Overview of Transluminal Extraction Coronary Atherectomy
Before the invention of the technique to place small tubes in coronary arteries, scientists sought out to improve the method of widening these arteries, known as percutaneous transluminal coronary angioplasty. The improvements were based on small tests, which showed that the healing response of the treated heart vessels matched the extent of the damage inflicted during the procedure. They discovered that the chance of recurrent narrowing of arteries was dependent upon the size achieved during the treatment. This led to the idea that excising or cutting away the build-up in the arteries and improving the treatment techniques might lead to better health outcomes and lower the chances of arteries narrowing again after a non-surgical procedure (Percutaneous Coronary Intervention or PCI).
The build-up of calcium in the heart arteries makes PCI more complex and less successful than those without such calcium deposits. Hard calcium deposits can create a higher risk of tearing in the artery, obstruct the placement and appropriate expansion of stents (small tubes to keep the artery open), and can lead to stents not fitting properly. Over time, various techniques for cutting and removing the plaque have been introduced. For example, in 1987, a technique called Directional Coronary Atherectomy was first used. In the following years, other methods like the Excimer Laser Coronary Angioplasty and the Percutaneous Transluminal Rotational Atherectomy were developed. The Holmium Laser Angioplasty was made commercially available in 1990. The Cutting Balloon Angioplasty arrived in 1991 and the most recent device, called the Orbital Atherectomy, was introduced in 2008.
In the past twenty years, several mechanical methods to remove or cut the plaque in the arteries have shown positive results in small-scale studies. Despite these findings, a widespread clinical trial failed to show that plaque removal can give better results than just widening the artery. This led to questioning the validity of the plaque removal method. Now, the guidelines specify that devices meant to remove plaque should not be used in routine PCI treatments.
Why do People Need Transluminal Extraction Coronary Atherectomy
Percutaneous transluminal rotational atherectomy (PTRA) is a medical procedure that is typically used only in specific situations due to its high risk of complications. This procedure comes into play when 1% to 3% of heart blockages can be crossed with a guide wire, but cannot be crossed or opened with balloon catheters, which are tubes that help open up narrowed or blocked heart arteries. Even when these tubes are used with extreme pressure, they may not succeed in some cases. This is when PTRA is useful, as it can help open up these resistant blockages and allow for the successful placement of a small mesh tube called a stent to help maintain an open artery.
PTRA is also helpful in treating small hardened blockages to change the flexibility of the blood vessel so that the balloon angioplasty can work. Balloon angioplasty is a procedure that inflates a small balloon to open blockages in the artery.
A method called orbital atherectomy might be suggested for severely hardened heart blockages. This method can be identified by a complete layer of hardened material seen on both sides of the blood vessels for at least 15 mm, or when a circular hardened material covering at least 270 degrees is detected on an intravascular ultrasound (IVUS), which is an imaging technique used inside blood vessels.
In addition to orbital atherectomy, another method called Excimer Laser Coronary Atherectomy (ELCA) has shown improved results in longer, moderately hardened, outflow tract blockages, vein graft blockages, and complete blockages in the heart blood vessels.
Heart blockages that branch out are particularly difficult to treat with conventional balloon angioplasty due to plaque movement and high failure rates. This is why Cutting Balloon Angioplasty (CBA), when used in these specific circumstances, shows fewer failure rates than Percutaneous Transluminal Coronary Angioplasty (PTCA) – 40% as compared to 67%.
The 2011 ACC/AHA guidelines advise the use of Rotational Atherectomy (RA) in highly calcified blockages, as it may be challenging to get across or widen these blockages.
When a Person Should Avoid Transluminal Extraction Coronary Atherectomy
In some cases where the blood vessel has a blockage due to a blood clot, a procedure called atherectomy (a method to remove the blockage) may actually lead to small pieces of the blockage breaking off and traveling to other parts of the body. Often, these clots develop over unstable or damaged parts of the blood vessel, which can split or puncture when we try to remove the clot.
If a person has spontaneous splitting of the coronary artery (the major blood vessel supplying the heart), or if this split is caused by an attempt to widen the blood vessel using a procedure called angioplasty, they can worsen with atherectomy. Also, if a blood vessel is very twisted, it could be challenging to get the surgical tools close to the blockage, and the spinning tool used to remove the blockage may increase the risk of bursting the blood vessel.
Patients who can’t have heart surgery because it’s not available, or because they are not deemed suitable for heart bypass surgery (a procedure where surgeons create a new route for blood to flow around a blockage in the coronary artery), are not usually recommended for atherectomy. These are seen as relative negatives, but not necessarily total barriers to the procedure.
Equipment used for Transluminal Extraction Coronary Atherectomy
For PTRA, or Percutaneous transluminal renal angioplasty (a procedure to open narrow or blocked arteries), the system known as the Rotablator includes several key parts: (1) the main component, called the rotablator, which has a small, replaceable cutting tool (or burr) and a device to move it forward. This part also contains an air turbine and a driveshaft; (2) a control unit that regulates the air supply and monitors the rotation of the cutting tool; and (3) a foot pedal that the surgeon steps on to activate the device.
The device used in orbital atherectomy, another type of procedure for unblocking arteries, consists of two main parts: a handheld device used by the surgeon and a control unit.
Cutting Balloon Angioplasty (CBA), yet another method for treating blocked arteries, uses a special device called a cutting balloon. This device, which is used to cut plaque away from the artery wall, is available in different designs to best fit the patient’s needs.
Finally, the fluid used in rotational atherectomy – another procedure to remove plaque from arteries – is a mix of water, proteins, and sodium. This fluid helps make the procedure smoother and safer.
