[Intracoronary blood flow velocity during angioplasty. Functional guide and indicator of the success of dilatation].

In order to assess the value of a new Doppler-fitted dilatation catheter, changes in blood flow velocities in the coronary arteries were recorded at various stages of transluminal angioplasty in 15 patients with isolated proximal coronary stenosis. A pulsed Doppler probe (emission frequency 20 MHz, recurrence frequency 62.5 MHz) attached to the distal end of the balloon catheter was used to measure blood flow velocities with a Doppler frequency/velocity relationship of about 3.75 cm/s per KHz. During each angioplasty the balloon was inflated 4 times on average, with successive increases of pressure from 7 to 12 atmospheres. Flow velocities were measured before and after each inflation and also when maximum hyperaemia occurred after temporary occlusion by the inflated balloon. Computer-assisted analysis of the coronary stenosis was carried out before and after the procedure. Patient's mean age was 53 years. Angioplasty was performed in the anterior interventricular artery (12 cases), the circumflex artery (2 cases) or the right coronary artery (1 case). Anatomical success was assessed by an increase of minimum luminal section area from 1.3 +/- 0.0 to 3.0 +/- 1.2 mm2. Functional success was assessed by a progressive and significant increase of the velocities measured during the first 3 dilatations. No further increase of velocity was observed between the last 2 inflations. Coronary reserve at the end of angioplasty was 2.1, corresponding to the theoretical value calculated taking into account the residual stenosis and the presence of the catheter in situ.(ABSTRACT TRUNCATED AT 250 WORDS)