Optical flow ratio for assessing stenting result and physiological significance of residual disease.

BACKGROUND: Optical flow ratio (OFR) is a novel method for fast computation of fractional flow reserve (FFR) from optical coherence tomography (OCT) images. AIMS: We aimed to evaluate the accuracy of OFR in predicting post-percutaneous coronary intervention (PCI) FFR and the impact of stent expansion on within-stent OFR pressure drop (in-stent OFR). METHODS: Post-PCI OFR was computed in patients with both OCT and FFR interrogation immediately after PCI. Calculation of post-PCI OFR (called simulated residual OFR) from pre-PCI OCT pullbacks after elimination of the stenotic segment by virtual stenting was performed in a subgroup of patients who had pre-PCI OCT images. Stent underexpansion was quantified by the minimum expansion index (MEI) of the stented segment. RESULTS: A total of 125 paired comparisons between post-PCI OFR and FFR were obtained in 119 patients, among which simulated residual OFR was obtained in 64 vessels. Mean post-PCI FFR was 0.92±0.05. Post-PCI OFR showed good correlation (r=0.74, p<0.001) and agreement (mean difference=-0.01±0.03, p=0.051) with FFR. The accuracy in predicting post-PCI FFR ≤0.90 was 84% for post-PCI OFR. Simulated residual OFR significantly correlated with post-PCI FFR (r=0.42, p<0.001). MEI showed a moderate correlation (r=-0.49, p<0.001) with in-stent OFR. CONCLUSIONS: Post-PCI OFR showed good diagnostic concordance with post-PCI FFR. Simulated residual OFR significantly correlated with post-PCI FFR. Stent underexpansion significantly correlated with in-stent pressure drop.

How can optical coherence tomography be used to optimize percutaneous coronary intervention?

Optical coherence tomography (OCT) imaging provides high resolution assessment of coronary parietal and endoluminal abnormalities. Clinical evidence and intuitive utilization make this tool relevant for use in daily practice in the catheterization laboratory. In the present review, we summarize the benefits of OCT for the optimization of percutaneous coronary intervention (PCI) in daily practice. First, we focus on the characterization of lesion type with a view to anticipating challenges during PCI. Then, we describe the utility of OCT to identify culprit lesions and ambiguous angiographic findings. Finally, we outline targets for optimization after PCI and the mechanisms underlying stent failure.

Automatic stent reconstruction in optical coherence tomography based on a deep convolutional model.

Intravascular optical coherence tomography (IVOCT) can accurately assess stent apposition and expansion, thus enabling the optimisation of a stenting procedure to minimize the risk of device failure. This paper presents a deep convolutional based model for automatic detection and segmentation of stent struts. The input of pseudo-3D images aggregated the information from adjacent frames to refine the probability of strut detection. In addition, multi-scale shortcut connections were implemented to minimize the loss of spatial resolution and refine the segmentation of strut contours. After training, the model was independently tested in 21,363 cross-sectional images from 170 IVOCT image pullbacks. The proposed model obtained excellent segmentation (0.907 Dice and 0.838 Jaccard) and detection metrics (0.943 precision, 0.940 recall and 0.936 F1-score), significantly better than conventional features-based algorithms. This performance was robust and homogenous among IVOCT pullbacks with different sources of acquisition (clinical centres, imaging operators, type of stent, time of acquisition and challenging scenarios). In addition, excellent agreement between the model and a commercialized software was observed in the quantification of clinically relevant parameters. In conclusion, the deep-convolutional model can accurately detect stent struts in IVOCT images, thus enabling the fully-automatic quantification of stent parameters in an extremely short time. It might facilitate the application of quantitative IVOCT analysis in real-world clinical scenarios.

Optical Coherence Tomography to Optimize Results of Percutaneous Coronary Intervention in Patients with Non-ST-Elevation Acute Coronary Syndrome: Results of the Multicenter, Randomized DOCTORS Study (Does Optical Coherence Tomography Optimize Results of Stenting).

