New formula for defining "normal" and "prolonged" QT in patients with bundle branch block.

OBJECTIVES: To predict the QT interval in the presence of normal QRS for patients with left bundle branch block (LBBB). BACKGROUND: There is no acceptable method for simple and reliable QT correction for patients with bundle branch block (BBB). METHODS: We measured the QT interval in patients with new onset LBBB who had a recent electrocardiogram with narrow QRS for comparison. 48 patients who developed in-hospital LBBB were studied. Patients who had similar heart rate before and after LBBB were included. We used linear regression, the Bogossian method, and our new fixed QRS replacement method to evaluate the most reliable correction method. RESULTS: JTc (QTc-QRS) interval was preserved before and after LBBB (328.9 ±â€¯25.4 ms before LBBB vs. 327.3 ms post LBBB (p = 0.550). Mean predicted preLBBB QTc difference was 1.3 ms, -21.3 ms and 1.6 ms for the three methods respectively (p < 0.001 for Bogossian comparison with the other methods). Coefficients of correlation (R) between actual preLBBB QTc with predicted preLBBB QTc were 0.707, 0.683 and 0.665 respectively (p > 0.3 for R comparisons between all methods). The average absolute difference in preLBBB QTc was 15.5 ms and 16.7 ms for the regression and fixed-gender methods (p value between the two = 0.321) and 25.5 ms for the Bogossian method, which was found to be significantly underperforming. CONCLUSIONS: In patients with LBBB, replacing of the QRS duration after deriving the QTc interval with a fixed value of 88 ms for female and 95 ms for male provides a simple and reliable method for predicting the QTc before the development of LBBB.

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.

Cell therapy for modification of the myocardial electrophysiological substrate.

BACKGROUND: Traditional antiarrhythmic pharmacological therapies are limited by their global cardiac action, low efficacy, and significant proarrhythmic effects. We present a novel approach for the modification of the myocardial electrophysiological substrate using cell grafts genetically engineered to express specific ionic channels. METHODS AND RESULTS: To test the aforementioned concept, we performed ex vivo, in vivo, and computer simulation studies to determine the ability of fibroblasts transfected to express the voltage-sensitive potassium channel Kv1.3 to modify the local myocardial excitable properties. Coculturing of the transfected fibroblasts with neonatal rat ventricular myocyte cultures resulted in a significant reduction (68%) in the spontaneous beating frequency of the cultures compared with baseline values and cocultures seeded with naive fibroblasts. In vivo grafting of the transfected fibroblasts in the rat ventricular myocardium significantly prolonged the local effective refractory period from an initial value of 84+/-8 ms (cycle length, 200 ms) to 154+/-13 ms (P<0.01). Margatoxin partially reversed this effect (effective refractory period, 117+/-8 ms; P<0.01). In contrast, effective refractory period did not change in nontransplanted sites (86+/-7 ms) and was only mildly increased in the animals injected with wild-type fibroblasts (73+/-5 to 88+/-4 ms; P<0.05). Similar effective refractory period prolongation also was found during slower pacing drives (cycle length, 350 to 500 ms) after transplantation of the potassium channels expressing fibroblasts (Kv1.3 and Kir2.1) in pigs. Computer modeling studies confirmed the in vivo results. CONCLUSIONS: Genetically engineered cell grafts, transfected to express potassium channels, can couple with host cardiomyocytes and alter the local myocardial electrophysiological properties by reducing cardiac automaticity and prolonging refractoriness.

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.

Comparison of 30-Day and Long-Term Outcomes and Hospital Complications Among Patients Aged <75 Versus ≥75 Years With ST-Elevation Myocardial Infarction Undergoing Percutaneous Coronary Intervention.

Our aim was to evaluate the mortality rate and occurrence of complications in patients aged <75 versus ≥75 years with ST-elevation myocardial infarction (STEMI). We studied 1,657 consecutive patients with STEMI hospitalized in the cardiac intensive care unit during 2008 to 2014. All patients underwent primary percutaneous intervention, of which 292 (18%) were aged ≥75 years. Patient records were evaluated for in-hospital complications, 30-day mortality, and long-term mortality over a mean period of 3.4 ± 2.1 years. Compared with younger patients, patients aged ≥75 years had a significantly higher rate of coronary disease risk factors, prolonged symptom duration (512 ± 640 vs 333 ± 545 minutes, p <0.01) and door-to-balloon time (51.1 ± 24 vs 45.6 ± 38, p = 0.02). Patients aged ≥75 years had more in-hospital noncardiac and cardiac complications, including cardiogenic shock and arrhythmia, and had higher 30-day and long-term mortalities. Cardiogenic shock was associated with increased short- and long-term mortality in the older group but was not incremental over the noncardiogenic shock cohort. In conclusion, in patients aged ≥75 years who underwent primary percutaneous intervention for STEMI, the short- and long-term mortality rate was greater than fourfold higher compared with younger patients.

Long term prognosis of atrial fibrillation in ST-elevation myocardial infarction patients undergoing percutaneous coronary intervention.

