Ask the Transradial Center of Excellence: Left Internal Mammary Artery Angiography Via Right Radial Approach

How does your center perform transradial catheterization on patients with previous bypass surgery involving the left internal mammary artery?

Great question. The following answer is based on our technique at Winter Haven Hospital and a review of the literature.

The right radial approach, despite obvious benefits to both the patient and the operator, has been a relative contraindication for patients with a history of coronary artery bypass grafting (CABG) involving the left internal mammary artery (LIMA). Many transradial operators opt for the left radial approach on patients with a LIMA to the left anterior descending (LAD) artery. Benefits of the transradial approach for the patient include a reduction in the risk of bleeding complications, as well as increased comfort for the patients following the procedure. Operators performing catheterization via the right radial approach may appreciate such benefits as eliminating the need to reach across the patient during the procedure or performing the procedure from the other side of the table, as would be necessary when utilizing the left radial artery due to CABG. The right radial approach is also believed to reduce radiation exposure to the operator.¹ The internal mammary artery has been proven superior to saphenous vein grafts for bypassing the LAD artery, due to its superior durability and longevity. Greater than 80% of all patients that have had CABG include the use of the internal mammary artery.² Due to benefits of LIMA to LAD bypass grafts, the transradial approach for cardiac catheterization as well as the operator-comfort advantages specific to the right radial approach, it is ideal to perform angiography of the LIMA via the right radial approach.

Selective angiography of the LIMA has been documented as both safe and feasible using specialized catheters.³ Specialty catheters, however, can be expensive, as well as hard to track down when it comes time to order product. There lies a solution to this problem, and it utilizes a catheter found in the majority of all catheterization laboratories: the left coronary bypass (LCB) catheter. Originally developed for selective angiography of bypass grafts to the left coronary system, the shape of the LCB allows it to be navigated into the left subclavian artery, and pulled back to cannulate the LIMA. The following describes a technique consistently used by Zaheed Tai, DO, FACC, FSCAI to perform selective angiography of the LIMA to LAD graft.

After access has been gained, a radial cocktail has been administered, and angiography of the native coronary arteries has been performed, an exchange length .035” J tip wire and LCB catheter are advanced into the descending aorta. The LCB catheter is advanced beyond the great vessels, then slightly pulled back and rotated counterclockwise to point the tip of the catheter toward the origin of the left subclavian artery. The J wire is then exchanged for an exchange-length hydrophilic wire.¹ In patients with tortuosity in the right subclavian artery, a stiff hydrophilic wire may help straighten the tortuous vessel and provide better torque control for the catheter.³ The hydrophilic wire and LCB are advanced to the distal portion of the left subclavian artery. The wire is removed, and small puffs of contrast are utilized to locate the origin of the LIMA. The LCB can then be pulled back and torqued to engage the LIMA (see Figure 1). These steps can be performed in either straight antero-posterior (AP) projection, or left anterior oblique (LAO), depending on the operator’s preference. Selective angiography is the preferred method, but nonselective angiography can also be an effective method for opacification of the LIMA to LAD graft. To aid in visualizing the artery during nonselective angiography, a blood pressure cuff may be placed on the left upper arm and inflated beyond systolic blood pressure.¹ Inflation of the blood pressure cuff helps eliminate contrast washout, providing a better image. A satisfactory image visualizes the entire native LIMA, the anastomosis site, and runoff into the native LAD. Angiography in two orthogonal views is recommended.³

The LCB may be difficult to torque in elderly patients with a tortuous innominate. Dr. Tai recommends utilizing a SIM 1 or AL 1 catheter in these patients in order to advance the hydrophilic wire into the left subclavian artery. The catheter may then be exchanged for the LCB to perform LIMA angiography. Limitations of this technique include tortuosity of the subclavian artery, known atherosclerotic plaque in the aortic arch, and a vertical aorta. Contraindications for the transradial approach include: arteriovenous fistula, abnormal Allen’s test, and radial artery that has been harvested for bypass surgery.¹ Over an 18-month period, only once have we been unable to perform sufficient angiography of the LIMA and been forced to access the left radial artery in order to properly opacify the vessel.

Daven Remley can be contacted at remleyd@gmail.com.

References

1. Tai Z. Selective LIMA injection via the right radial approach. Cardiac Interventions Today January/February 2011;31–32.
2. Kim MH, Cha KS, Kim HJ, Kim JS. Bilateral selective internal mammary artery angiography via right radial approach: clinical experience with newly designed Yumiko catheter. Catheter Cardiovasc Interv 2001;54:19–24.
3. Cha KS, Kim MH. Feasibility and safety of concomitant left internal mammary arteriography at the setting of the right transradial coronary angiography. Catheter Cardiovasc Interv 2002;56:188–195.