Lesion preparation






Goal


To adequately prepare the target lesion to facilitate stent delivery and expansion.



When is lesion preparation needed?


( Fig. 9.1 )




Figure 9.1


Lesion preparation algorithm.


Lesion preparation (in most cases with balloon angioplasty) should be performed in nearly all lesions because it:



  • 1.

    Facilitates stent delivery and decreases the risk of stent loss.


  • 2.

    Helps determine optimal stent diameter and length (especially when no intracoronary imaging is used and when there is poor flow of contrast distal to the target lesion).


  • 3.

    Facilitates stent expansion and helps determine the need for additional lesion modification (e.g., with atherectomy in heavily calcified lesions) to prevent “stent-regret.”




Confirm successful wiring


Coronary lesion preparation should not be performed until after successful wiring of the lesion (as described in Chapter 8 : Wiring). Optimal distal wire position should be confirmed before balloon angioplasty (and/or stenting).



Large thrombus


If large thrombus is present, coronary thrombectomy is often performed, as described in Chapter 20 : Acute coronary syndromes—thrombus.



Severe calcification


If severe calcification is present, atherectomy or intracoronary lithotripsy is often performed, as described in Chapter 19 : Calcification.



Degenerated SVG or thrombus


Primary stenting (i.e., stenting without balloon angioplasty or other lesion preparation) may be preferred in few lesion types, such as degenerated saphenous vein grafts with friable lesions, or lesion with thrombus (when no thrombectomy is planned or when thrombectomy fails).



Balloon angioplasty



Step 1. Confirm that the guidewire is optimally positioned through the target lesion



Goal


To ensure that the guidewire is optimally positioned (through the target lesion and advanced several centimeters distally, but not into small distal branches that could lead to perforation).



How?


Contrast injection is performed to confirm that the guidewire is in optimal position. If position is suboptimal, the guidewire is repositioned.



What can go wrong?


If the guidewire is suboptimally positioned, complications can happen at the time of balloon inflation, as follows:



Perforation


Causes:




  • Wire entered small distal branch.



Prevention:




  • Ensure optimal distal guidewire position (wire should not be in a small branch to minimize the risk of distal coronary perforation; this is, especially important for branches located close to the occlusion, as the balloon may enter that branch and perforate it while dilating the lesion).



Treatment:




  • Treatment of perforation is discussed in Chapter 26 : Perforation.




Step 2. Confirm that the guide catheter is aspirated and flushed



Goal


To ensure there is no air or debris inside the guide catheter.



How?




  • 1.

    Back bleed the Y-connector.


  • 2.

    Aspirate the guide catheter, then fill with contrast.




What can go wrong?



Distal embolization ( Section 25.2.3 )


Causes:




  • Air sucked into the guide catheter during balloon withdrawal. This is more likely when withdrawing large balloons.



  • Thrombus or plaque entry into the guide catheter while withdrawing a balloon (may be more likely with bulky large diameter balloons, or plaque modification balloons, such as the Angiosculpt, Chocolate, and cutting balloon, Section 30.9.3 ).



Prevention:




  • Guide aspiration followed by flushing, as described above.



Treatment:




  • Air embolization is treated with administration of 100% oxygen, possibly aspiration, and administration of intracoronary epinephrine in case of cardiac arrest. Air embolization usually resolves with supportive measures without needing additional intervention. Air embolization is described in detail in Section 25.2.3.3 .



  • Embolization of plaque or thrombus is usually treated with thrombectomy, as described in Chapter 20 : Acute coronary syndromes—thrombus.




Step 3. Select balloon type and size



Goal


To choose optimal balloon size and type.



How?



Balloon diameter


For achieving lesion expansion : for most lesions the balloon diameter is chosen to match the distal reference vessel diameter (1:1 ratio). The goal is to determine whether the balloon fully expands and therefore no additional lesion modification is needed before stenting. This is particularly important for calcified and in-stent restenotic lesions.


For crossing : for very tight lesions that are hard to cross, small balloons (≤1.5 mm, Section 30.9.2 ) are initially used to modify the lesion entry point and allow subsequent delivery of larger balloons to further modify the lesion before stent placement.



Balloon length


Balloon length should be shorter than the estimated lesion length (to avoid injury of coronary segments proximal or distal to the target lesion that will require implantation of longer length stents).



Balloon compliance


Noncompliant balloons are preferred, because they can also be used for postdilation of the target lesion after stenting. However, they are less deliverable than compliant balloons.



Balloon delivery system


There are two balloon delivery systems: monorail and over-the-wire. Monorail balloons should be used in the vast majority of cases, as they are simpler to use, do not require use of long guidewires, and are easier to deliver because they have a stiffer shaft.



Plaque modification balloons


Some balloons have nitinol wires (such as the Angiosculpt and the Chocolate) or cutting blades (cutting balloon) aiming to modify the lesion and facilitate expansion ( Section 30.9.3 ). Plaque modification balloons are harder to deliver (due to larger profile and lesser flexibility). The cutting balloon also requires slow inflation and deflation. Plaque modification balloons can, in some cases, facilitate expansion of “balloon undilatable lesions” ( Section 23.2 ). The SIS OPN balloon ( Section 30.9.7 ) can be very useful for dilating resistant lesions, but is not currently available in the United States.



Step 4. Prepare the balloon



Goal


Remove the air from the balloon, fill the balloon with a contrast solution, and connect to an indeflator.



How?




  • 1.

    The balloon is removed from its packaging.


  • 2.

    A luer-lock syringe is filled usually with a 50% contrast/50% saline solution. Lower concentration of contrast will speed the inflation/deflation of the balloon but will decrease the balloon visibility.


