PCI in the angulated or tortuous lesion
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Overview
Severe tortuosity and moderate-to-severe calcification have long been identified as significant predictors of procedure failure, as well as worse clinical outcomes.
Angulated Lesions
- Balloon angioplasty of highly angulated lesions is associated with an increased for risk coronary dissection.
- In the settings of coronary stenting, angulated lesions represent a challenge due to the inability of delivering the stent to the stenosis and straightening of the arterial silhouette after stent implantation that may predispose to the presence of stent fracture.
- Vessel curvature at the site of maximum stenosis should be measured in the most unforeshortened projection using a length of curvature that approximates the balloon length used for coronary dilation.
Treatment
In the treatment of angulated and tortuous lesions, the main goals include successfully delivering the equipment, avoiding complications, and maximizing procedural success. Complications to avoid include vessel perforation, dissection, and premature stent deployment. Procedural success includes the restoration of normal epicardial flow and myocardial perfusion.
When treating angulated and tortuous lesions, the treatment choices include guiding catheters, guidewires, PTCA balloons, and/or stents.
There are specific guiding catheters that may be selected so that coaxial alignment may be optimized. For instance, larger guiding catheters (8 French) offer improved support. Additionally, the material composition of the catheter is also important, as the material affects torque control, kink resistance, risk of vessel trauma, and stiffness. Different catheters can also be used depending on whether you are working with the left or right system. Extra backup (XB) guiding catheters in the left coronary system, and Ampltaz left (AL) guiding catheters in the right coronary system, can provide improved support. However, these catheters can increase the risk of guide trauma to the proximal vessel, so extra care must be taken.
Conventional 0.014-inch guidewires are often sufficient when treating angulated and tortuous lesions, but other options may offer distinct advantages. For instance, stiffer-tip guidewires offer a greater ability to manipulate the tip, while tapered-tip guidewires may be useful if the wire prolapses away from the lesion. Although stiff wires are better able to track balloons to lesions than flexible wires, they may handle poorly and be more likely to result in an adverse event. Since extra-support wires have a stiffer shaft, they may help straighten tortuosity and ease movement. However, extra-support wires can also increase the likelihood of vessel pleating. Thus, extra care should be taken depending on the chosen type of guidewire.
It is possible to first cross the lesion with a less rigid wire and then exchange it for a heavy-duty wire through a balloon lumen. This can be accomplished in an over-the-wire (OTW) system or an intracoronary catheter such as an Ultrafuse or Transit catheter. OTW balloon systems push and track more easily than monorail systems[1] and enable guidewires to be exchanged.
Monorail catheters, also known as rapid-exchange catheters, were designed to allow an easier exchange of catheters by a single operator. They consist of a short catheter shaft that contains two lumens; one is used for balloon inflation and extends through the whole length of the catheter, and the second houses the guidewire and only runs through a portion of the shaft. While monorail catheters have advantages, including its enhanced visualization and its low-profile balloons, its major limitation it how technically demanding it can be[2].
Fixed balloon catheters, which have distal flexible steering tips with the balloon mounted on a central hollow wire, may deliver more easily across tortuous vessels or stenosis, but also cannot recross the lesion without first removing the system[3]. Furthermore, steerable catheters, such as the Venture catheter, may allow for improved direction of the wire into extremely angulated side branches.
In some circumstances, the addition of a second guidewire across the stenosis, commonly referred to as a “buddy wire”, will aid in the delivery of the device. If a buddy wire is used, a wire of different stiffness and lubricity from the original wire is usually chosen.
Furthermore, concerns regarding wire entrapment and microembolization of wire coating should be considered. These topics are actively being researched, but to date, they have not proven to be significant clinical problems.
Making a Selection
When making a selection, it is important to choose a guiding catheter based on the vessel location, takeoff, and size so that coaxial alignment and support are maximized.
"Deep seating" the guide or selective coronary intubation may provide improved support to deliver guidewires, balloons, or stents. However, it also comes with the price of increasing the risk of vessel injury. If using this technique, a guide with side holes helps to maintain perfusion. If a guide catheter with sideholes is used, intracoronary pharamacotherapy may not be delivered at high concentrations.
References
- ↑ Bonzel T, Wollschläger H, Kasper W, Meinertz T, Just H (1987). "The sliding rail system (monorail): description of a new technique for intravascular instrumentation and its application to coronary angioplasty". Z Kardiol. 76 Suppl 6: 119–22. PMID 2964142.
- ↑ Kern, Morton J. and Deligonul, Ubeydullah. Interventional Cardiac Catherization Handbook. St. Louis: Mosby, Inc., 1996. 24-26
- ↑ Kern, Morton J. and Deligonul, Ubeydullah. Interventional Cardiac Catherization Handbook. St. Louis: Mosby, Inc., 1996. 24-26