Complex Right Subclavian Artery Dissection during Diagnostic Cardiac Catheterization

Management of vascular complications remains an important component of both diagnostic cardiac catheterization and percutaneous coronary intervention. We report a unique case of extensive right subclavian artery dissection following attempted diagnostic cardiac catheterization of a right internal mammary artery (RIMA) coronary bypass graft. This resulted in complex dissection of the right subclavian artery involving the origin of the right vertebral and internal mammary arteries, as well as critical right upper limb ischemia. Therapy consisted of both conservative management of the proximal dissection and endovascular treatment at the distal site of the vessel occlusion.
Case Report. A 42-year-old male with known coronary artery disease (CAD) underwent diagnostic cardiac catheterization. The patient had documented CAD with previous inferior myocardial infarction (MI) at age 31 and had undergone previous balloon angioplasty to the right coronary artery (RCA). The patient had a second MI at age 35, and underwent coronary artery bypass grafting surgery (CABG) following post-infarction angina. At the time of surgery, the patient had significant ischemic left ventricular systolic dysfunction (left ventricular ejection fraction 30–39%). The patient received a left internal mammary artery (LIMA) graft to the left anterior descending artery, a right internal mammary artery (RIMA) graft to the obtuse marginal artery and a saphenous vein graft to the RCA.

Following a positive exercise stress test at age 42, the patient underwent coronary angiography. The origin of the innominate artery was cannulated using a 6 Fr Diagnostic LIMA catheter, with a 0.035 inch J-tipped wire advanced into the distal vessel. The LIMA catheter was positioned in the right subclavian arteryand attempts were made to selectively engage the RIMA graft origin. During unsuccessful attempts to cannulate the RIMA graft in the diagnostic procedure, the patient developed right arm pain, with subselective angiography within the right subclavian artery demonstrating proximal dissection (Figure 1A). There was clinical evidence of limb ischemia with pain, cool periphery and absent distal pulses. There were no neurological symptoms consistent with vertebrobasilar ischemia. The patient was transferred to an institution with vascular surgery facilities and interventional radiology support.
The patient proceeded to the cardiac catheterization laboratory, with repeat right subclavian angiography demonstrating extensive spiral dissection commencing at the ostium of the subclavian artery and extending beyond the origin of the right vertebral artery and the RIMA graft. Imaging of the axillary and brachial arteries confirmed extension of the dissection to the midright brachial artery. The compressive effects of the false lumen upon the true lumen produced occlusion at the level of the mid brachial artery (Figure 1B). Delayed imaging demonstrated that downstream from the distal extent of the dissection, the distal right brachial artery was patent and opacified via collateral flow (Figure 1C). All coronary artery bypass grafts were patent. The patient was started on intravenous heparin to maintain an activated clotting time > 300 seconds. Intravenous eptifibatide was commenced to preserve patency of the RIMA graft.

Given the location of the dissection, it was felt surgical treatment options were limited due to the significant risk of stroke and MI, and percutaneous treatment was thus attempted. Under vascular ultrasound guidance, retrograde right brachial artery access was obtained above the elbow. This ensured that the true lumen distal to the dissection was accessed. A 0.035 inch Bentson wire (Cook, Bloomington, Indiana) was advanced retrogradely along the true lumen beyond the area of occlusion into the descending aorta and exchanged for a 4 Fr multipurpose Slipcath (Cook).
It was felt that endovascular angioplasty or stenting of the ostium of the right subclavian artery at the origin of the dissection was not a feasible option, given the possibility of compromising flow to either the right vertebral artery or the RIMA graft. We elected to stent from an area of the subclavian artery free of major branches and distal to the ostia of the right vertebral and internal mammary arteries (IMAs), and then extend the stents distally to beyond the occlusion into the true lumen of the right brachial artery to relieve limb ischemia.
The Slipcath was removed over an extra stiff Amplatz exchange wire (Cook), and 3 sequential self-expanding nitinol stents (Sentinol 8/60, Sentinol 7/78 and Sentinol 6/79, Boston Scientific Corp., Natick, Massachusetts) were placed extending from the mid-right subclavian artery to the mid-right brachial artery, beyond the dissection.
Post-stenting angiography demonstrated both the right vertebral artery and IMAs remained well perfused from the true and false lumens, respectively. The stented mid and distal right subclavian artery, axillary artery and proximal half-right brachial artery were widely patent, with restoration of flow to the right forearm and hand. The right hand demonstrated clinical and symptomatic improvement.
Computed tomography angiography following the procedure (Figure 2) confirmed the presence of an extensive spiral dissection within the subclavian artery, with the vertebral artery supplied by the false lumen and RIMA graft, thyrocervical trunk and inferior thyroid arteries supplied by the true lumen. The true lumen was stented and was widely patent from the mid-right subclavian artery to the right brachial artery in the upper arm.

The residual proximal dissection was managed conservatively with oral anticoagulation and dual antiplatelet therapy. The patient did not develop recurrent limb ischemia or neurological sequelae. Serial CK measurements performed after the procedure were not significantly elevated. Repeat transthoracic echocardiography showed no deterioration in left ventricular function.

