Transradial Occlusion of a Large Intercostal Branch of a Left Internal Mammary Artery Graft with the Novel Amplatzer Vascular Plug 4 Using a 4 French Diagnostic Catheter: Treatment of Coronary Steal Phenomenon

ABSTRACT: Sidebranches of the left internal mammary artery that are not ligated at the time of coronary artery bypass surgery can cause coronary steal syndrome, resulting in angina. Several isolated case reports have demonstrated successful resolution of this steal syndrome after transcatheter embolization of these branches. Here, we describe successful occlusion of such a sidebranch using an Amplatzer vascular plug via the transradial route with a 4 Fr Judkins Right coronary artery diagnostic catheter.

J INVASIVE CARDIOL 2011;23:E113–E116

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The left internal mammary artery (LIMA) is considered to be the best available conduit for surgical revascularization because of its excellent long-term patency rates and benefit of long-term survival.^1–3 Use of the internal mammary artery either as a single, sequential, bilateral or Y graft is common clinical practice in today’s age of complete coronary revascularization. However, almost 10% of LIMA grafts may possess large sidebranches (SB).⁴ These SB are usually ligated at the time of surgery. Although it has been suggested that failure to do so may produce the phenomenon of “coronary steal,” resulting in post-operative angina, this idea remains controversial.⁵ Isolated case reports have demonstrated objective functional evidence of steal and its resolution following occlusion of the SB.^6–8 Several surgical procedures and percutaneous devices are available for the same, with embolization coils the earliest used.^9,10 Here we present a patient who had objective evidence of ischemia and was treated with a new-generation vascular plug.

Case Report. A 64-year-old patient with multiple cardiovascular risk factors with unstable angina and severe ostial and proximal left anterior descending coronary artery (LAD) disease with a distal left main coronary artery plaque underwent coronary artery bypass graft (CABG) with LIMA graft to the LAD in 2004. Following the surgery, he continued to have mild exertional angina, which was controlled on medical therapy. He now presented with increasing angina over the last 6 months. The patient underwent a myocardial perfusion imaging study (SPECT), which revealed an extensive area of ischemia in the LAD territory. Coronary angiography revealed a patent LIMA-LAD graft with no evidence of progression of the native lesions. However, there was a large intercostal branch measuring 2.5 mm (almost the same size as the LIMA itself) arising from the proximal segment of the LIMA. On the basis of these findings, a diagnosis of coronary steal syndrome due to the large unligated sidebranch of the LIMA (Figure 1) was made. After discussion with the patient and the cardiac surgeons, a consensus decision to close the sidebranch was reached.

Through left radial arterial access, a 4 Fr diagnostic Judkins Right (JR) catheter (Terumo Corporation Europe, Lueven, Belgium) was used to cannulate the LIMA. A 0.014˝ Balanced Heavy Weight (BHW) guidewire (Abbott Vascular, Santa Clara, California) was passed into the SB. The 4 Fr JR catheter was then advanced over the wire into the SB and the position was confirmed with contrast injection. The Amplatzer Vascular Plug 4 (AGA Medical, Golden Valley, Minnesota; Figure 5) was advanced into the SB using the delivery cable and the device was released by counter-clockwise rotation of the delivery cable. Angiography confirmed excellent device position and complete occlusion of blood flow distal to the device with improvement of flow in the LIMA graft and LIMA-LAD flow (Figure 2). Following the procedure, the patient had complete resolution of his symptoms.

Discussion. Although the diagnosis of coronary steal phenomenon is still controversial,⁵ several studies have demonstrated subjective and objective evidence of improvement in patients who are suspected to have this syndrome after occlusion of the SB.^6–8However, opponents of this theory argue that coronary flow measurements have failed to document impaired flow to the LAD even in the setting of large LIMA sidebranches.^9,11 Nonetheless, it is gratifying to know that we now have safe and effective transcatheter treatment modalities for the subgroup of patients who demonstrate objective evidence of myocardial ischemia. Several methods of occlusion of the SB have been described. These include embolization,^10,12 the use of gelatin sponge particles,¹³ and the combined use of drug-eluting stents with covered stent. Surgical ligation both via the open route and by video-assisted thoracoscopic surgery^15,16 has been successfully performed. Recently, use of vascular plugs (originally developed for closing arteriovenous fistulae) for occluding such sidebranches has been described.8 Vascular plugs have also been used for occlusion of the LIMA graft inadvertently anastomosed to the coronary vein.¹⁷ However, most of these procedures were done through the femoral, and rarely the brachial route,¹⁸ using 5 Fr or larger therapeutic guiding catheters. The Amplatzer Vascular Plug 4 is a self-expanding Nitinol mesh occlusion device delivered through a 0.038˝ diagnostic catheter. The flexible mesh of the Amplatzer Vascular Plug 4 and the floppy distal section of the delivery wire enable the device to negotiate tortuous vessels with ease, while the multi-layered, double-lobed design ensures rapid occlusion. This plug is available in various sizes. Generally, it is important to select a plug size about 1.5–2.0 times the diameter of the vessel to be embolized (in the case of internal mammary artery, a 4 mm sized plug is usually adequate). Moreover, this particular vascular plug has a unique advantage of being deployable through small-diameter diagnostic catheters (as small as 4 Fr), thus minimizing the risk of injury to the LIMA graft. The use of transradial access instead of femoral access has its own advantages, including fewer local complications, better patient comfort, and ease of cannulation of the LIMA. When taken together with the previously known advantages of the plug, including ease of delivery and the ability to safely retrieve the device in case of improper deployment, transradial deployment of a vascular plug appears to be an attractive option for closing such LIMA sidebranches.

Coronary steal as seen in the present case is uncommon — not more than 45 cases have been described in the literature (Table 1). As discussed above, there is some debate regarding the benefits of treating these patients, mostly due to a controversy regarding the functional significance of this phenomenon. Also, owing to the rarity of the condition, a randomized clinical trial to resolve this controversy appears unlikely in the near future. However, we believe that in patients with progressive worsening of angina which can be clearly attributed to competitive run-off into the sidebranch and/or objective evidence of ischemia, transcatheter occlusion of the LIMA sidebranch appears to be a safe, effective, and reasonable option.

References

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From the Department of Interventional Cardiology, Juan Ramon Jimenez Hospital, Huelva, Spain.
The authors report no conflicts of interest regarding the content herein.
Manuscript submitted June 17, 2010, provisional acceptance given July 28, 2010, final version accepted October 4, 2010.
Address for correspondence: The Secretarial Office, Department of Interventional Cardiology, Juan Ramon Jimenez Hospital, C Ronda Norte sn. 21005, Huelva, Spain. Email: drsanghvia@yahoo.com