Outcomes of Transfemoral Transcatheter Aortic Valve Implantation in Patients With Previous Coronary Bypass.

Patients with previous coronary artery bypass grafting (CABG) are considered to be at increased perioperative risk for a redo cardiac operation. In the era of transcatheter aortic valve implantation (TAVI), these patients constitute a considerable portion of those with severe aortic stenosis referred for TAVI. We evaluated the impact of previous CABG on transfemoral TAVI outcomes. Patients with severe symptomatic aortic stenosis (n = 515) who underwent transfemoral TAVI were divided according to the presence of history of CABG. Patients with previous valvular surgery were excluded (n = 12). TAVI clinical end points and adverse events were considered according to the Valve Academic Research Consortium 2 definitions. Survival was estimated using Cox regression models at the enter mode with the dependent variable defined as all-cause mortality. Of the total 503 patients who underwent TAVI, 91 (18.1%) had previous CABG. At baseline, patients with previous CABG were younger (80.8 vs 83.1 years, p <0.001), mostly men (85% vs 35%, p <0.001), had more cardiac and vascular co-morbidities, higher mean logistic EuroSCORE (32.8 vs 22; p <0.001), lower ejection fraction (53% vs 56%, p <0.001), and lower AV gradients and larger valve area. At a mean follow-up of 636 days, the overall Valve Academic Research Consortium 2-adjudicated end points did not differ. No differences in mortality were observed at 30 days, 6 months, and 1 year after TAVI (hazard ratio 1.34, p = 0.55, Cox regression). We conclude that patients with previous CABG who underwent TAVI do not have increased risk of periprocedural complications or mortality, although having distinct clinical features compared with the total TAVI population.

Interspecies differences in reaction to a biodegradable subcutaneous tissue filler: severe inflammatory granulomatous reaction in the Sinclair minipig.

Soft tissue filler products have become very popular in recent years, with ever-increasing medical and aesthetic indications. While generally considered safe, the number of reported complications with tissue fillers is growing. Nevertheless, there is no specific animal model that is considered as the gold standard for assessing safety or efficacy of tissue fillers, and there are very little data on interspecies differences in reaction to these products. Here, we report on interspecies differences in reaction to a subcutaneous injectable co-polyester, composed of castor oil and citric acid. Comparison of the histopathological local tissue changes following 1-month postimplantation, indicated that in rats the reaction consisted of cavities, surrounded by relatively thin fibrotic enveloping capsule. In contrast, an unexpected severe inflammatory granulomatous reaction was noticed in Sinclair minipigs. To our knowledge, this is the first report on significant interspecies differences in sensitivity to tissue fillers. It emphasizes the importance of using the appropriate animal model for performing preclinical biocompatibility assays for biodegradable polymers, tissue fillers, and implanted medical devices in general. It also makes the Sinclair minipig subject for scrutiny as an animal model in future biocompatibility studies.

In vivo assessment of the electrophysiological integration and arrhythmogenic risk of myocardial cell transplantation strategies.

Cell replacement strategies are promising interventions aiming to improve myocardial performance. Yet, the electrophysiological impact of these approaches has not been elucidated. We assessed the electrophysiological consequences of grafting of two candidate cell types, that is, skeletal myoblasts and human embryonic stem cell-derived cardiomyocytes (hESC-CMs). The fluorescently labeled (DiO) candidate cells were grafted into the rat's left ventricular myocardium. Two weeks later, optical mapping was performed using the Langendorff-perfused rat heart preparation. Images were obtained with appropriate filters to delineate the heart's anatomy, to identify the DiO-labeled cells, and to associate this information with the voltage-mapping data (using the voltage-sensitive dye PGH-I). Histological examination revealed the lack of gap junctions between grafted skeletal myotubes and host cardiomyocytes. In contrast, positive Cx43 immunostaining was observed between donor and host cardiomyocytes in the hESC-CMs-transplanted hearts. Optical mapping demonstrated either normal conduction (four of six) or minimal conduction slowing (two of six) at the hESC-CMs engraftment sites. In contrast, marked slowing of conduction or conduction block was seen (seven of eight) at the myoblast transplantation sites. Ventricular arrhythmias could not be induced in the hESC-CM hearts following programmed electrical stimulation but were inducible in 50% of the myoblast-engrafted hearts. In summary, a unique method for assessment of the electrophysiological impact of myocardial cell therapy is presented. Our results demonstrate the ability of hESC-CMs to functionally integrate with host tissue. In contrast, transplantation of cells that do not form gap junctions (skeletal myoblats) led to localized conduction disturbances and to the generation of a proarrhythmogenic substrate.

Silicone-based scar therapy: a review of the literature.

