Reiber, J.H.C.

In vivo comparison of arterial lumen dimensions assessed by co-registered three-dimensional (3D) quantitative coronary angiography, intravascular ultrasound and optical coherence tomography (Article)

2012-01-19T00:00:00Z

This study sought to compare lumen dimensions as assessed by 3D quantitative coronary angiography (QCA) and by intravascular ultrasound (IVUS) or optical coherence tomography (OCT), and to assess the association of the discrepancy with vessel curvature. Coronary lumen dimensions often show discrepancies when assessed by X-ray angiography and by IVUS or OCT. One source of error concerns a possible mismatch in the selection of corresponding regions for the comparison. Therefore, we developed a novel, real-time co-registration approach to guarantee the point-to-point correspondence between the X-ray, IVUS and OCT images. A total of 74 patients with indication for cardiac catheterization were retrospectively included. Lumen morphometry was performed by 3D QCA and IVUS or OCT. For quantitative analysis, a novel, dedicated approach for co-registration and lumen detection was employed allowing for assessment of lumen size at multiple positions along the vessel. Vessel curvature was automatically calculated from the 3D arterial vessel centerline. Comparison of 3D QCA and IVUS was performed in 519 distinct positions in 40 vessels. Correlations were r = 0.761, r = 0.790, and r = 0.799 for short diameter (SD), long diameter (LD), and area, respectively. Lumen sizes were larger by IVUS (P < 0.001): SD, 2.51 ± 0.58 mm versus 2.34 ± 0.56 mm; LD, 3.02 ± 0.62 mm versus 2.63 ± 0.58 mm; Area, 6.29 ± 2.77 mm2versus 5.08 ± 2.34 mm2. Comparison of 3D QCA and OCT was performed in 541 distinct positions in 40 vessels. Correlations were r = 0.880, r = 0.881, and r = 0.897 for SD, LD, and area, respectively. Lumen sizes were larger by OCT (P < 0.001): SD, 2.70 ± 0.65 mm versus 2.57 ± 0.61 mm; LD, 3.11 ± 0.72 mm versus 2.80 ± 0.62 mm; Area 7.01 ± 3.28 mm2versus 5.93 ± 2.66 mm2. The vessel-based discrepancy between 3D QCA and IVUS or OCT long diameters increased with increasing vessel curvature. In conclusion, our comparison of co-registered 3D QCA and invasive imaging data suggests a bias towards larger lumen dimensions by IVUS and by OCT, which was more pronounced in larger and tortuous vessels.

Automated analysis of three-dimensional stress echocardiography (Article)

2011-06-01T00:00:00Z

Real-time three-dimensional (3D) ultrasound imaging has been proposed as an alternative for two-dimensional stress echocardiography for assessing myocardial dysfunction and underlying coronary artery disease. Analysis of 3D stress echocardiography is no simple task and requires considerable expertise. In this paper, we propose methods for automated analysis, which may provide a more objective and accurate diagnosis. Expert knowledge is incorporated via statistical modelling of patient data. Methods for identifying anatomical views, detecting endocardial borders, and classification of wall motion are described and shown to provide favourable results. We also present software developed especially for analysis of 3D stress echocardiography in clinical practice. Interobserver agreement in wall motion scoring is better using the dedicated software (96%) than commercially available software not dedicated for this purpose (79%). The developed tools may provide useful quantitative and objective parameters to assist the clinical expert in the diagnosis of left ventricular function.

Correspondence free 3D statistical shape model fitting to sparse X-ray projections (Article)

2010-12-01T00:00:00Z

In this paper we address the problem of 3D shape reconstruction from sparse X-ray projections. We present a correspondence free method to fit a statistical shape model to two X-ray projections, and illustrate its performance in 3D shape reconstruction of the femur. The method alternates between 2D segmentation and 3D shaoe reconstruction, where 2D segmentation is guided by dynamic programming along the model projection on the X-ray plane. 3D reconstruction is based on the iterative minimization of the 3D distance between a set of support points and the back-projected silhouette with respect to the pose and model parameters. We show robustness of the reconstruction on simulated X-ray projection data of the femur, varying the field of view; and in a pilot study on cadaveric femora.

Model driven quantification of left ventricular function from sparse single-beat 3D echocardiography (Article)

2010-08-01T00:00:00Z

This paper presents a novel model based segmentation technique for quantification of left ventricular (LV) function from sparse single-beat 3D echocardiographic data acquired with a fast rotating ultrasound (FRU) transducer. This transducer captures cardiac anatomy in a sparse set of radially sampled, curved cross-sections within a single cardiac cycle. The method employs a 3D Active Shape Model of the left ventricle (LV) in combination with local appearance models as prior knowledge to steer the segmentation. A set of local appearance patches generate the model update points for fitting the model to the LV in the curved FRU cross-sections. Updates are then propagated over the dense 3D model mesh to overcome correspondence problems due to the data sparsity, whereas the 3D Active Shape Model serves to retain the plausibility of the generated shape.Leave-one-out cross-validation was carried out on single-beat FRU data from 28 patients suffering from various cardiac pathologies. Detection succeeded in 24 cases, and failed in 4 cases due to large dropouts in echo signal. For the successful 24 cases, detection yielded Point to Point errors of 3.1 ± 1.1 mm, Point to Surface errors of 1.7 ± 0.9. mm and an EF error of 7.3 ± 4.9%. Comparison of fitting on single-beat versus denser multi-beat data showed a similar performance for both types of data irrespective of frame angles of the intersections. Robustness tests with respect to different model initializations showed acceptable performance for initial positions within a range of 26. mm for displacement and 12° for orientation. Furthermore, a comparison study between the proposed method and global LV function measured from MR studies of the same patients showed an underestimation of volumes estimated from echocardiographic data compared to MR derived volumes, similar to other results reported in literature. All experiments demonstrate that the proposed method combines robustness with respect to initialization with an acceptable accuracy, while using sparse single-beat FRU data.

Diagnostic accuracy of 320-row multidetector computed tomography coronary angiography in the non-invasive evaluation of significant coronary artery disease (Article)

2010-08-01T00:00:00Z

Aims Multidetector computed tomography coronary angiography (CTA) has emerged as a feasible imaging modality for non-invasive assessment of coronary artery disease (CAD). Recently, 320-row CTA systems were introduced, with 16 cm anatomical coverage, allowing image acquisition of the entire heart within a single heart beat. The aim of the present study was to assess the diagnostic accuracy of 320-row CTA in patients with known or suspected CAD. Methods and resultsA total of 64 patients (34 male, mean age 61 ± 16 years) underwent CTA and invasive coronary angiography. All CTA scans were evaluated for the presence of obstructive coronary stenosis by a blinded expert, and results were compared with quantitative coronary angiography. Four patients were excluded from initial analysis due to non-diagnostic image quality. Sensitivity, specificity, and positive and negative predictive values to detect ≥50 luminal narrowing on a patient basis were 100, 88, 92, and 100, respectively. Moreover, sensitivity, specificity, and positive and negative predictive values to detect ≥70 luminal narrowing on a patient basis were 94, 95, 88, and 98, respectively. With inclusion of non-diagnostic imaging studies, sensitivity, specificity, and positive and negative predictive values to detect ≥50 luminal narrowing on a patient basis were 100, 81, 88, and 100, respectively. Conclusion The current study shows that 320-row CTA allows accurate non-invasive assessment of significant CAD.

