Predictors of cardiovascular mortality after an electrical storm in patients with structural heart disease.

Background: Electrical storms (ESs) in patients with structural heart disease (SHD) have been reported to be associated with a poor prognosis. However, the detailed cause of death and influence of implantable cardioverter defibrillator (ICD) therapy in ES patients have not been fully investigated. Therefore, we sought to explore the detailed clinical course after an ES and the impact of the ICD therapy in patients with SHDs.

Positioning an ECG electrode to the dorsal side can record higher amplitude of CMAPs during cryoballoon ablation.

Purpose: Phrenic nerve injury (PNI) is one of the important complications during cryoballoon (CB) ablation. Recording diaphragmatic compound motor action potentials (CMAPs) during CB ablation can predict PNI. CMAP monitoring may be inaccurate when CMAP amplitudes are low.

Arrhythmogenic β-adrenergic signaling in cardiac hypertrophy: The role of small-conductance calcium-activated potassium channels via activation of CaMKII.

Sustained ventricular arrhythmias (SVAs) lead to sudden cardiac death, for which β- adrenoreceptor blockers are effective. We hypothesized that electrophysiological changes and arrhythmias by β- adrenoreceptor stimulation are crucially related to activation of small-conductance calcium-activated potassium (SK) channels via the increase in Ca/calmodulin-dependent protein kinase II (CaMKII) activity. We used normotensive Wistar-Kyoto (WKY) rats and spontaneous hypertensive rats (SHRs).

Long-term reliability of the defibrillator lead inserted by the extrathoracic subclavian puncture.

Background: As the transvenous defibrillator lead is fragile and its failure may cause a life-threatening event, reliable insertion techniques are required. While the extrathoracic puncture has been introduced to avoid subclavian crush syndrome, the reports on the long-term defibrillator lead survival using this approach, especially the comparison with the cephalic cutdown (CD), remain scarce. We aimed to evaluate the long-term survival of the transvenous defibrillator lead inserted by the extrathoracic subclavian puncture (ESCP) compared with CD.

Small-conductance Ca-activated K channel activation deteriorates hypoxic ventricular arrhythmias via CaMKII in cardiac hypertrophy.

The molecular and electrophysiological mechanisms of acute ischemic ventricular arrhythmias in hypertrophied hearts are not well known. We hypothesized that small-conductance Ca-activated K (SK) channels are activated during hypoxia via the Ca/calmodulin-dependent protein kinase II (CaMKII)-dependent pathway. We used normotensive Wistar-Kyoto (WKY) rats and spontaneous hypertensive rats (SHRs) as a model of cardiac hypertrophy.

Relation between total shock energy and mortality in patients with implantable cardioverter-defibrillator.

Background: Implantable Cardioverter-Defibrillator (ICD) shocks have been associated with mortality. However, no study has examined the relation between total shock energy and mortality. The aim of this study is to assess the association of total shock energy with mortality, and to determine the patients who are at risk of this association.

Influence of myopotential interference on the Wavelet discrimination algorithm in implantable cardioverter-defibrillator.

Background: Wavelet is a morphology-based algorithm for detecting ventricular tachycardia. The electrogram (EGM) source of the Wavelet algorithm is nominally programmed with the Can-RV coil configuration, which records a far-field ventricular potential. Therefore, it may be influenced by myopotential interference.

Small-conductance Ca2+-activated K+ current is upregulated via the phosphorylation of CaMKII in cardiac hypertrophy from spontaneously hypertensive rats.

Left ventricular hypertrophy is associated with an increased risk of ventricular arrhythmias. However, the underlying molecular basis is poorly understood. It has been reported that small-conductance Ca(2+)-activated K(+) (SK) channels are involved in the pathogenesis of ventricular arrhythmias in heart failure.

Predictors and Proarrhythmic Consequences of Inappropriate Implantable Cardioverter-Defibrillator Therapy.

Background: Despite the benefits of implantable cardioverter-defibrillator (ICD) therapy, inappropriate shocks can lead to multiple adverse effects. The aim of this study was to clarify the predictors of inappropriate ICD shocks and their proarrhythmic consequences.

Methods and results: We retrospectively studied 316 consecutive patients who underwent ICD implantation from December 2000 to December 2011.

Characteristics of idiopathic ventricular tachycardia originating above the pulmonary valve.

