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B J Rensing

Publications and source records attributed to B J Rensing.

At least 19 recordsLinked to original sources
PubMed2000

Coronary artery fly-through using electron beam computed tomography.

BACKGROUND: Virtual reality techniques have recently been introduced into clinical medicine. This study examines the possibility of coronary artery fly-through using a dataset obtained by noninvasive coronary angiography with contrast-enhanced electron-beam computed tomography. METHODS AND RESULTS: Ten patients were examined, and 40 to 60 transaxial tomograms (thickness, 1.5 mm; in-plane pixel dimensions, approximately 0.5x0.5 mm) were obtained after intravenous contrast injection. The datasets were processed on a graphics workstation using volume-rendering software. For fly-throughs, the contrast-enhanced lumen was made transparent and other tissue was made opaque. Then, key frames were selected in a path through the vessel, with software interpolation of frames between key frames. A typical movie contained 150 to 300 frames (10 to 15 key frames). Fly-throughs of coronary bypass grafts (n=3), left anterior descending arteries (LAD; n=6), and the intermediate branch (n=1) were reconstructed. Coronary calcifications were seen in 3 patients. The fly-through of the intermediate branch, the bypass grafts, and one of the LADs did not show any irregularities. In 2 cases, a stenosis was visible in the LAD; its presence was confirmed by conventional coronary angiography. CONCLUSIONS: Recent developments in fast-volume rendering using special-purpose hardware in combination with noninvasive coronary angiography with electron beam computed tomography have provided the possibility of performing coronary artery fly-throughs.

Calcinosis↗
PubMed2000

Stentocarditis.

Explore the source record for details and available documents.

Abscess↗
PubMed2000

MR coronary angiography with breath-hold targeted volumes: preliminary clinical results.

PURPOSE: To assess the clinical value of a magnetic resonance (MR) coronary angiography strategy involving a small targeted volume to image one coronary segment in a single breath hold for the detection of greater than 50% stenosis. MATERIALS AND METHODS: Thirty-eight patients referred for elective coronary angiography were included. The coronary arteries were localized during single-breath-hold, three-dimensional imaging of the entire heart. MR coronary angiography was then performed along the major coronary branches with a double-oblique, three-dimensional, gradient-echo sequence. Conventional coronary angiography was the reference-standard method. RESULTS: Adequate visualization was achieved with MR coronary angiography in 85%-91% of the proximal coronary arterial branches and in 38%-76% of the middle and distal branches. Overall, 187 (69%) of 272 segments were suitable for comparison between conventional and MR coronary angiography. The diagnostic accuracy of MR coronary angiography for the detection of hemodynamically significant stenoses was 92%; sensitivity, 68%; and specificity, 97%. The sensitivity in individual segments was 50%-77%, whereas the specificity was 94%-100%. CONCLUSION: Adequate visualization of the major coronary arterial branches was possible in the majority of patients. The observed accuracy of MR coronary angiography for detection of hemodynamically significant coronary arterial stenosis is promising, but it needs to be higher before this modality can be used reliably in a clinical setting.

Adult↗
PubMed1999

Stenting with a true bifurcated stent: acute and mid-term follow-up results.

Percutaneous therapy of coronary bifurcated lesions is associated with greater risk of acute complications and late restenosis. Numerous innovative techniques using various stent types have been proposed. We report the first clinical use of a truly bifurcated stent (Bard XT Carina). The implantation procedure, favorable medium-term angiographic and 1-year clinical follow-up of the first human use in a 43-year-old female are illustrated with angiography and intravascular ultrasound. As a single prosthesis that effectively covers the bifurcation, this stent presents appealing alternative for the treatment of coronary bifurcation lesions when compared to methods that involve multiple-stent implantation. Cathet. Cardiovasc. Intervent. 47:361-369, 1999.

Abciximab↗
PubMed1999

Spontaneous dissections of all three coronary arteries in a 33-week-pregnant woman.