Automated quantification of stenosis severity on 64-slice CT: A comparison with quantitative coronary angiography (Article)

2010-07-01T00:00:00Z

Objectives: This study sought to demonstrate the feasibility of a dedicated algorithm for automated quantification of stenosis severity on multislice computed tomography in comparison with quantitative coronary angiography (QCA). Background: Limited information is available on quantification of coronary stenosis, and previous attempts using semiautomated approaches have been suboptimal. Methods: In patients who had undergone 64-slice computed tomography and invasive coronary angiography, the most severe lesion on QCA was quantified per coronary artery using quantitative coronary computed tomography (QCCTA) software. Additionally, visual grading of stenosis severity using a binary approach (50% stenosis as a cutoff) was performed. Diameter stenosis (percentage) was obtained from detected lumen contours at the minimal lumen area, and corresponding reference diameter values were obtained from an automatic trend analysis of the vessel areas within the artery. Results: One hundred patients (53 men; 59.8 ± 8.0 years) were evaluated, and 282 (94%) vessels were analyzed. Good correlations for diameter stenosis were observed for vessel-based (n = 282; r = 0.83; p < 0.01) and patient-based (n = 93; r = 0.86; p < 0.01) analyses. Mean differences between QCCTA and QCA were -3.0% ± 12.3% and -6.2% ± 12.4%. Furthermore, good agreement was observed between QCCTA and QCA for semiquantitative assessment of diameter stenosis (accuracy of 95%). Diagnostic accuracy for assessment of <50% diameter stenosis was higher using QCCTA compared with visual analysis (95% vs. 87%; p = 0.08). Moreover, a significantly higher positive predictive value was observed with QCCTA when compared with visual analysis.

Assessment With Multi-Slice Computed Tomography and Gray-Scale and Virtual Histology Intravascular Ultrasound of Gender-Specific Differences in Extent and Composition of Coronary Atherosclerotic Plaques in Relation to Age (Article)

2010-02-15T00:00:00Z

Data evaluating gender- and age-specific differences in plaque observations on multislice computed tomography (MSCT) are scarce. Accordingly, the aim of this study was to evaluate coronary plaque patterns in men and women in relation to age using MSCT. The findings were compared to observations on grayscale intravascular ultrasound (IVUS) and virtual histology (VH) IVUS. In total, 93 patients (59 men, 34 women) underwent 64-slice MSCT followed by conventional coronary angiography with IVUS. Plaque extent and composition were assessed on MSCT, grayscale IVUS, and VH IVUS. Coronary plaque patterns were compared between men and women in 2 age groups (<65 and ≥65 years old). In patients aged <65 years, more plaques were observed on MSCT in men (6 ± 4 vs 2 ± 2 in women, p <0.001). Also, a larger plaque burden was observed on grayscale IVUS in men (45.7 ± 11.4% vs 36.3 ± 11.6% in women, p <0.001). Similarly, more mixed plaques were observed in men (3 ± 3 vs 1 ± 1 in women, p = 0.003), whereas a larger arc of calcium was detected on grayscale IVUS in men (91.7 ± 93.5° vs 25.7 ± 51.0° in women, p <0.001). On VH IVUS, the prevalence of thin-cap fibroatheroma was higher in men (31% vs 0%) compared to women. In patients aged ≥65 years old, no important differences in plaque patterns were observed between men and women. In conclusion, more extensive atherosclerosis and more calcified lesions were observed in men than in women. These differences were predominantly present in patients aged <65 years and were lost in those aged ≥65 years.

Evaluation of plaque characteristics in acute coronary syndromes: Non-invasive assessment with multi-slice computed tomography and invasive evaluation with intravascular ultrasound radiofrequency data analysis (Article)

2008-10-01T00:00:00Z

Aims: Atherosclerotic plaque characteristics play an important role in the development of coronary events. We investigated coronary plaque characteristics on multi-slice computed tomography (MSCT) and virtual histology intravascular ultrasound (VH IVUS) in patients with acute coronary syndromes (ACS) and stable coronary artery disease (CAD). Methods and results: Fifty patients (25 with ACS, 25 with stable CAD) underwent 64-slice MSCT followed by VH IVUS in 48 (96%) patients. In ACS patients, 32% of plaques were non-calcified on MSCT and 59% were mixed [corresponding odds ratio (95% confidence intervals): 3.9 (1.6-9.5), P = 0.003 and 3.4 (1.6-6.9), P = 0.001, respectively]. In patients with stable CAD, completely calcified lesions were more prevalent (61%). On VH IVUS, the percentage of necrotic core was higher in the plaques of ACS patients (11.16 ± 6.07 vs. 9.08 ± 4.62% in stable CAD, P = 0.02). In addition, thin cap fibroatheroma was more prevalent in ACS patients (32 vs. 3% in patients with stable CAD, P < 0.001) and was most frequently observed in mixed plaques on MSCT. Plaque composition both on MSCT and VH IVUS was identical between culprit and non-culprit vessels of ACS patients. Conclusion: On MSCT, differences in plaque characterization were demonstrated between patients with ACS and stable CAD. Plaques of ACS patients showed features of vulnerability to rupture on VH IVUS. Potentially, MSCT may be useful for non-invasive identification of atherosclerotic plaque patterns associated with higher risk.

Optimizing computed tomographic angiography image segmentation using Fitness Based Partitioning (Article)

2008-07-21T00:00:00Z

Computed Tomographic Angiography (CTA) has become a popular image modality for the evaluation of arteries and the detection of narrowings. For an objective and reproducible assessment of objects in CTA images, automated segmentation is very important. However, because of the complexity of CTA images it is not possible to find a single parameter setting that results in an optimal segmentation for each possible image of each possible patient. Therefore, we want to find optimal parameter settings for different CTA images. In this paper we investigate the use of Fitness Based Partitioning to find groups of images that require a similar parameter setting for the segmentation algorithm while at the same time evolving optimal parameter settings for these groups. The results show that Fitness Based Partitioning results in better image segmentation than the original default parameter solutions or a single parameter solution evolved for all images.

Time Continuous Detection of the Left Ventricular Long Axis and the Mitral Valve Plane in 3-D Echocardiography (Article)

2008-02-01T00:00:00Z

Automated segmentation approaches for the left ventricle (LV) in 3-D echocardiography (3DE) often rely on manual initialization. So far, little effort has been put into automating the initialization procedure to get to a fully automatic segmentation approach. We propose a fully automatic method for the detection of the LV long axis (LAX) and the mitral valve plane (MVP) over the full cardiac cycle, for the initialization of segmentation algorithms in 3DE. Our method exploits the cyclic motion of the LV and therefore detects salient structures in a time-continuous way. Probabilities to candidate LV center points are assigned through a Hough transform for circles. The LV LAX is detected by combining dynamic programming detections on these probabilities in 3-D and 2D + time to obtain a time continuous solution. Subsequently, the mitral valve plane is detected in a projection of the data on a plane through the previously detected LAX. The method easily adjusts to different acquisition routines and combines robustness with good accuracy and low computational costs. Automatic detection was evaluated using patient data acquired with the fast rotating ultrasound (FRU) transducer (n = 11 patients) and with the Philips Sonos 7500 ultrasound system (Philips Medical Systems, Andover, MA, USA), with the X4 matrix transducer (n = 14 patients). For the FRU-transducer data, the LAX was estimated with a distance error of 2.85 ± 1.70 mm (mean ± SD) and an angle of 5.25 ± 3.17 degrees; the mitral valve plane was estimated with a distance of -1.54 ± 4.31 mm. For the matrix data, these distances were 1.96 ± 1.30 mm with an angle error of 5.95 ± 2.11 and -1.66 ± 5.27 mm for the mitral valve plane. These results confirm that the method is very suitable for automatic detection of the LV LAX and MVP. It provides a basis for further automatic exploration of the LV and could therefore serve as a replacement of manual initialization of 3-D segmentation approaches. (E-mail: marijn.vanstralen@erasmusmc.nl).

