Various types or equipment, such as stents, guidewires, and various catheters can be lost or entrapped either within or outside the coronary artery . Such equipment can lead to occlusion or perforation of the coronary vessel. It could also lead to systemic embolization, such as embolization to an intracranial artery causing a stroke. Device entrapment is a more grave complication than device loss, and may require emergency surgery for removal . In this chapter we discuss how to prevent, diagnose and treat such complications. Entrapment of the Rotablator burr is discussed in Section 126.96.36.199.3 .
Stent loss or entrapment
Coronary tortuosity and calcification .
Poor vessel preparation prior to attempting stent delivery. In the ROTAXUS trial stent loss occurred in 2% of lesions in the no atherectomy arm of the study versus 0.5% of lesions in the rotational atherectomy arm of the study . Poor vessel preparation may result in stent deformation during attempts to deliver the stent, followed by stent loss when attempting to withdraw the stent into the guide catheter ( Fig. 27.1 ).
Use of small (such as 5 French guide catheters).
Forceful withdrawal of the stent inside the guide catheter (or inside a guide catheter extension, as described below) when resistance is felt .
Use of guide catheter extensions. Stent loss can occur both during advancement of the stent if the stent catches the proximal collar or during stent withdrawal, especially when the stent is deformed.
Stent advancement through a previously deployed stent .
Attempting to deliver equipment via a collateral during the retrograde approach to CTO interventions (which can predispose to both stent loss and wire entrapment ).
Avoid direct stenting, especially in tortuous and calcified vessels.
Meticulous vessel preparation, often using atherectomy in calcified lesions and intracoronary imaging to confirm adequate lesion expansion before attempting stent delivery.
Stent from distal to proximal. Sometimes, however, the need for distal stenting does not arise until after a proximal stent is deployed, for example, in cases of distal edge dissection .
Use a guide catheter extension for delivering stents in tortuous and calcified vessels.
Avoid forceful advancement attempts.
When using a guide catheter extension, always place the external push rod under a towel at the side of the Y-connector to reduce the risk of the guidewires “wrapping around” the guide catheter extension delivery rod.
Do not apply force if resistance is felt while advancing a stent through a guide catheter extension. Instead, remove the guide catheter extension and reinsert it, paying particular attention to avoiding wrapping up of the guidewire and the guide extension delivery rod. Inserting the stent into the guide catheter extension outside the guide catheter and advancing both into the guide catheter at the same time can help avoid stent dislodgement or loss.
Avoid using small (such as 5 French) guide catheters when treating complex lesions, as smaller guide catheters have less room to allow for withdrawal of deformed stents.
Treatment ( Fig. 27.2 )
Location of the lost stent
The location where the stent is lost determines the subsequent steps. If a stent is lost in a coronary artery it should be either retrieved or deployed/crushed. If a stent is lost in a noncritical location in the peripheral circulation (such as the lower extremity or pelvic vessels), it can often be left in place without attempting retrieval .
Occasionally, the lost stents may be difficult to visualize, especially thin strut stents in obese patients with calcified or previously stented coronary arteries. In such cases, intravascular ultrasonography may facilitate localization of the stent .
A lost stent does NOT always need to be retrieved. If the stent is lost in a noncritical location in the coronary artery, stent deployment (if wire position is maintained through the stent) or stent crushing (if wire position through the stent has been lost) can be a faster and safer approach. Similarly, if the stent is lost in a noncritical location of the peripheral circulation (such as the lower extremities), the risks of retrieval attempts often outweigh any potential benefit . Conversely, if the lost stent is located within a critical coronary artery (such as left main or major bifurcation) or peripheral artery (such as cerebral or renal arteries) location, retrieval is required.
Wire position maintained?
Maintaining wire position through the lost stent can greatly facilitate retrieval attempts (by using the small-balloon technique), and also allows for easier deployment if selected. If wire position is lost it is often impossible to rewire the lost stent, limiting retrieval options to snares or the “guidewire twirling” technique. Similarly loss of wire position does not allow deployment, making crushing the only option if retrieval is not needed or desired.
Small-balloon technique ( Fig. 27.3 )
The small-balloon technique can be used when a stent is dislodged from its delivery balloon but guidewire access is maintained through the lost stent. A small balloon is advanced through the stent, inflated distal to the stent, and then withdrawn together with the lost stent.
If the stent is not significantly deformed and the guide catheter is large, the balloon and the stent can be retrieved inside the guide catheter and removed. Often, however, the stent is too deformed to be withdrawn inside the guide catheter: in such cases the inflated balloon, lost stent, and the guide catheter are all removed together from the body ( PCI Manual Online case 10 ). It may be difficulty to advance the balloon through the stent, possibly pushing the stent more distally in the vessel. If the balloon is partially advanced through the stent, it can sometimes be inflated in the proximal-mid part of the lost stent, followed by removal of the entire system.