BACKGROUND: Atrial fibrillation (AF) is a well-known complication in the setting of ST elevation myocardial infarction (STEMI). Data on the long-term prognostic implications of New-Onset AF (NOAF) complicating STEMI in the era of complete revascularization remains controversial. Our aim therefore was to evaluate the long-term prognosis of prior AF (pAF) and new-onset AF (NOAF) in STEMI patients undergoing percutaneous coronary intervention (PCI). METHODS: We studied 1657 consecutive STEMI patients hospitalized in the cardiac intensive care unit during 2008-2014. We reviewed patient records for the occurrence of pAF and NOAF. NOAF was defined as AF occurring within 30days of the STEMI episode. Patients were followed for a mean period of 3.4±2.1years. RESULTS: Within our cohort 77 (4.6%) patients had pAF and 47 (2.8%) had NOAF. Patients with any AF were older and had a reduced systolic ejection fraction. Thirty-day mortality and all-cause mortality rates were significantly higher in patients with pAF in comparison to those without AF (9.1% vs. 2.2% p<0.001 and 31.2% vs. 9.4%, p<0.001, respectively). NOAF showed a trend for increased all-cause mortality (17% vs. 9.1%, p=0.07) and 30-days mortality (6.4% vs. 2.1%. p=0.09). In a multivariate regression model, pAF but not NOAF was a predictor of mortality throughout the follow-up period (HR 2.02, 95% CI 1.2 to 3.1, p=0.005 and HR 1.1, 95% CI 0.56 to 2.2, p=0.75, respectively). CONCLUSIONS: Prior AF and not new-onset AF is an independent predictor of both short and long term mortality in patients treated with PCI.

Norton scale for predicting prognosis in elderly patients undergoing trans-catheter aortic valve implantation: A historical prospective study.

BACKGROUND: The Norton scale is traditionally used to assess the risk of pressure ulcers. However, recent studies have shown its prognostic utilization in elderly patients with diverse medical conditions. The association between low admission Norton scale scores (ANSS), complications, and mortality in elderly patients following trans-catheter aortic valve implantation (TAVI) has never been studied. We aimed to determine if low ANSS (≤16) is associated with complications and 30-day and 1-year mortality in elderly patients undergoing TAVI. METHODS: The medical charts of elderly (≥70 years) TAVI patients at the Tel-Aviv Medical Center, a tertiary medical center, were studied for the following measurements: ANSS, demographics, co-morbidities, complications during hospitalization, and 30-day and 1-year mortality. Complications included: an atrio-ventricular block, stroke, and vascular complications. RESULTS: The cohort included 302 elderly patients: 179 (59.3%) were women; the mean age was 83.3±5.1 years. Following TAVI, 112 (37.1%) patients had complications other than pressure ulcers, 10 (3.3%) patients died within 30 days, and 42 (13.9%) patients died within one year. Overall, 36 (11.9%) patients had low ANSS. 1-year mortality rates were almost three times higher in patients with low ANSS relative to patients with high ANSS (27.8% vs. 12.0%; the relative risk 1.1; p=0.018). A stepwise logistic regression analysis showed that ANSS was independently inversely associated with 1-year mortality (p=0.018). Complications and 30-day mortality rates were similar in both groups. CONCLUSIONS: Low ANSS are associated with 1-year mortality after TAVI. The Norton scale may therefore be used as an additional tool for elderly patient selection before TAVI.

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.

Atrial fibrillation, stroke, and mortality rates after transcatheter aortic valve implantation.

Transcatheter aortic valve implantation (TAVI) is considered a suitable treatment for patients with severe symptomatic aortic stenosis and high operative risk. Our aim was to evaluate the effect of preprocedural and new-onset atrial fibrillation (NOAF) on mortality and stroke in patients who underwent TAVI. We performed a single-center study of 380 consecutive patients enrolled to a TAVI registry. NOAF was defined as postprocedural atrial fibrillation (AF) occurring within 30 days after the procedure. Patients were followed up for a mean of 528 ± 364 days. During follow-up, 19 (5%) new episodes of stroke occurred, of whom 6 and 18 cases occurred within 30 days and 1 year, respectively. Overall mortality during the follow-up was 68 (20%), of those 12 and 58 patients died within 30 days and 1 year, respectively. NOAF occurred in 31 (8.2%) patients and was not associated with higher stroke or mortality rates at 30 days or 1 year of follow-up. Notably, compared with patients without previous AF, patients with previous AF at baseline had increased rates of stroke and mortality at 1-year follow-up (2.1% vs 9.6%, p = 0.01, and 8.2% vs 34.9%, p <0.01; respectively). In multivariate analysis, AF at baseline but not NOAF was a significant predictor of mortality throughout the follow-up period (HR 2.2, 95% confidence interval 1.3 to 3.8, p = 0.003, and HR 1.5, 95% confidence interval 0.5 to 4.1, p = 0.390, respectively). In conclusion, previous AF at baseline but not NOAF significantly increases stroke and mortality rates after TAVI. The inclusion of AF into future TAVI risk stratification scores should be strongly considered.

Life-threatening events during endurance sports: is heat stroke more prevalent than arrhythmic death?

BACKGROUND: Two important causes of sudden death during endurance races are arrhythmic death and heat stroke. However, "arrhythmic death" has caught practically all the attention of the medical community whereas the importance of heat stroke is less appreciated. OBJECTIVES: The study sought to determine what percentage of life-threatening events during endurance races are due to heat stroke or cardiac causes. METHODS: This retrospective study examined all the long distance popular races that took place in Tel Aviv from March 2007 to November 2013. The number of athletes at risk was known. The number of athletes developing serious sport-related events and requiring hospitalization was known. Life-threatening events were those requiring mechanical ventilation and hospitalization in intensive care units. RESULTS: Overall, 137,580 runners participated in long distance races during the study period. There were only 2 serious cardiac events (1 myocardial infarction and 1 hypotensive supraventricular tachyarrhythmia), neither of which were fatal or life threatening. In contrast, there were 21 serious cases of heat stroke, including 2 that were fatal and 12 that were life threatening. One of the heat stroke fatalities presented with cardiac arrest without previous warning. CONCLUSIONS: In our cohort of athletes participating in endurance sports, for every serious cardiac adverse event, there were 10 serious events related to heat stroke. One of the heat stroke-related fatalities presented with unheralded cardiac arrest. Our results put in a different perspective the ongoing debate about the role of pre-participation electrocardiographic screening for the prevention of sudden death in athletes.

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.

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.