Automated Tracking of the Mitral Valve Annulus Motion in Apical Echocardiographic Images Using Multidimensional Dynamic Programming (Article)

2007-09-01T00:00:00Z

We developed a semiautomatic method for tracking the mitral valve annulus (MVA) in echocardiographic images, in particular, tracking the septal and the lateral mitral valve hinge points. The algorithm is based on multidimensional dynamic programming combined with apodized block matching. The method was tested on single-beat apical four chamber image sequences of 20 patients with acute myocardial infarction. The automated tracking results were evaluated by comparing them with the average manual tracking results of two experts. The mitral valve hinge point displacements and the total mitral excursions obtained by the automatic technique agreed well with those obtained manually and outperformed two commonly used tracking methods (forward tracking and minimum tracking). In conclusion, this novel semiautomatic tracking method is clinically valuable and capable of tracking the MVA motion within the limits of interobserver variability. The technique is robust, even in low frame rate, redigitized VCR images of clinical quality. (E-mail: S.T.Nevo@Student.TUDelft.NL).

In-vivo validation of on-line and off-line geometric coronary measurements using insertion of stenosis phantoms in procine coronary arteries (Article)

1992-01-01T00:00:00Z

Geometric coronary artery measurements with the Phillips Digital Cardiac Imaging System (DCI) and the Cardiovascular Angiography Analysis System (CAAS) were validated using percutaneous insertion of radiolucent stenosis phantoms in swine coronary arteries. Angiographic visualization of the stenosis lumens (phi 0.5, 0.7, 1.0, 1.4, 1.9 mm) was simultaneously recorded on DCI and cinefilm. The acquisition systems were calibrated by either the diameter of the guiding catheter (catheter CAL) or the isocenter method (isocenter CAL). Minimal luminal diameters (MLD) obtained with CAAS and DCI on 20 corresponding cineframes were compared with the true phantom diameters (PD). The accuracy of MLD measurements with the CAAS using isocenter CAL was -0.07mm, the precision 0.21 mm (r = 0.91; y = 0.30 + 0.79x; SEE = 0.19), with catheter CAL the accuracy was 0.09 mm, the precision 0.23 mm (r = 0.89; y = 0.19 + 0.74x; SEE = 0.19). The accuracy of MLD measurements using the DCI with isocenter CAL was 0.08 mm, the precision 0.15 min (r = 0.96; y = 0.08 + 0.86x; SEE = 0.14), with catheter CAL the accuracy was 0.18 mm, the precision 0.21 mm (r = 0.92; y = 0.09 + 0.76x; SEE = 0.17). DCI underestimated PD with isocenter CAL (p less than 0.05) and with catheter CAL (p less than 0.001). MLD can be measured with high accuracy, both applying on-line digital as well as off-line cineangiographic analysis. The results of digital measurements demonstrate high reliability of the new digital software package.

Edge detection versus densitometry in the quantitative assessment of stenosis phantoms: an in vivo comparison in procine coronary arteries (Article)

1992-01-01T00:00:00Z

The aim of this study was the in vivo validation and comparison of the geometric and densitometric technique of a computer-assisted automatic quantitative angiographic system (CAAS system). In six Landrace Yorkshire pigs (45 to 55 kg), precision-drilled phantoms with a circular lumen of 0.5, 0.7, 1.0, 1.4, and 1.9 mm were percutaneously introduced into the left anterior descending or left circumflex coronary artery. Twenty-eight coronary angiograms obtained with the phantom in a wedged intracoronary position could be quantitatively analyzed. Minimal lumen diameter, minimal cross-sectional area, percent diameter stenosis, and cross-sectional area stenosis were automatically measured with both the geometric and densitometric technique and were compared with the known phantom dimensions. When minimal lumen diameter was measured using the geometric approach, a nonsignificant underestimation of the phantom size was observed, with a mean difference of -0.06 +/- 0.14 mm. The larger mean difference observed with videodensitometry (-0.11 +/- 0.20 mm) was the result of the failure of the technique to differentiate the low lumen videodensities of two phantoms of smaller size (0.5 and 0.7 mm) from a dense background. Percent cross-sectional area stenosis measured with the two techniques showed a good correlation with the corresponding phantom measurements (mean difference between percent cross-sectional area stenosis calculated from the quantitative angiographic measurements and the corresponding phantom dimensions was equal to 2 +/- 6% for both techniques, correlation coefficient = 0.93 with both techniques, SEE = 5% with the geometric technique and 6% with the densitometric approach).(ABSTRACT TRUNCATED AT 250 WORDS)

Edge detection versus densitometry for assessing coronary stenting quantitatively (Article)

1991-01-01T00:00:00Z

The optimal method used to analyze quantitatively the immediate angiographic results of coronary stenting in the coronary arteries has not been studied. Accordingly, minimal luminal cross-sectional area was determined by 2 methods, edge detection and densitometry, in 19 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) and then coronary stent implantation for symptomatic coronary stenoses. The correlation coefficient, 0.73 before angioplasty, decreased to 0.59 after coronary angioplasty and then increased to 0.83 after stent implantation. The mean differences between edge detection and densitometric determinations of minimal luminal cross-sectional area were 0.31 +/- 0.51 mm2 before PTCA, -0.38 +/- 1.22 mm2 after angioplasty and 0.35 +/- 0.79 mm2 after coronary stenting. It is concluded that, although the correlation and variability in the measurement of minimal luminal cross-sectional area between edge detection and densitometry deteriorate after PTCA, they are improved after stenting, probably because of smoothing of the vessel contours by the stent and remodeling of the stented segment into a more circular configuration. Therefore, in the stented coronary artery, edge detection and densitometry are equally acceptable methods of analysis.

Do stents interfere with the densitometric assessment of a coronary artery lesion (Article)

1991-01-01T00:00:00Z

This in vitro study was designed to assess the contribution of three currently investigated coronary stents to the densitometric measurement of a known stenosis contained within two different sized plexiglass phantoms. These studies were performed at two concentrations of the contrast agent iopamidol (50 and 100%). The calculated minimal luminal cross-sectional area values in the control phantom ranged from 0-18% higher than the theoretical values. Insertion of a stainless steel stent (Wallstent, Schneider, Zurich or Palmaz-Schatz, Johnson and Johnson, Warren, NJ) resulted in further minor increases (less than or equal to 8% in the calculated minimal luminal cross-sectional area, except in the smaller phantom filled with 50% contrast medium. The Wiktor (tantalum) stent (Medtronic, Minneapolis, MN) had the largest impact of the three stents depending on the concentration of iopamidol (100% contrast medium: 9-13% values above control; 50% contrast medium; 23-56% higher). We conclude that although densitometry may overestimate the minimal luminal cross-sectional area in stented vessels, this effect is usually minor with stainless steel stents. However, tantalum-containing stents may result in serious overestimation of lesion area, particularly if contrast is diluted or the vessel is not well filled.

