Fortnightly Review: New methods of making blocked coronary arteries patent again

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Abstract
Balloon angioplasty The technical problems are predictable (box). None the less, increasing experience and improvements in the equipment now mean that in almost 90% of cases balloon angioplasty is a “primary” success (fig 2).*RF 1-3* This is usually defined radiographically as a reduction in the stenosis to less than 50% without major complications. The balloons are enormously sophisticated - each one is handmade and costs about pounds sterling 500 - but the split they create is uncontrolled and may continue into the “normal” vessel wall, causing an extensive dissection. This is especially likely with eccentric, calcified, or angular lesions. Such dissections are the commonest cause of abrupt closure of the vessel after balloon angioplasty, which is seen in 3-5% of patients.4 This accounts for most of the serious complications of angioplasty, including myocardial infarction (1.5- 3%), emergency coronary artery bypass grafting (2.5-4.5%), and death (0.5%).*RF 1-3* View larger version: In this window In a new window FIG 2 Angiogram of stenosis in left anterior descending coronary artery successfully relieved by balloon angioplasty. The balloon is filled with contrast and can be seen fully inflated during the angioplasty (middle panel) Technical problems with balloon angioplasty * Peripheral vascular disease may limit access of the guiding catheter to the coronary ostium * Extreme angulation of the diseased vessel may cause difficulties in passing guidewire or balloon * Guidewire may not be able to cross totally occluded vessels * Balloon may not be able to follow guidewire through very severe stenoses (rare with modern balloons) * Vessels with hard lesions may not dilate even at pressures likely to cause the balloon to rupture * Elastic lesions may recoil as soon as balloon is deflated * Bulky plaque is not removed * Balloon inflation may cause an uncontrolled dissection and risk abrupt closure In the first six months after operation exhuberant healing causes restenosis in 25-50% of cases,5 and this remains the Achilles' heel of percutaneous transluminal coronary angioplasty. There are no reliable features that can be used to predict restenosis in an individual. A vast worldwide research effort has tried to find drugs to prevent it, but as yet all have proved useless. The limitations of balloon angioplasty have encouraged the development of some ingenious new methods to unblock coronary arteries. This article describes some of these techniques and examines how they compare with balloon angioplasty.