From the Cardiology Division

Background-Cell therapy for myocardial infarction (MI) may be limited by poor cell survival and lack of transdifferentiation. We report a novel technique of implanting whole autologous myocardial tissue from preserved myocardial regions into infarcted regions. Methods and Results-Fourteen rats were used to optimize cardiomyotissue size with peritoneal wall implantation (300 m identified as optimal size). Thirty-nine pigs were used to investigate cardiomyotissue implantation in MI induced by left anterior descending balloon occlusion (10 animals died; male-to-female transplantation for tracking with in situ hybridization for Y chromosome, nϭ4 [2 donors and 2 MI animals]; acute MI implantation cohort at 1 hour, nϭ13; and healed MI implantation at 2 weeks, nϭ12 Key Words: myocardial infarction Ⅲ remodeling Ⅲ stem cells M yocardial infarction (MI) and its resultant left ventricular (LV) dysfunction remain a leading cause of mortality and morbidity. Different therapies for myocardial regeneration have been investigated with varying results and no definitive beneficial effects. [1][2] We have developed a novel approach to adult cardiomyocyte transplantation. In a porcine model of MI, core biopsies of myocardial tissue are obtained from the preserved basal ventricular septum and used for implantation into the myocardial scar Received January 28, 2006; accepted October 8, 2010 Methods All experiments were performed in accordance with National Institutes of Health guidelines and were approved by the Institutional Animal Care and Use Committee at Beth Israel Deaconess Medical Center. Myotissue Sizing Experiments Fourteen inbred rats (50 to 60 g) were used. Donor rats (nϭ3) were euthanized with CO 2 inhalation, and the heart was excised and placed in normal saline. Strips of varying diameters (100 to 500 mol/L) were obtained under a dissecting microscope. Eleven rats were then anesthetized with intraperitoneal ketamine/xylaxine (0.1 mL /100 g). The abdominal skin was incised and rectus muscle was exposed. Strips were implanted, and rectus fascia was closed with 10 -0 Prolene suture. Animals were divided into 5 groups (nϭ2 per group) with implantation of 100-, 200-, 300-, 400-, and 500-m strips (1 strip per animal). The animals were allowed to recover and were euthanized after 1 week, and the abdominal wall was formalin fixed, paraffin embedded, and sectioned for hematoxylin and eosin staining. Porcine Balloon Occlusion Catheter Model of Anterior MI Thirty-nine 30-to 40-kg Yorkshire pigs were anesthetized with intramuscular ketamine (10 mg/kg) and isoflurane (2 normal animals as donors for male-to-female transplantation and 37 infarcted animals: 13 animals for acute infarct study, 12 animals for healed infarct study, 2 recipient animals for tracking experiments, and 10 animals died during balloon occlusion of intractable ventricular fibrillation before being randomized, leading to more aggressive pretreatment with Mg, KCl, metoprolol, and lidocaine). A 2.75ϫ20-mm angioplasty balloon (Maverick, Boston Scientific, MA) was advanced over the wire and positioned in the mid left anterior descending artery after the takeoff of the first diagonal branch. The balloon was inflated to 6 atm for 60 minutes to produce an anterior MI. Balloon occlusion and Thrombolysis in Myocardial Infarction grade 0 flow were confirmed with contrast injection. The balloon was deflated after a minimum of 60 minutes of uninterrupted occlusion, and the surviving animals were allowed to recover. LV angiography was performed in all animals to confirm the presence of anterior wall motion abnormality. Septal Biopsy and Myotissue Implantation Into Myocardial Scar Tissue Implantations were performed acutely in acute MI cohort and 2 weeks after the initial infarction (ie, after the period of acute inflammation when scar formation and remodeling process have ensued in the healed infarct cohort). A right anterior thoracotomy through the fourth intercostal space was performed. The pericardium was opened and the lung retracted. The right ventricular free wall was incised, and a short 8F sheath (Cordis) was inserted and secured with a purse string suture. A liver bioptome (Cook Inc, Bloomington, IN) was inserted via an 8F sheath into the right ventricle and aimed at the