Invasive imaging of the coronary atherosclerotic plaque.

Coronary atherosclerosis has a high prevalence and is known as the leading cause of death worldwide. Clinically, coronary atherosclerosis is routinely evaluated by coronary angiography, which provides a luminogram of the coronary artery and allows for recognizing lumen narrowing. However, angiography does not allow for the direct assessment of the disease process within the coronary vessel wall. Today, a number of catheter-based imaging methods can overcome this shortcoming and provide physicians with additional information on specific morphological components of atherosclerotic lesions. This article discusses the abilities of intravascular imaging techniques such as intravascular ultrasound (IVUS), IVUS-VH, iMAP, integrated backscatter-IVUS, intravascular optical coherence tomography, near-infrared spectroscopy and angioscopy, to diagnose coronary atherosclerosis and their potential to guide clinical decision making.

New drug-eluting stents with biodegradable polymers.

Current drug-eluting stents (DES) perform well compared to bare metal stents. However, long-term rates of major adverse events and in particular repeat revascularization by PCI are still an issue. In this concise review we will discuss the possibilities of biodegradable coatings to improve biocompatibility of DES. Among the various members of the synthetic biodegradable polymer family, polyesters are widely used and attractive for their ease of degradation, with degradation products often being resorbed through general metabolic pathways. A new development is surface functionalization of polyesters to improve endothelialization.

Endothelial dysfunction after drug eluting stent implantation.

Endothelial dysfunction has been implicated in the pathological process of coronary artery disease as well as an adverse event after coronary drug eluting stent (DES) implantation. In this review, an overview will be given of the evidence to date regarding the effects of coronary DES on endothelial function obtained from both clinical and experimental studies. Stenting in general and DES seem to impair several aspects of endothelial function: provision of a permeable barrier function; modulation of adhesion, thrombosis and inflammation; and regulation of vascular tone. However, new insights show that the effects of DES can extend beyond the stent and peri-stent area: the vascular bed distal to the stent, starting with the distal conduit vessels up to the distal microvasculature, might be at risk. In addition, insight into the mechanism of DES induced endothelial dysfunction has been gained. To finalize this review, clinical complications and solutions of DES associated endothelial dysfunction will be discussed.

Neointimal hyperplasia and endothelial function after percutaneous coronary intervention.

Percutaneous coronary revascularisation has become much safer and efficacious since its introduction more than 25 years ago. Currently, the need for surgical backup is small and the rate of late complications is lower than 10%. Further improvements are being studied, especially directed towards more biocompatible stents, using pharmacological principles with wider therapeutic windows and enhancing the vascular healing response/reendothelialisation. This article reviews several activities within the ICIN theme group `Vessel Wall'.

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 2-4 seconds, 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 (18 × 3.0 mm) were randomly implanted in two epicardial coronary arteries. Serial FD-OCT imaging was performed immediately after implantation (T1) and at 3 (T2) and 6 months (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.

Thrombotic complication during intracoronary imaging.

Intracoronary imaging with intracoronary ultrasound and coherence tomography is often used in the follow-up of coronary stent implantation. The present case shows an infrequent complication of these procedures, suggesting our continued attention to the selective use of these invasive procedures.

An in vivo comparison of radiofrequency cardiac lesions formed by standard and magnetically steered 4 mm tip catheters.

Background. In vivo comparison of cardiac radiofrequency ablation lesions between standard and magnetically steered 4 mm tip catheters has never been reported.Methods. High and low right atrium (RA) free wall, isthmus, right ventricle (RV) free wall and outflow tract lesions were studied macroscopically and microscopically five days after lesion formation in seven pigs. Shape, size, thrombus formation, and ablation parameters were compared. The effect of minimal, medium and high wall contact was assessed by a contact measurement utility for magnetic catheters.Results. All 14 RA free wall lesions were transmural with a similar epicardial and endocardial surface area. In the RV, the epicardial area usually appeared to be smaller than the endocardial area with standard catheters. Isthmus lesions were difficult to assess transmurality. There was no difference in endocardial area: standard 39 mm(2) (range 16 to 82 mm(2)) vs. magnetic 36 mm(2) (range 23 to 111 mm(2)). If the catheter tip was perpendicular to the tissue, magnetic lesions were more often round or oval, while standard lesions were more often elongated (p<0.05). When the catheter tip was parallel to tissue, lesions always tended to be elongated. Microscopic characteristics were similar. The contact utility was not useful. Average impedance (p<0.0001) and energy delivered (p<0.05) were less with magnetic catheters.Conclusion. Lesions from magnetically steered catheters are transmural of similar size, but with less variability than standard catheter lesions when the tip is perpendicular to the tissue. Magnetic lesions are associated with lower impedance and energy delivery. This suggests a more stable tip-to-tissue contact. (Neth Heart J 2010;18:66-71.).