Monday, September 20, 2010


The carotid artery is that artery which carries blood supply to the brain. Any interruption with the blood flow to this artery may result in lost of brain function, if acute, we call it a stroke. There are two carotid arteries ( left and right ), just as there are two sides to the brain, the left half and the right half.
The carotid artery, like all arteries in the body, is prone to cholesterol deposits ( atherosclerosis ), which has the same risk factors as cholesterol deposits in heart arteries, namely cigarette smoking, hypertension, diabetes, raised serum cholesterol levels, familial, etc..
The carotid arteries can become narrowed to various degrees and when blood flows through them, the cholesterol deposits can flake ( washed ) off, and travel along the artery until it lodges in one of the small end arteries, blocking it off. This will then cause lost of brain function of that part of the brain resulting in lost of motor power, lost of vision, lost of speech, etc.. Sometimes the small cholesterol flakes, then dislodges ( luckily ), and the blood flow is restored again, so that the lost of brain function is temporary. The motor weakness is but for a few minutes, before it is restored again. We call this a transient ischemic attack ( TIA ). If the cholesterol flake is too large, it may not get dislodged or cleared, the lost of function may become prolonged or even permanent, and we call this a stroke. So a TIA is usually the result of a small blood clot or cholesterol flake, flying off a cholesterol deposit, and transiently blocking of a small brain artery, and a stroke is when the blockage is permanent and the deficit remain permanent.
This gave rise to the strategy that we must clear all cholesterol plaques in the carotid artery. In the good old days, we use to practise that if a carotid artery narrowing is >70% and the patients has had TIAs, then the blockage should be removed. In the 70s and 80s, this was done surgically, by a procedure called carotid endarterectomy ( literally opening the carotid artery surgically, and shelling out the inner layer of the artery, which contains the cholesterol plaque ). You can imagine that this is a major procedure, not without its own risk. But surgeons got better and those who do a lot if it ( pass the learning curve ), had very good results. There fore removal if the cholesterol plaque was an attempt to prevent TIAs and strokes.
With the advent of coronary angioplasty, vascular interventionist began to copy the idea, and felt that they can also use the balloons and stents, to clear carotid artery blockages. It is true, they can and the post procedure pictures look great and pretty. The narrowing is nor more, but did it do good for the patient?
Since the 90s and early 21st century, numerous clinical trails had been done to see if carotid artery stenting, is superior, or at least, not inferior, to carotid artery endarterectomy.
Well, the long and short is that carotid artery stenting is inferior to carotid artery endarterectomy.
This blog is prompted by a Lancet September 10 paper, which reported on a meta-analysis of three big trials comparing carotid artery stenting with endarterectomy ( the Carotid Stenting Trialist Collaboration ), and also a presentation at the just concluded American Neurological Association annual scientific session, on the CREST ( Carotid Endarterectomy Vs Stenting Trial ). All the reports showed that carotid endarterectomy was better in terms of stroke prevention, but suffered from an increase rate of heart attacks, post op, and was not so good for older ( >70 yrs ), patients, Stenting was inferior in all the primary outcome indices and had a higher TIA and stroke rates, especially peri-procedure. The results are highly dependent on the centers and surgeons doing carotid artery endarterectomy had to have specially certification.
Yet, it is somewhat disheartening to note ( as an interventionist ) that many interventionist are doing carotid artery stenting, having had very little training and they are literally learning on the job. And these procedures are not cheap, in terms of financial cost and patient physical cost ( morbidity and mortality ).
I do not do carotid artery stenting, as I feel that it should left to people who are trained in this and who do tens if not hundreds of this a year. You cannot get pass your learning curve, if you only do 2-3 a year. I am an interventional cardiologist.

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