BACKGROUND: No randomized study has investigated the value of optical coherence tomography (OCT) in optimizing the results of percutaneous coronary intervention (PCI) for non-ST-segment elevation acute coronary syndromes. METHODS: We conducted a multicenter, randomized study involving 240 patients with non-ST-segment elevation acute coronary syndromes to compare OCT-guided PCI (use of OCT pre- and post-PCI; OCT-guided group) to fluoroscopy-guided PCI (angiography-guided group). The primary end point was the functional result of PCI assessed by the measure of post PCI fractional flow reserve. Secondary end points included procedural complications and type 4a periprocedural myocardial infarction. Safety was assessed by the rate of acute kidney injury. RESULTS: OCT use led to a change in procedural strategy in 50% of the patients in the OCT-guided group. The primary end point was improved in the OCT-guided group, with a significantly higher fractional flow reserve value (0.94±0.04 versus 0.92±0.05, P=0.005) compared with the angiography-guided group. There was no significant difference in the rate of type 4a myocardial infarction (33% in the OCT-group versus 40% in the angiography-guided group, P=0.28). The rates of procedural complications (5.8%) and acute kidney injury (1.6%) were identical in each group despite longer procedure time and use of more contrast medium in the OCT-guided group. Post-PCI OCT revealed stent underexpansion in 42% of patients, stent malapposition in 32%, incomplete lesion coverage in 20%, and edge dissection in 37.5%. This led to the more frequent use of poststent overdilation in the OCT-guided group versus the angiography-guided group (43% versus 12.5%, P<0.0001) with lower residual stenosis (7.0±4.3% versus 8.7±6.3%, P=0.01). CONCLUSIONS: In patients with non-ST-segment elevation acute coronary syndromes, OCT-guided PCI is associated with higher postprocedure fractional flow reserve than PCI guided by angiography alone. OCT did not increase periprocedural complications, type 4a myocardial infarction, or acute kidney injury. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01743274.

Evaluation of lifting and antiwrinkle effects of calcium hydroxylapatite filler. In vitro quantification of contractile forces of human wrinkle and normal aged fibroblasts treated with calcium hydroxylapatite.

BACKGROUND: As it ages, the skin changes, it loses its natural hydration and its fundamental substance degenerates. Due to a lack of hydration and nutrients, collagen production decreases. This support tissue of the skin weakens, losing tone and firmness. Depressions form on the skin's surface: these are wrinkles. Wrinkles are one of the first visible signs of the skin's aging, and mainly occur on the face. OBJECTIVES: The purpose of the study was firstly to study the differences between contractile forces developed by normal aged fibroblasts (NF) and wrinkle fibroblasts (WF) of the same patients evaluating the loss of skin tone and secondly to evaluate the effects of a filler composed of calcium hydroxylapatite (CaHa) on the development of contractile forces of NF and WF. METHODS: Biopsies were performed on wrinkled and normal aged skin of facelifts of three patients. The forces generated by the both fibroblast lines in tense collagen lattices were quantified using GlaSbox device before and after the addition of a mixture composed of CaHa. RESULTS: The forces developed by WF were significantly lower than those of NF. In the presence of the mixture with CaHa, the contractile forces developed by normal NF were significantly increased. WF treated with CaHa also developed higher contractile forces in comparison with nontreated WF. CONCLUSION: The mixture composed of CaHa tends to restore the contractile properties of WF to the same level as NF. Therefore, this study shows that CaHa has positive overall effects on aging.

Mécano-Stimulation™ of the skin improves sagging score and induces beneficial functional modification of the fibroblasts: clinical, biological, and histological evaluations.

