Catheterization and Cardiovascular Interventions 84:443–444 (2014)
Editorial Comment Smaller is Better for the Radialist Giselle A. Baquero, MD, and Ian C. Gilchrist,* MD, FSCAI Pennsylvania State University, College of Medicine, Heart and Vascular Institute, MS Hershey Medical Center, Hershey, Pennysylvania
An Achille’s heel of the transradial (TR) technique is the mechanical limitation related to the finite radial artery diameter and its tendency to spasm that further reduces its functional luminal diameter. This restricts routine use of sheath and guide catheters to 5 or 6 French (Fr) in most patients [1]. Standard introducer sheaths have an outer diameter that is about 2 Fr sizes larger than the outer diameter of the corresponding guide catheter. This external diameter was an engineering requirement needed to design a sheath robust enough to survive the angle of incident required to enter the femoral artery without kinking. TR access kits evolved with smaller introducer diameter wires, access needles, and tapered sheath dilators, but the ultimate vascular sheath diameter remained the same as the legacy sheaths used in the femoral artery. Local radial complication rates increase significantly with escalation in sheath size. These complications comprise chronic regional pain syndrome, early and late radial artery occlusion (RAO), radial artery perforation [2] and more rarely yet radial artery perforation with forearm hematoma or compartment syndrome [3]. Although largely asymptomatic, the development of RAO may be the most pernicious complication as it precludes future intervention via the same radial artery and represents an ablation of the artery. This particular complication may be reduced by avoiding prolonged high-pressure compression of the radial artery after sheath removal by practicing perfused hemostasis [4], universal anticoagulation, and reducing arterial trauma with smaller diameter equipment. This latter approach has until recently only been possible at the expense of reduced guide catheter support and considerable restriction in the use of adjunctive interventional devices or dual balloon procedures. One potential solution may involve the use of sheathless guide catheters but most of these catheters require a 4 or 5 Fr introducer sheath to start and commercial products have been relatively C 2014 Wiley Periodicals, Inc. V
costly in most markets. Between eliminating the vascular sheath or reducing the diameter of the guiding catheter, remains improvements in the vascular sheath itself. As the angle of incidence to enter the radial artery is much shallower than the required for the femoral artery, a third approach to reducing vascular trauma may be to decrease the thickness of the vascular sheath wall itself for radial use as sheath kinking is not a particular concern for radial operators. Aminian et al. described their experience in using a new commercially available (in USA) sheath that has taken advantage of reducing the sheath wall thickness to decrease the net sheath diameter. This innovative sheath is a dedicated radial sheath with hydrophilic coating, an inner diameter appropriate for 6 Fr angiographic catheters yet an outer diameter equivalent to available 5 Fr sheaths. This paradoxical improvement is accomplished by reducing the thickness of the sheath wall from 0.20 to 0.12 mm while maintaining an internal diameter of 2.22 mm with a resultant decreased in the outer diameter from 2.63 to 2.45 mm. The study was aimed to evaluate procedural success and accesssite complications including development of RAO during routine studies while using this thinned wall sheath [5]. The authors analyzed 114 patients out of which 24% had acute coronary syndrome with 9% undergoing primary percutaneous coronary intervention (PCI). They use adjunctive interventional technologies in 30% of the PCI patients with only 1 case requiring accesssite crossover to femoral due to difficulty engaging the guide catheter secondary to abnormal implantation of the right coronary artery. Five percent of their patients experienced minor hematomas, 4% symptomatic radial spasm most of which had radial arteries anatomical variations seen on upper-limb retrograde angiography and only one patient developed RAO detected by Doppler ultrasound at 1 month follow up. Conflict of interest: Nothing to report. *Correspondence to: Ian C. Gilchrist, MD, FSCAI, Pennsylvania State University, College of Medicine, 500 University Drive, C1517, Hershey, PA 17033. E-mail: [email protected] Received 9 July 2014; Revision accepted 13 July 2014 DOI: 10.1002/ccd.25602 Published online 19 August 2014 in Wiley Online Library (wileyonlinelibrary.com)
444
Baquero and Gilchrist
