1

Introduction

The use of trans-radial access (TRA) for cardiac catheterization and percutaneous coronary intervention has increased substantially in recent years. However, trans-radial approach may not be feasible in 5%–10% of patients. Trans-ulnar access (TUA) can serve as an alternative approach in some of these patients but this approach is infrequently used.

This manuscript discusses the anatomy and technique of TUA interventions. We analyze the success and complication rates reported in the literature and present the analyzed content in a structured fashion addressing both feasibility and safety of this approach.

2

Anatomy

The ulnar artery is the larger of the two branches arising from the brachial artery. The ulnar artery typically originates distal to the bend of the elbow (5 to 7 cm. distal to the elbow or medial epicondyle) and courses obliquely and distally and reaches the medial (ulnar) aspect of the forearm (midway between the elbow and the wrist) and subsequently courses along the ulnar nerve towards the medial aspect of the forearm. After the ulnar artery crosses the transverse carpal ligament on the radial side of the pisiform bone and immediately beyond this bone divides into two branches which connect to the formation of the superficial and deep volar or palmar arches ( Fig. 1 ) The deep volar arch is fed by the radial artery (laterally) and the deep volar branch of the ulnar artery (medially) and is 99% complete ( Fig. 2 ). The superficial volar arch is fed by the ulnar artery (medially) and by the radial carpal superficial volar branch laterally (and is complete only in 40%–80% of patients). The ulnar nerve runs medial and parallel to the ulnar artery in the distal forearm and both of them are encased by the restrictive Guyton’s canal in the wrist. The ulnar artery is best palpated on the anterior medial aspect of the proximal wrist crease when the wrist is hyperextended. The ulnar artery varies in its origin and course in a significant proportion of cases. Occasionally the ulnar artery may emerge directly from the axillary artery proximal to the elbow. Most anatomy reports suggest that the ulnar artery is usually larger in size than radial artery especially in its proximal segment. Ultrasound based studies observed no significant differences between the diameters of the two arteries adjacent to the wrist.

Superficial and deep volar (palmar) arches.

Adapted and modified from anatomygroup.files @ wordpress.com

Forearm and palmar blood flow and puncture sites for radial and ulnar access.

Adapted and modified from anatomygroup.files @ wordpress.com

Liu at al reported that ulnar artery was slightly bigger than the radial artery both before intervention (3.62 ± 0.36 versus 3.26 ± 0.22 mm) and 1 year post intervention (3.33 ± 0.49 versus 3.01 ± 0.48 mm). However large diameters of both radial and ulnar arteries reported in this study could not be duplicated in any other study. The radial artery was slightly larger than ulnar artery in a report by Aptecar et al. (2.87 ± 0.6 and 2.83 ± 0.9 mm respectively, P = NS). In an ultrasound based study Bauman et al. showed that there was no significant difference (<20%) between the distal ulnar and radial distal diameters in most of the patients (58.5%) however, in 35% of patients the radial was bigger, while in 65% of them the ulnar was larger .

2

Anatomy

The ulnar artery is the larger of the two branches arising from the brachial artery. The ulnar artery typically originates distal to the bend of the elbow (5 to 7 cm. distal to the elbow or medial epicondyle) and courses obliquely and distally and reaches the medial (ulnar) aspect of the forearm (midway between the elbow and the wrist) and subsequently courses along the ulnar nerve towards the medial aspect of the forearm. After the ulnar artery crosses the transverse carpal ligament on the radial side of the pisiform bone and immediately beyond this bone divides into two branches which connect to the formation of the superficial and deep volar or palmar arches ( Fig. 1 ) The deep volar arch is fed by the radial artery (laterally) and the deep volar branch of the ulnar artery (medially) and is 99% complete ( Fig. 2 ). The superficial volar arch is fed by the ulnar artery (medially) and by the radial carpal superficial volar branch laterally (and is complete only in 40%–80% of patients). The ulnar nerve runs medial and parallel to the ulnar artery in the distal forearm and both of them are encased by the restrictive Guyton’s canal in the wrist. The ulnar artery is best palpated on the anterior medial aspect of the proximal wrist crease when the wrist is hyperextended. The ulnar artery varies in its origin and course in a significant proportion of cases. Occasionally the ulnar artery may emerge directly from the axillary artery proximal to the elbow. Most anatomy reports suggest that the ulnar artery is usually larger in size than radial artery especially in its proximal segment. Ultrasound based studies observed no significant differences between the diameters of the two arteries adjacent to the wrist.

Superficial and deep volar (palmar) arches.

Adapted and modified from anatomygroup.files @ wordpress.com

Forearm and palmar blood flow and puncture sites for radial and ulnar access.

Adapted and modified from anatomygroup.files @ wordpress.com

Liu at al reported that ulnar artery was slightly bigger than the radial artery both before intervention (3.62 ± 0.36 versus 3.26 ± 0.22 mm) and 1 year post intervention (3.33 ± 0.49 versus 3.01 ± 0.48 mm). However large diameters of both radial and ulnar arteries reported in this study could not be duplicated in any other study. The radial artery was slightly larger than ulnar artery in a report by Aptecar et al. (2.87 ± 0.6 and 2.83 ± 0.9 mm respectively, P = NS). In an ultrasound based study Bauman et al. showed that there was no significant difference (<20%) between the distal ulnar and radial distal diameters in most of the patients (58.5%) however, in 35% of patients the radial was bigger, while in 65% of them the ulnar was larger .

