Acoustic shock waves, a new weapon against angina?

In the years before direct revascularisation for drug-refractory angina pectoris, some indirect methods were explored to improve myocardial ischaemia. Carotid nerve stimulation activated by the patient when angina emerged and Vineberg surgery [1] with implantation of the free end of the mammary artery (started about 1963) are examples of desperate attempts to suppress untreatable symptoms. Both were abandoned because of non-proven effects in contrast to direct revascularisation, which arrived around 1967. The favourable effects and safety of the current percutaneous coronary intervention and bypass surgery permit direct revascularisation in almost all categories of patients with myocardial ischaemia. However, for some patients direct revascularisation or redo procedures are not feasible because of the poor condition of the coronary arteries, age or major comorbidity; the number of these patients is gradually increasing. This observation initiates new experimental, non-invasive methods to improve coronary circulation and myocardial perfusion with the option of relief of untreatable angina. These attempts vary from nerve stimulation to gene therapy [2]. Acoustic pulse waves are used in an experimental attempt to eradicate drug-refractory angina because it initiates angiogenesis in experimental conditions [3]. With an amount of energy about 10% of that usually applied to crush kidney stones, several favourable bio-effects have been documented. An increase of vascular endothelial