In this report, the authors demonstrated the feasibility and safety of the routine use of this innovative smaller sheath; however, this finding must be tempered by (1) acknowledging the limitations imposed by the relatively small sample size, (2) the single center experience, and (3) nonrandomized controlled trial design that excluded patients with previous TR procedures. These issues and other confounders may limit the applicability to the general population. Ultimately, comparison with currently available 6 Fr sheaths will be necessary to prove noninferiority and confirm decreased vascular access-site complications and RAO. The study by Aminian et al. represents the first published clinical experience of this new approach to a slimmer TR introducer device. With the most notable exception of Japan and few other European countries that have been aggressive in developing and using state of the art technology to accomplish sleeker TR diagnostic and interventional procedures, the newer seasoned radialists in this hemisphere of the world remain limited to equipment adapted from transfemoral use and shoehorning of existing tools. Part of the blame rests with industry’s ambivalence over the viability of the TR market, but further impediment stems from regulatory hurdles and tariff costs of international trade, all factors that contribute to inertia in the field. The results of Aminian et al. are encouraging as they show that there are still
opportunities for innovative ideas that may further improve TR procedures. While confirmation in a properly powered clinical trial would be welcomed in addition to this preliminary study, these are realistically expensive. Nevertheless, new approaches that permit more technology to pass through less diameters is exactly the type of innovation that radial operators dream about moving forward. REFERENCES 1. Saito S, Ikei H, Hosokawa G, Tanaka S. Influence of the ratio between radial artery inner diameter and sheath outer diameter on radial artery flow after transradial coronary intervention. Catheter Cardiovasc Interv 1999;46:173–178. 2. Rao SV, Cohen MG, Kandzari DE, Bertrand OF, Gilchrist IC. The transradial approach to percutaneous coronary intervention: Historical perspective, current concepts, and future directions. J Am Coll Cardiol 2010;55:2187–2195. 3. Tizon-Marcos H, Barbeau GR. Incidence of compartment syndrome of the arm in a large series of transradial approach for coronary procedures. J Interv Cardiol 2008;21:380–384. 4. Pancholy S, Coppola J, Patel T, Roke-Thomas M. Prevention of radial artery occlusion-patent hemostasis evaluation trial (PROPHET study): A randomized comparison of traditional versus patency documented hemostasis after transradial catheterization. Catheter Cardiovasc Interv 2008;72:335–340. 5. Aminian A, Dolatabadi D, Lefebvre P, Zimmerman R, Brunner P, Michalakis G, Lalmand J. Initial experience with the glidesheath slender for transradial coronary angiography and intervention: A feasibility study with prospective radial ultrasound follow-up. Catheter Cardiovasc Interv 2014;84:436–442.
Catheterization and Cardiovascular Interventions DOI 10.1002/ccd. Published on behalf of The Society for Cardiovascular Angiography and Interventions (SCAI).
Editorial Comment Smaller is Better for the Radialist Giselle A. Baquero, MD, and Ian C. Gilchrist,* MD, FSCAI Pennsylvania State University, College of Medicine, Heart and Vascular Institute, MS Hershey Medical Center, Hershey, Pennysylvania
An Achille’s heel of the transradial (TR) technique is the mechanical limitation related to the finite radial artery diameter and its tendency to spasm that further reduces its functional luminal diameter. This restricts routine use of sheath and guide catheters to 5 or 6 French (Fr) in most patients [1]. Standard introducer sheaths have an outer diameter that is about 2 Fr sizes larger than the outer diameter of the corresponding guide catheter. This external diameter was an engineering requirement needed to design a sheath robust enough to survive the angle of incident required to enter the femoral artery without kinking. TR access kits evolved with smaller introducer diameter wires, access needles, and tapered sheath dilators, but the ultimate vascular sheath diameter remained the same as the legacy sheaths used in the femoral artery. Local radial complication rates increase significantly with escalation in sheath size. These complications comprise chronic regional pain syndrome, early and late radial artery occlusion (RAO), radial artery perforation [2] and more rarely yet radial artery perforation with forearm hematoma or compartment syndrome [3]. Although largely asymptomatic, the development of RAO may be the most pernicious complication as it precludes future intervention via the same radial artery and represents an ablation of the artery. This particular complication may be reduced by avoiding prolonged high-pressure compression of the radial artery after sheath removal by practicing perfused hemostasis [4], universal anticoagulation, and reducing arterial trauma with smaller diameter equipment. This latter approach has until recently only been possible at the expense of reduced guide catheter support and considerable restriction in the use of adjunctive interventional devices or dual balloon procedures. One potential solution may involve the use of sheathless guide catheters but most of these catheters require a 4 or 5 Fr introducer sheath to start and commercial products have been relatively C 2014 Wiley Periodicals, Inc. V
