Burr Entrapment – Case 1
- 72-year-old male who presented to the hospital with chest pain (CCS Class III) and was referred for staged PCI of the LM bifurcation.
Past Medical History
- HTN, HLD, Former Tobacco Use, CAD s/p Multiple PCI’s
- LVEF 15%
- Prior Cardiac Catheterization: Distal LM 90-95% stenosis s/p successful PCI, mid LAD 90-95% stenosis s/p successful PCI, proximal LCx 50-60% stenosis, proximal RCA 80-90% stenosis.
- Home Medications: Aspirin, Clopidogrel, Atorvastatin, Carvedilol, Lisinopril, Spironolactone, Furosemide
- Adjunct Pharmacotherapy: Clopidogrel, Bivalirudin
- 70-80% calcified lesion in the left main (LM)
- 50-60% in-stent restenosis in the proximal left circumflex (LCx)
- 70-80% calcified lesion in the mid left anterior descending (LAD) artery with hazy appearance on angiography
- Underwent Impella supported intervention of the LM bifurcation.
- A stent was placed in the LM with final KBI.
- Wires were removed for final angiography; however, procedure was complicated by abrupt closure of the mid LAD at the location where there was haziness seen on the initial left coronary artery angiogram.
- IC vasodilators were administered through the guide catheter and failed to improve flow.
- LAD was wired and a balloon was used to dotter the mid LAD, restoring flow.
- Rotational atherectomy was performed using a 1.75mm rota burr. However, when retracting the burr, it became entrapped in the distal stent struts of the recently placed stent in the LM.
- Multiple techniques were used to retrieve the entrapped burr but all were unsuccessful (manual traction, upsizing the sheath and performing PTCA, Mother in Child catheter technique).
- While attempting to retrieve the entrapped burr, the procedure was further complicated by LSD of the proximal stent segment due to aggressive guide catheter handling, LSD of the distal stent segment due to manual traction, and exposure of a dissected LM segment.
- Further percutaneous attempts to retrieve the burr were abandoned and CT Surgery was consulted for surgical revascularization and burr retrieval.
- Underwent 3-Vessel CABG with successful retrieval of the burr.
- Patient was discharged home 8 days later without further sequelae.
- What is the likely explanation or reason why the complication occurred?
- Two mechanisms for burr entrapment include:
- ‘Kokesi’ phenomenon: When performing rotablation at high RPM, frictional heat is generated and it may enlarge the space between plaque. In addition, the coefficient of friction when the burr is in motion is less than that at rest, which may facilitate the burr to pass the calcified lesion easily without debulking a significant amount of calcified tissue. Once the burr traverses the lesion, and the plaque cools the between the plaque is again reduced, and the ledge of calcium proximal to the burr prevents the withdrawal of the burr, which is known as ‘Kokesi’ phenomenon, a name given after a Japanese doll.
- Burr can become entrapped within a severely calcified ,long and/or angulated lesion when the burr is advanced aggressively. When a large burr is pushed forcefully against this kind of lesion without an appropriate pecking motion, significant decelerations occur and this produces more debris which increases the risk for slow flow/no-reflow and burr entrapment.
- LM stent LSD and LM dissection occurred because of aggressive guide catheter movement/handling while attempting to retrieve the entrapped burr.
- LAD abrupt vessel closure (AVC) likely due to wire related dissection which resulted in thrombus formation.
- How could the complication have been prevented?
- The burr is oval shaped and coated with diamonds at its distal end, allowing for antegrade ablation. However, the proximal end is smooth and not coated with diamonds, prohibiting retrograde ablation. If a burr is advanced beyond a tight calcified lesion or embedded in a long, angulated and heavily calcified lesion, it can be entrapped. Burr entrapment can often be avoided using the following techniques/strategies:
- Use a gentle pecking motion with shorter runs of ablation (<20s).
- Do not exert excessive forward force during burr advancement. If the burr is advanced aggressively, it causes decelerations and can become embedded in the calcified lesion.
