More accurate characterization of coronary artery lesions is needed for evaluation of short and long-term interventions in coronary disease. A method of segmental artery analysis has been developed to maximize the information obtained from coronary arteriograms. Coronary lesions are traced from two projected, perpendicular, 35 mm cineangiographic views and transmetted, in digital form, to a PDP 11/45 computer. Magnification and distortion of the image are compensated for in order to determine the actual vessel profiles, using the catheter and its location as a scaling device. The two views are matched; a spatial representation of the vessel centerline is constructed mathematically; and orthogonal vessel diameters are computed at increments along this centerline. Assuming an elliptical lumen, the absolute and percentage reduction in diameter and cross-sectional area in the stenosis are computed. More complex functions (integrated atheroma mass, Poiseuille resistance, and orifice resistance) are then calculated. The accuracy and variability of the different steps involved in lesion analysis have been determined. Dimensional accuracies of +/- 150 microns (SD) are feasible. Examples are given of patients with Prinzmetal's angina and with progressive coronary disease.
Quantitative angiographic assessment of proximal coronary artery stenosis was performed in 15 patients with consecutive presentations in two categories defined by clinical and angiographic criteria. Group 1 consisted of 10 patients who had new onset of refractory rest angina and ischemic ST-T changes, but no infarction, single-vessel coronary disease without collateralization, and normal left ventricular (LV) angiograms. Group 2 consisted of five patients who were similar to patients in group 1, but had subendocardial infarction (SEI). Quantitative coronary arteriography, using paired perpendicular angiographic views and digital computation, yielded statistically different lesion dimensions and hemodynamic predictions for the two groups. Minimum stenosis diameters were 0.88 +/- 0.14 (SD) and 0.64 +/- 0.08 mm, respectively, for groups 1 and 2. This corresponded to 72% and 78% diameter reduction and 92% and 95% cross-sectional area reduction for the two groups. These small dimensional differences among lesions in the two groups resulted in large differences in their hemodynamic impact as predicted from classic fluid mechanics theory. We conclude that there are characteristic lesion dimensions for the isolated "critical" stenosis in these selected patients with rest angina. Further small increases in lesions severity result in SEI. Certain practical applications and limitations of these observations are discussed.
SUMMARY The immediate effect of contrast medium injection on left ventricular (LV) volume, stroke volume (SV) and ejection fraction (EF) was evaluated from postoperative LV biplane cineangiograms of 10 patients with 4-6 epicardial markers placed at the time of coronary artery surgery. After calibrating marker distances with respect to volume (r = 0.97-0.99) over one cardiac cycle for each patient, regression equations were used to compute LV volume from marker measurements for beats prior to, during and following injection.THERE HAS BEEN CONTROVERSY concerning the immediate effects of injected contrast medium as used for ventriculography upon human left ventricular (LV) volume and ejection fraction (EF). In animals, both are significantly increased soon after the onset of injection" 2 and, accordingly, the recommendation has been made that calculation of left ventricular end-diastolic (EDV) and end-systolic (ESV) volumes be made after the period of injection to avoid the immediate volume increase which results from the added volume of the injectate.1 In humans, results from one study suggest that there is a significant volume increase at enddiastole by the third cycle after opacification, leading to the recommendation that films taken early in the injection period be used for physiologic information.3 Another study demonstrated no consistent change in EDV or EF.4 For studies in man, a method has not been available for determining ventricular volumes from control beats immediately before the start of injection for comparison with volumes during and immediately following injection. Recently, we reported a method of determining spatial distances between metallic markers placed on the epicardium at the time of cardiac surgery and for calibrating these marker distances with respect to volume so that volumes and changes in volume could be derived subsequently from these measurements.' The purpose of the study reported here was to evaluate the immediate effects of injection of contrast medium on EDV, ESV, SV, and EF by comparing the volumes and ejection fractions immediately before injection with those during ventricular opacification. MethodsPatients who had had epicardial radiopaque markers placed at the time of cardiac surgery were selected for study. End-diastolic volumes (EDV) prior to injection ranged from 93-263 ml and did not change significantly with injection. End-systolic volumes (ESV) showed a mean decrease of 7.3 ml by beat 7 following injection; this was of borderline significance. Similarly, there was no significant change of SV or EF until beat 7 when there were small but significant increases of 6.4 ml and 0.04, respectively. The injection of moderate amounts of contrast in man does not cause significant changes in LV volume or EF through the sixth postinjection beat.The markers consisted of four or more silver vascular clips which were attached to the epicardium at the apex and on the anterior, posterior, and free wall of the left ventricle approximately two-thirds of the distance from the apex to t...
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