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The technique of coronary angioplasty was invented by Dr Gruentzig working in Switzerland in the late 1970s. It involves passing a wire and a tiny balloon shaped catheter across a narrowing or blockage in an artery. By inflating a balloon, the obstructive material is squashed out of the way and blood flow improved. This technique has developed and advanced enormously in the last 25 years, so there are now more coronary angioplasty procedures being done in the United Kingdom than coronary bypass operations. Over the last several years technology has improved out all recognition from what we used in 1980! Balloon catheters are much slimmer, the wires that guide them are much better and the technique is much safer. Nowadays most coronary angioplasty procedures are accompanied by the implantation of a stent as well. A stent is in fact a high tech metal spring which is bio engineered on to the balloon catheter and when the balloon expands over the narrowing, the stent is deployed inside the wall of the artery and it remains there even when the balloon is collapsed and removed. Stents have solved many of the problems associated with ordinary balloon treatment. Before stents, about 3-5% of patients experienced a tear in the artery which often necessitated an emergency bypass operation. These tears can now be repaired by stenting. Stents have improved the outcome no end, but the main Achilles heel of stenting has been recurrence of the narrowing in the first 6-12 months. The latest advanced in stenting has been the ability to coat the stents with a drug to prevent re-narrowing and these are called drug eluting stents. These stents have been shown to reduce drastically the re-narrowing rates and have been a major advance. Unfortunately in the National Health Service in the United Kingdom they are rationed for use only in patients with the highest risk of re-narrowing and these are patients with smaller arteries of less than 3mm in diameter and lesions that are longer than 18mm. Many of these patients will be diabetic. Hopefully in the future drug eluting stents will become more widely available and cost less so that more patients can have them than currently do. Figure 6 shows a severely narrowed artery before and after stenting
Drug eluting stents have certainly expanded the scope of stenting so that now Cardiologists can treat patients with multiple narrowings or complex narrowings who have previously would only be treated with bypass surgery. Stents can also be implanted in a coronary bypass that furs up some years after a heart bypass operation. Figure 7 shows a narrowed bypass graft before and after a stent has been placed.
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Figure 6: Angiogram of a patient with very bad angina due to a clot in the artery to the front of the heart before (top) and after (bottom) a stent was place, restoring flow to normal and curing the pain.
Figure 7: Angiogram from a patient with recurrent angina 10 years after a bypass operation. Left hand picture (top) show a tight narrowing in the bypass, and right hand picture (bottom) shows the bypass successfully stented to restore blood flow to normal. The large wires are the sutures in the breast bone.
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