The clinical course and angiographic follow-up of a woman with spontaneous coronary dissections in all three coronary arteries during the third trimester of pregnancy is described. Mother and child survived and subsequent clinical course was uneventful. At 6-month follow-up, dissections in the right and circumflex coronary artery had healed completely. At the site of the dissection in the LAD, an aneurysm had formed. This is to our knowledge the first report of antepartum and antemortem diagnosis of pregnancy related coronary dissections in all three coronary arteries. Cathet. Cardiovasc. Intervent. 48:207-210, 1999.

Adult↗
PubMed1999

Magnetic resonance imaging of the coronary arteries: clinical results from three dimensional evaluation of a respiratory gated technique.

BACKGROUND: Magnetic resonance coronary angiography is challenging because of the motion of the vessels during cardiac contraction and respiration. Additional challenges are the small calibre of the arteries and their complex three dimensional course. Respiratory gating, turboflash acquisition, and volume rendering techniques may meet the necessary requirements for appropriate visualisation. OBJECTIVE: To determine the diagnostic accuracy of respiratory gated magnetic resonance imaging (MRI) for the detection of significant coronary artery stenoses evaluated with three dimensional postprocessing software. METHODS: 32 patients referred for elective coronary angiography were studied with a retrospective respiratory gated three dimensional gradient echo MRI technique. Resolution was 1.9 x 1.25 x 2 mm. After manual segmentation three dimensional evaluation was performed with a volume rendering technique. RESULTS: Overall 74% (range 50% to 90%) of the proximal and mid coronary artery segments were visualised with an image quality suitable for further analysis. Sensitivity and specificity for the detection of significant stenoses were 50% and 91%, respectively. CONCLUSIONS: Volume rendering of respiratory gated MRI techniques allows adequate visualisation of the coronary arteries in patients with a regular breathing pattern. Significant lesions in the major coronary artery branches can be identified with a moderate sensitivity and a high specificity.

Adult↗
PubMed1999

In vivo assessment of three dimensional coronary anatomy using electron beam computed tomography after intravenous contrast administration.

Intravenous coronary angiography with electron beam computed tomography (EBCT) allows for the non-invasive visualisation of coronary arteries. With dedicated computer hardware and software, three dimensional renderings of the coronary arteries can be constructed, starting from the individual transaxial tomograms. This article describes image acquisition, postprocessing techniques, and the results of clinical studies. EBCT coronary angiography is a promising coronary artery imaging technique. Currently it is a reasonably robust technique for the visualisation and assessment of the left main and left anterior descending coronary artery. The right and circumflex coronary arteries can be visualised less consistently. Improvements in image acquisition and postprocessing techniques are expected to improve visualisation and diagnostic accuracy of the technique.

Contrast Media↗
PubMed1999

Magnetic resonance imaging of the coronary arteries: anatomy of the coronary arteries and veins in three-dimensional imaging.

Magnetic resonance imaging of coronary arteries will visualize, besides the arteries, the myocardium, blood in the cavities and cardiac veins. This will hamper the application of projectional visualization techniques such as those used in conventional coronary angiography. Volume rendering, a different visualization technique, can be used to create a three-dimensional impression of a magnetic resonance data set on a two-dimensional surface. In this article, we will review the volume-rendering technique and anatomy of the coronary arteries and veins in the obtained images. Also we will discuss the relation between arteries and veins and the possible sites of confusion.

Animals↗
PubMed1998

Intravenous coronary angiography by electron beam computed tomography: a clinical evaluation.

BACKGROUND: -Noninvasive detection of coronary stenoses with electron beam CT (EBCT) after intravenous injection of contrast medium has recently emerged. We sought to determine the diagnostic accuracy of EBCT angiography in the clinical setting using conventional coronary angiography as the "gold standard." METHODS AND RESULTS: Thirty-seven patients (30 men) were investigated. After intravenous injection of 150 mL of contrast medium, 40 to 60 consecutive transaxial tomograms, covering the proximal and middle parts of the coronary arteries, were obtained with ECG triggering at end diastole during breath-holding. Three-dimensional reconstructions of the proximal and middle parts of the arteries were compared with the conventional angiograms. Of the 259 proximal and middle coronary segments, 211 (81%) were analyzable by EBCT. Of the left anterior descending coronary artery (LAD) segments, 95% were assessable. Right coronary artery (RCA) and left circumflex artery (LCx) segments were assessable in 66% and 76%, respectively. Overall sensitivity and specificity to detect a >50% diameter stenosis were 77% and 94%, respectively. This was 82% and 92% for the LAD, 60% and 97% for the RCA, and 83% and 89% for the LCx (all figures based on assessable lesions). CONCLUSIONS: Intravenous EBCT coronary angiography is a promising coronary imaging technique. The technique is not yet robust enough to be an alternative to conventional coronary angiography. It can detect and rule out significant coronary artery disease of the left main proximal and mid portions of the LAD with good accuracy.