basal septum under fluoroscopic guidance. Between 6 and 10 core biopsies (average, 9) were obtained with the bioptome from the basal septum. The anterior wall was exposed by rotating the heart slightly with a sponge stick. Six biopsies were then implanted into the anterior wall of the LV 0.5 cm distal to the left anterior descending artery and D1 bifurcation (visually identified). This was done by unloading the liver bioptome (Cook Inc) and rotating it in situ so as not to remove the implanted biopsy material (see the online-only Data Supplement for a detailed description). In each cohort, animals were randomized to cardiomyotissue implantation or sham injections. Sham animals also underwent the septal biopsy. The empty liver bioptome without the implant tissue was then introduced into the anterior wall. In Situ Hybridization of the Y Chromosome for Implant Viability Assessment Four sibling pairs of male and female pigs were used for this experiment. Two animals died during MI induction, leaving 2 animals for implantation. Two weeks later, the female recipients were brought back with their male siblings. Male hearts were harvested via median sternotomy, and basal septal biopsies were immediately taken after opening of the right ventricular cavity. Cardiomyotissue from the basal septum of the male sibling was implanted into the anterior wall myocardial infarct area of the females under direct vision. The area of implantation (9 to 11 implants per animal) was demarcated with 6 -0 Prolene sutures. The female recipients received 3 days of pulse dose steroids (40 mg or 1 mg/kg) and 10 mg thereafter to prevent rejection (not HLA matched). The hearts of the recipients were harvested 2 weeks after implantation and 4 weeks after the initial MI. In situ hybridization for Y chromosome was performed on the harvested female recipient hearts to quantify the number of viable implants. Hybridization with Starfish biotinylated pig Y chromosome DNA probe (Cambio, Guildford, Surrey, UK) was performed overnight at 37°C in a humidified chamber. A streptavidin-biotin system with diaminobenzidine development (Vector, Burlingame, CA) followed by hematoxylin counterstaining was used to visualize male cells. Infarct Volume, Myocardial Perfusion, and Functional Assessment by Cardiac Magnetic Resonance Animals in the acute MI cohort underwent cardiovascular magnetic resonance on a 1.5-T General Electric TwinSpeed Scanner (GE Healthcare Technologies, Milwaukee, WI) 4 weeks after infarction as previously described. Functional Assessment of LV Function by Echocardiography (Transthoracic and Epicardial) In the healed infarct cohort, 2 weeks after MI, baseline 2-dimensional and 2-dimensional-directed M-mode epicardial echocardiography was performed in multiple views (standard short-axis and long-axis views, as well as epicardial views) 24 to assess LV ejection fraction (EF) and LV end-diastolic dimension. 25 Transthoracic echocardiography was performed before implantation with the animal chest closed. Epicardial echocardiography windows were obtained before implantation after the chest was open. Magnetic resonance imaging (MRI) was not performed because of multiple procedures in this cohort to reduce time under anesthesia. End-systolic and end-diastolic LV cavity dimensions at the level of midpapillary muscles were determined in the M mode. EF was calculated from the M-mode-derived cavity dimensions in the Teicholz formula: (enddiastolic dimensionϪend-systolic dimension)/end-diastolic dimensionϫ100. Measurements were repeated at 4 weeks after infarction at the time of tissue harvest. In the acute cohort, echocardiography was performed at the time of death (at 4 weeks). Echocardiographic analysis was performed quantitatively and qualitatively by 2 experienced echocardiographers in a blinded fashion. Hemodynamic Assessment LV pressure was measured with a high-fidelity micromanometer catheter placed in the LV cavity in a retrograde fashion. The rate of change of LV pressure was measured and averaged over 10 beats (dP/dt). Left atrial pressure was measured with a 3.5-JL 5F catheter advanced (retrograde) to left atrium. All data were recorded digitally and stored for offline analysis (Sonosoft, Sonometrics Corp, London, ON, Canada). Wykrzykowska et al Myotissue Implantation Regenerates