Voltage/Calcium Uncoupling Underlies Sustained Torsade de Pointes Ventricular Tachyarrhythmia in an Experimental Model of Long QT Syndrome.

Background: Clinical experience showed that the majority of Torsade de Pointes (TdP) ventricular tachyarrhythmia (VT) in patients with long QT syndrome (LQTS) are self-terminating (ST), but the few that are non-self-terminating (NST) are potentially fatal. A paramount issue in clinical arrhythmology is to understand the electrophysiological mechanism of ST vs. NST TdP VT.

Role of spatial dispersion of repolarization in reentry around a functional core versus reentry around a fixed anatomical core.

Introduction: Successful initiation of spiral wave reentry in the neonatal rat ventricular myocyte (NRVM) monolayer implicitly assumes the presence of spatial dispersion of repolarization (DR), which is difficult to quantify. We recently introduced a NRVM monolayer that utilizes anthopleurin-A to impart a prolonged plateau to the NRVM action potential. This was associated with a significant degree of spatial DR that lends itself to accurate quantification.

Healing of chronic sickle cell disease-associated foot and ankle wounds using transdermal continuous oxygen therapy.

Objective: Sickle cell disease (SCD) is a complex cause of capillary stasis that can lead to lower extremity venous ulcers. Since SCD is characterised by impaired oxygen delivery that can be exacerbated by lower extremity venous stasis, we sought to determine if direct delivery of oxygen to a lower extremity ulcer associated with SCD could augment healing.

Method: We performed a pilot study of a portable device that delivers oxygen directly to the wound site to assess this possibility.

Magnetic Resonance Imaging in Proximal Venous Outflow Obstruction.

Background: Proximal venous outflow obstruction (PVOO) in the abdomen and pelvis is increasingly recognized as an important contributor to venous disease of the lower extremity. There are currently no guidelines regarding a noninvasive screening tool for PVOO, although magnetic resonance venography (MRV) is commonly used in many practices. The objective of this study was to determine the value and utility of MRV in diagnosis and screening for PVOO.

Robust T-tubulation and maturation of cardiomyocytes using tissue-engineered epicardial mimetics.

Complex three-dimensional (3-D) heart structure is an important determinant of cardiac electrical and mechanical function. In this study, we set to develop a versatile tissue-engineered system that can promote important aspects of cardiac functional maturation and reproduce variations in myofiber directions present in native ventricular epicardium. We cultured neonatal rat cardiomyocytes within a 3-D hydrogel environment using microfabricated elastomeric molds with hexagonal posts.

Electrotonic suppression of early afterdepolarizations in the neonatal rat ventricular myocyte monolayer.

Pathologies that result in early afterdepolarizations (EADs) are a known trigger for tachyarrhythmias, but the conditions that cause surrounding tissue to conduct or suppress EADs are poorly understood. Here we introduce a cell culture model of EAD propagation consisting of monolayers of cultured neonatal rat ventricular myocytes treated with anthopleurin-A (AP-A). AP-A-treated monolayers display a cycle length dependent prolongation of action potential duration (245 ms untreated, vs.

Optical imaging of arrhythmias in the cardiomyocyte monolayer.

In recent years, cultured cardiac cell monolayers have become a contemporary experimental preparation for the study of fundamental mechanisms that underlie normal and pathologic electrophysiology at the tissue level. Ion channels and gap junctions in the cardiomyocyte monolayer may be modulated using drugs that suppress or enhance certain channels/junctions, or by genetic silencing or overexpression. The cardiomyocyte monolayer is particularly well suited for studies of functional electrophysiologic properties of mixtures of cardiac and noncardiac cells (eg, myofibroblasts), which otherwise would be difficult to investigate.

Single-detector simultaneous optical mapping of V(m) and [Ca(2+)](i) in cardiac monolayers.

Simultaneous mapping of transmembrane voltage (V(m)) and intracellular Ca(2+) concentration (Ca(i)) has been used for studies of normal and abnormal impulse propagation in cardiac tissues. Existing dual mapping systems typically utilize one excitation and two emission bandwidths, requiring two photodetectors with precise pixel registration. In this study we describe a novel, single-detector mapping system that utilizes two excitation and one emission band for the simultaneous recording of action potentials and calcium transients in monolayers of neonatal rat cardiomyocytes.

Early voltage/calcium uncoupling predestinates the duration of ventricular tachyarrhythmias during ischemia/reperfusion.

Background: Abnormal intracellular calcium (Ca(i)) kinetics during ischemia/reperfusion (I/R) can alter membrane voltage (V(m)) and destabilize wavefront propagation.

Objective: We used optical mapping to investigate the hypothesis that early V(m)/Ca(i) uncoupling during a ventricular tachyarrhythmia (VT) can play a primary role in perpetuation of VT episodes.

Methods: Seventeen Langendorff-perfused guinea pig hearts were subjected to 15 min I/15 min R.

Role of pharmacotherapy in cardiac ion channelopathies.

In the last decade there have been considerable advances in the understanding of the pathophysiology of malignant ventricular tachyarrhythmias (VA) and Sudden Cardiac Death (SCD). Over 80% of SCD occurs in patients with organic heart disease. However, approximately 10-15% of SCD occurs in the presence of structurally normal heart and the majority of those patients are young.

Role of subendocardial Purkinje network in triggering torsade de pointes arrhythmia in experimental long QT syndrome.