Panoptic studies of ventricular tachycardia (VT) originating above the pulmonary valve are scarce. The purpose of this study is to clarify the characteristic of idiopathic VT arising above pulmonary valve. We analyzed 15 consecutive patients with idiopathic VT that was successfully abolished by catheter ablation at the right ventricular outflow tract (RVOT-VT, n = 11) and above the pulmonary valve (PA-VT, n = 4).

Predictors of high defibrillation threshold in patients with implantable cardioverter-defibillator using a transvenous dual-coil lead.

Background: Defibrillation testing (DT) is considered a standard procedure during implantable cardioverter-defibrillator (ICD) implantation. However, little is known about the factors that are significantly related to patients with high defibrillation threshold (DFT) using the present triad system.

Methods And Results: We examined 286 consecutive patients who underwent ICD implantation with a transvenous dual-coil lead and DT from December 2000 to December 2011.

Ca2+/calmodulin-dependent protein kinase II increases the susceptibility to the arrhythmogenic action potential alternans in spontaneously hypertensive rats.

Action potential duration alternans (APD-ALT), defined as long-short-long repetitive pattern of APD, potentially leads to lethal ventricular arrhythmia. However, the mechanisms of APD-ALT in the arrhythmogenesis of cardiac hypertrophy remain undetermined. Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is known to modulate the function of cardiac sarcoplasmic reticulum and play an important role in Ca(2+) cycling.

Suppression of ventricular fibrillation by electrical modification of the Purkinje system in hypertrophic cardiomyopathy.

A 56-year-old man in hypertrophic cardiomyopathy had an electrical storm caused by ventricular fibrillation (VF). Mapping during the initiation of the VF triggered by a premature ventricular contraction (PVC1), with right bundle branch block (RBBB)-like morphology and superior axis, demonstrated a prominent Purkinje-muscle junction (PMJ) delay at the distal portion of the left posterior fascicle. Delivery of radiofrequency (RF) energy to this area abolished the VF triggered by the PVC1.

Involvement of the phosphatidylinositol kinase pathway in augmentation of ATP-sensitive K(+) channel currents by hypo-osmotic stress in rat ventricular myocytes.

The objective of this study was to investigate the mechanisms of increase in the efficacy of ATP-sensitive K(+) channel (KATP) openings by hypo-osmotic stress. The whole-cell KATP currents (IK,ATP) stimulated by 100 μmol/L pinacidil, a K(+) channel opening drug, were significantly augmented during hypo-osmotic stress (189 mOsmol/L) compared with normal conditions (303 mOsmol/L). The EC50 and Emax value for pinacidil-activated IK,ATP (measured at 0 mV) was 154 μmol/L and 844 pA, respectively, in normal solution and 16.

Strain rate dispersion index can predict changes in left ventricular volume and adverse cardiac events following cardiac resynchronization therapy.

Background: We previously reported that the strain rate dispersion index (SRDI), an index of left ventricular (LV) contractility loss because of mechanical dyssynchrony, better predicted the acute response to cardiac resynchronization therapy (CRT) than time-delay indices. However, it remains unclear whether the SRDI can predict the chronic response. Additionally, the SRDI needs to be simplified for use in clinical practice.

Anticoagulation management in the perioperative phase of implantable cardioverter defibrillator implantation.

Background: According to the current guidelines, substitution of warfarin with heparin is recommended as perioperative management in patients with high risk of thromboembolism. Optimal management of oral anticoagulation in patients undergoing implantable cardioverter defibrillator (ICD) implantation, however, remains controversial.

Methods And Results: Bleeding complications among 273 consecutive patients undergoing initial ICD implantation were retrospectively analyzed.

Unique preferential conduction within the isolated septal substrate in a patient with ventricular tachycardia complicated with non-ischemic dilated cardiomyopathy.

We describe the case of a 67-year-old woman with non-ischemic dilated cardiomyopathy who underwent successful radiofrequency catheter ablation for ventricular tachycardia (VT) originated from the isolated ventricular septal substrate. Pacemapping exhibited either left, identical to clinical VT, or right bundle branch block like wide QRS morphology. Time interval from the stimulus to QRS onset (St-QRS) was prolonged at the center of the substrate, while St-QRS at the border was shortened.

Conduction and refractory disorders in the diabetic atrium.

