Assessment of coronary stenosis severity from simultaneous measurement of transstenotic pressure gradient and flow. A comparison with quantitative coronary angiography

Abstract

Visual interpretation of the coronary angiogram is the method routinely used to assess the severity of a coronary stenosis and to plan, monitor and judge the results of coronary interventions. Quantitative arteriography allows accurate and reproducible measurements of absolute and relative vascular dimensions but, despite the progressive refinements of computer-assisted analysis in the last years, eccentricity, diffuse atherosclerotic involvement and vessel tortuosity remain major obstacles to a correct assessment. In addition, following interventions, the damage to the vessel wall greatly impairs the accuracy of quantitative angiography inducing haziness of the contours and intraluminal filling defects [1, 2]. Under these circumstances, videodensitometry was a promising alternative [3] but its application has been precluded so far by the presence of basic methodological limitations, requiring further refinement of the technique [4, 5]. Intracoronary ultrasound has the potential for a more accurate assessment of lumen dimensions in the presence of luminal cross-sectional area of complex geometry [6, 7]. The dimension of the currently available ultrasound catheters (diameter 1.0–1.45 mm), however, limits the application of intravascular ultrasound to the assessment of severe coronary stenoses. In addition, an accurate evaluation of all the geometric characteristics of a coronary stenosis (diameter of a normal reference segment, length of inlet-outlet segments and of the stenosis and minimal luminal cross-sectional area) can be obtained only with an automatic three-dimensional reconstruction of multiple ultrasonic cross-sections, a technology still in phase of development and requiring extensive clinical validation [8].