Criteria for successful coronary angioplasty as assessed by alterations in coronary vasodilatory reserve.

Currently, the success of coronary angioplasty is defined by anatomic criteria. Because of the known limitations of coronary arteriography, the translesional pressure gradient and coronary vasodilatory reserve were studied in 15 patients undergoing coronary angioplasty with the intent of defining a physiologically successful result. Coronary vasodilatory reserve was measured by a digital radiographic technique that has been previously validated against directly measured coronary sinus flow (r = 0.90, p less than 0.0001). A significant reduction in luminal stenosis from 71 +/- 12 to 34 +/- 11% (p less than 0.001) was accompanied by a reduction in translesional gradient from 47 +/- 19 to 21 +/- 12 mm Hg (p less than 0.001) and an increase in coronary vasodilatory reserve from 1.03 +/- 0.15 to 1.29 +/- 0.13 (p less than 0.001). There was a significant correlation between changes in luminal stenosis and changes in translesional gradient (r = 0.61, p less than 0.05), although a change of 20% or less in luminal diameter was accompanied by no change in pressure gradient. A more significant relation between changes in gradient and in coronary hyperemic reserve existed (r = 0.77, p less than 0.005). The relation was accurate even for small changes in gradient. Because saphenous vein bypass grafts have been shown to increase coronary vasodilatory reserve to at least 1.20, it is proposed that this physiologic criterion be used to define the success of revascularization by angioplasty. In patients in whom this value was achieved, translesional gradient was invariably 25% or less of ostial pressure and 20 mm Hg or less.(ABSTRACT TRUNCATED AT 250 WORDS)

Seven-pinhole tomography--a technical description.

A single-photon emission tomography system was developed and studied. Based upon a seven-pinhile-collimated Anger camera, interfaced to a digital minicomputer, this imaging configuration yielded seven independent, nonoverlapping projection images of the radioactivity in a commonly viewed volume. The computer was used to implement an iterative algorithm that processed these projections to yield a three-dimensional reconstruction of the soruce distribution. The algorithm provudes a nonlinear first approximation to the reconstruction, then use a single iteration technique to reduce errors resulting from that approximation. Point spread functions (PSF) at various distances from the collimator face, and point-source sensitivity (PSS) at a location in the middle of the reconstruction volume were determined. The system was used for thallium-201 imaging, where it was shown to reduce imaging time and increase sensitivity without loss in specificity when compared with standard parallel-hole-collimated imaging. Seven-pinhole tomography is a practical three-dimensional imaging system that has been demonstrated to be useful in the emission cardiology setting.

Quality control of scintillation cameras using a minicomputer.

A minicomputer-based technique compiles objective indicators of scintigraphic system performance. The evaluation begins with the acquisition of a single image of an orthogonal hole pattern from which quantitative and regional measurements of point-source sensitivity, spatial resolution, and spatial linearity are derived. Two computer programs offer the user different but complementary features. The first program is the basis of an evaluation performed by a technologist for purposes of quality control. Operator intervention is minimal, and the entire protocol, including data acquisition and processing, can be completed in 20 min. The results are automatically compiled and displayed as graphs showing 100 consecutive sets of daily performance measurements. A second computer program is designed as an interactive diagnostic and research tool to display measurements as histograms and functional images. The operator can use the program to determine the quantitative and spatial characteristics of the system's intrinsic performance measurements made during the quality-control evaluations.

Variability of quantitative digital subtraction coronary angiography before and after percutaneous transluminal coronary angioplasty.

