Curriculum in Cath Lab: Coronary Hardware-Part II
Guidewire Selection for Coronary Angioplasty
Sundeep Mishra, Vinay K Bahl
Department of Cardiology, All India Institute of Medical Sciences, New Delhi

behavior, as perceived by the operator. This is better appreciated with non-coated / hydrophobic coated, coil tipped wires and it is reduced with hydrophilic coating. Whereas with polymer tipped wires it may be minimal or
absent, making inadvertent perforation, dissection or traversing a plaque more likely. 10. Prolapse tendency: It is the tendency of the guidewire
tip to kink or buck-up once passed into a vessel. It is common with floppy tip guidewires and wires with abrupt taper. It can be a problem when lesions are very tight or occur in angulated vessels. If, however, this phenomenon occurs after crossing the lesion, it can be beneficial because it obviates the possibility of guidewire trauma to distal vessel during prolonged procedures.
COMPONENTS OF GUIDEWIRE
Guidewires generally consist of three components: a central “core” composed of stainless steel or Nitinol (Cross Wire™, IQ™), a distal flexible spring coil of stainless steel, platinum or tungsten, with/without radio-opaque markers, attached to the main body with a hinge joint and a coating such as silicone, Polytetrafluroethylene (PTFE) or hydrophilic substances (Fig. 1A). Central Core: Central core is the basic component of the guidewire. It contributes to the trackability, torqueability and push transmission of the interventional device. The greater is the strength of the material constituting the central core and the greater its thickness, the greater the torqueability and body support provided by it. Stainless steel contributes to more pushability, torqueability and good shape ability, but it
is less flexible than newer core materials like Nitinol and also has a tendency to kink. Super-elastic alloy like Nitinol are designed for kink resistance, excellent flexibility, steering and better tip mobility 3. The tip shape with Nitinol is more durable and less likely to prolapse. However, the downside is that it may store torque without necessarily transmitting it to
the tip, therefore wires with single Nitinol core have a tendency to “wind up”. Central core may be a single barrel, double barrel or tapered barrel. When the core extends to the tip, it is called a single barrel (uni-body) guidewire. If the core is made up of two barrels, it is called double barrel. If

Correspondence: Dr Sundeep Mishra, Associate Professor of Cardiology, All India Institute of Medical Sciences, New Delhi
email: drsundeepmishra@hotmail.com

however, a single core tapers down to tip with no distal spring coil, it is called a tapered core or a unicore construction. Single barrel guidewires provide maximum support (trackability) but have least push transmission (steerability). They also allow for precise tip control, torqueability and
have excellent tactile feel. They are useful only in relatively straight-forward, Type A lesions. Double barrel guidewires have better push transmission. Most workhorse guidewires in current use have a double barrel construction. The maximum push transmission can be achieved by having a tapered (unicore) guidewire or having a smooth transition between the core and distal tip (Responsease™ technology – Whisper or Pilot wire). Unicore wires also provide a smoother transition, enhanced torque response and are less prone to tip prolapse than dual core design but may have lesser tip mobility and provide less support for device delivery. The
distal taper and the hydrophilic coating also contribute to enhanced steerability. They are useful as initial wire for “difficult to cross lesions” and lesions in tortuous artery. Spring Coil: The spring coil surrounds the inner core on the body of the wire to keep outer diameter consistent at

0.014".The distal spring coil (may be composed of one or more material) and its joint with central core contributes to torque transmission and tip mobility. Use of special alloys in the spring coil may permit better shape memory retention. Stainless steel coils have more strength, whereas platinum coils are softer and are more radio-opaque. Another modification to enhance tip shapability and shape “wire memory” is to have a “shaping ribbon”. Here the guidewire tip is be made of two pieces instead of one, a tapered part of central core and a shaping ribbon (Abbott Vascular Balance
family of guidewires). The shaping ribbon also improves flexibility of the tip and makes it atraumatic. In some guidewires instead of metal coil tip there could be a polymer tip (Boston Scientific ChoICE PT™, PT Graphix™). The
polymer sleeve is known to be very smooth and improve trackability and pushability; however, one drawback is the loss of tactile feel as compared with metal coils. The loss of tactile feel partly accounts for the increased risk of perforation or dissection with polymer tip wires. Polymer tipped wires are particularly useful in negotiating micro-channels often found in total occlusions of relatively recent origin.

armamentarium. The generally have a tip load range between > 0.5 - < 0.9 g. They strike a nice balance between flexibility, support and steerability. Since one or two of these wires constitute the bulk of use in any given cath. lab they are also called frontline guidewires or “workhorse guidewires” (Table 1).
Table 1. Workhorse Guidewires

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• ATW/ATW Marker
• Stabilizer
• BMW / BMW Universal
• Zinger
• Cougar XT
• Asahi Light / Medium
• Asahi Standard
• Asahi Prowater Flex
• Choice Floppy
• Luge
• IQ
• Forte Floppy
• Runthrough NS
• Galeo