Adult↗
PubMed1998

Intravenous electron-beam computed tomographic coronary angiography for segmental analysis of coronary artery stenoses.

OBJECTIVES: We sought to identify and localize significant coronary stenoses on a segmental basis by electron-beam computed tomography (EBCT) and intravenous administration of a contrast agent. BACKGROUND: The clinical applicability and limitations of intravenous EBCT coronary angiography have not been defined. METHODS: EBCT was performed within 24 h of selective coronary angiography (SCA) in 28 patients (19 men and 9 women, mean [+/-SD] age 60 +/- 10 years). After examination for coronary calcium, EBCT coronary angiography was performed using overlapping slices (in-plane resolution 0.34 to 0.41 mm) with a nominal slice thickness of 1 mm. Based on quantitative analysis of SCA, lumen diameter narrowing > or = 50% (i.e., significant stenoses) was evaluated in 8 (major) or 12 (including side branches) coronary artery segments, using both two-dimensional (tomographic) and three-dimensional (volume) data sets. RESULTS: Of the 330 segments assessable by SCA, 237 (72%) were visualized by EBCT. The sensitivity (+/-SE) for detection of significant stenoses was 82 +/- 6%; specificity was 88 +/- 2%; positive and negative predictive values were 57 +/- 7% and 96 +/- 2%, respectively; and overall accuracy was 87 +/- 2%. If only eight (major) coronary artery segments were considered, 194 (88%) of 221 segments were visualized, and the overall accuracy was 90 +/- 2%. Seven (18%) of 38 significantly stenotic segments were classified as having < 50% stenoses by EBCT. Six of these segments (86%), but only 9 (29%) of the 31 correctly classified stenotic segments, were severely calcified (area > 20 mm2, p = 0.02). In 23 (12%) of 199 nonstenotic segments falsely classified as having > or = 50% stenosis by EBCT, the lumen diameter was significantly smaller than that of the segments correctly classified as negative (mean [+/-SD] 1.5 +/- 0.8 vs. 2.9 +/- 1.1 mm, p < 0.001). CONCLUSIONS: Intravenous EBCT coronary angiography allows for accurate segmental evaluation of significant disease in the major coronary arteries and may be of value for ruling out significant disease. The main determinant of false negative results is substantial segmental calcification, whereas the main determinant of false positive results is small vessel size.

Adult↗
PubMed1998

Reproducibility of right and left ventricular volume measurements by electron-beam CT in patients with congestive heart failure.

UNLABELLED: The applicability and reproducibility of electron-beam computed tomography (EBCT) was tested to define left and right ventricular volumes in patients with congestive heart failure in a clinical setting. METHODS: Ten patients (mean age 64 +/- 11 years) with dilated hearts and stable congestive heart failure (functional class III-IV) were studied. After determination of the individual circulation time, two serial short axis polytomographic EBCT studies were performed within a mean interval of 14.8 +/- 10 days. Following intravenous contrast administration, biventricular end-diastolic volumes (LVEDV, RVEDV), end-systolic volumes (LVESV, RVESV), and left ventricular muscle mass (LVMM) were determined using previously developed techniques. RESULTS: Adequate contrast opacification in both ventricular cavities was obtained in all patients at baseline and at follow-up. Values were 323.4 +/- 99.3 (mean +/- SD) and 332.6 +/- 105.4 ml for LVEDV, 249.3 +/- 75.6 and 250.5 +/- 79.3 ml for LVESV, 236.8 +/- 56.2 and 251.2 +/- 72.7 ml for RVEDV, 179.8 +/- 76.4 and 188.3 +/- 64.0 ml for RVESV, and 207.7 +/- 70.6 and 204.9 +/- 81.9 g for LVMM (p = NS, respectively, paired t-test). Linear regression analysis correlating biventricular volumes and left ventricular muscle mass measurements in the serial scans yielded r-values in the range of 0.89 to 0.95 and a small SEE. The SE of the mean differences between left and right ventricular ejection fraction measurements was 1 point, respectively. CONCLUSION: EBCT studies of ventricular volumes in patients with dilated hearts and congestive heart failure are highly reproducible and offer the potential for serial assessment of these patients in whom quantitation of ventricular volumes has been shown to be of prognostic value.