Preparing for Transluminal Extraction Coronary Atherectomy
Everyone who is getting an atherectomy, a procedure that helps open up narrowed arteries, is also prepared for PTCA. PTCA, or Percutaneous Transluminal Coronary Angioplasty, is another procedure used to open blocked arteries. Essentially, preparations are made for both procedures to help ensure the best possible outcome for the patient.
How is Transluminal Extraction Coronary Atherectomy performed
When your doctor uses percutaneous transluminal renal angioplasty (PTRA) and orbital atherectomy (OA), a procedure to open up blocked or narrow blood vessels, they will commonly give you aspirin beforehand. When rotary ablation, a procedure used to remove any blockages, is done, your doctor will make sure to provide a blood-thinner, carefully place a wire through the area of the blockage, and position the wire tip in a straight section lower down the blood vessel, but not in a branch off the main vessel.
During the rotary ablation of larger blood vessels, especially one called the right coronary artery, your doctor may also insert a temporary pacemaker, a device that helps to regulate the heartbeat, because of the risk of slow heart rhythms. They will manually move the burr, a device used to clear the blockage, over the guidewire to reach the target vessel.
If the first attempt to cross the blockage fails, they may need to use a smaller burr. Once successful, they’ll complete the procedure by smoothing down the area for any further treatments that might be needed, such as inserting a stent, a small tube to keep the vessel open. In both DCA (directional coronary atherectomy) and OA, your doctor will use special wires designed specifically for these procedures to guide through the hard, blocked area. They try to do shorter runs with a slower move to avoid the formation of tiny blood clots in the treated blood vessel.
After clearing the blockage, your doctor will carefully remove the equipment over the wire, making sure not to pull on the wire that’s been placed in your blood vessels. They have the option of using a parallel wire or operating over the OA wire if needed.
When you have coronary balloon angioplasty (CBA), the doctor uses similar wires and tubes to those used in regular balloon angioplasty. But the balloons they use in CBA may not move as smoothly because they’re less flexible than the usual ones.
Your doctor will give you an IV injection of heparin, a medicine that helps prevent clots, to keep your blood from clotting too easily during the procedure. A clotting time of more than 300 seconds is usually targeted. This is important to prevent a condition called slow-flow or no-reflow, that occurs due to small particles or clots blocking blood flow during the procedure. If this occurs, it can be treated by injecting certain medicine.
Possible Complications of Transluminal Extraction Coronary Atherectomy
Atherectomy is a procedure to clean out blocked arteries, but like all medical treatments, it also has some potential risks. These are events that aren’t supposed to happen but can occur sometimes. If the procedure is performed after careful patient selection and planning, these bad events rarely happen. However, records from multiple medical centers show that complications do sometimes occur.
In particular, some people might have a heart attack – known in medical terms as a myocardial infarction – after the procedure. This happens in about 1.3% of cases. In 2.5% of the cases, people might need an emergency operation to reroute the blood flow around the blocked artery, a surgery known as coronary artery bypass graft (CABG). In about 1% of the cases, the patient may unfortunately pass away as a result.
There can also be some complications seen on the images doctors take of the arteries during the procedure. These include a tear in the wall of the artery (dissection) in 10% of the cases, small holes (perforations) in 1.5% of the cases, sluggish blood flow (slow-flow) in 1.2% of the cases, and sudden closure of the artery (abrupt vessel closure) in 1% of the cases.
These complications are rare though. In clinical trials, dissection occurred in 3.3%, and perforation in 1.7% of cases. Another potential snag is slow or no blood flow, which happens less than 1% of the time. Burr trapping, which is when a part of the tool gets stuck, can also occur.
What Else Should I Know About Transluminal Extraction Coronary Atherectomy?
Various scientific trials have experimented to find the best use of Percutaneous Transluminal Renal Angioplasty (PTRA), which is a procedure to open up narrow blood vessels to the kidney. One such study (abbreviated as STRATAS) compared two different strategies; one was quite aggressive in removing a lot of plaque from the artery and the other was moderate. Results showed that both strategies were similarly successful. However, the aggressive approach led to more heart attacks (11% compared to 7%) and a higher rate of the artery becoming narrow again (58% compared to 52%).
A significant trial called ORBIT II studied 443 patients with severely hardened and narrowed heart vessels treated across 49 locations in the US. The study found that most patients (89.6%) didn’t experience any major heart problems in the 30 days following treatment. Additionally, almost all cases (97.7%) were successful at placing a stent, a small tube that helps keep the vessels open, with successful reduction of the narrowing in 98.6% of the patients. Hospital complications were generally low, with severe tears in the blood vessel walls occurring in 15 patients (3.4%) and 8 patients (1.8%) experiencing perforations, which are small holes.
Several small studies compared Cutting Balloon Angioplasty (CBA), a procedure that involves cutting the plaque from the vessels, with PTCA (Percutaneous Transluminal Coronary Angioplasty), a procedure to open up narrow heart blood vessels, and found that CBA decreased the occurrence of narrowed vessels by 41% to 69%. However, there were conflicting findings from other small studies and several larger trials which compared CBA with PTCA and found no difference in the rate of repeated narrowing of the vessels.
Several studies have also compared the use of pulsed-wave lasers with other treatments, but found no improvement over the traditional PTCA. A recent large-scale trial named ROTAXUS tested whether the presence or absence of Directional Coronary Atherectomy (DCA), a procedure to remove plaque from the blood vessels, affected patients with moderate to severe hardened and narrowed vessels. The trial found a higher success in the treatment steps with DCA, but a higher arterial narrowing at nine months in the DCA group.
A big trial comparing all the different devices used is unlikely to occur, hence a direct comparison of the outcomes isn’t possible given the limited data. The choice of device normally depends on the doctors’ discretion, based on the patient’s condition and the doctor’s experience.