Myocardium 63 at Harvard University on February 3, 2011 circ.ahajournals.org Downloaded from Histology, Morphometric Analysis, and Immunohistochemistry Four weeks after the initial infarction, animals were euthanized under general anesthesia, and the hearts were harvested and cut into 5 transverse slices. The apical and middle slices were used for myocardial viability with 1% triphenyltetrazolium chloride (TTC) in phosphate buffer (Sigma Chemical) and incubated for 20 minutes at 38°C as previously described. Molecular Studies Myocardial tissue samples were lysed in radioimmunoprecipitation assay solution (Boston Bioproducts, Ashland, MA). Protein concentrations were determined by Bradford assay. Equal amounts of protein were subjected to fractionation on 10% SDS-polyacrylamide under reducing conditions. Protein extracts were transferred to polyvinylidene difluoride membranes (Millipore, Bedford, MA). MMP-2 and TIMP-2 (Chemicon) were detected with specific antibodies. Immunoblots were visualized with appropriate secondary antibodies conjugated to horseradish peroxidase and chemiluminescence detection reagents (Amersham, Life Science, Arlington Heights, IL). Values of image densitometry were obtained with ImageJ software and adjusted by the ratio of sample loading as determined by Ponceau Red staining. Statistical Analysis Data analysis and graphing were performed with the Statview software package (SAS Institute Inc, Cary, NC). Groups were compared through the use of 2-tailed Student t test with a cutoff for statistical significance of Pϭ0.05. For comparisons of data at 2 and 4 weeks, paired t tests were used to compare means within groups, whereas unpaired tests were used to compare mean changes between groups. Normal distribution of the data was verified before parametric analysis was performed. Correction was made for multiple comparisons. Data are expressed as meanϮSD. Results Sizing Experiments Abdominal wall sections were obtained from implanted rats. Tissues Յ300 m remained viable at 1 week after implantation in all animals. Tissues 400 and 500 m in diameter showed necrosis, indicating that the maximal tissue size for implantation would be 300 m, probably related to revascularization of the implant Feasibility and Safety of Cardiomyotissue Implantation The initial creation of the MI model with balloon occlusion was associated with 31% mortality secondary to ventricular fibrillation during balloon occlusion. Twenty-seven of 37 animals survived: 2 for male-female transplantation, 13 in the acute MI cohort (6 sham and 7 treated animals), and 12 in the healed infarct cohort (6 sham and 6 treated animals). There was no additional mortality associated with cardiomyotissue implantation. The animals tolerated both the biopsy of the basal septum and the anterior wall implantation without hypotension or sustained arrhythmias. Histological Analysis and Male-Into-Female Transplantation Model Histological analysis by hematoxylin and eosin staining confirmed the presence of extensive areas of infarction and fibrosis in the anteroseptal area. In the treated animals, all implants were identified and were viable (marked with 6 -0 suture) in multiple tissue sections Acute MI Cohort MRI and Echocardiography Results The perfusion ratio of anterior to septal wall was greater in the treated animals than in controls (1.2Ϯ0.01 versus 0.86Ϯ0.05; PϽ0.01; Hemodynamics (dP/dt) Contractility as measured by positive maximal dP/dt was greater in the treated animals compared with controls (1235Ϯ215 versus 817Ϯ817; PϽ0.05), indicating that the overall systolic myocardial function was improved in treated animals. TTC Staining The percent infarct size of the anterior wall area in the treated animals was 3-fold smaller than in controls (10.3Ϯ4.6 versus 28.9Ϯ5.8; PϽ0.03; Healed MI Cohort Echocardiographic Assessment of LV Function Treated animals had the same EF at 2 and 4 week time points (49Ϯ6.5% versus 46Ϯ7.4%; Pϭ0.5; Hemodynamics Both systolic (positive dP/dt) and diastolic (negative dP/dt) function and LA pressures did not change in the treated animals between weeks 2 and 4 after infarction ( Morphometric Analysis Percent infarct size in the anterior wall of treated animals was significantly smaller than control animals (21Ϯ11 versus 38Ϯ8; Pϭ0.006). There was also