Cardiac Volume↗
PubMed1997

Right and left ventricular remodeling after orthotopic single lung transplantation for end-stage emphysema.

BACKGROUND: Orthotopic single lung transplantation (LTX) is now an established treatment modality for patients with end-stage emphysema. LTX has been shown to cause unloading of the right ventricle with improvement in right ventricular (RV) structure and function both immediately and up to weeks after surgery, mostly in patients with severe pulmonary hypertension and decreased RV function. Long-term effects of lung transplantation on both RV and left ventricular (LV) anatomy and function, however, are not well known. METHODS: Seventeen patients undergoing LTX for end-stage emphysema and preserved RV function underwent serial electron beam computed tomography RV and LV function studies before, 3 months after, 1 year after, and 2 years after transplantation. Right-sided heart catheterization was performed before transplantation and at 1 and 2 years follow-up. RESULTS: RV end systolic volume decreased significantly (-15.5%), and RV ejection fraction increased significantly (+16%) in the first 3 months after LTX. This change was paralleled by a decrease in pulmonary pressure and vascular resistance, indicating a permanent RV unloading. This improvement was maintained up to 2 years after LTX. LV end-diastolic volume (+25%), LV stroke volume (+29%), and LV muscle mass (+28%) increased significantly in the first 3 months after LTX. This remodeling was maintained during the 2-year follow-up. CONCLUSIONS: Significant changes in cardiac anatomy and function occur shortly after LTX, most likely as a consequence of adaptation to a new hemodynamic state in patients with well preserved RV function before LTX. Furthermore, these acute changes persist for at least 2 years after LTX.

Adult↗
PubMed1994

Morphologic changes during follow-up after successful percutaneous transluminal coronary balloon angioplasty: quantitative angiographic analysis in 778 lesions--further evidence for the restenosis paradox. MERCATOR Study Group (Multicenter European Research trial with Cilazapril after Angioplasty to prevent Transluminal Coronary Obstruction and Restenosis).

The purpose of this study was to determine if there are any morphologic characteristics of lesions that renarrow (that is, restenotic lesions) following successful coronary balloon angioplasty that are different from their appearance pretreatment or from the appearance of nonrestenotic lesions that might provide some new insight into the restenosis phenomenon. The study population consisted of 653 patients (778 lesions) with 6 months of angiographic follow-up (94% angiographic follow-up rate) who were participating in the Multicenter European Research trial with Cilazapril after Angioplasty to prevent Transluminal coronary Obstruction and Restenosis (MERCATOR) study. Detailed quantitative angiographic measurements, including the mean diameter of the vessel segment (in millimeters) that was subjected to balloon dilation, were performed preangioplasty, postangioplasty, and at follow-up using the cardiovascular angiographic analysis system to provide some objective measurement of the actual extent of luminal changes in the months following coronary balloon angioplasty. Two different approaches for restenosis were used: (1) static criterion of > 50% diameter stenosis at follow-up and (2) dynamic criteria of > or = 0.40 or > or = 0.72 mm change in minimal lumen diameter between postangioplasty and follow-up. Both approaches identified more severe stenosis to be a typical feature for restenotic lesions before angioplasty compared with nonrestenotic lesions. No differences were observed in lesion length, balloon-inflated vessel segment, or roughness index before angioplasty between the groups. Conflicting data were found for the amount of atherosclerotic plaque, symmetry index, and curvature index. The restenotic lesion at follow-up compared with its initial appearance gave conflicting results depending on which approach was used. The dynamic criteria illustrate that the reference diameter and the mean diameter of the entire segment dilated are reduced during follow-up. Two messages emerge from the study: (1) the restenosis process clearly involves the apparent normal vessel wall adjacent to the actual lesion, probably in response to the unavoidable injury caused by balloon dilatation and (2) the use of percentage diameter stenosis measurements depending on the assumptions of normality for a reference segment will therefore underestimate the true extent of the restenosis process and should be replaced in clinical angiographic studies by absolute luminal measurements.

