Percutaneous coronary intervention and coronary angiography are increasingly performed via radial artery access after resurrection of this route by Campeau in 1989.1 The reasons for this are reduced local complication rates compared to procedures using other access sites such as the femoral and brachial arteries,2-4 as well as reduced procedural costs and early patient mobilization.5 However, radial access is not always successful, and there are recent reports of ulnar artery cannulation in such cases. This article reviews the literature relating to ulnar artery access for coronary angiography and percutaneous coronary intervention. Methods Medline was searched for English language articles published before August 2005, using terms “ulnar artery” and “coronary angiography/percutaneous transluminal angioplasty”, “ulnar artery access”, “ulnar percutaneous intervention”, “transulnar”, and “trans-Ulnar”. Conference proceedings for major European, North American and Australasian cardiology meetings were also searched for abstracts relating to ulnar artery use for coronary procedures. Details of cases were compiled with reference to the type of procedure, success or failure, catheter size and complications. If operators proceeded to intervention after coronary angiography in the same session, the case was counted as a coronary intervention and not as a coronary angiogram. Results Nine journal publications and two conference abstracts were identified, detailing a total of 483 cases of attempted coronary angiography or intervention via the ulnar route in 463 patients. All of these were single case reports or single institution case series, the largest study having 172 subjects undergoing 187 procedures.6 Data from one conference abstract comprised part of a subsequent peer-reviewed publication that was also identified in the search.7 These data were not counted twice. Transulnar procedures were performed out of physician preference due to relatively small-caliber radial arteries or prior radial access failure. Both diagnostic angiography and coronary intervention procedures are described. There were no randomized, controlled trials of ulnar access compared to other routes of access for coronary procedures. Technique. The techniques described for ulnar cannulation and sheath placement were similar to those for radial artery access. In most cases, adequacy of radial collateralization to the hand was checked with the inverse Allen’s test or a variation of this based on oxygen plethysmography or Doppler signal assessment. Typically, the arm was abducted to approximately 70 degrees with mild hyperextension of the wrist. Local anesthetic was usually infiltrated in the region just proximal and lateral to the pisiform bone. The Seldinger technique was usually used to cannulate the vessel. Sheaths of between 4 Fr and 7 Fr diameter and 11 cm and 25 cm length were used. Antispasm cocktails were utilized at the discretion of the operator in some series and routinely in others. A standard range of angiographic and guide catheters were used. Success rates. Of the total 483 procedures in the literature, 439 were successful (90.9%), in that the intended coronary procedure was undertaken via the ulnar route after starting via this route. Not all publications gave sufficient information to deduce success rates for unselected patients, as most cases were selected specifically for ulnar access suitability. However, one study demonstrated successful procedural outcomes (91.9%) in 172 patients out of a total of 210 patients referred for a procedure, rendering a success rate of 75.2% on an intention-to-treat basis.6 There were 263 successful angiographic procedures and 176 successful coronary interventions, without counting as coronary angiograms those cases that proceeded to intervention after initial intention to undergo angiography. Only one series of 13 patients involved primary angioplasty for acute myocardial infarction (AMI),8 although another series included 2 patients undergoing primary percutaneous coronary intervention for AMI. Among all 483 cases, reasons for lack of success were usually failure to access the vessel or to advance the guidewire or catheter, while 1 case was unsuccessful due to problematic guiding catheter position in the aortic root.9 Safety. It is difficult to establish the long-term effects of ulnar artery access on the vessel itself, as only a small percentage of published cases have been subject to formal investigative follow up. However, clinical problems appear uncommon as far as the first few weeks postprocedure are concerned. Among all published cases, there were 2 large hematomas affecting a substantial part of the arm and 7 localized subcutaneous hematomas, although it is possible that not all minor hematomas were documented. There was evidence of false aneurysm arising from the ulnar artery in 2 cases, and ulnar spasm in 7 cases. One case of ulnar spasm required a general anesthetic to relieve it,6 although it is noted that the summary table and associated text in the particular publication suggested that no major adverse events occurred. Two studies assessed the artery