a significant difference in Wykrzykowska et al Myotissue Implantation Regenerates Myocardium 65 at Harvard University on February 3, 2011 circ.ahajournals.org Downloaded from the infarct size in the untreated septum, suggesting a global effect of cardiomyotissue on myocardial salvage (16Ϯ11 versus 27Ϯ10; Pϭ0.02), an effect not seen in acute MI cohort. TTC staining assessment was consistent between the 2 independent observers (rϭ0.82, Pϭ0.0005). Adjacent to the implants and within the infarct region, a 2-fold greater number of cells positive for mdr-1 were observed Molecular Analysis We explored the expression of MMP-2 and TIMP-2, known to be involved in remodeling after infarction. Discussion Cell-based therapies for myocardial regeneration have demonstrated variable initial results. 4 -7,29 We have developed a new method of myocardial autotransplantation that obviates the need for cell culture and could be implemented during planned revascularization procedures. Implantation of cardiomyotissue appears to reduce infarct size and to prevent the decline in myocardial function after extensive anterior MI. This was evident in the preservation of EF, LV dimensions, and hemodynamic parameters and the decrease in infarct size in the treated animals compared with controls. In addition, implants remain viable and appear to express connexin 43 66 Circulation January 4/11, 2011 at Harvard University on February 3, 2011 circ.ahajournals.org Downloaded from and N-cadherin (gap junctions and desmosomes between the implant and surrounding myocardium). The effects in acute MI cohort were more robust than in the healed MI cohort, but this finding may be related in part to shorter treatment duration in this cohort. Our study was controlled for nonspecific effects of implantation by use of sham implants. We propose that several mechanisms and intrinsic properties of whole-tissue implantation may be responsible for preventing the decline in myocardial function. It may avoid cell shearing and preserve tissue architecture and growth factor milieu within the extracellular matrix scaffold. In addition, we hypothesize that our biopsies may contain resident stem cells that may contribute to myocardial repair. Wykrzykowska et al Myotissue Implantation Regenerates Myocardium 67 at Harvard University on February 3, 2011 circ.ahajournals.org Downloaded from definition of a stem cell and its recognition based on cell surface markers. Furthermore, the differentiation potential of the adult cardiac stem cells may be limited by the trophic factor-impoverished milieu of the infarct. We observed that treated animals tended to have lower levels of MMP-2 and higher levels of TIMP-2, with more favorable hemodynamic parameters in treated animals. As demonstrated in murine models of MI, MMP-2 expression increases and is maintained for several weeks after infarction. MMP-2 knockout mice appear to have decreased dilation response after infarction. 32 TIMP knockout mice, on the other hand, have an exaggerated unfavorable remodeling with higher incidence of LV rupture and mortality. Finally, the effects of cardiomyotissue implantation can be contrasted with the effects of skin microorgan transplantation. Limitations This preliminary "proof of concept" study suffers from the limitation of lack of long-term follow-up and safety data. A major limitation was that randomization was not based on baseline infarct size and LV function. Furthermore, the worsening LV function in the acute MI control cohort conflicts with previous studies that surprisingly showed preserved LV function. Conclusions We presented here a novel approach to cellular therapy for MI, which involves septal biopsy and implantation of the intact tissue into the infarcted area. This novel implantation technique has low mortality in our swine model of MI and is technically simple to perform. These whole-biopsy implants were efficacious in preventing myocardial dysfunction as measured by MRI, echocardiography, and hemodynamic parameters and in decreasing infarct size. They obviate the need for tissue manipulation and culture. The implants are viable at 2 weeks after implantation and may be electromechanically coupled with the host myocardium. Further studies are needed to explore the beneficial mechanism of this novel technology

