Angiographically tight coronary stenoses without transstenotic pressure gradient

: The availability of coronary angioplasty catheters has made it possible to measure transstenotic pressure gradients. This parameter provides direct information on coronary haemodynamics. In 2 patients with proximal concentric stenosis of the left anterior descending artery the gradient was zero in spite of a more than 50% reduction in vascular diameter. The reason for this emerged from a study of the characteristics of these stenoses: they were short, and the vascular area at their level clearly was superior to 1 mm2. None of the 2 patients suffered from angina. One had negative exercise ECG, the other had an inconclusive exercise test without pain but with ST segment depression on anterior leads. This patient had a history of posterior infarction with postero-inferior dyskinesia at angiography, and exercise scintigraphy with thallium showed no decreased uptake in the antero-septal territory. The presence of coronary transstenotic pressure gradient implies a fall in coronary blood pressure downstream of the stenosis, a pressure which constitutes the perfusion pressure in the territory fed by the narrowed artery. on the value of this perfusion pressure depends the possibility of coronary blood flow autoregulation in the territory threatened by ischaemia.