costly in most markets. Between eliminating the vascular sheath or reducing the diameter of the guiding catheter, remains improvements in the vascular sheath itself. As the angle of incidence to enter the radial artery is much shallower than the required for the femoral artery, a third approach to reducing vascular trauma may be to decrease the thickness of the vascular sheath wall itself for radial use as sheath kinking is not a particular concern for radial operators. Aminian et al. described their experience in using a new commercially available (in USA) sheath that has taken advantage of reducing the sheath wall thickness to decrease the net sheath diameter. This innovative sheath is a dedicated radial sheath with hydrophilic coating, an inner diameter appropriate for 6 Fr angiographic catheters yet an outer diameter equivalent to available 5 Fr sheaths. This paradoxical improvement is accomplished by reducing the thickness of the sheath wall from 0.20 to 0.12 mm while maintaining an internal diameter of 2.22 mm with a resultant decreased in the outer diameter from 2.63 to 2.45 mm. The study was aimed to evaluate procedural success and accesssite complications including development of RAO during routine studies while using this thinned wall sheath [5]. The authors analyzed 114 patients out of which 24% had acute coronary syndrome with 9% undergoing primary percutaneous coronary intervention (PCI). They use adjunctive interventional technologies in 30% of the PCI patients with only 1 case requiring accesssite crossover to femoral due to difficulty engaging the guide catheter secondary to abnormal implantation of the right coronary artery. Five percent of their patients experienced minor hematomas, 4% symptomatic radial spasm most of which had radial arteries anatomical variations seen on upper-limb retrograde angiography and only one patient developed RAO detected by Doppler ultrasound at 1 month follow up. Conflict of interest: Nothing to report. *Correspondence to: Ian C. Gilchrist, MD, FSCAI, Pennsylvania State University, College of Medicine, 500 University Drive, C1517, Hershey, PA 17033. E-mail: [email protected] Received 9 July 2014; Revision accepted 13 July 2014 DOI: 10.1002/ccd.25602 Published online 19 August 2014 in Wiley Online Library (wileyonlinelibrary.com)
444
Baquero and Gilchrist
In this report, the authors demonstrated the feasibility and safety of the routine use of this innovative smaller sheath; however, this finding must be tempered by (1) acknowledging the limitations imposed by the relatively small sample size, (2) the single center experience, and (3) nonrandomized controlled trial design that excluded patients with previous TR procedures. These issues and other confounders may limit the applicability to the general population. Ultimately, comparison with currently available 6 Fr sheaths will be necessary to prove noninferiority and confirm decreased vascular access-site complications and RAO. The study by Aminian et al. represents the first published clinical experience of this new approach to a slimmer TR introducer device. With the most notable exception of Japan and few other European countries that have been aggressive in developing and using state of the art technology to accomplish sleeker TR diagnostic and interventional procedures, the newer seasoned radialists in this hemisphere of the world remain limited to equipment adapted from transfemoral use and shoehorning of existing tools. Part of the blame rests with industry’s ambivalence over the viability of the TR market, but further impediment stems from regulatory hurdles and tariff costs of international trade, all factors that contribute to inertia in the field. The results of Aminian et al. are encouraging as they show that there are still
opportunities for innovative ideas that may further improve TR procedures. While confirmation in a properly powered clinical trial would be welcomed in addition to this preliminary study, these are realistically expensive. Nevertheless, new approaches that permit more technology to pass through less diameters is exactly the type of innovation that radial operators dream about moving forward. REFERENCES 1. Saito S, Ikei H, Hosokawa G, Tanaka S. Influence of the ratio between radial artery inner diameter and sheath outer diameter on radial artery flow after transradial coronary intervention. Catheter Cardiovasc Interv 1999;46:173–178. 2. Rao SV, Cohen MG, Kandzari DE, Bertrand OF, Gilchrist IC. The transradial approach to percutaneous coronary intervention: Historical perspective, current concepts, and future directions. J Am Coll Cardiol 2010;55:2187–2195. 3. Tizon-Marcos H, Barbeau GR. Incidence of compartment syndrome of the arm in a large series of transradial approach for coronary procedures. J Interv Cardiol 2008;21:380–384. 4. Pancholy S, Coppola J, Patel T, Roke-Thomas M. Prevention of radial artery occlusion-patent hemostasis evaluation trial (PROPHET study): A randomized comparison of traditional versus patency documented hemostasis after transradial catheterization. Catheter Cardiovasc Interv 2008;72:335–340. 5. Aminian A, Dolatabadi D, Lefebvre P, Zimmerman R, Brunner P, Michalakis G, Lalmand J. Initial experience with the glidesheath slender for transradial coronary angiography and intervention: A feasibility study with prospective radial ultrasound follow-up. Catheter Cardiovasc Interv 2014;84:436–442.
Catheterization and Cardiovascular Interventions DOI 10.1002/ccd. Published on behalf of The Society for Cardiovascular Angiography and Interventions (SCAI).