with ultrasound at follow up. Aptekar et al detected asymptomatic ulnar artery occlusion in 1 of 124 patients assessed by ultrasound examination a mean of 10 days postprocedure. The remaining 34 patients in their series did not undergo ultrasound examination, but 32 of them remained asymptomatic on questioning, while 2 patients were not available for follow up.6 A much smaller series by Limbruno et al found no evidence of ulnar artery plaque, flow disturbance, stenosis, pseudoaneurysm or arteriovenous fistula in 13 patients examined by ultrasound 30 days postprocedure.8 There do not appear to be any recorded cases of symptomatic ulnar nerve damage associated with the procedure or evidence of tendon damage. Sheath and catheter size. Sheath and catheter sizes varied between 4 Fr and 7 Fr. On the whole, coronary angiography was usually performed via 4 or 5 Fr catheters, while coronary intervention tended to be performed via 6 Fr, and rarely 7 Fr equipment. There were 214 procedures carried out successfully with 6 Fr catheters, and only 2 procedures performed using 7 Fr catheters. Frequently, a 4 or 5 Fr diagnostic angiogram was converted into a coronary intervention using a larger sheath and catheter through the same ulnar puncture.6 Time factors and repeat punctures. Time from the start of the procedure to sheath insertion varied from 2 to 5 minutes in one series,8 but not all authors reported this parameter. Some studies specified how many attempts were required to puncture the artery, but again, this information was not always available. The largest study reported success with the first attempt in 101 cases, and the need for second, third, fourth and fifth attempts in 36, 13, 5 and 3 patients, respectively, out of a total caseload of 158 patients.6 Discussion The usual arrangement of arterial vasculature in the arm and forearm deserves attention prior to any discussion of clinical implications, although fine detail is best dealt with in specialist texts.10,11 Typically, the brachial artery, which is a continuation of the axillary artery at the lower border of the teres major muscle, gives rise to the profunda brachial artery high in its course. This vessel travels along the humerus in the spiral groove towards the lateral side of the arm. Here, two branches arise, often termed anterior and posterior or anterior and radial collateral branches. The anterior branch continues as the radial recurrent vessel, which then joins the radial artery shortly after its origin, slightly beyond the elbow. The posterior branch of the profunda brachial artery usually contributes branches to an anastomosing network around the posterior aspect of the elbow joint, which in turn receives branches from the superior and inferior ulnar collateral branches of the main brachial artery in the lower part of the upper arm. Meanwhile, the posterior branch of the profunda brachial travels dorsally into the forearm, where it connects with the dorsal interosseous branch of the common interosseous artery, itself a branch of the ulnar artery. The main brachial artery continues down the upper arm from the point at which the profunda arises, giving a number of unnamed but often large muscular branches, as well as the superior and inferior ulnar collateral arteries on the ulnar side of the upper arm. These vessels usually also supply branches to the anastomosis around the elbow joint, but continue as anterior and posterior ulnar recurrent vessels, ultimately joining the ulnar artery shortly after its origin form its parent vessel just distal to the elbow joint. The next set of branches to be aware of are those of the radial and ulnar arteries at the wrist. The radial artery divides at the wrist into superficial and deep branches, the former continuing in the palm to contribute to the superficial palmar arch, while the latter joins branches of the dorsal interosseous and deep branch of the ulnar artery to form the main supplying vessel of the deep palmar arch. The ulnar artery continues at the wrist, after giving rise to the deep ulnar branch, to be the main contributor to the superficial palmar arch (Figures 1 and 2 provide an illustration of the relative dominance of the radial and ulnar vessels). A common anatomical variation is the relative size of the radial and ulnar arteries. Henry Gray described the ulnar artery as “the larger of the two subdivisions of the Brachial”, while stating “The Radial artery appears, from its direction, to be a continuation of the Brachial, but in size it is smaller than the Ulnar”.11 Others have supported the notion that the ulnar artery is the larger of the two brachial bifurcations,12,13 but there is equally valid evidence suggesting that the radial artery is usually the largest branch.14 Variations in size, position, angulation, tortuosity or disease burden can prevent initial vascular access, while the interventionists’ guidewire, arterial sheath or catheter may adopt a number twists, turns and deviations from the desired route on their journey up the arm. Radial artery access has found favor among interventional cardiologists, with clear evidence of reduced procedural complication