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Table of Contents
Year : 2022  |  Volume : 8  |  Issue : 1  |  Page : 28-30

Radial loop: Can straightening of the loop push the guiding catheter? Do we need to be more watchful? A case report and literature review

Department of Cardiology, NHL Municipal Medical College, Ahmedabad, Gujarat, India

Date of Submission27-Oct-2021
Date of Decision14-Dec-2021
Date of Acceptance28-Dec-2021
Date of Web Publication22-Mar-2022

Correspondence Address:
Dr. Bhupesh Shah
Department of Cardiology, NHL Municipal Medical College, Ahmedabad - 380 006, Gujarat
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijca.ijca_53_21

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Radial loops are the most common radial anatomical entity for deferring or failure of transradial approach. Complex loops may not straighten immediately after traversing the loop and may take a few minutes to straighten out. Here, we describe a case of a complex radial artery loop encountered during transradial percutaneous coronary intervention. We furthermore present a literature review and outline tips and techniques to successfully traverse the radial loop.

Keywords: Access site, dissection, guide catheter, percutaneous coronary intervention, radial loop

How to cite this article:
Shah B, Shah H, Shah D. Radial loop: Can straightening of the loop push the guiding catheter? Do we need to be more watchful? A case report and literature review. Int J Cardiovasc Acad 2022;8:28-30

How to cite this URL:
Shah B, Shah H, Shah D. Radial loop: Can straightening of the loop push the guiding catheter? Do we need to be more watchful? A case report and literature review. Int J Cardiovasc Acad [serial online] 2022 [cited 2023 Jan 29];8:28-30. Available from: https://www.ijcva.com/text.asp?2022/8/1/28/340330

  Introduction Top

Transradial access for coronary angiography and percutaneous coronary intervention (PCI) has rapidly emerged as the predominant access route favored by several operators worldwide. The paradigm shift witnessed this past decade has emanated from lower access site complications, increased patient comfort, and earlier ambulation as compared to traditional transfemoral intervention.[1] However, in some cases, tracking and navigating hardware through radial artery vasculature prove challenging due to smaller radial artery diameter, or complex, variable, or anomalous anatomy.[2] Radial loop is one of the more challenging coronary anomalies encountered and is synonymous with procedural failure. Its prevalence ranges from 0.8% to 2.3%.[3] We describe one such challenging case of a radial loop encountered through transradial PCI.

  Case Report Top

A male patient presented with unstable angina. Coronary angiography revealed 95% occlusion in left anterior descending (LAD) coronary artery, 70% occlusion in the obtuse marginal branch, and a mild diffuse lesion in right coronary artery [Figure 1]a and [Figure 1]b. However, while pushing the guiding catheter through the radial artery, a radial loop was encountered [Figure 2]a and [Figure 2]b and attempts were made to straighten the catheter [Figure 1]c. A 1.5-mm GLIDEWIRE Baby-J Hydrophilic Coated Guidewire (Terumo Interventional Systems) successfully crossed the radial loop. A drug-eluting stent (DES) was implanted in LAD. However, we noticed left main coronary artery (LMCA) dissection. Attempts to straighten the loop might have pushed the catheter into the LMCA causing dissection of the artery. A second DES was deployed from the LMCA to LAD by overlapping with the first DES to treat the dissection. The DES was postdilated. However, the dissection was still visible, so postdilation was performed again [Figure 1]d and [Figure 2]e. Thrombolysis in myocardial infarction III was achieved, and the patient was discharged 2 days later [Figure 1]f.
Figure 1: Coronary angiography revealed: (a) 95% occlusion in the left anterior descending coronary artery, (b) 70% occlusion in the obtuse marginal branch, (c) looping of the catheter whilst attempting to straighten the loop, another stent was deployed from left main coronary artery to left anterior descending by overlapping the first stent (d and e) dissection still visible after postdilation, hence another postdilation was performed (f) final thrombolysis in myocardial infarction III flow

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Figure 2: Coronary angiography revealed: (a) A radial loop and (b) schematic vascular anatomy of a radial artery with a radial loop

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  Discussion Top

Radial loop is the most encountered anatomical variation responsible for procedural failure even for experienced radial interventionalists. However, with the growing numbers of transradial interventions, interventional cardiologists are bound to face obstacles at various anatomical levels beginning from the radial artery to the coronary artery level, as demonstrated in the present case and [Figure 2]. We present a case from our institution along with a literature review [Table 1].[1],[2],[3],[4],[5],[6],[7],[8],[9] We also outline tips and techniques to successfully traverse the loop.
Table 1: Clinical and technical details of other cases of radial loop in recent literature

