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Vascular scaffolds

24 Oct

During the heavy snow in 1980’s I was working as a GP in South Wales and after heavy blizzards I had woken up to find that I was literally trapped in the snow . When I opened the door to go to the coal house to get fuel for my central heating boiler there was a wall of snow blocking my exit and I had to dig a tunnel along the short path to the shed. Having dug myself out the only way I could get to the surgery was by walking up the disused railway line.
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During that time it was challenging in that the only way patients could get to hospital was being airlifted by helicopter. We soon set up an emergency plan to manage our patients. We spoke to patients on the phone and then if appropriate we arranged delivery of medication. Local young men rallied together with their motorbikes and set up a courier service and prided themselves by getting medication delivered in record time whilst able residents cleared paths and roads. At the time there was great enthusiasm regarding CBR(Citizens Band Radio) and they facilitated communication between couriers as well as helping those people who had no telephone or connection. It was interesting because most calls were about getting their sick certificates or their Valium prescriptions!!
When the snow cleared surgeries were busy and I particularly remember one consultation about 2 weeks later.
“Dr when we were cut off the Brains (beer) lorry couldn’t get up the hill to the club and I had to help by pushing a barrel by hand and during that time I had an awful pull”. (A common description which could mean anything) “What do you mean by that?” I asked. He responded immediately with a distorted facial expression,”I had an awful gripping feeling across my chest”,he said, clenching his fist and pressing on the middle of his chest. I don’t know how I got the barrel through the door, good job someone was there to help and I came over very cold and sweaty so Dai, the bar man had to pour me a stiff brandy”.
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( the resounding, stuttering words of Dr Byron Evans, consultant physician & medical tutor in medical school whilst on a ward round came to me, “Listen here,good boys, if ever you hear a man describe a gripping chest pain and he clenches his fist and draws it to the centre of his chest it has to be cardiac” and he repeated it in Welsh with even greater gusto).
I gently explained that to  that he had probably had a heart attack and prescribed some GTN tablets to put under the tongue if the pain should recur as there was no other specific treatment and getting an ECG was not easy to arrange. At that time a study had been shown that a patients survival rate was greater if they stayed at home especially as ambulances were minimally equipped and the nearest hospital was 20miles away and coronary care units had not evolved generally.
If the pain did recur these patients often became more and more incapacitated to the point that they became bed bound and were called ‘cardiac cripples’ I remember one such patient that I visited frequently and every time a new drug appeared in the form of slow release GTN he was willing to be the ‘guinea pig’ I got to know him very well and on the visits we used to discuss the many photos of pigeons he had decorating his living room and talk about the ins and outs of rearing racing pigeons and where he used to ‘toss’ them.
It was about this time that cardiologists were beginning to perform angioplasties far away in London and if I wanted to refer a patient for an angiogram and or angioplasty they had to travel to London. Many people were fearful of going as several had not come back or returned having had a stroke.

It was not until 1986 that bare metal stents(BMS)were implanted into the coronary arteries.
Since that time preventative measures and treatment has evolved so that peoples lives have been extended and the quality of life improved. Patients at risk are now actively encouraged to change their lifestyle – smoking cessation, low fat diets and regular exercise and medicines such as statins and beta-blockers have decreased mortality by as much as 25%. Investigation by angiogram has led to better understanding of coronary artery disease.
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From 1994 implantation of stents has become common place and several generations of bare metal stents (BMS) have been developed often using cobalt chrome alloy.
The permanence of these metallic stents is not considered ideal as they can induce late clotting (thrombosis).
Also, although these stents are highly successful and most people have had significant improvement of symptoms the rate of restenosis (re-narrowing of the treated artery) causes limitation and often results in having to repeat the procedure.

This has led to the development of the DES (drug-routing stents) in 2003. These stents are coated with a special material that release (elutes) a drug(such as paclitaxel, sirolimus or tacrolimus) over a period of 30-90 days in order to reduce restenosis. The polymer coating degrades by the time the drug has been released and the metallic structure remains. DES are more expensive than BMS and are not necessarily superior in terms of reducing death, heart attack or thrombosis. According to NICE, the decision to use either a BMS or a DES should be based on the anatomy of the target vessel and the symptoms and mode of the disease.

During the past 3 yrs Bioresorbable stents (BVS), also referred to as vascular scaffolds, represent a new concept in stents for treating coronary artery disease. Stents are vascular scaffolds that are used to hold open a blocked vessel to restore blood flow to the heart.
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Bioresorbable stents are designed to slowly disappear over time, leaving patients with a treated vessel free of a permanent implant. With no material left behind, the vessel has the potential to return to a more natural state and function reducing the risk of late thrombosis. Other advantages may include:
 A reduction in the risk of bleeding complications which can be caused by anti-clotting treatments.
Anti-clotting therapy, with two anti-platelet drugs, is given after a stent is implanted, and it may be that bioresorbable stents require a shorter period of this treatment because of resorption of the device. However, some patients may still need long term anti-clotting treatments because of their underlying heart condition.
 Patient acceptability. Some patients may prefer a temporary implant rather than a permanent one.

Five bioresorbable stents are in various stages of development. So far, clinical studies are encouraging and have shown that bioresorbable stents may offer an additional option to current stents.

On September 25th 2012 Abbott announced that Absorb™, the world’s first drug eluting bioresorbable vascular scaffold (BVS), and it is now widely available across Europe and parts of Asia Pacific and Latin America. Absorb is a first-of-its-kind device for the treatment of coronary artery disease (CAD).
We are awaiting long term follow up………..

If you want to find out more patient information about angioplasty and insertion of stents use the following link:-
http://www.bhf.org.uk/heart-health/treatment/coronary-angioplasty-and-stent.aspx

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Posted by on October 24, 2013 in Training and Advice

 

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