"Rotational Atherectomy," Excerpted from Invasive Cardiology: A Manual for Cath Lab Personnel

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The primary purpose for the development of the Rotablator was to tackle the rock-hard, calcified lesions that standard angioplasty balloons have failed to effectively treat. It is the belief of many physicians that the selective tissue ablation effect of the Rotablator is the best choice for calcified coronary lesions.3 The system is powered by pressurized nitrogen, rather that electricity, and its speed is monitored digitally.

Equipment

The following equipment is needed in order to begin the procedure of rotational atherectomy: Rotablator burr, guidewire, guiding catheter, hemostatic valve, Rotablator console and nitrous tank.

The guiding catheter will be selected by the physician performing the procedure. The manufacturer, Scimed (Boston Scientific, Maple Grove, MN) recommends the following guidelines when selecting the French size of the guide. ⁴

8F guide for burr sizes ranging from 1.25 to 2.0 mm

9F guide for burr sizes ranging from 2.15 to 2.38 mm

10F guide for the 2.5 mm burr

Depending on the manufacturer, current 8F guide catheters may have an .082 inch or a .086 inch inner lumen. The latter will safely fit up to a 2.55 mm burr. One must use a 10F guide when a 2.5 mm burr is anticipated. The inner lumen of currently available 9F guide catheters will not accept a 2.5 mm burr.

There are four different Rotablator guidewires on the market today: C wire, A wire, Roto-Floppy wire and Roto-Standard wire. All four wires are 325 mm in length and have a maximum shaft diameter of .009 inch. The guidewire shafts are uncoated stainless steel (any coating on the wire could potentially be stripped off of the wire by friction produced by the high-speed rotating burr). The maximum lumen tip diameter on the A and C wires is .017 inch whereas it is only .014 inch on the floppy and standard wires.
The shorter lumen tip diameter on the floppy and standard wires allows for a greater steerability by the operator in comparison to the A and C wire. The C and floppy wires are softer and thus less traumatic to the artery than the A and standard wires. Most physicians will start the procedure with a soft wire (C or floppy) rather than a stiff wire (A or standard), thus decreasing the chance of potential complications associated with the manipulation of guidewires. If they are unable to cross the lesion with the softer wire they may then change to a stiffer wire. The Roto-Floppy wire is the most flexible and steerable of the wires. ⁴

Each of the Rotablator guidewires comes packaged with a guidewire clip. The clip is intended to be used as a torque device. The manufacturing company recommends using the clop as a torque device to eliminate any kinking, sharp bends or fractures while using the wire. The wire clop also acts as a secondary brake to prevent the wire from vibrating during burr exchanges.

The Rotablator catheter consists of an oval-shaped burr coated with diamond dust on the distal tip of the drive shaft (Figure 11“1). The drive shaft is covered with a 4F Teflon sheath that is continuously lubricated by a pressurized saline flush solution. The proximal end of the device has a housing unit containing the burr advancer, a fiberoptic tachometer cable, irrigation port and a nitrogen gas delivery hose (Figure 11“2).

There are eight different burr sizes available for coronary rotational atherectomy. The smallest burr is 1.25 mm and the largest is 2.5 mm. The other sizes include 1.5 mm, 1,75 mm, 2.0 mm, 2.15 mm, 2.25 mm and 2.38 mm. The selection of burr size should be based on the ratio of 0.7 or less of final burr to artery.3, 5 Progression to the final burr size should be in 0.5 mm steps, with the first burr being 1,75 mm for routine cases and 1.5 mm for long, heavily calcified, or angulated segments. ³ This progressive approach to device sizing is believed to decrease the chances of arterial dissection.

Until recently, it it was desirable to upsize the Rotablator burr, the entire device had to be removed from the body, discarded, and a new system had to be opened and prepped. Technologic advances and concerns over procedural costs have led to the development of an exchangeable burr system. The Rotablator Rotational Angioplasty System is composed of the Rotablator Advancer (the housing unit with fiberoptics, compressed gas connector, infusion port, Catheter advancer, and driveshaft connector; Figure 11-3), and the RotaLink catheter (the Rotablator burrs in sizes 1.25 to 2.5 mm).

