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The vast majority of patients with angina due to underlying coronary artery disease can have their symptoms adequately controlled by anti-anginal drugs, percutaneous coronary intervention or coronary artery bypass surgery. There is, however, a cohort of patients with extensive coronary artery disease whose angina persists despite medical treatment and who are not suitable for conventional revascularisation procedures. A variety of treatments have been used in this patient group, including cognitive behavioural therapy, precordial transcutaneous electrical nerve stimulation, spinal cord stimulator implantation, intermittent local anaesthetic, sympathectomy, opioids, external enhanced counter pulsation, percutaneous myocardial laser revascularisation (PMR) and transmyocardial laser revascularisation (TMR). The last two treatments have recently been evaluated by the National Institute for Health and Clinical Excellence (NICE).
TMR is a surgical procedure carried out under general anaesthesia and was first described in 1983. High-energy lasers are used to create channels within the wall of the left ventricular myocardium. The original theory was that these channels carried blood from the ventricular cavity into the myocardium, thereby relieving the symptoms of myocardial ischaemia. This was based on the model of the reptilian heart, in which the left ventricle is directly perfused from endothelium-lined channels which radiate out from the cavity of the left ventricle. This mechanism of action is unlikely, since the channels have been shown to occlude in the weeks following surgery. Other theories on the mechanism of action include the development of new blood vessels (angiogenesis) and also damage to the nerve supply of the heart (denervation). It is possible that there may be a placebo effect which contributes to the improvement in patient's symptoms.
The area to be treated …