CORONARY-ARTERY DISEASE - SHOULD IMAGES BE TREATED

Precise digitized images of the coronary arteries displaying the dimensions of high risk stenoses and giving objective measurements of their contours and density can be provided by coronarography. On-line angioscopic images of tissue flaps flotting in the lumen, recent or structured thrombi, artery wall dissections, plaque ruptures, deep fissurations and sub-intimal haemorrhages demonstrate, in live colour, the pathophysiological mechanisms of coronary artery stenosis. Histological sections of the artery wall, without biopsy, can be visualized with endocoronary echography offering a global view of the wall and differentiating all the physiological layers including the intima and the internal elastic lamina, the blood-wall interface, the media and the adventitia. Our technical imaging capacity is impressive, but is anatomic imaging synonymous with coronary circulation ? Certainly not. Sophisticated imaging techniques have led us to associate the severity of the stenosis with its effect on myocardial irrigation, but today therapeutic decisions require not only considering coronary anatomy but also downstream consequences which can be evaluated by measuring coronary artery flow on both sides of the stenosis. Carried on the tip of the angioplasty guide, a piezo-electric crystal emits and receives a Doppler signal. The data is processed in real time giving a complete pattern of blood flow velocity and describing diastolic and systolic flow, differences between upstream and downstream flow, and the effect of pharmacological or physiological tests such as maximal dilatation to measure coronary vascular reserve. Transstenosic pressure measurements complete the diagnostic armentorium. Thus therapeutic decisions can now be made not only on the basis of precise anatomic imaging, but also on functional imaging, giving a complete view of the pathophysiology of the coronary arteries and the effect of disease on myocardial blood supply. It is now up to us to optimize these imaging techniques and to propose treatments which provide patients with coronary artery disease with the best benefit-risk-cost ratio.