3

Modified Allen’s test (MAT) or Barbeau test

Some studies suggest that ulnar interventions are both feasible and safe even in the absence of a palpable ipsilateral radial artery or known occluded, harvested or removed radial artery (Barbeau class D) . These authors see no benefit performing MAT prior to trans-ulnar intervention. Similar findings were reported in a comprehensive study to date evaluating the role of MAT prior to transradial catheterization . Valgimigli et al. studied a broad spectrum of patients undergoing transradial catheterization with normal, intermediate and abnormal MAT results. There was no difference in capillary lactate levels, hand strength, discomfort ratings and ischemic complications between the three groups. This calls into question the routine use of MAT. However these results are yet to be validated in a large study. We believe that MAT still has a role and can be an important tool to assess the baseline palmar and brachial vascular flow. We routinely use it for pre-procedural documentation and post procedural assessment. The implications are that consideration of alternative access (contralateral wrist or femoral access) can be entertained when a Barbeu class D is encountered. Also conservative sheath insertion (the smallest diameter and the shortest possible sheath) should be used to avoid ulnar vessel thrombosis or injury to the anterior interosseous artery. The anterior interosseous artery ( Figs. 2 and 3 ) emerges from the proximal portion of the ulnar artery and provides collateral flow in most cases of radial artery occlusion or harvesting. Contrast injection into the accessed ulnar artery in case of radial occlusion can be considered to confirm the presence of such collateral network via the deep palmar arch.

Ulnar artery angiogram using left ulnar access.

4

Technique

The patient should be counseled about details of TUA and its related complications. These are essentially similar to the TRA except for nerve related complications as outlined below. A Barbeau test (using pulse-oximetry) can be performed to assess dual arterial flow in the hand and results of the test documented. The palm should be supported and fixed in a supinated hyperextended position similar to TRA procedure. Hyperextension of the wrist is extremely important since it greatly enhances our ability to palpate the ulnar artery at the level of the wrist crease. Use of ultrasound to locate the ulnar artery and also to determine the size and suitability for catheterization has been promising.

The puncture is performed proximally to the pisiform bone, in the proximal wrists crease. The ulnar artery is punctured using a 21-gauge needle (aiming 60–75° cephalad) with either the Seldinger’s technique or Modified Seldinger’s technique. Like TRA, there is no evidence favoring either of these two approaches. In our lab, we have adopted an “anterior wall stick” approach for all our TUA procedures. This intuitive decision is based on close anatomical relationship of the ulnar artery to ulnar nerve along with the fact that the ulnar artery is more deep seated and less compressible than the radial artery. After cannulation of the ulnar artery, a 0.018 in., soft tip guide wire is introduced, over which a sheath with dilator is advanced. A 4F or 5F sheath is suitable for diagnostic angiography and 5F or 6F sheaths are preferred for PCI. As and when needed, use of larger sheaths or sheathless PCI can also be considered. The sheath can be only partially inserted into the ulnar artery especially when resistance is encountered. Sheath fixation by either suturing it or fixing it with Tegaderm (3M, Minneapolis, MN) can minimize sheath movement. Vasodilators like verapamil (2.5–5 mg) or Nicardipine (250–500 μg) with optional nitroglycerin (200–600 μg) are administered intra-arterially to prevent vasospasm. The use of anticoagulation (40–70 U/kg unfractionated heparin) is also standard practice to prevent ulnar artery thrombosis. Right TUA is preferred over the left TUA approach in majority of cases, mainly due to operator’s familiarity and convenience. However, left TUA is preferred in patients with prior left internal mammary coronary artery bypass surgery. The left TUA is also preferably used in Right Coronary Artery (RCA) PCI of heavily calcified, tortuous or totally occluded RCA. These suggestions are extrapolated from TRA guided PCI of the RCA. Left wrist approach provides additional support during complex RCA interventions. Similarly right wrist approach is preferred for PCI to the left coronary artery.

During the upsizing of radial sheath, caution should be exercised not to push the sheath against resistance and to insert only a small segment (3–4 cm) of the sheath to minimize vessel trauma. When there is concern regarding the size of the vessel and suitability for 6F sheath, use of a 6F dilator preceding the 6F sheath insertion could be considered. If there is resistance to 6F dilator insertion, alternative approaches including use of a 5F sheath guided PCI are used.

Advancing the 0.035 in. j-shaped wire across the ulnar and brachial arteries can be done without fluoroscopic guidance for the initial 50 cm. In case of resistance, use of a soft tip 0.035 in. wire (angled tip glide or Wholey wire) under fluoroscopic guidance would help with advancement of the catheter. On rare occasion of extreme tortuosity, a 0.014 in. hydrophilic wire (like Whisper) should be used to negotiate the angulations under fluoroscopy. Choice of catheter shapes & sizes is similar to TRA. Compared to left TUA, smaller curve Judkins left catheters are used to intubate the left coronary ostium using the right TUA. Catheter exchanges should be done over a long (240 cm) J-wire. The ulnar sheath should be meticulously flushed with heparinized saline with every catheter exchange. Catheter or wire friction and reduced or absent backflow from the ulnar sheath side-port are possible clues to severe spasm or thrombosis and should be addressed immediately. Minimizing catheter exchanges and use of single catheter for evaluating both right and left coronaries are recommended. At the end of the procedure the ulnar sheath should be removed and radial arteriotomy compressive devices should be applied to the TUA arteriotomy site in a protocol resembling TRA procedures emphasizing non-occlusive pressure on the access site and optional ipsilateral radial artery compression to enhance flow via the ulnar artery.