Early Regeneration of Thymic Progenitors in Rhesus Macaques Infected with Simian Immunodeficiency Virus

The thymus plays a critical role in the maturation and production of T lymphocytes and is a target of infection by human immunodeficiency virus (HIV) and the related simian immunodeficiency virus (SIV). Using the SIV/macaque model of AIDS, we examined the early effects of SIV on the thymus. We found that thymic infection by SIV resulted in increased apoptosis 7–14 d after infection, followed by depletion of thymocyte progenitors by day 21. A marked rebound in thymocyte progenitors occurred by day 50 and was accompanied by increased levels of cell proliferation in the thymus. Our results demonstrate a marked increase in thymic progenitor activity very early in the course of SIV infection, long before marked declines in peripheral CD4+ T cell counts

Науково-інформаційні ресурси порталу бібліотеки: формування, використання

Визначено шляхи вдосконалення процесів формування та використання електронних ресурсів порталу національної бібліотеки як базової компоненти єдиного науково-інформаційного простору держави.Определены пути усовершенствования процессов формирования и использования электронных ресурсов портала национальной библиотеки как базовой компоненты единого научно-информационного пространства государства.The ways of improvement of formation and usage processes of the electronic resources of the national library portal as a base component of unified scientific information space of the state are determined

Angiography-based superficial wall strain of de novo stenotic coronary arteries:serial assessment of vessels treated with bioresorbable scaffold or drug-eluting stent

Objectives: This study sought to present an angiography-based computational model for serial assessment of superficial wall strain (SWS, dimensionless) of de-novo coronary stenoses treated with either bioresorbable scaffold (BRS) or drug-eluting stent (DES). Background: A novel method for SWS allows the assessment of the mechanical status of arteries in-vivo, which may help for predicting cardiovascular outcomes. Methods: Patients with arterial stenosis treated with BRS (n = 21) or DES (n = 21) were included from ABSORB Cohort B1 and AIDA trials. The SWS analyses were performed along with quantitative coronary angiography (QCA) at pre-PCI, post-PCI, and 5-year follow-up. Measurements of QCA and SWS parameters were quantified at the treated segment and adjacent 5-mm proximal and distal edges. Results: Before PCI, the peak SWS on the ‘to be treated’ segment (0.79 ± 0.36) was significantly higher than at both virtual edges (0.44 ± 0.14 and 0.45 ± 0.21; both p &lt; 0.001). The peak SWS in the treated segment significantly decreased by 0.44 ± 0.13 (p &lt; 0.001). The surface area of high SWS decreased from 69.97mm2 to 40.08mm2 (p = 0.002). The peak SWS in BRS group decreased to a similar extent (p = 0.775) from 0.81 ± 0.36 to 0.41 ± 0.14 (p &lt; 0.001), compared with DES group from 0.77 ± 0.39 to 0.47 ± 0.13 (p = 0.001). Relocation of high SWS to device edges was often observed in both groups after PCI (35 of 82 cases, 41.7 %). At follow-up of BRS, the peak SWS remained unchanged compared to post-PCI (0.40 ± 0.12 versus 0.36 ± 0.09, p = 0.319). Conclusion: Angiography-based SWS provided valuable information about the mechanical status of coronary arteries. Device implantation led to a significant decrease of SWS to a similar extent with either polymer-based scaffolds or permanent metallic stents.</p

Non-culprit MACE-rate in LRP:The influence of optimal medical therapy using DAPT and statins

Background/Purpose: The Lipid Rich Plaque (LRP) study demonstrated the association between coronary plaque lipid content and outcomes. In this LRP substudy, we assessed the impact of optimal medical therapy (OMT) on the occurrence of non-culprit major adverse cardiac events (NC-MACE). Advanced intracoronary imaging modalities are able to identify patients with vulnerable coronary lesion morphology associated with future events. Methods/Materials: A total of 1270 patients who underwent cardiac catheterization for suspected coronary artery disease (CAD) with evaluable maxLCBI4mm in non-culprit vessels and known medical therapy after discharge were followed for 2 years. OMT was defined as the use of a statin and dual antiplatelet therapy (DAPT). Results: Among the 1270 patients included in this substudy, 1110 (87.7%) had PCI for an index event, and 1014 (80%) patients received OMT. Estimated cumulative incidence functions of NC-MACE did not differ significantly between patients treated with or without OMT (log-rank p-value = 0.876). In patients labeled high risk (maxLCBI4mm > 400), cumulative incidence function also did not differ between patients treated with vs without OMT (log-rank p-value = 0.19). Conclusions: In the current LRP analysis, we could not identify a beneficial effect of OMT in the reduction of NC-MACE rate, even in patients with high-risk plaques during 24-month follow-up