Quantitative coronary angiography has been proposed as a means of reducing observer variability in the interpretation of coronary angiograms, especially before and after percutaneous transluminal coronary angioplasty (PTCA). Analysis of 13 consecutively acquired biplane digital subtraction angiograms before and after PTCA was undertaken to determine intra- and interobserver variability of absolute lesion diameter, relative videodensitometric cross-sectional area, automated percent diameter stenosis and visual percent diameter stenosis using a new fully automated quantitative computer program. The reliability of single-view measurements was also assessed. Both before and after PTCA, measures of absolute diameter showed less interobserver variability than densitometry, percent automated diameter stenosis and percent visual diameter stenosis measurements (before, r = 0.95, 0.83, 0.86, 0.70; after, 0.95, 0.88, 0.81, 0.62, respectively). Relative videodensitometric cross-sectional area correlated poorly with images from the orthogonal view (r = 0.46). These data suggest that quantitative angiography reduces variability from visual estimates; of all quantitative angiographic measurements, the highest interobserver reproducibility is achieved using absolute lesion diameter both before and after PTCA, probably because no operator interaction is needed to identify a "normal" segment. Unselected, single-view quantitative arteriography is poorly reproducible using videodensitometry. Therefore, automated determination of absolute lesion diameter in at least 2 projections provides the most reproducible evaluation of coronary lesions both before and after PTCA.

Validation in dogs of a rapid digital angiographic technique to measure relative coronary blood flow during routine cardiac catheterization.

Assessment of the functional significance of anatomically defined coronary stenoses has been hampered by the lack of clinically applicable techniques of measuring coronary blood flow or flow ratios. A digital angiographic technique is reported that allows rapid analysis of relative regional coronary blood flow during routine cardiac catheterization. This technique was validated in dogs by comparing digital flow ratio estimates with electromagnetic-flow (EMF) ratio measurements. Fourteen open-chest dogs had EMF probes placed on the proximal left anterior descending artery before selective coronary angiography. Electrocardiographically gated images were acquired directly by a digital radiographic system during both baseline blood flow and either contrast or papaverine-induced hyperemia. Dual-parameter functional images were generated using color and intensity coding to represent contrast arrival time and contrast density, respectively. For analysis, myocardial areas of interest were created over the distal perfusion bed of the left anterior descending coronary artery. Mean contrast density/appearance time (CD/AT) values were computer calculated as the mean density divided by the mean arrival time for each. Coronary flow reserve was determined as the ratio of the CD/AT value for a hyperemic image divided by the CD/AT value for the corresponding baseline image. CD/AT ratios correlated well (r = 0.92) with actual EMF ratios (CD/AT Ratio = 0.90 EMF Ratio +0.12, n = 48 ratios). Reproducibility was +/- 13%. Interobserver (r = 0.99) and intraobserver (r = 0.98) variability was excellent. Thus, rapid, accurate and reproducible estimates of relative regional coronary blood flow are possible using digital radiography.

Quantitative assessment of global and regional left ventricular function with low-contrast dose digital subtraction ventriculography.

Few studies have compared the use of low-contrast dose digital subtraction ventriculography with conventional ventriculography for quantitative assessment of both global and regional left ventricular function. Accordingly, 34 patients underwent conventional ventriculography using 36 ml of ionic contrast material and digital ventriculography (mask-mode) using 10 ml of contrast diluted in 10 ml of saline and injected over two seconds. Data from two patients were excluded because of ectopy during cineventriculography and from one because of ectopy during both studies. End-diastolic and end-systolic volumes were calculated from both studies by an area-length method and used to calculate ejection fractions. Regional wall motion was quantitated by the centerline method. Results of linear regression analysis demonstrated high correlations for all parameters (end-diastolic volume, r = 0.85; end-systolic volume, r = 0.93; ejection fraction, r = 0.92; quantitative regional wall motion, r = 0.90). Thus, low-contrast dose digital subtraction ventriculography provides an accurate assessment of both global and regional ventricular function and minimizes the required dose and inherent risks of contrast media.

A comparison of 35 mm cine film and digital radiographic image recording: implications for quantitative coronary arteriography. Film vs. digital coronary quantification.

To assess potential differences in the intrinsic properties of image recording media and their impact on quantitative coronary arteriography, we used an automatic quantitative arteriography computer program to analyze cine film and digital radiographic images of a radiographic arterial phantom. The phantom consisted of a lucite plate with precision-drilled lumena ranging from 0.5 to 5.0 mm in diameter. Film images were digitized at 2048 X 2048 pixel resolution, and digital radiographic images were acquired at 512 X 512 and 1024 X 1024 resolution. Arterial geometric diameter, percent diameter stenosis, densitometric relative cross-sectional area, and densitometric percent area stenosis were measured. All three techniques were equivalent in measuring diameters with a high degree of overall accuracy (R greater than .992). All methods overestimated diameters below 1.0 mm. Both 512 X 512 and 1024 X 1024 digital images were superior to film for densitometric measurement of relative area (R = .995 vs. R = .940, P = .0032). We conclude that automated analysis of digital radiographic images yields results that are similar in geometric precision but greater in densitometric precision than film analysis.

