Successful Transradial Intervention by Switching from 6 French to 5 French Guiding Catheter

ABSTRACT: We report a case of percutaneous coronary intervention (PCI) where a 6 French (Fr) guiding catheter could not be advanced through extremely tortuous subclavian and brachiocephalic arteries with a right transradial approach. Downsizing from a 6 Fr to 5 Fr guiding catheter was effective to reach to the coronary cusp, and we successfully performed transradial PCI without access-site crossover. When a catheter cannot be advanced in a tortuous vessel during transradial intervention, downsizing the catheter is an option to reduce resistance and enable successful PCI without access-site crossover.

J INVASIVE CARDIOL 2011;23:E153–E155

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In recent years, studies have been conducted to minimize the invasiveness of percutaneous coronary intervention (PCI), and transradial intervention (TRI) has been reported to decrease hemorrhagic complications and enable early ambulation.^1–3 Further reduction of such complications has been reported with decreasing catheter size, and the rates of arterial occlusion and intraprocedural patient discomfort were also found to decrease.^4–6 In addition, TRI has been demonstrated to reduce major adverse events, including death and periprocedural major bleeding in cases with acute myocardial infarction (AMI).⁷

One problem with TRI is the difficulty of catheter manipulation when there is tortuosity of the brachiocephalic artery or the ascending aorta.^8–10 There may be a severely tortuous vessel between the radial arterial access site and the site of insertion into the coronary artery. In such a case, a catheter might be unable to pass through the tortuous site. Even if it passes through the site, subsequent catheter manipulations are often difficult. Access-site crossover is needed in some cases upon encountering such a tortuous site. A meta-analysis showed that the rate of access-site crossover was higher in TRI than transfemoral intervention (TFI), thereby tending to increase procedural time and fluoroscopic time.⁷

In the present study, we were unable to engage a 6 Fr guiding catheter into the coronary artery ostium because of a severely tortuous brachiocephalic artery. We report here a case in which a successful PCI was performed via the transradial approach without access-site crossover by downsizing from a 6 Fr to a 5 Fr guiding catheter.

Case Report. An 87-year-old woman presented to an emergency room with a chief complaint of chest pain continuing for 3 hours. Electrocardiography showed ST elevations in leads V3–V6, and the patient was diagnosed with AMI by emergency coronary angiography. A 4 Fr sheath (Terumo Corporation, Tokyo, Japan) was placed in the right radial artery, and 7,000 IU of heparin were administered through the sheath. Left and right coronary angiograms were obtained using 4 Fr Judkins catheters, JL4 and JR4 (Asahi-Intecc, Nagoya, Japan), respectively. Coronary angiography revealed total occlusion of the proximal left anterior descending artery (LAD). Thus, PCI was performed for the occlusion (Figures 1A and 1B). The 4 Fr sheath in the right radial artery was replaced with a 6 Fr sheath, and a 6 Fr guiding catheter (IL4.0; Terumo Corporation) was inserted. When an attempt was made to advance the guiding catheter to the coronary artery, a strong resistance was felt at a bend of the right brachiocephalic artery and the coronary artery could not be engaged (Figure 2A). We tried to advance the guiding catheter by manipulating a 0.035˝ Amplatz Super Stiff guidewire (Boston Scientific, Natick, Massachusetts) inside. However, it was not successful. Therefore, the guiding catheter was switched from a 6 Fr to a 5 Fr IL4.0 catheter, and the coronary artery was engaged, although there was still resistance (Figure 2B). Next, the first guidewire (Ten-Nyo HT; Kaneka Medix, Osaka, Japan) was passed into the LAD and the second guidewire (Athlete Eel Slender; Japan Life Line, Tokyo, Japan) was also passed into the diagonal branch (Figure 3A). Intravascular ultrasound (IVUS) (Atlantis SR Pro2; Boston Scientific) was used to examine the vascular properties at the site of the lesion. A 3.0 x 18 mm Gazelle stent (Biosensors International, Kampong, Singapore) was placed and TIMI 3 flow was obtained (Figure 3B). The patient had no complications and was discharged on the fifth day.

Discussion. In PCI, the role of the guiding catheter is to direct a device, such as a balloon catheter or stent, to the lesion. It was reported that back-up force of a guiding catheter is determined by the catheter size and shape.¹¹ A small-diameter guiding catheter lacks resilience and mechanical back-up force. Therefore, it is often difficult to direct a device to the lesion. In contrast, a large-diameter guiding catheter is stiff and produces a strong back-up force. It enables easy passage of a device through a large lumen, and thus, large guiding catheters are generally considered to have many advantages over small ones in PCI. However, in this particular case, arterial bending did not accept the advancement of a 6 Fr guiding catheter even with a stiff 0.035˝ guidewire inside. Thus, we changed the guiding catheter from 6 Fr to 5 Fr. Furthermore, the smaller guiding catheter unexpectedly generated greater back-up force, because the arterial bending locked the catheter in this case.

The Appendix shows information on the physical property of bending stiffness. Bending stiffness can be calculated using a formula with Young’s modulus. A small-diameter catheter is less stiff than a large-diameter one.¹² There is a linear relationship between stiffness and frictional resistance. When a linear material, such as a wire, is passed through a vessel, a narrow-diameter material (with low stiffness) is thought to generate lower resistance compared with one of a larger diameter (with higher stiffness).¹³ A highly stiff, large catheter has a strong ability to retain its shape, which lowers its conformability (compliance) to the tortuous vessel. The resistance against the vessel is strong even after the catheter passes through the tortuous site. A small catheter with low stiffness is flexible and compliant even in a tortuous vessel, resulting in lower resistance.

In this case, a strong frictional resistance was felt when a guiding catheter was passed into a severely tortuous vessel. Thus, the highly stiff 6 Fr guiding catheter could not be advanced to the coronary artery. When the catheter was switched to a 5 Fr guiding catheter with low stiffness, the resistance decreased, enabling the catheter to pass through the tortuous vessel and to engage the coronary artery (Figure 4). Radial spasm is one of the main reasons for radial approach failure. Radial spasm may correlate with a large catheter size compared with the radial artery size. Using a smaller guiding catheter, it may prevent radial spasm. It is another benefit of the slender system.

In TRI, a catheter might be unable to advance due to the tortuosity of brachiocephalic artery or ascending aorta, and TRI has a significantly higher rate of access-site crossover compared to transfemoral intervention.^3,7,9,10 Downsizing of the catheter might decrease resistance and help achieve successful PCI without access-site crossover.

Conclusion. In the present study, we were unable to engage a 6 Fr guiding catheter into the coronary artery ostium because of a severely tortuous brachiocephalic artery. In this case, a successful PCI was performed via the transradial approach without access-site crossover by downsizing from a 6 Fr to a 5 Fr guiding catheter. This report shows that when a catheter cannot be advanced in a tortuous vessel during TRI, downsizing the catheter is an option to complete the procedure smoothly without access-site crossover.

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From the Department of Cardiology, Tokai University School of Medicine, Isehara, Japan.
The authors report no conflicts of interest regarding the content herein.
Manuscript submitted January 24, 2011, provisional acceptance given February 7, 2011, final version accepted February 16, 2011.
Address for correspondence: Takashi Matsukage, MD, PhD, FAPSIC, Assistant Professor of Medicine, Department of Cardiology, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Japan 259-1143. Email: ptc@b03.itscom.net