BACKGROUND: Loss of mechanical tension appears to be the major factor underlying decreased collagen synthesis in aged skin. Numerous in vitro studies have shown the impact of mechanical forces on fibroblasts through mechanotransduction, which consists of the conversion of mechanical signals to biochemical responses. Such responses are characterized by the modulation of gene expression coding not only for extracellular matrix components (collagens, elastin, etc.) but also for degradation enzymes (matrix metalloproteinases [MMPs]) and their inhibitors (tissue inhibitors of metalloproteinases [TIMPs]). A new device providing a mechanical stimulation of the cutaneous and subcutaneous tissue has been used in a simple, blinded, controlled, and randomized study. MATERIALS AND METHODS: Thirty subjects (aged between 35 years and 50 years), with clinical signs of skin sagging, were randomly assigned to have a treatment on hemiface. After a total of 24 sessions with Mécano-Stimulation™, biopsies were performed on the treated side and control area for in vitro analysis (dosage of hyaluronic acid, elastin, type I collagen, MMP9; equivalent dermis retraction; GlaSbox(®); n=10) and electron microscopy (n=10). Furthermore, before and after the treatment, clinical evaluations and self-assessment questionnaire were done. RESULTS: In vitro analysis showed increases in hyaluronic acid, elastin, type I collagen, and MMP9 content along with an improvement of the migratory capacity of the fibroblasts on the treated side. Electron microscopy evaluations showed a clear dermal remodeling in relation with the activation of fibroblast activity. A significant improvement of different clinical signs associated with skin aging and the satisfaction of the subjects were observed, correlated with an improvement of the sagging cheek. CONCLUSION: Mécano-Stimulation is a noninvasive and safe technique delivered by flaps microbeats at various frequencies, which can significantly improve the skin trophicity. Results observed with objective measurements, ie, in vitro assessments and electron microscopy, confirm the firming and restructuring effect clinically observed.

A skin substitute based on human amniotic membrane.

Human amniotic membrane (HAM) has biological properties which are useful for wound healing. HAM is notably one of the therapeutic alternatives for venous leg ulcer care. Indeed, a prospective clinical study has demonstrated that cryopreserved HAM transplantation for leg ulcer is feasible, safe and has beneficial effects: 80 % of the patients had a significant clinical response. Nevertheless, at the end of the 3-month follow-up period, only 20 % of the ulcers were totally closed. The aim of this work was to create and characterize a model of epidermized HAM. The method of HAM desepithelialization was validated by histology, immunohistochemistry and scanning electron microscopy. Then, de-epithelialized HAM was seeded with primary keratinocytes. After 21 days of culture, 15 at the air-liquid interface, the model obtained was analyzed histologically and by immunohistochemistry. The amniotic basement membrane was preserved during enzymatic desepithelialization of HAM. Primary keratinocytes proliferated on HAM: the model obtained showed involucrin expression and had a good basement membrane. As re-epithelialization is an important step for ulcer closure, a model of epidermized HAM could be used to speed up the healing of such wounds.

Development and characterization of a human dermal equivalent with physiological mechanical properties.

BACKGROUND/AIMS: Different models of reconstructed skin are available, either to provide skin wound healing when this process is deficient, or to be used as an in vitro model. Nevertheless, few studies have focused on the mechanical properties of skin equivalent. Indeed, human skin is naturally under tension. Taking into account these features, the purpose of this work was to obtain a cellularized dermal equivalent (CDE), composed of collagen and dermal fibroblasts. METHODS: To counteract the natural retraction of CDE and to maintain it under tension, different biomaterials were tested. Selection criteria were biocompatibility, bioadhesion properties, ability to induce differentiation of fibroblasts into myofibroblasts and mechanical characterization, considering that of skin in vivo. These assays led to the selection of honeycomb of polyester. CDE constructed on this biomaterial was further characterized mechanically using tensile tests. RESULTS: The results showed that mechanical features of the obtained dermal equivalent, including myofibroblasts, were similar to skin in vivo. CONCLUSION: The original model of dermal equivalent presented herein may be a useful tool for clinical use and as an in vitro model for toxicological/pharmacological research.