Diabetes mellitus (DM) is an independent risk of atrial fibrillation. However, its arrhythmogenic substrates remain unclear. This study sought to examine the precise propagation and the spatiotemporal dispersion of the action potential (AP) in the diabetic atrium.

Kinetic study on the binding of lectin to mannose residues in a polymer brush.

A disulfide-carrying polymer with many pendent mannose residues (dithiolated poly(2-methacryloyloxyethyl D-mannopyranoside)) was obtained by atom transfer radical polymerization (ATRP) method using 2-(2'-bromoisobutyroyloxy)ethyl disulfide as initiator. The obtained disulfide-carrying glycopolymer (DT-PMEMan) was accumulated as a polymer brush on a colloidal gold-immobilized glass substrate, and the binding processes of a lectin, Concanavalin A (Con A), to mannose residues in the polymer brush were examined using a UV-vis spectrophotometer with the help of a localized surface plasmon resonance. Con A showed a concentration-dependent specific binding to the glycopolymer brush, and the apparent association constant of Con A with mannose residues in the brush was much larger than the association constant for small sugars due to the so-called cluster effect.

Anti-biofouling properties of polymers with a carboxybetaine moiety.

The resistance of random copolymers of BMA and CMB against biofouling was evaluated. The amount of proteins adsorbed onto the CMB copolymers was smaller than that onto other polymers (non-ionic polymers and copolymers of ordinary ionic monomers and BMA) and decreased with an increase in the content of CMB residues. Furthermore, there was a dramatic decrease in the number of cells (platelets and fibroblasts) that adhered to the CMB copolymers compared with that to other polymers.

Binding of Ricinus communis agglutinin to a galactose-carrying polymer brush on a colloidal gold monolayer.

A polymer with many pendent galactose residues was prepared by atom-transfer radical polymerization (ATRP) of galactose-carrying vinyl monomer, 2-lactobionamidoethyl methacrylate (LAMA), with a disulfide-carrying ATRP initiator, 2-(2'-bromoisobutyroyl)ethyl disulfide (DT-Br). The galactose-carrying polymer obtained (DT-PLAMA) was accumulated as a polymer brush via Au-S bond on a colloidal gold monolayer deposited on a cover glass. For comparison, a disulfide which carried one galactose residue at both ends (2-lactobionamidoethyl disulfide, Cys-Lac) was accumulated as a self-assembled monolayer (SAM) on the colloidal gold monolayer, too.

Interaction of wheat germ agglutinin with an N-acetylglucosamine-carrying telomer brush accumulated on a colloidal gold monolayer.

A disulfide-carrying telomer with many pendent N-acetylglucosamine (GlcNAc) residues (Cys-PMHGlcNAc) was obtained by photo-polymerization of 1-(6'-methacryloylaminohexyl)-2-N-acetoamido-2-deoxy d-glucopyranoside) (MHGlcNAc) using a benzyl N,N-diethyldithiocarbamoyl (BDC) derivative that shows abilities of initiation, transfer, and termination (iniferter). The disulfide-carrying telomer was accumulated on a monolayer of colloidal Au on a glass substrate, and the interaction of wheat germ agglutinin (WGA) with GlcNAc residue at the polymer brush-solution interface was examined by using the localized surface plasmon resonance (LSPR) technique. For comparison, an amphiphile carrying many pendent GlcNAc residues was also prepared with MHGlcNAc and a lipophilic radical initiator and was incorporated in a phospholipid liposome to examine interaction of the GlcNAc residue with WGA on the liposome surface using turbidity measurements.

Sensing capabilities of colloidal gold modified with a self-assembled monolayer of a glucose-carrying polymer chain on a glass substrate.

A disulfide-carrying polymer with pendent glucose residues (poly(2-methacryloyloxyethyl D-glucopyranoside)) was obtained by using a benzyl N,N-diethyldithiocarbamoyl derivative which shows the abilities of initiation, chain transfer, and termination (iniferter). The disulfide-carrying polymer was accumulated on a colloidal Au-immobilized glass substrate, and the usefulness of the polymer as a sensing element of concanavalin A (Con A) was examined by using a UV-visible spectrophotometer with the help of surface plasmon resonance. The sensor showed a concentration-dependent specific binding of Con A with a detection limit of 1.