For catheter exchange, the burr is removed from the body, leaving the guidewire in place. The advancer knob on the housing of the unit is moved forward completely and locked into place. The catheter connector latch is depressed and the burr detached from the advancer, exposing the driveshaft connection. The brown hypotube connection of the RotaLink catheter is slid forward gently, and the connections are carefully pulled apart. To attach the next catheter, the connections of the Rotablator Advancer and RotaLink catheter should be aligned, and the brown hypotube slid back and carefully pulled to assure a tight connection. At this point the RotaLink catheter is ready to be connected to the Rotablator Advancer. ⁴

The rotational speed of the Rotablator device is controlled by a foot pedal console activated by the physician or scrub assistant. The fiberoptic tachometer cable and nitrogen gas delivery hose are connected to the front of the console; the tachometer cable produces a digital readout of the revolutions per minute (rpm), which is displayed on the front of the console.

The nitrogen tank is hooked up to the back side of the console. Once the tank is hooked up, the wheel of the on/off valve is turned on (to the right). The tank should show a pi of 90 to 110, or be in the green. The amount of gas available in the tank should always be checked prior to the procedure; 500 pi is the lowest acceptable range to begin a procedure. If the tank is at or slightly about 500 pi the circulating nurse should pay special attention to make sure the tank does not run out. A pi of 750 or greater should not warrant close monitoring of nitrogen level.

Specific Nursing Considerations

A pressure bag will be needed to infuse a flush solution through the Rotablator device. The pressurized flush allows for rapid lubrication and cooling of the burr, preventing it from overheating during the operation.

Coronary vasospasm as a result of the high-speed burr spinning inside the artery has led to the development of specific flush recipes that are added to the pressure bag. Medications included in such recipes are nitroglycerin, verapamil and heparin. various doses can be used and tend to vary by institution or physician. Our institution most frequently uses the following:

500 cc normal saline
1000 units heparin
2 mg nitroglycerin
5 mg verapamil

It is believed by many physicians that adding these specific medications may aid in the reduction of coronary vasospasm during the procedure. ⁶

A nitroglycerin cup and syringe should always be on the sterile tray when a rotational atherectomy is being performed. Injections of 100 to 200 ug of nitroglycerin are frequently given for coronary vasospasm. Verapamil and adenosine may also be injected, and they should always be readily available.

The monitoring nurse/technician should pay close attention to the ECG monitor and blood pressure during each rota run. Hypotension, bradycardia, and short runs of asystole and ventricular tachycardia are commonly seen during the procedure. We recommend having a dopamine drip on standby drawn up to the following calculation: 5 ug/kg per minute.

A temporary pacer, wire and cable should always be kept in the room anticipation of any rhythm problems. The physician may elect to place a temporary pacer prior to the procedure in high-risk patients, especially those undergoing a procedure involving the right coronary artery.

Cardiac enzymes should be ordered on all patients post-procedure to rule out the possibility of a non Q-wave myocardial infarction. Rotational atherectomies carry a higher risk of procedural-induced non Q-wave myocardial infarctions than do angioplasties. It is believed that the higher risk is due to the debulking of the plaque, producing small embolic particles. ⁵

An emergency cart equipped with a defibrillator, intra-aortic balloon pump kit, and appropriate emergency medications should be readily available in the room. Rotational atherectomy carries a small risk of cardiac arrest, as do all coronary interventions. It is therefore a good idea to be prepared for such an event. Having a balloon pump on standby in the room is also a good idea. Placing the balloon pump leads on the patient prior to the procedure as well as ensuring that the pump works should be standard nursing practice. This will allow for easy access in the event that extra cardiac support is needed during the procedure.

One should also be prepared for the rare complication of cardiac tamponade as a result of coronary perforation. Having a pericardiocentesis tray available in the cardiac catheter laboratory will allow for rapid treatment of this complication.

Indications

Rotational atherectomy is indicated for discrete, complex lesions. It is also appropriate for lesions that are calcified, ostial in origin, or thought to be inappropriate for dilatation via balloon angioplasty, due to their fibrocalcific nature. It is also quite effective in some native vessels in which restenosis has occurred after PTCA. ⁵

Contraindications

Rotational atherectomy is not recommended when a lesion contains thrombus. Thrombotic lesions should be treated with balloons, stents, or thrombolytics and allowed a 2- to 4-week healing period prior to performing rotational atherectomy. It is also contraindicated for lesions within saphenous vein grafts. This is because of the potential risk of distal embolization and decreased or absent flow. Lesions at the anastomoses site, however, have been successfully treated with rotational atherectomy. ⁵

Complications

The most frequently seen complications associated with rotational atherectomy include intimal dissection, distal artery spasm, perforation, acute target vessel closure, and non Q-wave myocardial infarction. ^3,6

If there is a drop in speed of the Rotablator of 5000 rpm or more, the risk of dissection or no-reflow due to distal embolization of large particles increases. The smaller burrs (<=2 mm) safely operate at 180,000 rpm, while burrs larger than 2 mm should have speeds of 160,000 rpm or higher to minimize the threat of dissection or large-particle embolization. A strip recorder can be attached to the Rotablator console to closely monitor for excessive drops in rpm. ^2,6

The first line of treatment for intimal dissection is usually adjunctive balloon angioplasty of the affect artery. This is done in an attempt to tack up the affected artery. The physician may also elect to treat the patient with heparin for several hours after the procedure. In the event that balloon tacking is not achieved, the patient may need bypass surgery.

