J. Ligthart

Usefulness of multislice computed tomography for detecting obstructive coronary artery disease

The latest generation of multislice spiral computed tomography (MSCT) scanners is capable of noninvasive coronary angiography. We evaluated its diagnostic accuracy to detect stenotic coronary artery disease (CAD). In 53 patients with suspected CAD, contrast-enhanced MSCT and conventional angiography were performed. The CT data were acquired within a single breathhold, and isocardiophasic slices were reconstructed by means of retrospective electrocardiographic gating. Coronary segments of > or = 2 mm in diameter, measured by quantitative angiography, were evaluated. In 70% of the 358 available segments, image quality was regarded as adequate for assessment. The overall sensitivity, specificity, and positive and negative predictive values to detect > or = 50% stenotic lesions in the assessable segments were 82% (42 of 51 lesions), 93% (285 of 307 nonstenotic segments), and 66% and 97%, respectively, regarding conventional quantitative angiography as the gold standard. Proximal segments were assessable in 92%, and distal segments and side branches in 71% and 50%, respectively. Including the undetected lesions in non-assessable segments, overall sensitivity decreased to 61% but remained 82% for lesions in proximal coronary segments. MSCT correctly predicted absent, single, or multiple lesions in 55% of patients. Thus, despite potentially high image quality, current MSCT protocols offer only reasonable diagnostic accuracy in an unselected patient group with a high prevalence of CAD.

Optical Coherence Tomography Assessment Of The Acute Effects Of Stent Implantation On The Vessel Wall. A Systematic Quantitative Approach

Objective: To observe and characterise vessel injury after stenting using optical coherence tomography (OCT), to propose a systematic OCT classification for periprocedural vessel trauma, to evaluate its frequency in stable versus unstable patients and to assess its clinical impact during the hospitalisation period. Setting: Stenting causes vessel injury. Design and interventions: All consecutive patients in whom OCT was performed after stent implantation were included in the study. Qualitative and quantitative assessment of tissue prolapse, intra-stent dissection and edge dissection were performed. Results: Seventy-three patients (80 vessels) were analysed. Tissue prolapse within the stented segment was visible in 78/80 vessels (97.5%). Median number of tissue prolapse sites was 8 (IQR 4–19), mean (SD) area 1.04 (0.9) mm2. Intra-stent dissection flaps were visible in 69/80 vessels (86.3%) (median number 3 (IQR 1.25–6), maximum flap length 450 (220) μm). Fifty-five out of 80 vessels (68.8%) showed dissection cavities (median number 2 (IQR 0–4.75), maximum depth 340 (170) μm). Edge dissection was visible in 20 vessels (mean (SD) length flap 744 (439) μm). The frequency of tissue prolapse or intra-stent dissection was similar in stable and unstable patients (95.6% vs 100%, pu200a=u200a0.5 for tissue prolapse; 91.1% vs 82.9%, pu200a=u200a0.3 for intra-stent dissection). There were no events during the hospitalisation period. Conclusions: OCT allows a detailed visualisation of vessel injury after stent implantation and enables a systematic classification and quantification in vivo. In this study, frequency of tissue prolapse or intra-stent dissections after stenting was high, irrespective of the clinical presentation of the patients, and was not associated with clinical events during hospitalisation.

β-Particle–Emitting Radioactive Stent Implantation A Safety and Feasibility Study

Background—This study represents the Heart Center Rotterdam’s contribution to the Isostents for Restenosis Intervention Study, a nonrandomized multicenter trial evaluating the safety and feasibility of the radioactive Isostent in patients with single coronary artery disease. Restenosis after stent implantation is primarily caused by neointimal hyperplasia. In animal studies, b-particle‐ emitting radioactive stents decrease neointimal hyperplasia by inhibiting smooth muscle cell proliferation. Methods and Results—The radioisotope 32 P, a b-particle emitter with a half-life of 14.3 days, was directly embedded into the Isostent. The calculated range of radioactivity was 0.75 to 1.5 mCi. Quantitative coronary angiography measurements were performed before and after the procedure and at 6-month follow-up. A total of 31 radioactive stents were used in 26 patients; 30 (97%) were successfully implanted, and 1 was embolized. Treated lesions were in the left anterior descending coronary artery (n512), the right coronary artery (n58), or the left circumflex coronary artery (n56). Five patients received additional, nonradioactive stents. Treated lesion lengths were 13 64 mm, with a reference diameter of 2.9360.47 mm. Minimum lumen diameter increased from 0.8760.28 mm preprocedure to 2.8460.35 mm postprocedure. No in-hospital adverse cardiac events occurred. All patients received aspirin indefinitely and ticlopidine for 4 weeks. Twenty-three patients (88%) returned for 6-month angiographic follow-up; 17% of them had in-stent restenosis, and 13% had repeat revascularization. No restenosis was observed at the stent edges. Minimum lumen diameter at follow-up averaged 1.8560.69 mm, which resulted in a late loss of 0.9960.59 mm and a late loss index of 0.5360.35. No other major cardiac events occurred during the 6-month follow-up. Conclusions—The use of radioactive stents with an activity of 0.75 to 1.5 mCi is safe and feasible. (Circulation. 1999;100:1684-1689.)