Discussion
Management of vascular complications remains an important component of interventional cardiology. While femoral artery complications, including local dissection, are not uncommon,^1,2 dissection of coronary vessels, including the left main,^3,4 as well as the aorta⁵ during diagnostic and interventional procedures is well documented. While subclavian artery dissection complicating diagnostic and interventional cardiac procedures has been described, it is uncommon, with subclavian occlusion a rare cause of MI in patients with IM grafting.⁶ These have been managed with either a conservative⁷ or interventional⁸ approach, in contrast to the hybrid approach our patient required. In our patient, the presence of critical limb ischemia mandated that perfusion to the distal limb be restored. Vascular surgical repair in this area is challenging, in part due to the large area of exposure required.⁹ The presence of an extremely complex dissection at the origin of the right subclavian artery involving the origins of the vertebral artery and the RIMA was a relative contraindication to endovascular stent placement at this site due to concerns for potentially compromising flow in these vessels with subsequent significant cardiac and neurological sequelae. Stent placement within the proximal subclavian artery may have impaired vertebral flow, producing cerebral ischemia, in light of the fact that spontaneous subclavian artery dissection associated with stroke has been described.^10,11 Occlusion of flow into the false lumen may have also compromised RIMA flow, with resultant lateral wall infarction, an important consideration given the pre-existing impairment of left ventricular function in this young man.
Catheterization of the subclavian arteries, in particular the right subclavian artery, to engage IM bypass grafts can be technically challenging. Given the potential neurological and cardiac sequelae of vascular injury during both diagnostic and interventional procedures involving the RIMA, the clinical indication and the role of medical therapy should be carefully considered before proceeding with angiography. When invasive assessment is required, meticulous technique to prevent vascular trauma is mandatory. In particular, using a softtipped wire, such as a Bentson or Wholey wire (Mallinckrodt, St. Louis, Missouri), to assist in cannulation of the right subclavian artery is advisable. Ensuring appropriate pressure tracings before obtaining angiographic images is also critical. If difficulty in cannulating IM grafts is encountered, early consideration of an ipsilateral radial approach is an appropriate alternative instead of excessive manipulation within the subclavian vessels. Taking these appropriate steps to avoid vascular injury is obviously preferable to employing complex salvage strategies, as required in this case.
Vascular complications complicating cardiac catheterization remain an important cause of morbidity in patients undergoing these invasive procedures. The need for prompt recognition and appropriate management is critical in optimizing outcomes in these fortunately uncommon situations. The potential complexity of vascular complications reflects the need for a cooperative approach with skills relevant to interventional cardiology, vascular surgery and interventional radiology.

References

1. Blankenship JC, Balog C, Sapp SK, et al. Reduction in vascular access site bleeding in sequential abciximab coronary intervention trials. Catheter Cardiovasc Interv 2002;57:476–483.
2. Blankenship JC, Hellkamp AS, Aguirre FV, et al. Vascular access site complications after percutaneous coronary intervention with abciximab in the Evaluation of c7E3 for the Prevention of Ischemic Complications (EPIC) trial. Am J Cardiol 1998;81:36–40.
3. Awadalla H, Sabet S, El Sebaie A, et al. Catheter-induced left main dissection incidence, predisposition and therapeutic strategies experience from two sides of the hemisphere. J Invasive Cardiol 2005;17:233–236.
4. Awadalla H, Salloum JG, Smalling RW, Sdringola S. Catheter-induced dissection of the left main coronary artery with and without extension to the aortic root: A report of two cases and a review of the literature. J Interv Cardiol 2004;17:253–257.
5. Gorog DA, Watkinson A, Lipkin DP. Treatment of iatrogenic aortic dissection by percutaneous stent placement. J Invasive Cardiol 2003;15:84–85.
6. Barlis P, Brooks M, Hare DL, Chan RK. Subclavian artery occlusion causing acute myocardial infarction in a patient with a left internal mammary artery graft. Catheter Cardiovasc Interv 2006;68:326–331.
7. Frohwein S, Ververis JJ, Marshall JJ. Subclavian artery dissection during diagnostic cardiac catheterization: The role of conservative management. Cathet Cardiovasc Diagn 1995;34:313–317.
8. Galli M, Goldberg SL, Zerboni S, Almagor Y. Balloon expandable stent implantation after iatrogenic arterial dissection of the left subclavian artery. Cathet Cardiovasc Diagn 1995;35:355–357.
9. Castelli P, Caronno R, Piffaretti G, et al. Endovascular repair of traumatic injuries of the subclavian and axillary arteries. Injury 2005;36:778–782.
10. Garewal M, Selhorst JB. Subclavian artery dissection and triple infarction of the nervous system. Arch Neurol 2005;62:1917–1919.
11. Iwamuro Y, Nakahara I, Tanaka M, et al. Occlusion of the vertebral artery secondary to dissection of the subclavian artery — Case report. Neurol Med Chirzsssssssss 2005;45:97–99.