Long-term clinical outcomes of everolimus-eluting bioresorbable scaffolds versus everolimus-eluting stents:final five-year results of the AIDA randomised clinical trial

Background: Absorb bioresorbable vascular scaffold (BVS)-related events have been reported between 1 and 3 years – the period of active scaffold bioresorption. Data on the performance of the Absorb BVS in daily clinical practice beyond this time point are scarce. Aims: This report aimed to provide the final five-year clinical follow-up of the Absorb BVS in comparison with the XIENCE everolimus-eluting stent (EES). In addition, we evaluated the effect of prolonged dual antiplatelet therapy (DAPT) administration on events in the scaffold group. Methods: AIDA was a multicentre, investigator-initiated, non-inferiority trial, in which 1,845 unselected patients with coronary artery disease were randomly assigned to either the Absorb BVS (n=924) or the XIENCE EES (n=921). Target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction or target vessel revascularisation, was the primary endpoint. Scaffold thrombosis cases were matched with controls and tested for the effect of prolonged DAPT. Results: Up to five-year follow-up, there was no difference in TVF between the Absorb BVS (17.7%) and the XIENCE EES (16.1%) (hazard ratio [HR] 1.31, 95% confidence interval [CI]: 0.90-1.41; p=0.302). Definite or probable device thrombosis (DT) occurred in 43 patients (4.8%) in the scaffold group compared to 13 patients (1.5%) in the stent group (HR 3.32, 95% CI: 1.78-6.17; p<0.001). DT between 3 and 4 years occurred six times in the Absorb arm versus three times in the XIENCE arm. Between 4 and 5 years, the incidence was three versus two, respectively. Of those three DT in the scaffold group, two occurred in XIENCE EES-treated lesions. The odds ratio of scaffold thrombosis in patients on DAPT compared to off DAPT throughout five-year follow-up was 0.36 (95% CI: 0.15-0.86). Conclusions: The excess risk of the Absorb BVS on late adverse events, in particular device thrombosis, in routine PCI continues up to 4 years and seems to plateau afterwards

A prospective multicenter validation study for a novel angiography-derived physiological assessment software:Rationale and design of the radiographic imaging validation and evaluation for Angio-iFR (ReVEAL iFR) study

Background Angiography-derived physiological assessment of coronary lesions has emerged as an alternative to wire based assessment aiming at less-invasiveness and shorter procedural time as well as cost effectiveness in physiology-guided decision making. However, current available image-derived physiology software have limitations including the requirement of multiple projections and are time consuming. Methods/Design The ReVEAL iFR (Radiographic imaging Validation and EvALuation for Angio-iFR) trial is a multicenter, multicontinental, validation study which aims to validate the diagnostic accuracy of the Angio-iFR medical software device (Philips, San Diego, US) in patients undergoing angiography for Chronic Coronary Syndrome (CCS). The Angio-iFR will enable operators to predict both the iFR and FFR value within a few seconds from a single projection of cine angiography by using a lumped parameter fluid dynamics model. Approximately 440 patients with at least one de-novo 40% to 90% stenosis by visual angiographic assessment will be enrolled in the study. The primary endpoint is the sensitivity and specificity of the iFR and FFR for a given lesion compared to the corresponding invasive measures. The enrollment started in August 2019, and was completed in March 2021. Summary The Angio-iFR system has the potential of simplifying physiological evaluation of coronary stenosis compared with available systems, providing estimates of both FFR and iFR. The ReVEAL iFR study will investigate the predictive performance of the novel Angio-iFR software in CCS patients. Ultimately, based on its unique characteristics, the Angio-iFR system may contribute to improve adoption of functional coronary assessment and the workflow in the catheter laboratory