A comparison of two methods to measure coronary flow reserve in the setting of coronary angioplasty: intracoronary blood flow velocity measurements with a Doppler catheter, and digital subtraction cineangiography (Article)

1989-01-01T00:00:00Z

Intracoronary blood flow velocity measurements with a Doppler balloon catheter and the radiographic assessment of myocardial perfusion with contrast media, before and after the intracoronary administration of papaverine, have previously been used to investigate regional coronary flow reserve. In the present study we applied both techniques in 21 patients to measure coronary flow reserve in the setting of coronary angioplasty. Pre-angioplasty (N = 14) and post-angioplasty (N = 19) measurements of coronary flow reserve were obtained by digital subtraction cineangiography in the myocardial region supplied by the dilated coronary artery, and with the Doppler probe in the proximal part of the dilated vessel. The reactive hyperaemia following the final balloon inflation was recorded with the Doppler balloon catheter still positioned across the stenotic lesion. Coronary stenosis geometry was quantified with the Cardiovascular Angiography Analysis System. When the epicardial stenosis was the only factor causing a reduction in coronary flow reserve, flow reserve measured with both digital subtraction cineangiography and with the Doppler probe correlated well with the cross-sectional area at the site of obstruction, r = 0.88, SEE = 0.36 and r = 0.77, SEE = 0.45 respectively. In contrast, when other factors decreasing coronary flow reserve were present (intimal dissection, left ventricular hypertrophy, previous myocardial infarction, collaterals) measurements obtained with both techniques correlated poorly with cross-sectional area (r = 0.55, SEE = 0.57, and r = 0.59, SEE = 0.50). Flow reserve measurements obtained with digital subtraction cineangiography correlated well with the measurements obtained with the Doppler probe (r = 0.85, SEE = 0.38, and r = 0.87, SEE = 0.34), although the two approaches have methodologically nothing in common and their respective regions of interest (myocardium for the radiographic technique and intracoronary lumen for the Doppler technique) are basically different. Furthermore, the reactive hyperaemia following the final balloon inflation was related to the flow reserve measured with both the angiographic technique (r = 0.85, SEE = 0.34) and the Doppler technique (r = 0.83, SEE = 0.32) using pharmacologically induced coronary vasodilation with intracoronary papaverine. This suggests that the same quantity of coronary flow reserve that can be recruited pharmacologically can be recruited by ischaemia following a transluminal occlusion.

How critical is frame selection in quantitative coronary angiographic studies? (Article)

1989-01-01T00:00:00Z

To analyse quantitatively a coronary arterial segment from a cineangiogram, an end-diastolic or neighbouring frame is usually selected. However, different cardiologists may select other (although usually neighbouring) frames, even when the same selection criteria are followed. It is also possible that the frames are selected from different cardiac cycles. In this study the effects of such phase shifts on the reproducibility of the quantitative measurements were studied. In a total of 38 consecutive patient films obtained at a filmspeed of 25 frames s-1, the frame phi demonstrating the severity of a lesion optimally as judged by a senior cardiologist, the three preceding frames, the three following frames and one frame exactly one cycle prior to or following frame phi were selected; frame phi was always chosen in the end-diastolic phase of the cardiac cycle. In each film one coronary arterial segment with a focal lesion was analysed quantitatively in these total of 8 frames with the Cardiovascular Angiography Analysis System (CAAS). No significant differences were found in the mean difference and the standard deviations of the differences (variabilities) in the obstruction diameter, interpolated reference diameter, percent diameter stenosis, extent of the obstruction and area of atherosclerotic plaque obtained in the various frames with respect to frame phi. Therefore, it may be concluded that the selection of a cineframe for quantitative analysis in the end-diastolic phase of the cardiac cycle is not very critical.(ABSTRACT TRUNCATED AT 250 WORDS)

Does intracoronary papaverine dilate epicardial coronary arteries? Implications for the assessment of coronary flow reserve (Article)

1988-01-01T00:00:00Z

Intracoronary papaverine is used as a means to induce a strong and short-lasting hyperemia in several recently developed methods to measure coronary flow reserve. Changes in stenosis geometry from papaverine would influence the measured coronary flow reserve. Therefore, we investigated the influence of intracoronary papaverine on stenosis geometry with quantitative analysis of the coronary angiogram and assessed the influence of papaverine on pressure-flow characteristics of the stenosis and coronary flow reserve. The cross-sectional areas (mean +/- SD) of the stenosis increased 18% +/- 7% after papaverine. The normal proximal and distal parts of the coronary artery dilated 5% +/- 2% after papaverine. This results in a decrease of the calculated pressure drop over the stenosis varying from 20% to 30%. Coronary flow reserve of a flow-limiting epicardial stenosis is overestimated by 16% when papaverine is used to induce hyperemia. These papaverine-induced changes can nevertheless be circumvented by maximal vasodilation of the major epicardial coronary artery with 3 mg intracoronary isosorbidedinitrate prior to the investigation of the coronary flow reserve with papaverine.

Normalization of coronary flow reserve by percutaneous transluminal coronary angioplasty (Article)

1988-01-01T00:00:00Z

Fifteen patients undergoing routine follow-up angiography 5 months after successful percutaneous transluminal coronary angioplasty (PTCA) without angina and with normal exercise thallium scintigraphy were selected for analysis. The coronary flow reserves of these patients were compared with those of 24 patients with angiographically normal coronary arteries to establish whether PTCA can restore to normal the coronary flow reserve of patients with chronic coronary artery disease. The quantitative cineangiographic changes and the concomitant alterations in coronary flow reserve as an immediate result of the PTCA and the subsequent changes 5 months later are described. Coronary flow reserve was measured with digital subtraction cineangiography. PTCA resulted in an increase in minimal obstruction area (mean +/- standard deviation) from 0.8 +/- 0.3 to 3.4 +/- 0.7 mm2 and in coronary flow reserve from 1.0 +/- 0.3 to 2.5 +/- 0.6. Five months later a further substantial and significant (p less than 0.05) late increase in obstruction area (3.8 +/- 0.9 mm2) and flow reserve (3.6 +/- 0.5) had occurred. In 11 of 15 patients coronary flow reserve was restored to normal. Changes in stenosis geometry are likely to be 1 of the major determinants of this late normalization of coronary flow reserve.

