Morgan H. Randall, MD, FSCAI (Author), Konstantinos Dean Boudoulas, MD, FSCAI 

Introduction

Transradial access has become the preferred approach worldwide for cardiac catheterizations. However, radial arterial spasm (RAS) is a complication that can produce discomfort for the patient and limit the operator’s ability to manipulate catheters. While RAS cannot be prevented entirely, there are interventions that have been shown to reduce the rate of this complication. In this Tip of the Month, we focus on ways to reduce RAS. 

What Is RAS? 

RAS refers to the sudden, temporary narrowing of a radial artery. This is thought to be mediated by the abundant a-adrenoreceptors in the radial adventitia making this artery prone to vasoreactivity.¹ The radial artery diameter, female sex, vessel tortuosity, a younger age, a lower body mass index (BMI), diabetes mellitus, the number of catheters used, and an unsuccessful first access attempt have all been associated with increased rates of RAS.² In part due to the variable methods used to make this diagnosis, reported rates of RAS vary widely from 4% to 20%.1 However, avoiding this complication can lead to lower rates of patient discomfort, catheter or sheath entrapment, or crossover to other access sites.^{1, 3} 

The procedural technique has important implications for rates of RAS. Achieving moderate procedural sedation can dramatically reduce spasm rates with an odds ratio of 0.26 compared to no sedation (95% CI 0.18-0.47).3 Furthermore, adequate sedation improves patient satisfaction with no significant differences in safety outcomes.³  

Once radial access has been obtained, sheath selection can further reduce rates of spasm. Hydrophilic sheaths have been shown to reduce RAS incidence and should be used in preference to uncoated alternatives.⁴ Utilizing smaller sheath sizes has limited randomized data but has shown to result in numerically, albeit not statistically significant, fewer spasms.^{5, 6}  

A “radial cocktail” is a selection of medication(s) used to decrease RAS. The composition of this cocktail typically varies by operator, and the trials examining effects of these spasmolytic medications are similarly varied. Dosage, administration routes, concomitant medication use, and procedural technique differ across studies and, therefore, complicate the assessment of any single intervention. However, a preponderance of data suggests that many of these medications have their desired effect. 

Nitroglycerin and verapamil are perhaps the best-studied medications in the radial cocktail. Nitroglycerin is routinely administered in the cath lab and, therefore, commonly used to prevent RAS. Pooled data are heterogenous, with doses ranging from 100–500 mg, but support its use in reducing spasms with a relative risk (RR) of 0.71 (95% CI 0.59-0.84). However, while subcutaneous administration has demonstrated a clear reduction in RAS, intra-arterial or transdermal applications have not consistently shown a statistically significant improvement.⁷ Adversely, nitroglycerin is associated with increased rates of hypotension (RR 2.11; 95% CI 1.20-3.70), particularly when administered intra-arterially. Verapamil, on the other hand, has been studied at doses of 2.5 mg or 5 mg and has shown to dramatically reduce RAS with an RR compared to the placebo of 0.38 (95% CI 0.19-0.58) with a favorable safety profile.⁸ Data are again heterogenous, but there is no signal that one dose has an advantage over the other.  

Adjunctive measures proposed for the management of severe vasospasm include forearm heating, flow-mediated hyperemia by inflating a blood pressure cuff above systolic blood pressure for three minutes at the target site, a regional nerve block, or general anesthesia. However, these strategies have less robust data and should not be used routinely.¹ 

Summary 

RAS is a frequently encountered complication in the cath lab. However, moderate sedation, hydrophilic sheath selection, nitroglycerin, and verapamil all have a role in mitigating this obstacle and lead to better patient outcomes. 

References 

1. Sandoval Y, Bell MR, Gulati R. Transradial Artery Access Complications. Circ Cardiovasc Interv. 2019 Nov;12(11):e007386.
2. Ho HH, Jafary FH, Ong PJ. Radial artery spasm during transradial cardiac catheterization and percutaneous coronary intervention: incidence, predisposing factors, prevention, and management. Cardiovasc Revasc Med. 2012 May–June;13(3):193–195.
3. Deftereos S, Giannopoulos G, Raisakis K, et al. Moderate procedural sedation and opioid analgesia during transradial coronary interventions to prevent spasm: a prospective randomized study. JACC Cardiovasc Interv. 2013 Mar;6(3):267–273.
4. Rathore S, Stables RH, Pauriah M, et al. Impact of length and hydrophilic coating of the introducer sheath on radial artery spasm during transradial coronary intervention: a randomized study. JACC: Cardiovasc Interv. 2010 May;3(5):475–483.
5. Dahm JB, Vogelgesang D, Hummel A, et al. A randomized trial of 5 vs. 6 French transradial percutaneous coronary interventions. Catheter Cardiovasc Interv. 2002 Oct;57(2):172–176.
6. Horie K, Tada N, Isawa T, et al. A randomised comparison of incidence of radial artery occlusion and symptomatic radial artery spasm associated with elective transradial coronary intervention using 6.5 Fr SheathLess Eaucath Guiding Catheter vs. 6.0 Fr Glidesheath Slender. EuroIntervention. 2018 Apr 20;13(17):2018–2025.
7. Abdelazeem B, Abuelazm MT, Swed S, et al. The efficacy of nitroglycerin to prevent radial artery spasm and occlusion during and after transradial catheterization: A systematic review and meta-analysis of randomized controlled trials. Clin Cardiol 2022 Dec;45(12):1171–1183.
8. Curtis E, Fernandez R, Lee A. The effect of vasodilatory medications on radial artery spasm in patients undergoing transradial coronary artery procedures: a systematic review. JBI Database System Rev Implement Rep. 2017 Jul;15(7):1952–1967.