Coronary fractional flow reserve measurements of a stenosed side branch: A computational study investigating the influence of the bifurcation angle

Background: Coronary hemodynamics and physiology specific for bifurcation lesions was not well understood. To investigate the influence of the bifurcation angle on the intracoronary hemodynamics of side branch (SB) lesions computational fluid dynamics simulations were performed. Methods: A parametric model representing a left anterior descending-first diagonal coronary bifurcation lesion was created according to the literature. Diameters obeyed fractal branching laws. Proximal and distal main branch (DMB) stenoses were both set at 60%. We varied the distal bifurcation angles (40°, 55°, and 70°), the flow splits to the DMB and SB (55%:45%, 65%:35%, and 75%:25%), and the SB stenoses (40, 60, and 80%), resulting in 27 simulations. Fractional flow reserve, defined as the ratio between the mean distal stenosis and mean aortic pressure during maximal hyperemia, was calculated for the DMB and SB (FFRSB) for all simulations. Results: The largest differences in FFRSB comparing the largest and smallest bifurcation angles were 0.02 (in cases with 40% SB stenosis, irrespective of the assumed flow split) and 0.05 (in cases with 60% SB stenosis, flow split 55%:45%). When the SB stenosis was 80%, the difference in FFRSB between the largest and smallest bifurcation angle was 0.33 (flow split 55%:45%). By describing the PSB-QSB relationship using a quadratic curve for cases with 80% SB stenosis, we found that the curve was steeper (i.e. higher flow resistance) when bifurcation angle increases (P=0.451*Q+0.010*Q 2 and P=0.687*Q+0.017*Q 2 for 40° and 70° bifurcation angle, respectively). Our analyses revealed complex hemodynamics in all cases with evident counter-rotating helical flow structures. Larger bifurcation angles resulted in more pronounced helical flow structures (i.e. higher helicity intensity), when 60 or 80% SB stenoses were present. A good correlation (R2=0.80) between the SB pressure drop and helicity intensity was also found. Conclusions: Our analyses showed that, in bifurcation lesions with 60% MB stenosis and 80% SB stenosis, SB pressure drop is higher for larger bifurcation angles suggesting higher flow resistance (i.e. curves describing the PSB-QSB relationship being steeper). When the SB stenosis is mild (40%) or moderate (60%), SB resistance is minimally influenced by the bifurcation angle, with differences not being clinically meaningful. Our findings also highlighted the complex interplay between anatomy, pressure drops, and blood flow helicity in bifurcations

Quantitative assessment of the stent/scaffold strut embedment analysis by optical coherence tomography

The degree of stent/scaffold embedment could be a surrogate parameter of the vessel wall-stent/scaffold interaction and could have biological implications in the vascular response. We have developed a new specific software for the quantitative evaluation of embedment of struts by optical coherence tomography (OCT). In the present study, we described the algorithm of the embedment analysis and its reproducibility. The degree of embedment was evaluated as the ratio of the embedded part versus the whole strut height and subdivided into quartiles. The agreement and the inter- and intra-observer reproducibility were evaluated using the kappa and the interclass correlation coefficient (ICC). A total of 4 pullbacks of OCT images in 4 randomly selected coronary lesions with 3.0 × 18 mm devices [2 lesions with Absorb BVS and 2 lesions with XIENCE (both from Abbott Vascular, Santa Clara, CA, USA)] from Absorb Japan trial were evaluated by two investigators with QCU-CMS software version 4.69 (Leiden University Medical Center, Leiden, The Netherlands). Finally, 1481 polymeric struts in 174 cross-sections and 1415 metallic struts in 161 cross-sections were analyzed. Inter- and intra-observer reproducibility of quantitative measurements of embedment ratio and categorical asses