Coronary artery perforation is another complication associated with rotational atherectomy. Perforations are more likely to occur in lesions located on bends or in very tortuous vessel segments. Perforation of the artery, depending upon its extent and location, may be successfully treated with long balloon inflations (usually with perfusion balloon). The anticoagulant effects of heparin must be revered with protamine sulfate. In the event that any other anticoagulant medication is infusing (e.g., ReoPro) it must also be discontinued. Some perforations will require emergency pericardiocentesis. This is because fluid accumulates around the heart, causing cardiac tamponade. confirmation of tamponade is usually done be means of a portable echocardiography machine brought into the catheterization laboratory. Depending upon the amount of fluid drained, the physician may decide to hook up a continuous drainage system for several hours. Some perforations will require immediate surgery to create a cardiac window. The ECG and arterial pressure must be monitored very closely for changes such as hypotension and tachyarrhythmias.

Distal artery spasm is treated with intracoronary injections of nitroglycerin, verapamil, or adenosine. Spasms refractory to medicine may require additional balloon inflations in an attempt to halt the spasm. Spontaneous resolution of spasm may also occur.6 Acute closure of the target vessel usually requires balloon angioplasty, stenting, and occasionally consultation with a cardiac surgeon.

Non-Q-wave myocardial infarction as a result of ischemia during rotational atherectomy is yet another possible complication. High-risk patients may have an intra-aortic balloon pump inserted prior to the procedure in an attempt to minimize this.

Shorter burr runs, appropriate sizing up of burrs, slow advancement of the burr (less than 5000 rpm drop), and post procedure low-pressure balloon inflations are new theories on how to decrease complications associated with rotational atherectomy. Several studies are now being conducted to confirm these theories. ⁶

Outcomes

Several studies have verified the effectiveness of rotational atherectomy, with the most recent ^(7,8) displaying procedural success rates in the realm of 95%. It is worth noting, however, that adjunctive angioplasty was necessary in the vast majority of these cases to achieve acceptable results.

Postprocedural Care

Care following rotational atherectomy differs little from that of post-PTCA care. The patient should be admitted to a cardiac telemetry step-down unit or intensive care unit per institution policy. A 12-lead ECG is performed immediately after and the following morning for comparison to baseline to rule out silent ischemic events. Cardiac enzymes should be ordered on all patients post-procedure to rule out the possibility of a non-Q-wave myocardial infarction.

Frequent monitoring of vital signs, assessment of pedal pulses, and groin site checks are a must for optimal patient care following any coronary intervention. Groin site observation is especially important where larger bore sheaths have been used, as is often the case with rotational atherectomy. Patient comfort must also be considered. With current patients care protocols, these patients are required to lie on their backs with the head of the bed no greater than 30 degrees for several hours post-procedure. Oral pain medication such as Tylenol III or Percocet usually help relieve the back discomfort frequently experienced while on bed rest.

Costs

Rotational atherectomy can be an expensive treatment modality. The recent development of the exchangeable catheter system has, however, allowed for significant savings. For example, the cost of one burr attached to the advancer is approximately $1100. By using the same advancer throughout the entire procedure and exchanging only the burr, one can save about $200 a burr. The Rotablator Advancer costs about $200; each Rotablator Burr costs approximately $900. Costs vary from institution to institution, depending on contract pricing. Through the use of capitated pricing contracts, there is the potential for significant savings if a hospital performs a number of these procedures.

Limited data is available concerning cost efficiency of rational atherectomy versus PTCA. Contractual agreements, capitated procedures, and major hospital buying groups have brought the costs of may balloon catheters down from over $700 to around $300 to $400. Incremental procedural costs, in-house hospital length of stay, long-term restenosis rates, and the advancements in minimally invasive coronary bypass surgery will figure into whether or not the Rotablator and other newer interventional devices will continue to be used in the future.

In our institution, each device is discarded once the procedure is complete. In the United States there is no approved method for the resterilization of any of the equipment used during the rotational atherectomy procedure. Thus, the potential for significant savings through equipment reuse is currently not an option.