A comparison of traditional wall motion assessment and quantitative shape analysis: a new method for characterizing left ventricular function in humans.

To forego the need to arbitrarily choose coordinate, reference, and indexing systems and to make other assumptions mandated by traditional methods of measuring wall motion, a technique of regional function analysis based on shape characteristics and pattern recognition was developed. The method is based on curvature analysis, a fundamental shape parameter, and is adaptive to the complex geometry of cineangiographic ventricular images. Quantitative shape parameters were compared to a standard method of regional function analysis (center-line method) in 130 patients. Quantitative shape and wall motion indexes showed a positive correlation over a broad range of normal and abnormal function (r = 0.748, p less than 0.001). Overall sensitivity and specificity for categorization of regional function were not statistically different for either technique. Within regions, however, shape criteria were more specific in categorizing inferior zones than anterior zones and were more often abnormal in the presence of mild regional abnormalities that were not located in the apical region. In conclusion, shape analysis and pattern recognition techniques can be used to forego dependence on the numerous assumptions and approximations required by traditional wall motion techniques, while providing performance characteristics that are similar to, and in some instances better than, traditional approaches. Incorporation of shape information in assessments of regional function provides a more comprehensive evaluation that includes the important visual cues used by experienced observers or "experts."

Automated quantitative coronary arteriography: morphologic and physiologic validation in vivo of a rapid digital angiographic method.

Quantitative coronary arteriography has been shown to be useful in assessing the extent of coronary disease, its functional significance, and its response to therapeutic interventions. Most current methods rely either on hand-drawn arterial contours or automatic edge-detection algorithms applied to 35 mm cineangiograms. To assess the performance in vivo of a new, fully automatic, rapid coronary quantitation program, dogs were instrumented with precision-drilled, plastic cylinders to create intraluminal stenoses in the left anterior descending and/or circumflex arteries, as well as with high-fidelity micromanometers and electromagnetic flow probes. Stenosis diameters ranged from 0.83 to 1.83 mm. Biplane, on-line, digital coronary angiograms and cineangiograms were recorded during standard selective coronary arteriography in the closed-chest preparation. The on-line digital images were analyzed in nonsubtracted and subtracted modes. Cineangiograms were digitized to allow coronary quantitation by the same computer program. There was an excellent correlation between known and measured minimal diameter stenoses (r = .87 to .98, SEE = 0.09 to 0.24 mm). Interobserver and intraobserver variability analysis showed high reproducibility (r = .90 to .97, SEE = 0.12 to 0.23 mm). The best results in both analyses were achieved by nonsubtracted digital imaging and the worst by cineradiography. Measures of percent diameter stenosis, percent area stenosis (geometric and videometric), and absolute minimal cross-sectional area (geometric and videometric) were all significantly correlated with independent measures of actual coronary flow reserve. This study provides direct anatomic and physiologic validation in vivo of a new and rapid coronary quantitation method suitable for analysis of both digital angiograms and cineangiograms.

Quantitative regional curvature analysis: an application of shape determination for the assessment of segmental left ventricular function in man.

All traditional techniques of regional ventricular function analysis depend upon one or more assumptions about coordinate, reference, or indexing systems, idealized ventricular geometry, and the uniformity of ventricular contraction. Therefore, a method of shape analysis was developed that allows the quantitation of regional curvature and is independent of the assumptions outlined. This was implemented on a commercial image processing unit and applied to silhouettes of 30-degree right anterior oblique left ventriculograms. Three groups with abnormal wall motion (anterior abnormality, n = 23; inferior abnormality, n = 23; anterior and inferior abnormalities, n = 22) were analyzed and compared to a group with normal regional function (n = 22). Relatively few significant quantitative curvature differences were noted at end diastole among the groups. These few abnormalities described a slight increase in curvature or globularity of the anterior and inferior walls. More marked and extensive aberrations were detected at end systole. The group with anterior wall motion disturbances showed four distinct areas of curvature abnormality. Excessive curvature was present on either side of the apex (anterior and inferoapical regions) and apical curvature was less than normal. The fourth region was in the inferior zone, which showed curvature values that were less than normal, suggesting increased inward motion contralateral to the anterior abnormality. The group with inferior wall motion abnormalities also showed excessive end-systolic curvature on either side of the apex (diaphragmatic and anteroapical zones) and deficient curvature at the apex. A combination of these regional morphologic abnormalities was noted in the group with both anterior and inferior dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