Guidance of intracoronary radiation therapy based on dose-volume histograms derived from quantitative intravascular ultrasound

Application of ionizing radiation to prevent restenosis in atherosclerotic vessels treated by balloon angioplasty is a new treatment under investigation in interventional cardiology and radiology. There is variability in dose prescription, and both /spl gamma/- and /spl beta/-emitters are used, leading to a wide range of dose distribution over the arterial vessel wall. The authors present a new modality of dosimetry based on a method that three-dimensional (3-D) image reconstruction of electrocardiogram (ECG)-gated intravascular ultrasound (IVUS) images. Dose volume histograms (DVH) are used to describe the cumulative distribution of dose over two specific volumes: i) at the level of the luminal surface, defined with a thickness of 0.1 mm from the automatically detected contour of the highly echogenic blood-vessel interface, and ii) the adventitia volume is computed considering a 0.5-mm thickness from the echogenic media-adventitia interface. DVH provide a tool for reporting the actual delivered dose at the site believed to be the target: the adventitia, and to detect excessive radiation which could lead to vascular complications. Simulation of a /spl gamma/-emitter or of a radioactive source train in the center of the lumen are possible. The data obtained from the first ten patients included in the /spl beta/-irradiation trial (BERT 1.5) conducted in the authors institution are presented, supporting the use of DVH based on quantitative IVUS measurements for optimal dose prescription in vascular interventional radiation therapy.

Optical Coherence Tomography: Potential Clinical Applications

Optical coherence tomography (OCT) is a novel intravascular imaging modality using near-infrared light. By OCT it is possible to obtain high-resolution cross-sectional images of the vascular wall structure and assess the acute and long-term effects of percutaneous coronary intervention. For the time being OCT has been mainly used in research providing new insights into the pathophysiology of the atheromatic plaque and of the vascular response to stenting, however, it seems that there is potential for clinical application of OCT in various fields, such as pre-interventional evaluation of coronary arteries, procedural guidance in coronary interventions, and follow-up assessment of vascular healing after stent implantation. This review will focus on the potential and advantages of OCT in the clinical practice of a catheterization laboratory.

Assessment of atherosclerotic plaques at coronary bifurcations with multidetector computed tomography angiography and intravascular ultrasound-virtual histology.

AIMSnWe evaluated the distribution and composition of atherosclerotic plaques at bifurcations with intravascular ultrasound-virtual histology (IVUS-VH) and multidetector computed tomography (MDCT) in relation to the bifurcation angle (BA).nnnMETHODS AND RESULTSnIn 33 patients (age 63±11 years, 79% male) imaged with IVUS-VH and MDCT, 33 bifurcations were matched and studied. The analysed main vessel was divided into a 5 mm proximal segment, the in-bifurcation segment, and a 5 mm distal segment. Plaque contours were manually traced on MDCT and IVUS-VH. Plaques with >10% confluent necrotic core and <10% dense calcium on IVUS-VH were considered high risk, whereas plaque composition by MDCT was graded as non-calcified, calcified, or mixed. The maximum BA between the main vessel and the side branch was measured on diastolic MDCT data sets. Overall the mean plaque area decreased from the proximal to the distal segment [8.5±2.8 vs. 6.0±3.0 mm2 (P<0.001) by IVUS-VH and 9.0±2.6 vs. 6.5±2.5 mm2 (P<0.001) by MDCT]. Similarly, the necrotic core area was higher in the proximal compared with the distal segment (1.12±0.7 vs. 0.71±0.7 mm2, P=0.001). The proximal segment had the higher percentage of high-risk plaques (13/25, 52%), followed by the in-bifurcation (6/25, 24%), and the distal segment (6/25, 24%); these plaques were characterized by MDCT as non-calcified (72%) or mixed (28%). The presence of high-risk and non-calcified plaques in the proximal segment was associated with higher BA values (71±19° vs. 55±19°, P=0.028 and 74±20° vs. 50±14°, P=0.001, respectively).nnnCONCLUSIONnThe proximal segment of bifurcations is more likely to contain high-risk plaques, especially when the branching angle is wide.