Adult↗
PubMed1993

Usefulness of quantitative and qualitative angiographic lesion morphology, and clinical characteristics in predicting major adverse cardiac events during and after native coronary balloon angioplasty. CARPORT and MERCATOR Study Groups.

Major, adverse cardiac events (death, myocardial infarction, bypass surgery and reintervention) occur in 4 to 7% of all patients undergoing coronary balloon angioplasty. Prospectively collected clinical data, and angiographic quantitative and qualitative lesion morphologic assessment and procedural factors were examined to determine whether the occurrence of these events could be predicted. Of 1,442 patients undergoing balloon angioplasty for native primary coronary disease in 2 European multicenter trials, 69 had major, adverse cardiac procedural or in-hospital complications after > or = 1 balloon inflation and were randomly matched with patients who completed an uncomplicated in-hospital course after successful angioplasty. No quantitative angiographic variable was associated with major adverse cardiac events in univariate and multivariate analyses. Univariate analysis showed that major adverse cardiac events were associated with the following preprocedural variables: (1) unstable angina (odds ratio [OR] 3.11; p < 0.0001), (2) type C lesion (OR 2.53; p < 0.004), (3) lesion location at a bend > 45 degrees (OR 2.34; p < 0.004), and (4) stenosis located in the middle segment of the artery dilated (OR 1.88; p < 0.03); and with the following postprocedural variable: angiographically visible dissection (OR 5.39; p < 0.0001). Multivariate logistic analysis was performed to identify variables independently correlated with the occurrence of major adverse cardiac events. The preprocedural multivariate model entered unstable angina (OR 3.77; p < 0.0003), lesions located at a bend > 45 degrees (OR 2.87; p < 0.0005), and stenosis located in the middle portion of the artery dilated (OR 1.95; p < 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1993

Matching based on quantitative coronary angiography as a surrogate for randomized studies: comparison between stent implantation and balloon angioplasty of native coronary artery lesions.

Although intracoronary stenting has been advocated as an adjunct to balloon angioplasty to circumvent late restenosis, its effectiveness has not yet been verified. Therefore the aim of this study was to determine the differences in the immediate and long-term changes in stenosis geometry between Wallstent implantation and balloon angioplasty in native coronary artery lesions. To obtain two study populations with identical baseline stenosis characteristics, patients were matched for lesion site, vessel size, and minimal luminal diameter. Only patients undergoing elective and successful coronary intervention of a native coronary artery, in whom a control angiographic study had been performed, were included. A total of 186 patients (93 in each group) were selected. The coronary angiograms were analyzed with the computer-assisted cardiovascular angiographic analysis system. Matching was considered adequate, since there was an equal number of lesion sites in each study population and there were no differences in baseline reference diameter and minimal luminal diameter. Wallstent implantation resulted in a significantly greater increase in minimal luminal diameter (from 1.22 +/- 0.34 mm to 2.49 +/- 0.40 mm, p < 0.00001) compared with balloon angioplasty (from 1.21 +/- 0.29 mm to 1.92 +/- 0.35 mm, p < 0.00001). Despite a greater decrease in minimal luminal diameter after Wallstent implantation (0.48 +/- 0.74 mm) than after balloon angioplasty (0.20 +/- 0.46 mm), the minimal luminal diameter at follow-up was significantly greater after stent implantation (2.01 +/- 0.75 mm vs 1.72 +/- 0.54, p < 0.0001). It was concluded that Wallstent implantation results in a superior immediate and long-term increase in minimal luminal diameter compared with balloon angioplasty. The larger initial gain after stent implantation compensates for the late loss, and thus an improved initial result and not lessened neointimal hyperplasia is responsible for a reduced incidence of restenosis. Studies based on matching of angiographic variables are a surrogate for randomized studies, forecasting their results and offering insight into the effects of different interventional techniques. Moreover, these studies yield statistical information that may be helpful for the proper design of a randomized study (sample size, type II error).