- The risk for burr entrapment is greater when the lesion is long and heavily calcified, and the vessel is highly angulated.
- When advancing the burr, avoid decelerations >5000 RPM because this results in more debris production and increases risk for slow flow/no-reflow and burr entrapment.
- When using a smaller burr, avoid using a higher speed of rotation (>180k RPM) to prevent ‘Kokesi’ phenomenon.; optimal speed is around 150k RPM.
- If the vessel or lesion is highly tortuous/angulated, a stiffer wire can be used to straighten the vessel or lesion to lessen the resistance and reduce wire bias.
- Avoid performing rotational or orbital atherectomy in vessels which are highly tortuous, especially if severe wire bias is present.
- Rotational atherectomy should be avoided after placement of a fresh stent. In this case, atherectomy using a larger burr could have been deferred, or we could have used a cutting/scoring balloon instead.
- There was a hazy lesion present in the mid LAD for which the differential diagnosis included a calcified nodule, thrombus, hematoma or less likely SCAD. Imaging would have helped in identify the etiology of the lesion. In hindsight, this lesion in the LAD should have been treated prior to performing LM intervention.
- Is there an alternate strategy that could have been used to manage the complication?
- Several bailout techniques can be used to retrieve a trapped burr, but prior to proceeding forward.
- Assure patient is adequately anticoagulated (ACT >300) before attempting percutaneous retrieval.
- Administer intracoronary vasodilators to facilitate antegrade coronary flow and relieve possible spasm.
- Potential strategies for retrieval of an entrapped burr include the following:
- 1st: Manual traction of the rotablator system by pulling the burr, guidewire and/or guide catheter as a unit. This can be performed on or off Dynaglide. The vessel is at risk for perforation, dissection, and AVC. In addition, the burr shaft can fracture. If you are pulling the burr and guidewire as unit (and not the guide catheter), remember to disengage the guide catheter to prevent injury to the coronary artery from it deep seating during traction.
- 2nd: Pass a second wire (hydrophilic-coated guidewire) beyond the trapped burr, followed by balloon dilatation around the burr. This may alter the architecture of the calcified lesion and possibly free the trapped burr. However, a 4.3 Fr rotablation drive shaft sheath may prohibit introduction of a balloon catheter into the guide catheter (consider this possibility if using a 6 or 7 Fr guide catheter). To overcome this, use a two-catheter strategy (Ping-Pong technique) where a second vascular access is obtained and equipment necessary for burr retrival is introduced through. If a single guide catheter strategy is preferred, there are two options. On approach includes cutting the rota system near the advancer, and remove the sheath to expose the driveshaft surrounding the rota-wire. This approach makes room for introduction of a second guidewire and balloon. This approach is useful when using a 6 Fr guide catheter. Alternatively, you can upsize the access sheath and guide catheter to a 8 Fr.
- 3rd: Mother-child catheter technique can be used to wedge the burr and facilitate retrieval. The system is cut near the advancer, and the Teflon sheath is removed exposing the driveshaft which surrounds the rota-wire. A child catheter (monorail 5 Fr Guideliner or 5 Fr Guidezilla) is inserted over the exposed drive shaft and positioned as close as possible to the entrapped burr. With simultaneous traction on the burr shaft and counter-traction on the child catheter, the catheter tip wedges between the burr and the surrounding plaque, exerting a larger and direct pulling force to retrieve the burr.
- 4th: Exclusion with a stent (As was done in this case).
- 5th: Emergent surgical retrieval should always be the last option for removing an entrapped burr, but is often required.
- What are the important learning points?
- Interventional cardiologists who uses rotablation, must be familiar with complications associated with its use and their management, particularly burr entrapment which is a rare but serious complication (incidence is ~0.4%, and occurs more frequently when rotablation is used off-label).
- Prior to retracting the burr using the various techniques above, consider disengaging the guide catheter and holding it fixed with one hand (usually the left) to prevent injury to the coronary artery from it deep seating while pulling the equipment with the opposite hand (usually the right).