Incidence of restenosis after successful coronary angioplasty: a time-related phenomenon. A quantitative angiographic study in 342 consecutive patients at 1, 2, 3, and 4 months (Article)

1988-01-01T00:00:00Z

Data from experimental, clinical, and pathologic studies have suggested that the process of restenosis begins very early after coronary angioplasty. The present study was performed to determine prospectively the incidence of restenosis with use of the four National Heart, Lung, and Blood Institute and the 50% or greater diameter stenosis criteria, as well as a criterion based on a decrease of 0.72 mm or more in minimal luminal diameter. Patients were recatheterized at 30, 60, 90, or 120 days after successful percutaneous transluminal coronary angioplasty (PTCA). After PTCA all patients received 10 mg nifedipine three to six times a day and aspirin once a day until repeat angiography. Of 400 consecutive patients in whom PTCA was successful (less than 50% diameter stenosis), 342 underwent quantitative angiographic follow-up (86%) by use of an automated edge-detection technique. A wide variation in the incidence of restenosis was found dependent on the criterion applied. The incidence of restenosis proved to be progressive to at least the third month for all except NHLBI criterion II. At 4 months a further increase in the incidence of restenosis was observed when defined as a decrease of 0.72 mm or more in minimal luminal diameter, whereas the criteria based on percentage diameter stenosis showed a variable response. The lack of overlap between the different restenosis criteria applied affirms the arbitrary nature of angiographic definitions currently in use. Restenosis should be assessed by repeat angiography, and preferably ascertained according to the change in absolute quantitative measurements of the luminal diameter.

Change in diameter of coronary artery segments adjacent to stenosis after percutaneous transluminal coronary angioplasty: failure of percent diameter stenosis measurement to reflect morphologic changes induced by balloon dilation (Article)

1988-01-01T00:00:00Z

To determine the changes in stenotic and nonstenotic segments of a dilated coronary artery, detailed quantitative angiographic measurements were performed in 342 patients (398 lesions) immediately after angioplasty and at a predetermined follow-up time of 30, 60, 90 or 120 days after the dilation. Measurements of the stenotic segments were expressed as minimal luminal diameter, and the adjacent nonstenotic segments were expressed as interpolated reference diameter (both in millimeters). A follow-up rate of 86% was achieved. In the patients followed up at 30 and 60 days, there was no significant change in either the mean minimal luminal diameter or the mean reference diameter. However, at 90 and 120 days, there was significant deterioration in both the mean minimal luminal diameter (-0.37 and -0.42 mm, respectively) and the mean reference diameter (-0.17 and -0.26 mm, respectively), all of the changes being highly significant (p less than 0.00001). The reference diameter is involved in the dilation process and may be subject to the same restenosis process that takes place in initially stenotic segments. Percent diameter stenosis measurements, which are conventionally used to express the change in the severity of a stenosis after angioplasty, will tend to underestimate the change when there is a simultaneous reduction in the reference diameter.

Three-dimensional reconstruction of myocardial contrast perfusion from biplane cineangiograms by means of linear programming techniques (Article)

1988-01-01T00:00:00Z

The assessment of coronary flow reserve from the instantaneous distribution of the contrast agent within the coronary vessels and myocardial muscle at the control state and at maximal flow has been limited by the superimposition of myocardial regions of interest in the two-dimensional images. To overcome these limitations, we are in the process of developing a three-dimensional (3D) reconstruction technique to compute the contrast distribution in cross sections of the myocardial muscle from two orthogonal cineangiograms. To limit the number of feasible solutions in the 3D-reconstruction space, the 3D-geometry of the endo- and epicardial boundaries of the myocardium must be determined. For the geometric reconstruction of the epicardium, the centerlines of the left coronary arterial tree are manually or automatically traced in the biplane views. Next, the bifurcations are detected automatically and matched in these two views, allowing a 3D-representation of the coronary tree. Finally, the circumference of the left ventricular myocardium in a selected cross section can be computed from the intersection points of this cross section with the 3D coronary tree using B-splines. For the geometric reconstruction of the left ventricular cavity, we envision to apply the elliptical approximation technique using the LV boundaries defined in the two orthogonal views, or by applying more complex 3D-reconstruction techniques including densitometry. The actual 3D-reconstruction of the contrast distribution in the myocardium is based on a linear programming technique (Transportation model) using cost coefficient matrices. Such a cost coefficient matrix must contain a maximum amount of a priori information, provided by a computer generated model and updated with actual data from the angiographic views. We have only begun to solve this complex problem. However, based on our first experimental results we expect that the linear programming approach with advanced cost coefficient matrices and computed model will lead to acceptable solutions in the 3D-reconstruction of the myocardial contrast distribution from biplane cineangiograms.

Which cineangiographically assessed anatomic variable correlates best with functional measurements of stenosis severity? A comparison of quantitative analysis of the coronary cineangiogram with measured coronary flow reserve and exercise/redistribution thallium-201 scintigraphy (Article)

1988-01-01T00:00:00Z

The goal of this investigation was to establish which measured anatomic variable of stenotic coronary lesions correlates best with functional severity. Therefore, 38 patients with single vessel disease underwent coronary cineangiography and exercise/redistribution thallium-201 scintigraphy. The computer-based Cardiovascular Angiography Analysis System was used to determine the cross-sectional area at the site of obstruction (OA) and percent diameter stenosis (DS), and to calculate the pressure drop over the stenosis (PD) with use of fluid dynamic equations. Coronary flow reserve was measured radiographically. Myocardial perfusion defects on thallium scintigrams were analyzed quantitatively and by visual interpretation. The relations between coronary flow reserve (CFR) and the three anatomic variables were described by the following equations: 1) CFR = 4.6 - 0.053 DS, r = 0.82; SEE: 0.79, p less than 0.001. 2) CFR = 0.5 + 0.75 OA, r = 0.87; SEE: 0.68, p less than 0.001). 3 CFR = 3.6 - 1.5 log PD, r = 0.90; SEE: 0.62, p less than 0.001. The calculated pressure drop was highly predictive of the thallium scintigraphic results with a sensitivity of 94% and a specificity of 90%. The calculated pressure drop is a better anatomic variable for assessing the functional importance of a stenosis than is percent diameter stenosis or obstruction area. However, the 95% confidence limits of the relation between pressure drop and coronary flow reserve are wide, making the measurement of coronary flow reserve an indispensable addition to quantitative angiography, especially when determining the functional importance of moderately severe coronary artery lesions.

Assessment of immediate and long-term functional results of percutaneous transluminal coronary angioplasty (Article)