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All Track Wire (ATW™) / ATW™ Marker wire (Cordis Inc.) is a general purpose, moderate support guidewire with floppy tip and integrated Flex-Joint ™ bond which contributes to flexibility and precise steering and atraumatic vessel tracking. The central core is coated with PTFE providing
non-thrombogenic and durable platform for smooth delivery of multiple devices. The distal 3 cm radio-opaque tip is however, uncoated providing for good tactile response. For measurement of lesion length, four markers span 31 mm in 10 mm increments proximal to the radio-opaque tip. The distal placement of these markers reduces interference in the working
zone and light radio-opacity of these markers allows easy distinction from device marker bands (Figure 2).These markers allow for accurate measurement of lesion length which is especially helpful when direct stenting is planned. The only limitation of this wire is relatively poor tip support and lack of tip durability (multi-lesion/multi-vessel interventions may not be possible with a single wire). Stabilizer™ marker wire, (Cordis Inc.). Basic design is like ATW but provides slightly more support and its tip is more resilient. Its highly visible six marker bands span 75 mm in 15 mm increments. Zinger™ (Medtronic Inc.) is a frontline wire where stainless steel core wire provides excellent torque transmission for advanced steerability and optimal control. It is available in light, medium and support versions offering different support levels for a variety of clinical situations. Figure 2 Cougar XT™ (Medtronic Inc.) is medium weight, Nitinol wire with

Table 2. Extra-support Guidewire

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A) Extra Support Guidewire
• BHW
• Stabilizer Plus / Stabilizer XS
• Zinger Support
• Thunder
• Choice Extra-support
• Forte Extra-support
• All Star
B) Super Extra Support Guidewire
• Asahi Grand Slam
• Iron Man
• Mail Man
• Platinum Plus

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Balanced Heavy Weight (BHW™) (Abbott Vascular Inc.) has a basic design like BMW wire except that its core provides more support. The Hi-Torque All Star™ guidewire is a second generation high-torque and extra-support guidewire. It features a softer, less traumatic tip for good lesion access, and has a large diameter stainless steel inner core that offers good support and vessel-straightening for stenting. A PTFE clear sleeve over the wire’s working area has been added, providing a constant .014" outer diameter for an even better catheter fit. The All Star is an excellent wire for use when a high level of guide wire support is required for stent delivery. Iron Man™ (Abbott Vascular Inc.) guidewire represents an advance in supportive guide wire technology that can be used for delivery of bulky devices like atherectomy catheters. It gives about the highest support among all the heavy duty guidewires (Figure 4). It is a stiff wire with poor steerability. Its rigidness is used to straighten vessel segments and allow better transmission of forces pushing balloons or stents. This property comes from the tendency of the wire to retain its shape rather than conform to the contours of the vessel. This feature makes “cheese cutter” effects on the vascular intima at their bends. This effect may be demonstrated angiographically by a “pleating artifact” and in extreme situations could lead to a transient “no-reflow” state. Though this wire transmits more force to the balloon or the stent, sometimes it could actually make device delivery more difficult in tortuous vessels. Stabilizer Plus™ (Cordis Inc.) has a thicker core and broad transition design contributing to outstanding support and flexibility for delivering longer stents and bulkier devices in complex and tortuous anatomy. Stabilizer XS™ (Cordis Inc.) provides even more support, allowing for maximum chance for delivery of a device. Thunder™ (Medtronic Inc.) guidewire has a stainless steel, core-to-tip design, a short distal taper, a single coil tip and

perforations4,5. Therefore specialized guide catheter, guidewire and other techniques are employed to overcome this problem6. Lesions of tortuous vessels require more steerability and trackability of the guidewire. To reduce the friction and thus enhance steerability and tip response, nearly all wires have a lubricious coating. In performing PCI on a lesion in a tortuous artery,
conventionally a two wire technique is followed. Initially the first wire used is a very soft tip wire (to avoid dissection and perforation), which has an improved torque response, is extremely flexible and kink resistant (may be having Nitinol core). The use of a guide wire of lower stiffness may lessen the friction force of the catheter upon the vessel wall and obstruction allowing it to glide through multiple bends. However, the reduced stiffness may also lead to insufficient pushability and cause prolapse of the guide wire. In that case tapered cone guidewires may be useful. If the wire is unable to cross the lesion, support to wire may be improved by partial advancement of balloon catheter or a transport catheter (which also improves torque control and steerability). However, even though the soft guidewires may negotiate the tortuous anatomy they may not provide enough body support for device tracking. Therefore, once lesion is crossed, the soft guidewire may have to be exchanged with extra-support guidewires. Heavy-duty guidewires are not well suited as primary guidewires because of their stiffness and poor torque control, however, as a second wire (once they are exchanged with floppy guidewires), they provide excellent support and will permit enhanced tracking of balloons, stents and other interventional devices. Even when used as second wires these extra-stiff guidewires are very prone to straightening arteries and may cause accordion effect and pseudo-lesions7-11. As a result currently, more and more operators prefer new generation of guidewires, which are not only flexible, kink resistant and have improved torque response but also provide
enough support for device delivery thus obviating the need for two wire strategy. Asahi Grand Slam, Terumo Runthrough NS are some frontline wires which are specially adapted to be used as single wires in challenging tortuous anatomy.
Table 3 Floppy Guidewires

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• Whisper
• Pilot
• Wizdom / Wizdom ST
• Reflex
• Cougar LS
• Zinger Light / Zinger Marker
• In - Silk
• Rinato
• Wiggle

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