Hypertrophic and keloid scars still are among the banes of plastic surgery. In the treatment arsenal at the disposal of the plastic surgeon, topical silicone therapy usually is considered the first line of treatment or as an adjuvant to other treatment methods. Yet, knowledge concerning its mechanisms of action, clinical efficacy, and possible adverse effects is rather obscure and sometimes conflicting. This review briefly summarizes the existing literature regarding the silicone elastomer's mechanism of action on scars, the clinical trials regarding its efficacy, a description of some controversial points and contradicting evidence, and possible adverse effects of this treatment method. Topical silicone therapy probably will continue to be the preferred first-line treatment for hypertrophic scars due to its availability, price, ease of application, lack of serious adverse effects, and relative efficacy. Hopefully, future randomized clinical trials will help to clarify its exact clinical efficacy and appropriate treatment protocols to optimize treatment results.

Transplantation of human embryonic stem cell-derived cardiomyocytes improves myocardial performance in infarcted rat hearts.

OBJECTIVES: We evaluated the ability of human embryonic stem cells (hESCs) and their cardiomyocyte derivatives (hESC-CMs) to engraft and improve myocardial performance in the rat chronic infarction model. BACKGROUND: Cell therapy is emerging as a novel therapy for myocardial repair but is hampered by the lack of sources for human cardiomyocytes. METHODS: Immunosuppressed healthy and infarcted (7 to 10 days after coronary ligation) rat hearts were randomized to injection of undifferentiated hESCs, hESC-CMs, noncardiomyocyte hESC derivatives, or saline. Detailed histological analysis and sequential echocardiography were used to determine the structural and functional consequences of cell grafting. RESULTS: Transplantation of undifferentiated hESCs resulted in the formation of teratoma-like structures. This phenomenon was prevented by grafting of ex vivo pre-differentiated hESC-CMs. The grafted cardiomyocytes survived, proliferated, matured, aligned, and formed gap junctions with host cardiac tissue. Functionally, animals injected with saline or nonmyocyte hESC derivatives demonstrated significant left ventricular (LV) dilatation and functional deterioration, whereas grafting of hESC-CMs attenuated this remodeling process. Hence, post-injury baseline fractional shortening deteriorated by 50% (from 20 +/- 2% to 10 +/- 2%) and by 30% (20 +/- 2% to 14 +/- 2%) in the saline and nonmyocyte groups while improving by 22% (21 +/- 2% to 25 +/- 3%) in the hESC-CM group. Similarly, wall motion score index and LV diastolic dimensions were significantly lower in the hESC-CM animals. CONCLUSIONS: Transplantation of hESC-CMs after extensive myocardial infarction in rats results in the formation of stable cardiomyocyte grafts, attenuation of the remodeling process, and functional benefit. These findings highlight the potential of hESCs for myocardial cell therapy strategies.

Identification and selection of cardiomyocytes during human embryonic stem cell differentiation.

Human embryonic stem cells (hESC) are pluripotent lines that can differentiate in vitro into cell derivatives of all three germ layers, including cardiomyocytes. Successful application of these unique cells in the areas of cardiovascular research and regenerative medicine has been hampered by difficulties in identifying and selecting specific cardiac progenitor cells from the mixed population of differentiating cells. We report the generation of stable transgenic hESC lines, using lentiviral vectors, and single-cell clones that express a reporter gene (eGFP) under the transcriptional control of a cardiac-specific promoter (the human myosin light chain-2V promoter). Our results demonstrate the appearance of eGFP-expressing cells during the differentiation of the hESC as embryoid bodies (EBs) that can be identified and sorted using FACS (purity>95%, viability>85%). The eGFP-expressing cells were stained positively for cardiac-specific proteins (>93%), expressed cardiac-specific genes, displayed cardiac-specific action-potentials, and could form stable myocardial cell grafts following in vivo cell transplantation. The generation of these transgenic hESC lines may be used to identify and study early cardiac precursors for developmental studies, to robustly quantify the extent of cardiomyocyte differentiation, to label the cells for in vivo grafting, and to allow derivation of purified cell populations of cardiomyocytes for future myocardial cell therapy strategies.

From gene therapy and stem cells to clinical electrophysiology.

Gene therapy, cell therapy, and tissue engineering are emerging as novel experimental therapeutic paradigms for a variety of cardiovascular disorders. In the current report we will review the possible implications of these emerging technologies in the field of cardiac electrophysiology. Initially, the possible role of myocardial gene and cell therapies in creating a biological alternative to electronic pacemakers for the treatment of bradyarrhythmias will be discussed. This will be followed by a description of the possible applications of using similar strategies for the treatment of common tachyarrhythmias. Finally, the electrophysiological implications of cardiac stem cell therapy for heart failure, as well as the possible in vitro applications of stem cell technology for electrophysiological studies and drug screening, will be discussed. While these emerging strategies provide a paradigm shift from conventional treatment modalities, this field is still at its infancy and several obstacles, discussed in this review, should be overcome before any clinical breakthroughs can be expected.