1988-01-01T00:00:00Z

Assessment of the functional significance of coronary artery lesions during cardiac catheterization has recently become possible by calculating coronary flow reserve from both myocardial contrast appearance time and density in the resting and hyperemic states determined from digitized coronary cineangiograms. However, the interobserver and intraobserver variabilities, as well as the short-, medium-, and long-term variabilities of the coronary flow reserve measurements, have to be established before this technique becomes an acceptable means of assessing the immediate and long-term functional results of revascularization procedures such as percutaneous transluminal coronary angioplasty (PTCA). Variability was defined as the mean difference and standard deviation of the difference between duplicate determinations of coronary flow reserve. The intraobserver variability (mean difference +/- SD) in the measurement of coronary flow reserve was -0.01 +/- 0.07. Interobserver variability by two observers was +0.08 +/- 0.52. Short-term variability based on the analysis of two coronary cineangiograms taken 5 minutes apart was -0.02 +/- 0.26. Medium-term variability (coronary cineangiographies repeated 1-3 hours apart) was found to be -0.06 +/- 0.52. Long-term variability (coronary cineangiographies repeated 3-5 months apart) was 0.11 +/- 0.63. Having established the reproducibility of this radiographic method, we studied the prospective changes in coronary flow reserve in 25 patients undergoing PTCA for single vessel coronary artery disease. Coronary flow reserve measurements and quantitative coronary cineangiography were performed before, immediately after, and 3-5 months after PTCA. PTCA resulted in an immediate increase in coronary flow reserve from 1 +/- 0.3 to 2.3 +/- 0.6 with a concomitant increase in obstruction area from 0.9 +/- 0.3 to 3.3 +/- 0.7 mm2. Nine of the 25 patients developed restenosis defined as a diameter stenosis greater than 50% at follow-up. The other 16 patients had a coronary flow reserve of 3.3 +/- 0.6, which was measured 3-5 months after PTCA. Coronary flow reserve measurement from digitized coronary cineangiograms is a reproducible method for the assessment of the physiological importance of coronary artery obstructions. Short-, medium-, and long-term investigations of the functional results of interventions such as pharmacological therapy or revascularization can be performed reliably with this technique.

Variabilities in measurement of coronary arterial dimensions resulting from variations in cineframe selection (Article)

1988-01-01T00:00:00Z

To quantitatively analyze a coronary arterial segment from a cineangiogram, an end-diastolic or neighboring cineframe is usually selected, such that a possibly existing coronary lesion is visualized optimally, as judged by the cardiologist. However, different cardiologists may select different (although usually neighboring) frames, even when following the same selection criteria. It is also possible that the frames are selected from different cardiac cycles. In this study the effects of such phase shifts on the reproducibility of the quantitative measurements were studied. In a total of 38 consecutive patient films obtained at a filmspeed of 25 frames/sec, the frame 0 demonstrating the severity of a lesion optimally, as judged by a senior cardiologist, the three preceding frames, the three following frames and one frame exactly one cycle prior to or following frame 0 were selected; frame 0 was always chosen in the end-diastolic phase of the cardiac cycle. In each film one coronary arterial segment with a focal lesion was analyzed quantitatively in these eight frames with the Cardiovascular Angiography Analysis System (CAAS). No significant differences were found in the mean difference and the standard deviations of the differences (variabilities) in the obstruction diameter, interpolated reference diameter, percent diameter stenosis, extent of the obstruction and area of atherosclerotic plaque obtained in the various frames with respect to frame 0. Therefore, it may be concluded that the selection of a cineframe for quantitative analysis in the end-diastolic phase of the cardiac cycle is not very critical; in other words, the obstruction measurements are not time-dependent for frames in the end-diastolic phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of continued rt-PA administration on the residual stenosis after initially successful recanalization in acute myocardial infarction - a quantitative coronary angiography study of a randomized trial (Article)

1987-01-01T00:00:00Z

Does the quantitative assessment of coronary artery dimensions predict the physiologic significance of a coronary stenosis? (Article)

1987-01-01T00:00:00Z

To study the relationship between the quantitatively assessed coronary artery dimensions and the regional coronary flow reserve as measured by digital subtraction cineangiography, we investigated 17 coronary arteries with a single discrete proximal stenosis and 12 normal coronary arteries before and after intracoronary administration of papaverine. Coronary flow reserve was found to be curvilinearly related to minimal luminal cross-sectional area (r = .92, SEE = 0.73) and to percentage area stenosis (r = .92, SEE = 0.74). Normal coronary arteries had a coronary flow reserve of 5.0 (+/- 0.8 [SD]), which differed significantly from the coronary flow reserve of the coronary arteries with obstructive disease, in which values ranging from 0.5 to 3.9 were found. Coronary arteries with a percentage area stenosis between 50% and 70% and a minimal luminal cross-sectional area between 2 and 4.5 mm2 differed significantly (p = .001), with respect to the coronary flow reserve, from coronary arteries with a percentage area stenosis in excess of 70% and a minimal luminal cross-sectional area less than 2 mm2. With the use of hemodynamic equations that describe the pressure loss over a stenosis, a theoretical pressure-flow relationship can be inferred that characterizes the severity of the stenosis. Based on this theoretical pressure-flow relationship, coronary arteries that have a limited coronary flow reserve and critical stenosis (distal coronary perfusion pressure below 40 mm Hg at coronary flow of 3 ml/sec) can be identified with high sensitivity (83%) and specificity (82%). Thus, in coronary artery disease the consequent reduction in coronary flow reserve can be predicted with reasonable accuracy by quantitative assessment of coronary artery dimensions.

Long-acting coronary vasodilatory action of the molsidomine metabolite Sin I: a quantitative angiographic study (Article)

1987-01-01T00:00:00Z

The vasodilatory action of molsidomine was studied by intracoronary injection of its active metabolite, Sin 1. In 10 patients repeat coronary angiography in multiple projections was performed before and 2 minutes after administration of 1 mg of Sin 1, and before and after a second injection 60 minutes later. Contours of obstructed and non-obstructed segments of the left coronary artery were quantitatively analysed with a computer-based angiography analysis system. Immediately after its administration, Sin 1 increased the mean diameters of 44 normal coronary segments by 12% (P less than 0.001). Significant vasodilation (8%) was still observed after 60 minutes. At that time, repeated administration of Sin 1 increased the vasodilation by an additional 14% with respect to the control situation. An increase in obstruction diameter was observed in 6 out of 8 obstructed segments. Mean increase in the minimal obstruction diameter was still 10% after 60 minutes.

Quantitative assessment of regional left ventricular motion using endocardial landmarks (Article)

1986-01-01T00:00:00Z

In this study the hypothesis is tested that the motion pattern of small anatomic landmarks, recognizable at the left ventricular endocardial border in the contrast angiocardiogram, reflects the motion of the endocardial wall. To verify this, minute metal markers were inserted in the endocardium of eight pigs with a novel retrograde transvascular approach. Marker motion was subsequently recorded with roentgen cinematography and compared with the motion of the landmarks on the endocardial contours detected from the contrast ventriculogram with an automated contour detection system. Linear regression analysis of the directions of the systolic metal marker and endocardial landmark pathways yielded a correlation coefficient of 0.86 and a standard error of the estimate of 10.3 degrees. Landmark pathways were also measured in 23 normal human left ventriculograms. Normal left ventricular endocardial wall motion during systole, as observed in the 30 degrees right anterior oblique view, is characterized by a dominant inward transverse motion of the opposite anterior and inferoposterior walls and a descent of the base toward the apex. The apex itself is almost stationary. On the basis of these observations, a widely applicable model for the assessment of left ventricular wall motion is described in mathematical terms.

