she needs an intervention in the future rather than an immediate intervention. The lesion was then predilated with 5 × 20 mm OTW EverCross balloon at 5 ATM (ev3, Plymouth, Minnesota) and a VisiPro 7.0 × 27 mm balloon expandable stent (ev3, Plymouth, Minnesota) was then deployed at 10 ATM successfully just before the ostium of the left VA. There was initially slow antegrade flow in LIMA due to possible vasospasm just after BA, atherectomy and stenting with continued competitive retrograde flow in the LIMA in the meantime, this was normalized about 30 s after intra-arterial nitroglycerine administration. Final angiogram showed competitive flow in LIMA ( Fig. 5 ), the left VA ostium continued to have high grade disease with normal flow during the whole case. Patient had experienced vibration type of sensation in her arm during atherectomy other than that she did not have any symptoms during procedure. Injections by the left coronary catheter showed normal flow in distal LAD and there was antegrade competitive flow in the LIMA from SA. Post procedure hospital course was uneventful; she did not have any chest pain or EKG changes. There was equalization of blood pressure of both arms with normalized radial and ulnar pulses in the physical exam.
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