Angioplasty, Balloon, Coronary↗
PubMed1993

Which angiographic variable best describes functional status 6 months after successful single-vessel coronary balloon angioplasty?

OBJECTIVES: The aim of this study was to determine which quantitative angiographic variable best describes functional status 6 months after coronary balloon angioplasty. BACKGROUND: Several angiographic restenosis criteria have been developed. These can be divided into those that describe the change in lesion severity and those that merely describe lesion severity at follow-up angiography. The functional significance of these criteria is unknown. METHODS: We studied 350 patients with single-vessel coronary artery disease who underwent a single-site balloon dilation. Sensitivity and specificity curves were constructed for the prediction of anginal status and exercise electrocardiography of four quantitative angiographic variables that describe restenosis. The point of highest diagnostic accuracy for the variables was determined at the intersection of the sensitivity and specificity curves. Results of exercise electrocardiography were considered indicative for ischemia 6 months after angioplasty if horizontal or downsloping ST segment depression > or = 1 mm occurred. RESULTS: The points of highest diagnostic accuracy of the angiographic variables were similar for both anginal status and exercise electrocardiography: 1.45 and 1.46 mm for the minimal lumen diameter measurements, 45.5% and 46.5% for the percent diameter stenosis measurements at follow-up, -0.30 and -0.32 mm for change in minimal lumen diameter and -10% and -10% for the change in percent diameter stenosis at follow-up. CONCLUSIONS: Angiographic variables reflecting a change in lesion severity at follow-up angiography were only slightly less accurate than variables that describe lesion severity at follow-up. The large study group and the fact that the same optimal values for diagnostic accuracy of the various quantitative angiographic variables were obtained for the prediction of two different markers of ischemia suggests that these values reflect the lesion severity or increase in lesion severity in major epicardial vessels at which coronary flow reserve is unable to meet myocardial demands.

Angina Pectoris↗
PubMed1993

Luminal narrowing after percutaneous transluminal coronary angioplasty. A study of clinical, procedural, and lesional factors related to long-term angiographic outcome. Coronary Artery Restenosis Prevention on Repeated Thromboxane Antagonism (CARPORT) Study Group.

BACKGROUND: The renarrowing process after successful percutaneous transluminal coronary angioplasty (PTCA) is now believed to be caused by a response-to-injury vessel wall reaction. The magnitude of this process can be assessed by the change in minimal lumen diameter (MLD) at follow-up angiography. The aim of the present study was to find independent patient-related, lesion-related, and procedure-related risk factors for this luminal narrowing process. A model that accurately predicts the amount of luminal narrowing could be an aid in patient or lesion selection for the procedure, and it could improve assessment of medium-term (6 months) prognosis. Modification or control of the identified risk factors could reduce overall restenosis rates, and it could assist in the selection of patients at risk for a large loss in lumen diameter. This population could then constitute the target population for pharmacological intervention studies. METHODS AND RESULTS: Quantitative angiography was performed on 666 successfully dilated lesions at angioplasty and at 6-month follow-up. Multivariate linear regression analysis was performed to obtain variables with an independent contribution to the prediction of the absolute change in minimal lumen diameter. Diabetes mellitus, duration of angina < 2.3 months, gain in MLD at angioplasty, pre-PTCA MLD, lesion length > or = 6.8 mm, and thrombus after PTCA were independently predictive of change in MLD. Overall prediction of the model was poor, however, percentage-correct classification for a predicted change between -0.1 to -0.4 mm was approximately 10%. Lesions showing no change or regression (change > -0.1 mm) and lesions showing large progression (< or = -0.4 mm) were more predictable (correct classification, 59.5% and 49.7%, respectively). CONCLUSIONS: Renarrowing after successful PTCA as determined with contrast angiography is a process that cannot be accurately predicted by simple clinical, morphological, and lesion characteristics.

Angioplasty, Balloon, Coronary↗