PCI in the angulated or tortuous lesion: Difference between revisions
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==Considerations for Alternative Approach== | ==Considerations for Alternative Approach== | ||
The initial strategy can be modified based on the [[angiographic]] success of the delivery and deployment of equipment. When the [[guidewire]], [[balloons]], or [[stents]] cannot navigate the vessel tortuosity or angulation, improved guiding catheter support may improve success. Also, having the patient breathe deeply can help straighten the vessel. | |||
With sufficient experience, the operator will be able to determine whether continued attempts will eventually be successful or whether additional maneuvers and/or equipment change(s) will be more successful. Patients with severely angulated or tortuous lesions that supply large areas of the [[myocardium]] should be considered for [[CABG|coronary artery bypass graft (CABG) surgery]], especially if multivessel disease is present and percutaneous revascularization is deemed high risk or unsuccessful. | With sufficient experience, the operator will be able to determine whether continued attempts will eventually be successful or whether additional maneuvers and/or equipment change(s) will be more successful. Patients with severely angulated or tortuous lesions that supply large areas of the [[myocardium]] should be considered for [[CABG|coronary artery bypass graft (CABG) surgery]], especially if multivessel disease is present and percutaneous revascularization is deemed high risk or unsuccessful. | ||
Revision as of 14:46, 7 July 2010
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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 choosing a guiding catheter, it is important to base your decision 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 side holes is used, intracoronary pharamacotherapy may not be delivered at high concentrations. Generally, the trade off for using a more aggressive guide is an increased likelihood for guide trauma to the proximal vessel. Furthermore, a long femoral sheath can straighten iliac tortuosity and improve guiding catheter support.
The choice of balloon, guidewire, and stent is ultimately based on the operator preference and vessel anatomy. There are some guidelines that can be followed, though. For initial attempts at crossing the lesion, start with a "workhorse" wire. It is important to remember that a stiff guidewire in a very tortuous vessel will frequently lead to vessel pleating and deformation of the vessel. If unable to direct a wire into an angulated vessel, consider using a steerable catheter, such as a Venture catheter, to assist in guiding the wire in the right direction.
Long balloons (30-40 mm) help straighten angulation and are highly conformable. If additional guidewire support is necessary, then Over-the-Wire (OTW) balloon systems may be superior. In such systems, the balloon can be advanced to a position proximal to the lesion, thereby providing additional support. If OTW systems fail, then lower profile monorail and fixed wire systems, such as the SVELTE stent in some countries. Also, shorter stents are easier to deliver than longer stents, and newer bare metal stents, such as those made of a chromium cobalt alloy, may be easier to deliver than older generation stents. Furthermore, newer drug eluting stents (DES), such as Xience/Promus or Endeavor, have smaller strut profiles and may also be easier to deliver, in comparison to first generation DES.
Anticipated Outcomes
In general, high procedural success (>85%) and low complication rates (<3%) have been reported. However, these assessments of outcomes are limited by variable definitions of angulation and tortuosity. More specifically, angulation >60 degrees is associated with an increased risk of failure. Also, rotational atherectomy of lesions >45 degrees should be avoided, as they are have lower success rates and an increased risk of dissection and mortality.
Stenting of highly angulated lesions may be associated with higher restenosis rates at the points of angulation.
Real-time Technical Assessment
Easy torque response, advancement, and absence of distal wire kinking suggest an intraluminal position. Optimal intraluminal position of the guidewire, angioplasty balloons, and stents can be confirmed angiographically by using standard proximal injections through the guiding catheter, or by using distal injections through the central lumen of the angioplasty balloon or transit catheter.
Considerations for Alternative Approach
The initial strategy can be modified based on the angiographic success of the delivery and deployment of equipment. When the guidewire, balloons, or stents cannot navigate the vessel tortuosity or angulation, improved guiding catheter support may improve success. Also, having the patient breathe deeply can help straighten the vessel.
With sufficient experience, the operator will be able to determine whether continued attempts will eventually be successful or whether additional maneuvers and/or equipment change(s) will be more successful. Patients with severely angulated or tortuous lesions that supply large areas of the myocardium should be considered for coronary artery bypass graft (CABG) surgery, especially if multivessel disease is present and percutaneous revascularization is deemed high risk or unsuccessful.
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