Truncus Bicaroticus With Arteria Lusoria: A Rare Combination of Aortic Root Anatomy Complicating Cardiac Catheterization

Methods

Due to the presence of CABG in our patient, left radial and ulnar artery approaches were used rather than a right radial artery approach. Engagement of the LIMA is performed most commonly with left radial or femoral artery access using an internal mammary catheter that has a more steeply angled tip (80º-85º) compared with the standard JR catheter. An accessory left radial artery anatomic variant was encountered in our case precluding left radial approach. In addition, abnormal takeoffs of the great vessels thwarted multiple attempts at intubation of the LSA (Figure 1, right). Some data suggest CT imaging can be of assistance in establishing patency of bypass grafts in CABG patients.¹⁵ This can be considered an option if branch-vessel anatomy remains unclear. Our patient exhibited several risk factors for stroke, including female gender, hypertension, and prior CABG. These and other risk factors may influence clinical decisions such as continued catheter manipulation, choice of catheter type, and further contrast studies.¹⁶

Nonselective angiography in these cases often can require excessive iodinated contrast, exposing the patient to increased risk of contrast-induced nephropathy (CIN).^7,17 Although the amount of contrast used in our case was average for diagnostic catheterization,the patient went on to undergo a second catheterization and CT angiography to establish LIMA graft patency.¹⁷ CT imaging reconstruction elucidated her aberrant branch-vessel anatomy. Patients are at increased risk of CIN with contrast loads < 200 mL per study, and this effect is compounded when the patient is elderly, has diabetes mellitus, and/or antecedent renal disease.¹⁸ Attention to the patient’s preoperative glomerular filtration rate, avoidance of nephrotoxic agents, and intraoperative left ventricular end-diastolic pressure during cardiac catheterization with postcontrast administration of IV isotonic fluids have been shown to prevent CIN.^19,20 In the POSEIDON trial, fluid administration on a sliding scale based on the left ventricular end-diastolic pressure resulted in lower absolute risk of CIN postcatheterization vs standard postprocedure hydration in cardiac catheterization.²¹ Further, the now widespread use of low and iso-osmolar contrast agents further reduces the risk of CIN.²²

For cardiac catheter laboratory operators, it is important to note that ARSA is more frequently encountered due to increased use of the transradial approach to coronary angiography.¹¹ It should be suspected when accessing the ascending aorta proves exceptionally challenging and the catheter has a predilection for entering the descending aorta.¹¹ While more technically demanding, 2 cases described by Allen and colleagues exhibited safe and successful entry into the ascending aorta with catheter rotation and hydrophilic support wires indicating the right radial approach is feasible despite presence of ARSA.¹² Several patient-initiated maneuvers can be utilized to aid in accessing the ascending aorta. For example, deep inspiration to reduce the angulation between the aortic arch and ARSA. The use of curved catheters, such as Amplatz left, internal mammary catheter, or Simmons catheter may be considered to cannulate the ascending aorta if ARSA is encountered. Complications associated with a transradial approach include dissection and intramural hematoma. Minor bleeds and vasospasm also can occur secondary to increased procedural duration.^6,8