C A T H E T E R I N T E R V E N T I O N S
Open-heart surgery for blocked coronary arteries (bypass surgery) was a tremendous advance in treatment. The techniques have continued to advance, and the procedure is done more frequently and more safely than ever. However, major disadvantages remain, most notably the relatively large incision and prolonged recovery time. Over the last two decades, procedures which open plugged arteries using far less invasive catheter techniques have assumed an ever-increasing role in the treatment of Coronary Artery Disease (CAD).
These procedures are carried out in a manner similar to a diagnostic heart catheterization , and are sometimes completed at the same time as that procedure. Catheters, or small hollow-tubes, are advanced from the groin or the arm through the arteries and situated at the beginning of the arteries to the heart (the coronary arteries). During a diagnostic procedure, dye is injected through the catheters into the coronary vessels, and the pictures recorded on videotape, film, or captured as digital computer images.
With an "interventional" procedure, the same approach is used. Now, a catheter with a deflated balloon is advanced within the "guiding" catheter. Since the balloon catheter is relatively large and cannot be steered to any great extent, a wire which can be shaped and steered is advanced under x-ray guidance well beyond the blockage. The catheter with its deflated balloon is then advanced over the wire to the site of narrowing. It is inflated with dye (so that it can be seen) under varying amounts of pressure to enlarge the artery and compress the plaque. The inflations are done several times until the physician feels a satisfactory result is obtained. The deflated balloon catheter is then pulled back over the wire back into the guiding catheter, and then the wire is likewise withdrawn. When the procedure is completed, the guiding catheter is also removed.
This procedure can be fairly simple and straightforward, and can sometimes be completed in 20 minutes or so. Sometimes, it can be very technically challenging and require hours. It does cause injury to the vessel wall and clot may form at the site of the ballooning which could lead to complete closure and a heart attack. Therefore, blood thinner of some type is administered. If the blood thinner is continued after the procedure, the "introducers" through which the catheters were advanced will be sewn in place at the skin. They will be removed later when blood thinners have been stopped. The leg or arm whose vessel was utilized must be moved very little while the introducer is in place, and for several hours thereafter.
There have been three main problems with these types of procedures, and some progress has been made in solving each, at least to some degree:
- The artery can be injured in such a way as to result in the vessel getting worse and not better. The vessel may close in this circumstance, and a heart attack (myocardial infarction) may result. In this case, urgent or emergency bypass surgery may need to be performed to restore blood flow to the affected artery immediately. This generally occurs in the range of 1-2% of cases. It is because of this possibility that the procedure is done most frequently where surgical "back-up" is available.
- Not all blockages are suitable for these procedures. The improvement in equipment and techniques has dramatically decreased these situations, but they still exist. Blockages can be at very critical locations, or it may be felt that the procedure would be too risky if the vessel were to close as noted above. Totally blocked vessels are not good candidates for these techniques, nor are vessels with very long blockages. There may simply be too many blockages. Some people have arteries which aren't very straight, and it may not be possible to steer the wire and/or balloon catheter around too many or too tight of bends.
- The most frequent problem has been the tendency of the vessel to block off again gradually after it has been dilated. This problem of "restenosis" is also slowly being solved and new techniques continue to be developed. It is not clear why it does occur, but if it does, it tends to occur gradually. It is found most frequently in the first three months after the procedure, occasionally in the next three months, and only rarely after one year. In fact, if the vessel stays open for one year, studies to date show that it is rare to re-occur in patients who are studied 5-10 years later.
What are my options?
These catheter-based techniques then, as virtually all medical procedures, have risks and benefits:
Catheter-based techniques are certainly simpler than bypass surgery, and often the patient can go home on the same day or the next day and resume normal activities. This compares with a large incision that is generally needed for bypass (although less invasive techniques are currently being investigated), 3-7 days in the hospital, and 4-6 weeks of recuperation at home.
Emergency surgery may be necessary for the complications of catheter interventions, and emergency surgery has a somewhat higher risk than elective bypass. Bypass Surgery may be able to take care of more areas which are blocked, and there will be a lesser chance of having a blockage come back in the near future. Medications may be all that is necessary.
The decision is a relatively complicated one that takes into account a number of factors such as the number of vessels blocked, the number and shape and location of the blockages in each vessel, the age and general health of the patient, the experience and ability of the physician performing the procedure, and many more factors. There is more about some of these areas in the "tell me more" . . . section, but you'll need to discuss the specific aspects of your case with your physician.
Remember though . . . Don't get frustrated because the decision may be difficult or there isn't a perfect procedure. The reason it may be hard to choose may very well be because there are so many good options! Thank goodness we can do so much these days . . . it just makes the choice a little harder sometimes.
What about athrectomy?
"Athrectomy" involves actual removal of plaque out of the artery. Two major types are performed using special catheters, one of which cuts out blockage, while the other "cuts and sucks" clot and other debris.
The cutting technique ("DCA" for "directional coronary athrectomy") uses a rather large catheter that also has a balloon that is inflated to push the cutting device against the plaque. A motor turns the device which cuts the plaque out. The athrectomy catheter is removed, the cut material taken out of it, and it is reinserted if needed to do more cutting.
The extraction device ("TEC" for "transluminal extraction catheter") uses a conical cutting head with two blades. The catheter is attached to a motorized drive to turn the catheter for cutting as well as a vacuum bottle to suck out the material which has been cut.
Both may be done in conjunction with ballooning (PTCA), rotoblating,or stenting as well which may be used to obtain a better final result. They are generally used in only a few situations due to the characteristics of the catheters involved, but may be very useful in blockages at the beginning of certain vessels (DCA), or in bypass grafts (TEC) or vessels with clots (TEC). "Stents" have been available for only the last several years, but are very popular and effective. There are several such devices.
What are stents and are they any good?
While very popular, these devices are large, and cannot be passed through many vessels due to the fact they are overly curved or when the blockage is very far down the vessel. They also cannot be used in vessels as small as can be treated with balloons.
How about those lasers I've heard about?
Laser catheters garnered a large amount of attention in the late 80's and early 90's presumably due their "sexy" or "modern" image. Star Trek had reached the heart! However, the laser is very occasionally or rarely used today due to a lack of proven benefit despite higher costs and substantially increased risks.
My friend had a "rotorooter" (rotablator)...how about those?
Rotablators are catheters which "burr" through blockages, pulverizing the plaque material to a very small size which then (mostly) passes through the circulation. A burr with diamond chips is rotated by compressed air using a foot pedal while the speed of the rotation is monitored to prevent overheating of the artery.
This technique is very useful in vessels which have a large amount of calcium, or with very long blockages. Usually, further work with a balloon or stent is needed to finish the job. A certain amount of damage to the heart muscle is expected, since some of the debris which is created by the burr will get trapped in the very small vessels of the heart and cut off flow temporarily but long enough to cause a small heart attack.
Interventional techniques are:
- A valuable and frequently used techniques for treatment of CAD.
- Actually make a larger area for blood to flow through the arteries.
- Are associated with re-blockage rate from 15-50%
- Are generally "easier on the patient" than bypass surgery.
- Sometimes require bypass surgery to "bail out" a bad result.
- Have a number of different types of characters and techniques.
Questions To Ask Your Doctor
How many blocked arteries do I have?
Can they all be taken care of with catheter-based techniques?
Could they all be taken care of with bypass?
What are my risks of dying with intervention? With bypass? With medications?
How experienced are you with this technique?
Will there be surgical "backup" in case anything goes wrong?
©COPY;1997 HeartPoint Updated July 1997
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