In vivo evaluation of neointimal healing after stenting with optical coherence tomography

__Abstract__ Ischemic heart disease is still today the first cause of mortality in the world, especially in the developed countries. The vast majority of cases are due to atherosclerosis, a complex systemic degenerative process resulting in cholesterol accumulation in the extra-cellular space of the arterial intima, with inflammation, foam-cells formation, and necrosis. The clinical manifestations of coronary atherosclerosis comprise from stable angina, due to flow-limiting stenosis of the artery, to acute myocardial infarction or sudden death, when the atheroma gets complicated by thrombotic phenomena. The first revolution in the treatment of this disease came in 1977, when Andreas Grüntzig performed the first coronary balloon angioplasty. The inflation of a balloon in a narrowed coronary vessel resulted in smash of the atheroma plaque and enlargement of the lumen, thus solving the flow limitation imposed by the stenosis. The success of this therapy was however mitigated by the risk of acute coronary occlusion due to extensive dissection requiring emergency bypass surgery and also by high restenosis rates at follow-up (about 30-50% after 1 year). The mechanism of restenosis had at least two differentiated components: constrictive remodelling of the vessel, defined as reduction in the area of the elastic external lamina (accounting for 73% of the lumen reduction) and neointimal hyperplasia (accounting for 27% of the lumen reduction)

Researches of Automatic Steering Control Systems Using an Optical Flow Model

博士（工学）神戸大

How should I treat impaired systolic function and clinical deterioration after surgery of type A aortic dissection?

BACKGROUND: A 50-year-old male with diagnosis of acute type A aortic dissection underwent surgical repair. Immediately after surgery the patient had transient ECG changes, a raise in serum cardiac markers and physical signs of heart failure. INVESTIGATION: Physical examination, electrocardiography, echocardiography (transthoracic and transoesophageal), coronary angiography, intravascular ultrasound. DIAGNOSIS: Type A aortic dissection. MANAGEMENT: Surgical repair, coronary angiography, percutaneous coronary intervention

Paclitaxel-coated balloon in combination with bare metal stent for treatment of de novo coronary lesions: An optical coherence tomography first-in-human randomised trial, balloon first vs. stent first

Aims: To test the efficacy of sequential application of drug-coated balloon (DCB) and bare metal stent (BMS) for treatment of de novo coronary lesions, comparing the sequence of application (DCB first vs. BMS first). Methods and results: In a multicentre pilot trial, 26 patients with de novo coronary lesions were randomised to receive a paclitaxel-coated balloon application followed by BMS implantation (DCB first) or vice versa (BMS first). Quantitative coronary angiography (QCA) and optical coherence tomography (OCT) were performed post-procedure and at six months, with OCT % neointimal volume obstruction as primary endpoint. Longitudinal geographical miss was only observed in DCB first (23.1 vs. 0.0%, p=0.220). Implantation of BMS first resulted in fewer malapposed struts (p=0.013) but similar coverage at six months. No significant difference was found regarding the primary endpoint (25.5 vs. 24.9%, p=0.922), mean thickness of coverage (261 vs. 225 μm, p=0.763), late loss (0.53 vs. 0.45 mm, p=0.833), binary restenosis (27.3 vs. 16.7% in-segment, p=0.640) or clinical endpoints. Conclusions: Sequential application of DCB and not pre-mounted BMS for treatment of de novo coronary lesions results in efficient inhibition of neointimal hyperplasia. The sequence of application (DCB first vs. BMS first) does not seem to influence the outcome, except for better apposition in BMS first

Optical coherence tomography: From research to practice

Optical coherence tomography (OCT) is a high-resolution imaging technique with great versatility of applications. In cardiology, OCT has remained hitherto as a research tool for characterization of vulnerable plaques and evaluation of neointimal healing after stenting. However, OCT is now successfully applied in different clinical scenarios, and the introduction of frequency domain analysis simplified its application to the point it can be considered a potential alternative to intravascular ultrasound for clinical decision-making in some cases. This article reviews the use of OCT for assessment of lesion severity, characterization of acute coronary syndromes, guidance of intracoronary stenting, and evaluation of long-term results

In vivo evaluation of stent strut distribution patterns in the bioabsorbable everolimus-eluting device: An OCT ad hoc analysis of the revision 1.0 and revision 1.1 stent design in the ABSORB clinical trial

Aims: The ABSORB Cohort A clinical study has shown the feasibility and safety of the fully bioabsorbable everolimus-eluting structure (BVS, revision 1.0). However, the study also demonstrated somewhat higher acute and late recoil with the BVS structure compared to metallic drug eluting stents. Based on these clinical observations, modifications to the stent design (BVS, revision 1.1) were introduced for the ABSORB Cohort B study in order to decrease recoil. The aim was to compare in vivo the strut distribution between the BVS revision 1.0 (Cohort A), and BVS revision 1.1 (Cohort B) designs. Methods and results: OCT analysis was performed by two independent analysts in four patients from each cohort of the ABSORB study. Strut distribution was assessed in cross-section, and longitudinally in a frame-by-frame analysis. Variables recorded included inter-strut angle, maximum inter-strut angle and number of frames with ≥3 struts. The inter-observer correlation coefficient was also assessed. For both designs, on a patient level there was no significant difference in the number of analysed struts corrected for the length of the scaffold (p=0.78). Likewise, on a frame by frame analysis mean stent area, number of struts per frame, mean maximum inter-strut angle, and mean inter-strut angle were similar for both groups. However, in both structures there was a cyclical variation in the maximum number of struts per frame. The frequency of this variation was significantly higher in Cohort B. The inter-observer correlation coefficient for strut counts, inter-strut angle and maximum inter-strut angle was 0.91, 0.87 and 0.74 respectively. Conclusions: This ad hoc analysis confirms that the revision 1.1 BVS design has a different longitudinal strut distribution to the revision 1.0 BVS design, indicating that the new design has a reduced maximum circular unsupported cross sectional area

In vivo characterisation of bioresorbable vascular scaffold strut interfaces using optical coherence tomography with Gaussian line spread function analysis

Aims: Optical coherence tomography (OCT) of a bioresorbable vascular scaffold (BVS) produces a highly reflective signal outlining struts. This signal interferes with the measurement of strut thickness, as the boundaries cannot be accurately identified, and with the assessment of coverage, because the neointimal backscattering convolutes that of the polymer, frequently making them indistinguishable from one another. We hypothesise that Gaussian line spread functions (LSFs) can facilitate identification of strut boundaries, improving the accuracy of strut thickness measurements and coverage assessment. Methods and results: Forty-eight randomly selected BVS struts from 12 patients in the ABSORB Cohort B clinical study and four Yucatan minipigs were analysed at baseline and follow-up (six months in humans, 28 days in pigs). Signal intensities from the raw OCT backscattering were fit to Gaussian LSFs for each interface, from which peak intensity and full-width-at-half-maximum (FWHM) were calculated. Neointimal coverage resulted in significantly different LSFs and higher FWHM values relative to uncovered struts at baseline (p<0.0001). Abluminal polymer-tissue interfaces were also significantly different between baseline and follow- up (p =0.0004 in humans, p <0.0001 in pigs). Using the location of the half-max of the LSF as the polymer- tissue boundary, the average strut thickness was 158±11 μm at baseline and 152±20 μm at six months (p=0.886), not significantly different from nominal strut thickness. Conclusions: Fitting the raw OCT backscattering signal to a Gaussian LSF facilitates identification of the interfaces between BVS polymer and lumen or tissue. Such analysis enables more precise measurement of the strut thickness and an objective assessment of coverage