Calculation of maximum coronory, myocardial, and collateral blood flow by pressure measurements in the coronary circulation

Abstract

Since many years it has been widely recognized that the functional significance of coronary artery disease cannot be completely understood from anatomic information obtained by the coronary arteriogram. The shortcomings of the angiogram are most pronounced in the evaluation of PTCA-results, where the edges of the lesion are often hazy and hard to determine, whereas especially in this situation on-line information about the impeding effect of the (dilated) stenosis on blood flow is of paramount importance. Also in diagnostic catheterization, especially in intermediate lesions, determination of the functional significance of the stenosis remains cumbersome. Therefore, may attempts have been made to measure coronary blood flow directly. Most approaches in this field, however, are either crude, inaccurate, laborious, expensive, require complex equipment or imply certain risks for the patient [1–4]. Of all those methods, only comparison of blood flow velocities by the Doppler wire and ECG-triggered digital subtraction angiography have gained some clinical application [5,6]. Both methods, however, only provide information about anterograde blood flow through the large epicardial coronary arteries. No information about the contribution of collateral flow to total myocardial perfusion can be obtained. In fact, no quantitative methods to assess collateral flow in conscious man are available at present. Both in diagnostic catheterization and in PTCA, it would be of great importance if a method would be available that enables measurement of myocardial perfusion by simple means and inexpensively, without extra instruction to the patient and without prolongation of the procedure. It would be of even more importance if the contribution of coronary blood flow (in the stenotic artery) and collateral blood flow to total myocardial perfusion could be separately quantified. In this chapter, the theoretical background and experimental validation of such a method will be discussed, which allows to achieve all information about flow simply from pressure measurements in the coronary circulation.