Assessment of short-, medium- and long-term variations in arterial dimensions from computer-assisted quantitation of coronary cineangiograms (Article)

1985-01-01T00:00:00Z

A computer-assisted technique has been developed to assess absolute coronary arterial dimensions from 35 mm cineangiograms. The boundaries of optically magnified and video-digitized coronary segments and the intracardiac catheter are defined by automated edge-detection techniques. Contour positions are corrected for pincushion distortion. The accuracy and precision of the edge detection procedure as assessed from cinefilms of contrast-filled acrylate (Perspex) models were -30 and 90 micrometers, respectively. The variability of the analysis procedure itself in terms of absolute arterial dimensions was less than 0.12 mm, and in terms of percentage arterial narrowing for coronary obstructions less than 2.74%. Short-, medium-, and long-term variability measurements were assessed from repeated coronary angiographic examinations performed 5 min, 1 hr, and 90 days apart, respectively. For all studies the mean differences in absolute diameters were less than 0.13 mm. The variability in obstruction diameter ranged from 0.22 mm for the best-controlled study (medium-term) to 0.36 mm for the least-controlled study (long-term); variability in reference diameter ranged from 0.15 to 0.66 mm, respectively. It is concluded that the biological variations are a source of major concern and that further attempts toward standardization of the angiographic procedure are seriously needed.

Quantitative angiography of the left anterior descending coronary artery: correlations with pressure gradient and results of exercise thallium scintigraphy (Article)

1985-01-01T00:00:00Z

To evaluate, during cardiac catheterization, what constitutes a physiologically significant obstruction to blood flow in the human coronary system, computer-based quantitative analysis of coronary angiograms was performed on the angiograms of 31 patients with isolated disease of the proximal left anterior descending coronary artery. The angiographic severity of stenosis was compared with the transstenotic pressure gradient measured with the dilation catheter during angioplasty and with the results of exercise thallium scintigraphy. A curvilinear relationship was found between the pressure gradient across the stenosis (normalized for the mean aortic pressure) and the residual minimal area of obstruction (after subtracting the area of the angioplasty catheter). This relationship was best fitted by the equation: normalized mean pressure gradient = a + b . log [obstruction area], r = .74. The measurements of the percent area of stenosis (cutoff 80%) and of the transstenotic pressure gradient (cutoff 0.30) obtained at rest correctly predicted the occurrence of thallium perfusion defects induced by exercise in 83% of the patients.

Predictive value of early maximal exercise test and thallium scintigraphy after successful percutaneous transluminal coronary angioplasty (Article)

1985-01-01T00:00:00Z

Restenosis of the dilated vessel after percutaneous transluminal coronary angioplasty can be detected by non-invasive procedures but their ability to predict later restenosis soon after a successful angioplasty as well as recurrence of angina has not been assessed. A maximal exercise test and myocardial thallium perfusion scintigraphy were, therefore, performed in 91 asymptomatic patients a median of 5 weeks after they had undergone a technically successful angioplasty. Primary success of the procedure was confirmed by the decrease in percentage diameter stenosis from 64(12)% to 30(13)% as measured from the coronary angiograms and in the trans-stenotic pressure gradient (normalised for mean aortic pressure) from 0.61(0.16) to 0.17(0.09). A clinical follow up examination (8.6(4.9) months later) was carried out in all patients and a late coronary angiogram obtained in 77. The thallium perfusion scintigram showing the presence or absence of a reversible defect was highly predictive for restenosis whereas the exercise test was not. The positive predictive value of an abnormal scintigram was 82% compared with 60% for the exercise test (ST segment depression/or angina or both at peak workload). Angina or a new myocardial infarction occurred in 60% of patients with abnormal and in 21% of patients with normal scintigrams.

Early detection of restenosis after successful percutaneous transluminal coronary angioplasty by exercise-redistribution Thallium scintigraphy (Article)

1985-01-01T00:00:00Z

The value of exercise testing and thallium scintigraphy in predicting recurrence of angina pectoris and restenosis after a primary successful transluminal coronary angioplasty (PTCA) was prospectively evaluated. In 89 patients, a symptom-limited exercise electrocardiogram (ECG) and thallium scintigraphy were performed 4 weeks after they had undergone successful PTCA. Thereafter, the patients were followed for 6.4 +/- 2.5 months (mean +/- standard deviation) or until recurrence of angina. They all underwent a repeat coronary angiography at 6 months or earlier if symptoms recurred. PTCA was considered successful if the patients had no symptoms and if the stenosis was reduced to less than 50% of the luminal diameter. Restenosis was defined as an increase of the stenosis to more than 50% luminal diameter. The ability of the thallium scintigram (presence of a reversible defect) to predict recurrence of angina was 66%, vs 38% for the exercise ECG (ST-segment depression or angina at peak workload). Restenosis was predicted in 74% of patients by thallium scintigraphy, but only in 50% of patients by the exercise ECG. Thus, thallium scintigraphy was highly predictive but the exercise ECG was not (p less than 0.005). These results suggest that restenosis had occurred to some extent already at 4 weeks after the PTCA in most patients in whom it was going to occur.

Assessment of dimensions and image quality of coronary contrast catheters from cineangiograms (Article)

1985-01-01T00:00:00Z

In the quantitative assessment of coronary arterial dimensions from coronary cineangiograms, the contrast catheter is usually used as a scaling device, requiring the definition of the catheter contours by semi- or fully automated contour detection procedures. The image quality of the x-ray radiated catheter is dependent on the catheter material, concentration of the contrast agent in the catheter, and kilovoltage of the x-ray source. The effects of these variables on the image quality and accuracy of the size-measurement of the filmed catheters were studied for four different catheter materials: woven dacron (wd), polyvinylchloride (pv), polyurethane (pu), and nylon. The following parameters were studied: measured size, image contrast, and average brightness gradient along the edges of the displayed catheters. The average differences of the angiographically measured size with the true size for the wd, pv, pu, and nylon catheters were +0.2, -3.2, -3.5, and +9.8%, respectively. The image contrast at various fillings of the catheters was roughly identical for the wd, pv, and pu catheters, and significantly lower for the nylon catheter. Image gradient was highest for the wd catheter, followed by the pv and pu catheters, and lowest for the nylon catheter. From these data it may be concluded that the woven dacron catheter is most suitable for quantitative coronary angiographic studies. The polyvinylchloride and polyurethane catheters perform about equally well but slightly less than the woven dacron catheter. The nylon catheter should not be used for such quantitative studies.

Values and limitations of transstenotic pressure gradients measured during percutaneous coronary angioplasty (Article)

1985-01-01T00:00:00Z

The pressure gradient across coronary stenoses is measured routinely during angioplasty. Due to the finite size of the angioplasty catheter within the stenotic cross section, the remaining luminal area is further reduced and the transstenotic gradient may be overestimating the "true" pressure drop. This "true" pressure gradient can be approximated from the mean coronary blood flow and the stenosis geometry from theoretical models. Goal of this study was to assess the values and limitations of the in vivo measurements of the pressure gradient versus the calculated values. Therefore, flow in the great cardiac vein was measured in 13 patients before and/or after angioplasty of a proximal left anterior descending stenosis, not filled by collaterals. The Poiseuille and turbulent contributions to flow resistance were determined from stenosis geometry assessed by quantitative coronary angiography. A fourfold increase in the luminal area (from 0.7 mm2 pre- to 2.8 mm2 post angioplasty) was associated with a fourfold decrease in the in vivo measured transstenotic gradient (from 59 mm Hg pre- to 13 mm Hg post angioplasty). The occlusion area and the measured gradient were linearly correlated: gradient = 69-17 X occlusion area (r = 0.76). However, as expected, the transstenotic gradient systematically overestimated the theoretical gradient calculated from the laws of fluid dynamics. A nonlinear relation was found between the calculated gradient P and the occlusion area As: P = 15 X As-2 (r = 0.87).