  • 3.

    The syringe is connected with the balloon proximal hub.


  • 4.

    Negative suction is performed with the syringe plunger positioned up.


  • 5.

    The balloon is connected with the indeflator and negative suction is applied.




Challenges




  • 1.

    Operator finger injury . The balloon/stent should be slowly removed from the container hoop to reduce the risk of the balloon/stent stylet injuring the operator’s hands.




What can go wrong?



Inability to visualize balloon when inflated


Causes:




  • Inadvertent filling of the balloon with saline instead of contrast solution.



  • Poor balloon preparation with significant amount of air remaining in the balloon.



Prevention:




  • Ensure that diluted contrast (and not pure saline) is used to prepare and inflate the balloon. The syringe containing the contrast/saline solution should be appropriately labeled.



  • Ensure that air is removed during balloon preparation.



Treatment:




  • If balloon cannot be visualized once inflated, it should be prepared again using a contrast solution and optimal preparation technique.




Step 5. Load the balloon on the guidewire



Goal


To load the balloon on guidewire to allow subsequent advancement to the target coronary lesion.



How?




  • 1.

    The balloon tip is advanced over the back end of the guidewire.


  • 2.

    This maneuver is easier to perform by holding the guidewire with the thumb and index finger of the left hand with the tip of the guidewire resting on the middle finger at an angle. The balloon tip is held by the right hand and its tip is advanced over the guidewire tip ( Fig. 9.2 panel A).




    Figure 9.2


    Loading a balloon over a guidewire. (Panel A) Holding the guidewire with the thumb and index finger of the left hand with the tip of the guidewire resting on the middle finger at an angle. (Panel B) Using the groove of a syringe plunger.


  • 3.

    A variation of the above maneuver to facilitate advancing the balloon over the guidewire is to place them both in the groove of a syringe plunger ( Fig. 9.2 , panel B).




Step 6. Advance the balloon monorail segment through the Y-connector



Goal


To insert the balloon through the Y-connector into the guide catheter.



How?




  • 1.

    The back end of the guidewire is fixed by an assistant or another operator (or the other hand of the operator if there is no assistant or second operator) ( Fig. 9.3 ).




    Figure 9.3


    Inserting a balloon through the Y-connector.


  • 2.

    For standard Y-connectors: the Y-connector is opened up followed by advancement of the balloon. The Y-connector is subsequently closed.


  • 3.

    For Y-connectors with automated hemostatic valves: there is no need to open the hemostatic valve. The balloon is advanced through the valve.




What can go wrong?



Balloon deformation/damage


Causes:




  • Forceful balloon advancement through too tightly closed hemostasis valve.



  • Cutting balloons may be at higher risk for damage.



Prevention:




  • Open hemostasis valve before inserting balloon or use automated hemostasis devices, such as the Copilot, Guardian, Watchdog, and OKAY II ( section 30.5 ).



Treatment:




  • Replace the damaged balloon with a new one.




Step 7. Advance the balloon to the tip of the guide catheter



Goal


To advance the balloon to the tip of the guide catheter.



How?




  • 1.

    The left hand is holding the Y-connector. The thumb and index finger of the left hand is fixing the guidewire.


  • 2.

    The balloon is advanced without fluoroscopy until the first marker (for 90 cm long guide catheters) or the second marker (for 100 cm long guide catheters) is at the Y-connector.


  • 3.

    The balloon is advanced under fluoroscopy to the tip of the guide catheter.




What can go wrong?



Resistance to balloon advancement


Causes:




  • Guide catheter extensions, when the guidewire wraps around the delivery rod.



  • Guide catheter kinking.



  • Too much equipment inside the guide catheter (too many balloons, wires, stents, etc.) ( Section 30.2.2 ). Deciding the needed guide catheter size based on the types of equipment planned to be used can be estimated using the “Complex PCI Solutions” app ( Section 30.2.2 , Fig. 30.7 ).



  • Wrapped guidewires.



Prevention:




  • If guide catheter extensions are used, place the push rod of the guide extension in a towel to avoid wrapping with the guidewire.



  • If there are additional guidewires and balloons/stents inside the guide, remove them before advancing the balloon.



  • The “Complex PCI Solutions” app ( Section 30.2.2 ) can be used to determine equipment compatibility within various sizes (6, 7, 8 Fr) guide catheters.



Treatment:




  • If the resistance to balloon advancement is at the level of entry through a guide extension cylinder, then the guide extension is removed and reinserted (to correct wire wrapping around the guide catheter extension).



  • If the resistance is due to too much equipment, the balloon is removed and reinserted after some of the equipment is removed.



  • If the resistance is due to guide catheter kinking, the guide catheter is replaced with another guide catheter.




Kinking of the balloon shaft


Causes:




  • Forceful balloon advancement.



  • Resistance to balloon advancement.



Prevention:




  • Avoid forceful advancement.



  • Advance balloon by a short distance with each movement (“small bites”).



Treatment:




  • For small kinks the procedure can usually continue without any changes. The operator should not attempt to “straighten the kink” before inserting the balloon, as this may weaken the shaft and potentially lead to fracture.



  • For large kinks, the balloon should be removed and discarded, as there is risk of balloon shaft fracture ( Section 27.3.1.2 ).




Inadvertent advancement of the balloon into the coronary artery


Causes:




  • Poor visualization, especially in obese patients.



  • Lack of attention to balloon shaft markers.



Prevention:


Feb 4, 2021 | Posted by in CARDIOLOGY | Comments Off on Lesion preparation
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