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After obtaining an arteriogram, the first strategy is to traverse the radial loop with specialized wires. If a 0.035”J-wire is unsuccessful, an atraumatic 0.035” wire such as a Wholey guidewire (Medtronic) or Magic Torque guidewire (Boston Scientific Corporation) followed by a 0.014” angioplasty wire or a 0.0250.035” hydrophilic wire may be attempted. The 0.035” 1.5-mm GLIDEWIRE Baby-J Hydrophilic Coated Guidewire (Terumo Interventional Systems) is a more advanced specialized wire that can also be employed in such cases. This wire provides lubricity of a hydrophilic wire while maintaining safety of a small trackable J-tip. If greater support is necessitated to straighten out the loop, a 4-F multipurpose diagnostic catheter or a hydrophilic catheter, such as a Glidecath Hydrophilic Coated Catheter (Terumo Interventional Systems), can be employed to track over the wire. Furthermore, rotating a low-profile catheter while pullback may straighten the loop.[10]

Motherdaughter technique can be employed if the loop has been crossed with a wire but difficulty straightening out the loop for safe delivery of the diagnostic catheter persists. An earlier method details a pigtail-assisted tracking method. In this method, a 5-F pigtail catheter is loaded in a 6-F guide catheter. The distal pigtail is extended outside the guide and tracked over the wire through the loop. This method circumvents the razor-blade effect of the guide catheter as it passes through the tortuous segment of the radial loop. This avoids dissection in cases where the catheter is aggressively passed through the loop. The protruding pigtail lessens contact between the sharp edge of the guide catheter tip and the vessel wall.[11]

The balloon-assisted tracking (BAT) is a technique that may be adopted. This is a technique wherein an inflated percutaneous transluminal coronary angioplasty balloon is partially protruded through the distal end of a guide catheter and deployed at 3 or 6 atm. Low-pressure inflation aids the catheter to negotiate extreme curves and loops. A 1.5-mm balloon is recommended for a 5-F diagnostic or guide catheter, whereas a 2.0-mm balloon is recommended for 6-F guide catheter. Balloons of 15 or 20 mm are sufficient. Once the balloon is partially protruded from the distal end of the catheter and deployed, the entire assembly is advanced over a soft-tipped 0.014” guidewire facilitating smooth and nontraumatic progression through difficult vasculature. The key benefit of BAT is prevention of the “razor effect” of the catheter tip to the radial artery endothelium.[1],[2]

  Conclusion Top

Radial loop is a rare, yet challenging anomaly associated with transradial intervention. However, technical difficulties can be overcome with adequate training, specialized wires, and techniques such as pigtail-assisted tracking and BAT. After crossing the loop with a wire, slight pull on the catheter or wire can straighten the loop. However, caution should be taken as straightening the loop may push the guide catheter a little deep into the artery.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Deora S, Shah S, Patel T. Balloon-assisted tracking in dealing with radial artery loop by transradial approach: A technical report. J Invasive Cardiol 2014;26:E61-2.  Back to cited text no. 1
Patel T, Shah S, Pancholy S, Rao S, Bertrand OF, Kwan T. Balloon-assisted tracking: A must-know technique to overcome difficult anatomy during transradial approach. Catheter Cardiovasc Interv 2014;83:211-20.  Back to cited text no. 2
Chitsaz S, Malik F, Shunk K. Radial artery loop perforation with a transient arterio-venous fistula during transradial catheterization. J Clin Exp Cardiol 2012;3:1-3.  Back to cited text no. 3
Esente P, Giambartolomei A, Simons AJ, Levy C, Caputo RP. Overcoming vascular anatomic challenges to cardiac catheterization by the radial artery approach: Specific techniques to improve success. Catheter Cardiovasc Interv 2002;56:207-11.  Back to cited text no. 4
Barbeau GR. Radial loop and extreme vessel tortuosity in the transradial approach: Advantage of hydrophilic-coated guidewires and catheters. Catheter Cardiovasc Interv 2003;59:442-50.  Back to cited text no. 5
Farman MT, Khan NU, Rizvi SN. Successful transradial percutaneous coronary intervention with radial artery anomaly. J Pak Med Assoc 2010;60:593-5.  Back to cited text no. 6
Sarji R, Sricharoen N. Beyond the bend: A literature review and case report of radial artery loop. J Invasive Cardiol 2011;23:E271-2.  Back to cited text no. 7
D'Amario D, Paraggio L, Porto I. Combining balloon-assisted tracking and sheathless guiding catheter: Unloosening the Gordian knot. Cardiovasc Revasc Med 2015;16:432-4.  Back to cited text no. 8
Dossani R, Waqas M, Tso MK, Rajah GB, Smolar DE, Davies JM. Navigating a proximal loop in the radial artery and avoiding the recurrent radial artery. J Neurointerv Surg 2020;12:724.  Back to cited text no. 9
Wong S, Desai S. Navigating complex radial loops. Cardiac Interventions Today 2019;13:36-8.  Back to cited text no. 10
Garg N, Sahoo D, Goel PK. Pigtail assisted tracking of guide catheter for navigating the difficult radial: Overcoming the “razor effect”. Indian Heart J 2016;68:355-60.  Back to cited text no. 11


  [Figure 1], [Figure 2]

  [Table 1]


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