Coronary artery changes 3 years after reimplantation of an anomalous right coronary artery (Article)

1984-01-01T00:00:00Z

In this paper we report the sequelae of a patient with an anomalous right coronary artery (RCA) originating from the pulmonary artery (PA) in association with a normal heart, operated upon at the age of 13 years. Three years after the end-to-side reimplantation of the RCA, with a rim of the PA, into the aorta, the surgical result has been evaluated by cineangiography. Before operation both coronary arteries were tortuous and increased in size. Afterwards the left coronary artery showed a normalized calibre, although the RCA remained tortuous with no decrease of the internal diameter. The notable postoperative changes in shape and size of the LCA may be due to the disappearance of the steal phenomenon. The lack of involutive changes in the RCA could be explained by its thinner wall. Left ventricular wall motion, evaluated under resting conditions and during an atrial pacing stress test, was found to be normal.

Assessment of percutaneous transluminal coronary angioplasty by quantitative coronary angiography: diameter versus densitometric area measurements (Article)

1984-01-01T00:00:00Z

Cineangiograms of 138 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) were analyzed with a computer-based coronary angiography analysis system. The results before and after dilatation are presented. In a first study group (120 patients), the severity of the obstructive lesions derived from the automatically detected contours was evaluated in absolute terms and in percent-diameter reduction. In a second group of patients, 18 coronary lesions were selected for their extreme severity and symmetric aspect before angioplasty as assessed from multiple views. In the second group, the densitometric percent-area stenosis was used to assess the changes in cross-sectional area after PTCA and was compared with the circular percent-area stenosis computed from the diameter measurements. Before PTCA, a good agreement exists between the densitometric percent-area stenosis and the circular percent-area stenosis. After PTCA, important discrepancies between these 2 types of measurements are observed. It is suggested that these discrepancies in results after PTCA can be accounted for by asymmetric morphologic changes in luminal cross section, which cannot be assessed accurately from diameter measurements in a single-plane view.

Contribution of dynamic vascular wall thickening to luminal narrowing during coronary arterial vasomotion (In Book)

1984-01-01T00:00:00Z

Contribution of dynamic vascular wall thickening to luminal narrowing during coronary arterial vasomotion (Article)

1983-01-01T00:00:00Z

The hypothesis has been developed that increased coronary artery vasomotor tone superimposed on a preexisting obstruction is a possible mechanism responsible for resting and exertional angina. In 18 patients (22 stenotic lesions), the maximal changes in coronary artery diameter (mm) induced by an ergometrine test followed by an injection of isosorbide dinitrate were assessed by a quantitative computer-based angiographic system. If we assume that there is no change in the length of the artery as the result of changes in its diameter, then at any point of the artery the area of the arterial wall on a transverse cross section of the vessel will be constant regardless of its state of its contraction or dilatation. As vasoconstriction occurs, the luminal diameter decreases proportionally more than the outer diameter of the vessel and the wall thickness increases. Using elementary geometric principles, we calculated and reconstructed the changes that might occur at the stenotic sites as the result of vasomotion acting on the entire coronary segment. From the reference diameter in the control state (Ri:3.7 +/- 1.1 mm) and after vasoconstriction (Ric: 3.3 +/- 1.0 mm) and the obstruction diameter in the control state (ri: 2.2 +/- 0.9 mm), the minimal obstruction diameter after vasoconstriction (ric: 1.0 +/- 0.8 mm) was derived using the following equation: ric2 = ri2 - Ri2 + Ric2. In four of 22 lesions, the decrease in diameter of the lumen of the normal vessel was fully translated to the stenotic point and the decrease in diameter at the stenosis was correctly predicted.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of intracoronary nifedipine on left ventricular function, coronary vasomotility, and myocardial oxygen consumption (Article)

1983-01-01T00:00:00Z

The effect of intracoronary nifedipine on regional and global left ventricular performance, coronary vasomotility, and myocardial oxygen consumption is reported. Left ventricular pressures and volume indices of contractility and relaxation were simultaneously recorded in five patients without coronary artery disease. In these patients, nifedipine in the left main coronary artery not only delayed (+115 ms) anterior wall contraction but also slowed (3.5 vs 1.9 cm/s) and depressed it (-26%), resulting in a depression of global left ventricular ejection. This asynchrony and depression of regional contraction is considered to be responsible for the slowed isovolumic contraction and relaxation of the whole ventricle. In 10 other patients with coronary artery disease, coronary sinus blood flow and myocardial oxygen consumption were measured before and after intracoronary nifedipine. The observed decrease in myocardial oxygen consumption (-28%) depended primarily on a decrease in contractility and left ventricular performance. In a third study group of 12 patients with coronary artery disease, the effects of intracoronary nifedipine on the coronary vasomotility of 40 coronary segments (normal, prestenotic, stenotic, poststenotic) were quantitatively determined. Left ventricular haemodynamics and coronary sinus saturation were monitored while the cineangiograms were recorded before and after nifedipine. Nifedipine provoked vasodilatation of the normal (+10.3%), prestenotic, stenotic (+4 to 30%), and poststenotic (+16.4%) coronary segments, which persisted after the disappearance of its direct effects on the myocardium. This transient regional "cardioplegic" effect of nifedipine, associated with an increase in coronary blood flow, a reduction in myocardial oxygen consumption, and a vasodilatation of the epicardial vessels is likely to be beneficial during temporary coronary occlusion such as occurs in spasm or transluminal angioplasty.

Is transluminal coronary angioplasty mandatory after successful thrombolysis? Quantitative coronary angiographic study (Article)

1983-01-01T00:00:00Z

Clinical validation of fully automated computation of ejection fraction from gated equilibrium blood-pool scintigrams (Article)

1983-01-01T00:00:00Z

A fully automated procedure for the computation of left-ventricular ejection fraction (EF) from cardiac-gated Tc-99m blood-pool (GBP) scintigrams with fixed, dual, and variable ROI methods is described. By comparison with EF data from contrast ventriculography in 68 patients, the dual-ROI method (separate end-diastolic and end-systolic contours) was found to be the method of choice; processing time was 2 min. Success score of dual-ROI procedure was 92% as assessed from 100 GBP studies. Overall reproducibility of data acquisition and analysis was determined in 12 patients. Mean value and standard deviation of differences between repeat studies (average time interval 27 min) were 0.8% and 4.3% EF units, respectively, (r = 0.98). We conclude that left-ventricular EF can be computed automatically from GBP scintigrams with minimal operator-interaction and good reproducibility; EFs are similar to those from contrast ventriculography.

The effect of intracoronary thrombolysis with streptokinase on myocardial thallium distribution and left ventricular function assessed by blood-pool scintigraphy (Article)

1982-01-01T00:00:00Z

The effect of recanalization of the occluded coronary artery in acute myocardial infarction on left ventricular function (Article)

1982-01-01T00:00:00Z

L'angiographie coronaire quantitative. Application à l'èvaluation des angioplasties transluminales coronaires (Article)

1981-01-01T00:00:00Z

Can unstable angina pectoris be due to increased coronary vasomotor tone? (Article)

1980-01-01T00:00:00Z