Sunday, October 20, 2013

Heart - Coronary Artery Stents and Cosmetic Surgery

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Heart (coronary) artery blockage is a local blocking or narrowing in the arteries on the outer surface of the heart by accumulated deposits of plaque, which is mostly bad cholesterol. Every artery in the body is a blood pipeline. These pipelines get blocked with accumulation of bad cholesterol. When a cardiologist suspects blockage or narrowing of any of these heart arteries he/she will perform an angiography (threading a catheter up a thigh artery to the heart to inject a dye that is visible on X-ray) to view the inside of the arteries. When an area of artery narrowing or blockage is identified a catheter with a balloon is inserted along the same path and inflated at the problem area to open it up. This is called angioplasty. Increasingly stents are placed at these angioplasty sites to keep them open in the long term. In some cases multiple stents are sequentially placed in the same artery. If the area cannot be treated in such a fashion open heart surgery is required which involves opening the rib cage and bypassing the blocked area with a vein graft or connecting an artery from inside the rib cage to the downstream side of the blockage. These procedures have helped prolong the life of countless heart disease victims. This blog only addresses patients who have had stents placed. It does not address those who have had open heart surgery.

Stents are thin wire metal meshes of stainless steel shaped in the form of a tube. They are foreign bodies so they stimulate the laying down of scar tissue and formation of blood clots on their surface which is exposed to blood inside the artery, either of which can re-block the artery. These patients are given aspirin and other medications to prevent the blood clots from forming. Bare-metal stents are metal stents with no special coating. Bare-metal stents act as simple scaffolding to prop open blood vessels after they're widened with angioplasty. #DrugElutingStents are coated with medication that is slowly released (eluted) to help prevent the growth of the scar tissue in the artery lining. They are associated with a lower blockage rate and lower incidence of heart attack, repeat hospitalizations and repeat angioplasty procedures than bare metal stents.

Blood clots forming in a stent is associated with a 64% rate of death or heart attack for bare metal stents and and a death rate of between 9% and 45% for drug eluting stents. Therefore patients are prescribed 2 anticoagulation (blood thinner) medications for a year or more after placement of stents. Non-heart surgery soon after stent placement is associated with an increased risk of clotting within the stents. This can be due to incomplete incorporation of the stent into the wall of the artery, interruption of the blood thinning medication in preparation for surgery and the blood clotting tendency of the surgery itself. Furthermore, these clots are detected late after their formation around the time of such surgery because of the effects of anesthesia and narcotic pain killers may impair patient recognition of symptoms.

Two possibilities exist in these types of patients. The first is a patient who in being medically cleared for cosmetic surgery is newly diagnosed with coronary artery disease and subsequently undergoes angiography and stenting. The second is a patient who has known stent(s) placed before deciding to have cosmetic surgery. In either case it is important to know the reason for stenting (the characteristics of the initial blockage), the date of stent implantation (how long it has been in place), and the type(s) of stent(s) used, as the current blood thinning therapy and proposed duration of that therapy. Clotting is more likely to occur in patients who have had stents placed at the opening mouth of arteries, in arteries that split in 2, in smaller arteries, in multiple areas of the same artery, to treat an actual heart attack or if the stents are longer. Clotting is also more likely in patients with diabetes or kidney disease. The cardiologist who placed the stent has to clear the patient for surgery and the discontinuance of the blood thinner. Another cardiologist will usually not suffice due to the number of factors I have mentioned above.

When possible, surgery should be delayed until the patient is outside the recommended period of blood thinning medication, as determined by the stent and lesion characteristics. This would mean that surgery should be delayed until 6 weeks after implantation of a bare-metal stent (4 weeks of blood thinning therapy and 4 to 10 days for the medications to wear off) and 1 year after implantation of a drug eluting stent. Earlier non-heart surgery in these patients is associated with a high risk of clotting off the stents resulting in heart attacks and/or death. Stent clotting has been known to occur during operations performed 18 months or more after drug-eluting stent placement, so vigilance is always in order. These clinical guidelines were devised in 2007. Current  second-generation drug eluting stents have more biocompatible, durable polymer coating so the most recent recommendations is that nonurgent operations should be postponed until six months after stent implantation.

I had a patient whose stent was in the vertebral artery which runs along the spinal column of the neck into the back side of the brain and had been in place for more than a year. The patient was on also on a blood thinner that could not be stopped but we were able to remove a small skin tumor by temporarily switching to a different type of blood thinner. Because of the location of the stent, near her brain, and the nature of her disease she will have to be on blood thinners for the rest of her life. This required planning and coordination between groups of doctors.

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