Snaring is an effective technique for retrieving lost or entrapped equipment. Available snares are discussed in Section 30.18.5 .
Stents lost in the coronary circulation ( Fig. 27.4 )
Once a loop snare is positioned around the stent to be snared, the snare wire is held still and the snare catheter advanced forward until the lasso loop secures the lost stent, followed by withdrawal of the assembly into the guide catheter.
For retrieval of stents lost in the coronary circulation the Micro-Elite snare (Vascular Solutions) (which is 0.014 in. in diameter, has loop sizes of 2, 4, or 7 mm, is 180 cm in length and does not require a delivery catheter) or the 2 mm or 4 mm En Snare (Merit Medical) are commonly utilized. An example of lost stent snaring from the coronary circulation is shown in Fig. 27.5 .
Stents lost in the peripheral circulation
For retrieving stents lost in the peripheral circulation an 18–30 mm En Snare through a JR4 or multipurpose diagnostic or guide catheter is often the snare of choice, because of the three-loop design that facilitates object retrieval. However, it should be used with caution as the snare wires may still cause vessel injury .
Guidewire “twirling” ( Fig. 27.6 )
In this technique, two or more 0.014 in. guidewires are advanced through or around the lost stent, and rotated several times to entangle their distal ends. The guidewires are then withdrawn often bringing the lost stent with them.
Reassess need for retrieval
If attempts to retrieve a stent lost in the coronary circulation fail, the need for retrieval may need to be reassessed, considering the risks and benefits associated with further retrieval attempts, including surgery versus deploying or crushing the stent. In most cases, deploying or crushing the stent is the fastest and safest approach.
Surgical retrieval of lost stents can be challenging and carries high risk of complications. It should, therefore, only be done under extenuating circumstances.
If a stent is lost inside the coronary circulation and wire position is maintained, deployment may be the safest and fastest treatment strategy. Crossing the lost stent with a balloon can sometimes be challenging: using a small balloon can allow advancement within the lost stent, followed by increasingly larger balloons until deployment is optimized. Sometimes, attempts to advance a balloon through a lost stent may lead to more distal displacement of the stent. If a balloon cannot advance through the lost stent (usually due to stent deformation), crushing of the stent could be performed, as described below.
Stent crushing ( Fig. 27.7 )
If wire position is lost within the lost stent and retrieval is not feasible or desired, crushing the stent with another stent can be the strategy of choice, unless the stent is located in a critical location, such as the left main. A coronary guidewire is advanced around the lost stent, a balloon is used to crush the stent against the coronary artery wall, and another stent is placed, “excluding” the lost stent from the coronary circulation. It is important to avoid inadvertently passing through one or more stent struts with the second wire, especially if the lost stent has been partially deployed. This should be suspected if balloon delivery is challenging around the lost stent and rewiring should be performed, ideally using a knuckled polymer-jacketed guidewire ( Fig. 27.8 ). If balloon delivery remains challenging after rewiring, consider rewiring again or using a Glider balloon or a Wiggle guidewire.
Meticulous attention should be given to completely appose the stent struts to the vessel wall to avoid limitations of blood flow through the coronary artery, ideally using intracoronary imaging . Both stent crushing and stent deployment carry risk of restenosis, which is, however, much lower than the potential risk of aggressive stent retrieval attempts. Intentional stent crushing is also being performed during PCI of in-stent coronary chronic total occlusions with encouraging results .
Leave in peripheral artery
If the lost stent is removed from the coronary artery into the iliac or femoral vessels but cannot subsequently be removed through the sheath or the vessel wall, the lost stent could be crushed against the iliac or femoral artery wall using a peripheral stent ( Fig. 5.8 ). Distal stent embolization into a small arterial branch (such as a femoral artery branch) may be left untreated, since the distally embolized stents appear to have a benign clinical course. None of the 12 patients with distal stent embolization in three series had clinical sequela. Hence, the risk of extraction usually exceeds the risk of local complications .
Guidewire entrapment and fracture
CTO Manual Online case 24
Guidewire entrapment and fracture is an infrequent and often preventable complication, but can potentially have devastating consequences, especially if the guidewire unravels .
Jailing of the guidewire during bifurcation stenting.
Guidewire deformation (e.g., during aggressive attempts for guidewire knuckling) ( CTO Manual Online case 24 ).
Withdrawal of a guidewire with a loop at its tip through a proximal stent ( PCI Manual Online case 33 ) .
Use of a buddy wire together with a filter-based embolic protection device (see Section 188.8.131.52.3). Inadvertent stenting over the buddy wire can result in entrapment of the filter, that can be very challenging or impossible to remove .
Severe lesion calcification.
Aggressive pulling of an entrapped guidewire.
Atherectomy over a kinked guidewire.
Some advocate to avoid jailing the side branch guidewire during bifurcation stenting; the risk of side branch occlusion in most cases, however, exceeds the risk of guidewire entrapment.
Avoid aggressive guidewire manipulation, especially in small branches.