The chronic coronary flow reserve provided by saphenous vein bypass grafts as determined by digital coronary radiography.

Intraoperative measurements following aortocoronary revascularization have demonstrated a reduced coronary flow reserve (CFR) in saphenous vein bypass grafts. To determine whether chronic bypass graft flow reserve returns to normal, we studied patients in the cardiac catheterization laboratory by means of a newly developed digital coronary radiographic technique. CFR ratios were determined for 54 arterial distributions from 33 men. Twenty-two distributions were normal (group I) 22 had saphenous vein bypass grafts (group II), seven had high-grade stenoses, which were subsequently bypassed (group III), and three were bypassed but had flow-limiting stenoses (group IV). Group II arteries had approximately half the CFR of group I arteries (1.40 +/- 0.17 vs 1.78 +/- 0.31; p less than 0.0001) but significantly improved CFR compared to group III arteries (1.40 +/- 0.17 vs 1.05 +/- 0.13; p less than 0.002) or group IV arteries (1.40 +/- 0.17 vs 1.05 +/- 0.12; p less than 0.02). These results indicate that regional CFR is improved by nonstenotic saphenous vein bypass grafts but does not return to normal.

Accuracy and reproducibility of quantitative coronary arteriography using 6 and 8 French catheters with cine angiographic acquisition.

To determine the suitability of 6 French catheters for quantitative coronary arteriography, the relative accuracy and reproducibility of one type of these catheters was compared to that obtained with standard 8 French catheters in 20 stenoses. Duplicate injections with polyurethane 6 French catheters were obtained using hand and power injection technique with cineangiographic acquisition (four 6 French catheter injections total per stenosis). Measurements of both percent diameter stenosis and absolute dimensions were compared to those obtained with hand injection and cine acquisition using 8 French catheters as a "gold standard." While the reproducibility of dimension determination with the 6 French catheter was generally similar to that obtained with the 8 French catheter (0.27 +/- 0.23 mm for absolute diameter and 8.1 +/- 7.4% for percent diameter stenosis), accuracy was significantly less for the 6 French catheter for measurement of absolute dimensions. Thus, while apparently well suited for serial measurements of the same stenoses, 6 French catheters may not be as accurate in the determination of absolute artery dimensions as 8 French catheters.

Comparative long-term effects of coronary artery bypass graft surgery and percutaneous transluminal coronary angioplasty on regional coronary flow reserve.

To evaluate the relative long-term improvement in coronary artery hemodynamics after revascularization by coronary artery bypass graft surgery (CABG) or percutaneous transluminal coronary angioplasty (PTCA), regional coronary flow reserve (CFR) was measured, by digital computer analysis of 35 mm cine film, in 50 men undergoing cardiac catheterization. CFR (mean +/- SEM) in 12 atherosclerotic arteries before revascularization was 1.02 +/- 0.05. Mean CFR in 29 normal arteries of men with normal coronary arteriograms was significantly higher (2.59 +/- 0.11) than that in 16 atherosclerotic arteries of patients revascularized by CABG (2.02 +/- 0.17, p less than .01) or in 14 atherosclerotic arteries of those revascularized by PTCA (1.97 +/- 0.12, p less than .01). No difference in CFR between the CABG and PTCA groups was found and variables known to influence CFR were similar between groups. Equivalent and significant long-term improvement in coronary artery hemodynamics is provided by CABG or PTCA. We postulate that the difference in CFR in the men with normal arteries and those who underwent revascularization was related to the effects of the general atherosclerotic process, which remain despite successful treatment by these techniques.