Invasive coronary imaging in animal models of atherosclerosis

Experimental disease models have enhanced our understanding of the pathogenesis of atherosclerosis development. For example, insight has been gained into the role of the endothelium, lipids, platelets and inflammation, as well as into potential diagnostic and therapeutic interventions. Moreover, transgenic and knock-out technologies have become a widespread approach and this is a growing field to assess the role of individual genes in vascular biology and pathology. However, atherosclerosis is most of all a multifactorial disease, influenced by a multitude of environmental factors. Therefore, it is important to also study non-transgenic animal models that closely resemble the human situation with atherosclerotic lesions at anatomical locations that mimic the clinical manifestation of the disease, e.g. coronary artery disease (CAD). Although no model completely mimics human atherosclerosis, much can be learned from existing models in the study of this disease, also with respect to the development of new interventions. Here, we describe the most relevant animal models of atherosclerosis, while focusing on CAD development and the use of coronary diagnostic and therapeutic interventions. In addition, we show examples of features of a large animal model of CAD including pictures of invasive coronary imaging.

The impact of Fourier-Domain optical coherence tomography catheter induced motion artefacts on quantitative measurements of a PLLA-based bioresorbable scaffold

Intracoronary Fourier-Domain optical coherence tomography (FD-OCT) enables imaging of the coronary artery within 2–4xa0seconds, a so far unparalleled speed. Despite such fast data acquisition, cardiac and respiratory motion can cause artefacts due to longitudinal displacement of the catheter within the artery. We studied the influence of longitudinal FD-OCT catheter displacement on serial global lumen and scaffold area measurements in coronary arteries of swine that received PLLA-based bioresorbable scaffolds. In 10 swine, 20 scaffolds (18xa0×xa03.0xa0mm) were randomly implanted in two epicardial coronary arteries. Serial FD-OCT imaging was performed immediately after implantation (T1) and at 3 (T2) and 6xa0months (T3) follow-up. Two methods for the selection of OCT cross-sections were compared. Method A did not take into account longitudinal displacement of the FD-OCT catheter. Method B accounted for longitudinal displacement of the FD-OCT catheter. Fifty-one OCT pullbacks of 17 scaffolds were serially analyzed. The measured scaffold length differed between time points, up to one fourth of the total scaffold length, indicating the presence of longitudinal catheter displacement. Between method A and B, low error was demonstrated for mean area measurements. Correlations between measurements were high: R2 ranged from 0.91 to 0.99 for all mean area measurements at all time points. Considerable longitudinal displacement of the FD-OCT catheter was observed, diminishing the number of truly anatomically matching cross-sections in serial investigations. Global OCT dimensions such as mean lumen and scaffold area were not significantly affected by this displacement. Accurate co-registration of cross-sections, however, is mandatory when specific regions, e.g. jailed side branch ostia, are analyzed.

Left Main Rapamycin-Coated Stent

A 47-year-old man with a history of recurrent coronary interventions underwent percutaneous coronary intervention (PCI) of the left main coronary artery with implantation of a rapamycin-coated stent (BX Velocity 4.0×18 mm). At 6-month follow-up, with no physical complaints, he underwent conventional and multislice spiral computed tomography (MSCT) coronary angiography.nnIntravenously contrast-enhanced MSCT (Siemens Somatom Plus 4 Volume Zoom, Siemens AG) showed a well-positioned stent in the left main coronary artery with no indication of lumen diameter reduction or neointimal hyperplasia (Figure 1). By means of virtual coronary angioscopy, a 3-dimensional reconstructed internal view is provided (Movie …

Distinct Pattern of Constrictive Remodeling in Radiotherapy-Induced Coronary Artery Disease

A 31-year-old woman with a history of chemotherapy and mediastinal radiation therapy for Hodgkin’s lymphoma presented with stable angina followed by a positive stress test.nnA coronary computed tomography scan revealed a high-grade ostial right coronary artery stenosis without calcium (Agatston