Aims: The present study addresses the controversy regarding the 'primary' role of the subendocardial Purkinje network in triggering torsade de pointes (TdP) ventricular tachyarrhythmia (VAs) in the long QT syndrome (LQTS).

Methods And Results: We investigated the well-established canine anthopleurin-A (AP-A) surrogate model of LQT3 to study the role of the subendocardial Purkinje network in triggering VAs. Three-dimensional activation and repolarization patterns were analysed from unipolar extracellular electrograms utilizing 64 plunge needle electrodes.

Comparison of optical and electrical mapping of fibrillation.

Optical recordings with transmembrane potential (Vm)-sensitive fluorescent dye, or extracellular potential (Ve) recordings are used to map spatiotemporal patterns of cardiac excitation during ventricular fibrillation (VF). While the optical and electrical methods are accepted, there has not been a test of whether they yield equivalent excitation times during VF. Times may differ since previous results indicate optical Vm interrogates deeper than Ve.

Translesion stimulus-excitation delay indicates quality of linear lesions produced by radiofrequency ablation in rabbit hearts.

Failure of cardiac antiarrhythmic ablation to block action potential conduction produces poor outcomes which lead to repeat procedures. To overcome this, an intraoperative index of the quality of an ablation lesion is needed. We hypothesized that a rise in the translesion stimulus-excitation delay (TED) can indicate a continuous, transmural, linear lesion, and that the TED is related to the path length in the viable tissue around the lesion.

Imaging of cardiac movement using ratiometric and nonratiometric optical mapping: effects of ischemia and 2, 3-butaneodione monoxime.

Transmembrane voltage-sensitive fluorescent dyes are used to study electrical activity in hearts. Green and red fluorescence emissions from di-4-ANEPPS excited with 488 nm light indicate both transmembrane voltage changes and heart movement. We have previously shown that the ratio, green fluorescence divided by red fluorescence, indicates the transmembrane voltage without effects of movement.

Hyperbaric oxygen therapy for sudden sensorineural hearing loss: a prospective trial of patients failing steroid and antiviral treatment.

Objective: To investigate the safety and efficacy of hyperbaric oxygen therapy (HBOT) in adult patients with sudden sensorineural hearing loss (SSNHL) who fail standard of care steroid and antiviral therapy.

Study Design: Prospective cohort study.

Setting: An urban tertiary referral center.

Major burn injuries among restaurant workers in New York City: an underappreciated public health hazard.

Major burns among food service workers appears to be an underappreciated source of morbidity and public expense in New York City. A retrospective study was conducted to identify workers requiring hospital admission over the past 3 years. Seventy-six restaurant workers (3.

Vascular trauma induces rapid but transient mobilization of VEGFR2(+)AC133(+) endothelial precursor cells.

Bone marrow (BM)-derived circulating endothelial precursor cells (CEPs) are thought to play a role in postnatal angiogenesis. Emerging evidence suggests that angiogenic stress of vascular trauma may induce mobilization of CEPs to the peripheral circulation. In this regard, we studied the kinetics of CEP mobilization in two groups of patients who experienced acute vascular insult secondary to burns or coronary artery bypass grafting (CABG).

Gait variables of patients after lower extremity burn injuries.

Functional ambulation is an expected outcome of physical therapy after burn injuries on the lower extremities. The purpose of this study was to document temporal and spatial gait parameters of adult patients with the use of the GAITRite system (CIR Systems Inc, Clifton, NJ) after the patients were burned on their lower extremities and to compare these results with previous data reported for normal subjects. Twenty-five adults with lower extremity burns (19 men and 6 women; mean age, 35.

Pilot study of a unique film dressing for the treatment of donor site wounds.

The clinical benefits of using the VENTEX Wound Dressing System (VWDS) (The Kendall Co.) in the management of donor site wounds were evaluated in this pilot study involving 10 informed and consenting patients. The study was a prospective, randomized, controlled study in which one donor site wound was managed with VWDS, and the other donor site wound on the same patient was managed by our standard of care, which involved the use of Xeroform gauze (The Kendall Co.

A multicenter clinical trial of a biosynthetic skin replacement, Dermagraft-TC, compared with cryopreserved human cadaver skin for temporary coverage of excised burn wounds.

This multicenter study compared the use of a biosynthetic human skin substitute with frozen human cadaver allograft for the temporary closure of excised burn wounds. Dermagraft-TC (Advanced Tissue Sciences, Inc.) (DG-TC) consists of a synthetic material onto which human neonatal fibroblasts are cultured.

Chondritis of the ear: a late sequela of deep partial thickness burns of the face.

Chondritis of the ear is a late sequela of deep partial thickness burns of the face. It is the purpose of this article to describe two patients who came to the emergency department 21 days and 35 days after sustaining deep partial thickness burns of the face from explosions. The patients were hospitalized for incision and drainage of the infected wound that included excision of the infected cartilage complemented by systemic antibiotic therapy.

Frostbite of the face after recreational misuse of nitrous oxide.

Exposure of the skin to nitrous oxide, a liquified gas stored under pressure in a cylinder, can occur in anaesthesiologists and in those involved in recreational misuse of the gas. A case is reported of a man who presented to the emergency department after sniffing nitrous oxide and sustaining frostbite injury to his left cheek. Conservative management of this injury allowed spontaneous separation of the necrotic tissue and healing of the granulating wound by contraction.