rates compared to femoral and brachial access.2,15,16 However, there is a failure rate of between 4 and 6% with radial access, mainly due to small-vessel caliber and/or vasospasm.17,18 Furthermore, Allen’s testing suggests inadequate collateralization of the hand by the ulnar artery through its connections with the superficial palmar arch in up to one-fourth of cases,19 making radial access potentially dangerous if the vessel subsequently occludes. It is therefore important to consider the merits of ulnar artery access in such cases, especially given the fact that the main alternatives are femoral and brachial access, with their associated morbidity and even mortality. Whether the ulnar artery is a viable alternative to the radial artery for coronary procedures depends not only on the likelihood of accessing the artery with a needle puncture, but also on the relative extent to which these vessels supply the deep and superficial palmar arches, the chances of damaging nearby nerves and tendons, the size and propensity of each vessel for spasm, the tendency for guidewires to deflect into recurrent vessels, and the likelihood of immediate or long-term vascular complications. The technique for ulnar cannulation and sheath insertion is essentially the same as that for the radial approach, other than the fact that the ulnar artery lies in a different anatomical position. Time required to access the ulnar artery is not excessive and is comparable to that for radial access. There is no reason to suppose ulnar access will be any more difficult than radial access for operators familiar with the latter, although a slight learning curve probably exists. From the available published material, it appears that ulnar artery access is feasible for both coronary angiography and intervention, using sheath sizes of between 4 Fr and 7 Fr. The bulk of published cases support use of small sheaths and catheter diameters, but approximately one-third of cases were undertaken successfully using 6 Fr sheaths and catheters, and a very small number of cases with 7 Fr equipment. It is likely that this reflects the necessary caution of early experience with ulnar access, and that greater familiarity will be accompanied by use of larger diameter sheaths and catheters where necessary. Although the published data are not of a randomized, controlled nature, it seems appropriate to conclude that ulnar access is likely to be successful in most cases without an excess of immediate or early postprocedure complications. Procedural success rates of almost 90% for selected cases and 75% among referred cases on an intention-to-treat basis seem both acceptable and plausible. It is not possible to state, from the available published material, whether ulnar access is any safer than radial access. Although the case of severe ulnar artery spasm requiring general anesthesia reported by Aptekar et al needs to be kept in mind, it would seem unlikely that the ulnar artery is generally more prone to spasm than the radial artery. The available data is insufficient to draw any conclusions about long-term arterial patency or postprocedure stenosis, as follow-up information is limited in depth and timescale. However, there is no reason to suppose that this would be different from rates of such complications following radial procedures. Similarly, there does not appear to be a particular risk of clinically relevant tendon or muscle damage associated with ulnar procedures. However, one aspect of ulnar artery access that does raise concerns is the proximity of the vessel to the ulnar nerve in the lower third of the forearm. The nerve runs immediately along the medial side of the artery in the region where arterial puncture would be undertaken. Damage to the nerve at this point could, at worst, result in paralysis of all small muscles of the hand except those of the thenar eminence and the first two lumbricals, with sensory loss over the palmar aspect of the medial side of the hand, the little finger, the medial aspect of the ring finger and the dorsal aspect of the distal half of the same fingers. It is likely, however, that damage to the ulnar nerve during access for coronary procedures would be neuropraxic in nature and therefore less severe and more likely to recover than complete ulnar nerve transection. Nevertheless, further data are required before one could state with confidence that significant ulnar nerve damage during these procedures is acceptably rare. This review collates important data that can inform clinical practice and ongoing research. Available evidence suggests that ulnar access for coronary procedures is feasible, highly successful and probably as safe as radial access. However, more safety data are required before we can regard ulnar access as a standard option, particularly in relation to the possibility of ulnar nerve damage. Cases of ulnar access for coronary procedures should form part of a registry at least, with success determined by “intention-to-investigate or treat”, careful follow up for neurovascular complications and appropriate dissemination of findings.
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