Techniques in the Angiographic Analysis of Coronary Flow: Past, Present, and Future

The current method of analyzing coronary flow data is the TIMI flow grade method. This method is convenient and easy to apply, but there are limitations to this categorical method of analyzing coronary artery flow. We have developed a new method of analyzing coronary blood flow called the “TIMI frame count.” Using the TIMI frame counting method, we have shown that the flow in the coronary arteries is in fact distributed as a continuous variable and that there are nondiscrete categories of slow and fast flow. This article discusses the statistical basis for the development of this new, simple, and continuous index of coronary flow and provides a “how-to manual“ describing the practical implementation of the new TIMI frame count method. We also describe simple new techniques for measuring the distance to the landmark used for TIMI frame counting. Knowing the distance and the time from the TIMI frame count, velocity can easily be calculated. Tables are provided that can be used for these calculations on-line in the cardiac catheterization laboratory. If the diameter is known, flow can also be calculated from these tables. We also describe new applications of marker wires to measure distance and velocity.