Diagnosis and Management of Complex Reentrant Arrhythmias Involving the His-Purkinje System.

The His-Purkinje system is a network of bundles and fibres comprised of specialised cells that allow for coordinated, synchronous activation of the ventricles. Although the histology and physiology of the His-Purkinje system have been studied for more than a century, its role in ventricular arrhythmias has recently been discovered with the ongoing elucidation of the mechanisms leading to both benign and life-threatening arrhythmias. Studies of Purkinje-cell electrophysiology show multiple mechanisms responsible for ventricular arrhythmias, including enhanced automaticity, triggered activity and reentry.

Cellular Physiology and Clinical Manifestations of Fascicular Arrhythmias in Normal Hearts.

Fascicular ventricular arrhythmias represent a spectrum of ventricular tachycardias dependent on the specialized conduction system. Although they are more common in structurally abnormal hearts, there is an increasing body of literature describing their role in normal hearts. In this review, the authors present data from both basic and clinical research that explore the current understanding of idiopathic fascicular ventricular arrhythmias.

Bidirectional Ventricular Tachycardia Due to a Mixture of Focal Fascicular Firing and Reentry.

Bidirectional ventricular tachycardia (BDVT) is a well-known phenomenon since it was first described in 1922. Various mechanisms have been proposed for BDVT, including digitalis toxicity, hypokalemia, Anderson-Tawil syndrome, acute myocarditis, and catecholaminergic polymorphic ventricular tachycardia. It is characterized by rapid, wide complex electrocardiogram pattern with alternating QRS morphology and axis.

Spectrum of Fascicular Arrhythmias.

Fascicular arrhythmias encompass a wide spectrum of ventricular arrhythmias that depend on the specialized conduction system of the right and left ventricles. These arrhythmias include premature ventricular complexes, monomorphic ventricular tachycardia, polymorphic ventricular tachycardia, and ventricular fibrillation. These arrhythmias may be organized by mechanism, including intrafascicular reentry, interfascicular reentry, and focal.

Measured Lead Parameters and Electrogram Sensing Over Time in Patients With Cardiac Sarcoidosis and an Implanted Cardiac-Defibrillator.

Objectives: The study sought to characterize the performance of implanted leads among a cohort of patients with cardiac sarcoidosis (CS) and implantable cardiac-defibrillators (ICDs).

Background: An ICD is indicated for some patients with CS for the prevention of sudden cardiac death. CS can lead to myocardial inflammation and scar that may interfere with lead performance.

Effect of catheter movement and contact during application of radiofrequency energy on ablation lesion characteristics.

Background: The efficient delivery of radiofrequency (RF) energy through an endocardial ablation catheter is affected by variable tissue contact due to cardiac motion with myocardial contraction and respiration. In addition, many operators intentionally move an ablation catheter during the delivery of radiofrequency energy when targeting specific arrhythmias that require lines of conduction block such as atrial flutter and atrial fibrillation. We sought to characterize and quantify any effects of catheter movement and intermittent ablation catheter contact on lesion characteristics.

Diagnosis and ablation of multiform fascicular tachycardia.

Introduction: Fascicular tachycardia (FT) is an uncommon cause of monomorphic sustained ventricular tachycardia (VT). We describe 6 cases of FT with multiform QRS morphologies.

Methods And Results: Six of 823 consecutive VT cases were retrospectively analyzed and found attributable to FT with multiform QRS patterns, with 3 cases exhibiting narrow QRS VT as well.

Long-term electrical survival analysis of Riata and Riata ST silicone leads: National Veterans Affairs experience.

Background: A medical device advisory issued by St Jude Medical in November 2011 estimated 0.63% all-cause abrasion rate on their Riata and Riata ST silicone high-voltage lead families (Riata/ST), leading to Food and Drug Administration class I recall. We performed an independent comparative, long-term electrical survival analysis of Riata/ST and 3 other high-voltage lead families in a large national cohort of patients.

QTc prolongation and family history of sudden death in a patient with desmin cardiomyopathy.

This case report describes a pregnant female patient who presented with new-onset congestive heart failure symptoms and prolonged QTc, with strong family history of sudden death. Endomyocardial biopsy and genetic testing revealed myocardial desmin accumulation and a previously described mutation in the DES (desmin) gene, as well as variants in two LQT genes, SCN5A and KCNH2. The case highlights the phenotypic variability for a particular desmin genotype, and the possible interaction of desminopathy with LQT variants not independently associated with large differences in current properties or QT prolongation from wild type.

The role of selection in the evolution of human mitochondrial genomes.

High mutation rate in mammalian mitochondrial DNA generates a highly divergent pool of alleles even within species that have dispersed and expanded in size recently. Phylogenetic analysis of 277 human mitochondrial genomes revealed a significant (P < 0.01) excess of rRNA and nonsynonymous base substitutions among hotspots of recurrent mutation.

PRR5 encodes a conserved proline-rich protein predominant in kidney: analysis of genomic organization, expression, and mutation status in breast and colorectal carcinomas.

Loss of heterozygosity on chromosome 22q13.31 is a frequent event during human breast and colorectal carcinogenesis. Herein we characterize a novel gene at chromosome 22q13.

Beta-parvin inhibits integrin-linked kinase signaling and is downregulated in breast cancer.

We analysed breast tumors and breast cancer cell lines for the expression of beta-parvin (ParvB), an adaptor protein that binds to the integrin-linked kinase (ILK). Quantitative RT-PCR indicated that ParvB mRNA was downregulated, by at least 60%, in four of nine breast tumors, relative to patient-matched normal mammary gland tissue. We also found that ParvB protein levels were reduced by > or =90% in five of seven advanced tumors, relative to matched normal breast tissue.

ARHGAP8 is a novel member of the RHOGAP family related to ARHGAP1/CDC42GAP/p50RHOGAP: mutation and expression analyses in colorectal and breast cancers.

The RHO family of small GTPases has multiple functions, including regulation of cytoskeletal organization, cell cycle progression and cell migration, among others. The key members of this family are RHO, RAC and CDC42. Active GTP-bound RHO proteins are down-regulated by RHO GTPase-activating proteins (RHOGAPs).

Conservation of the class I beta-tubulin gene in human populations and lack of mutations in lung cancers and paclitaxel-resistant ovarian cancers.

The goal of this study was to determine the prevalence of sequence variants in the class I beta-tubulin (clone m40) gene and their occurrence in human tumors and cancer cell lines. DNA was isolated from 93 control individuals representing a wide variety of ethnicities, 49 paclitaxel-naive specimens (16 ovarian cancers, 17 non-small cell lung cancers, and 16 ovarian cancer cell lines), and 30 paclitaxel-resistant specimens (9 ovarian cancers, 9 ovarian cancer cell lines, and 12 ovarian cancer xenografts in nude mice). Denaturing high-performance liquid chromatography and direct sequence analysis detected two silent polymorphisms in exon 4, Leu217Leu (CTG/CTA) and Gly400Gly (GGC/GGT), with minor allele frequencies of 17 and 0.

Population genetic implications from DNA polymorphism in random human genomic sequences.

Denaturing high performance liquid chromatography (DHPLC) in combination with dye-terminator sequencing was used to survey 516 random genomic sequence tagged sites (STSs) for biallelic polymorphisms in 24 representatives of the major ethnic groups residing in the United States. Of the 301 polymorphic STSs (58.3%), 172 contained a single simple sequence polymorphism (SSP), while 78, 35, and 16 contained 2, 3, and 4-6 SSPs, respectively.