Electro-anatomically confirmed sites of origin of ventricular tachycardia and premature ventricular contractions and occurrence of R wave in lead aVR: A proof of concept study.

Background: The R wave in lead aVR, during the wide QRS complex tachycardia, is commonly observed in a ventricular tachycardia (VT) arising from certain locations in the ventricles.

Objectives: This was a retrospective and a proof of concept study to correlate the sites of origin of VT and premature ventricular contractions (PVCs) with the occurrence of R wave in lead aVR.

Methods: Patients with VT or high density of PVCs were included.

Atrial flutter with multilevel atrioventricular block and cyclical occurrence of varying QRS morphologies.

An electrocardiogram showing atrial flutter in which varying ratios of AV conduction and the cyclical recurrence of varying QRS morphologies are observed is presented.

Failure to Treat Life-Threatening Ventricular Tachyarrhythmias in Contemporary Implantable Cardioverter-Defibrillators: Implications for Strategic Programming.

Background: In clinical trials, manufacturer-specific, strategic programming of implantable cardioverter-defibrillators (ICDs), including faster detection rates, reduces unnecessary therapy but permits therapy for ventricular tachycardia/ventricular fibrillation (VF). Present consensus recommends a generic rate threshold between 185 and 200 beats per minute, which exceeds the rate tested in clinical trials for some manufacturers. In a case series, we sought to determine the relationship between programmed parameters and failure of modern ICDs to treat VF.

Linear left atrial lesions in minimally invasive surgical ablation of persistent atrial fibrillation: techniques for assessing conduction block across surgical lesions.

Minimally invasive surgical (MIS) ablation, with pulmonary vein (PV) isolation and ganglionated plexi (GP) ablation, has proven highly successful for paroxysmal atrial fibrillation but has limited success in patients with persistent and long-standing persistent (P-LSP) AF. A set of linear left atrial (LA) lesions has been added to interrupt some macroreentrant components of P-LSP AF. This includes a Transverse Roof Line and Left Fibrous Trigone Line (from Roof Line to mitral annulus at the left fibrous trigone).

Mechanical stress analysis of a rigid inclusion in distensible material: a model of atherosclerotic calcification and plaque vulnerability.

The role of atherosclerotic calcification in plaque rupture remains controversial. In previous analyses using finite element model analysis, circumferential stress was reduced by the inclusion of a calcium deposit in a representative human anatomical configuration. However, a recent report, also using finite element analysis, suggests that microscopic calcium deposits increase plaque stress.

Modulation of the sinus rate during ventricular fibrillation.

Background: During supraventricular and ventricular tachycardia, the arterial baroreflex predominates with minimal contribution from the cardiopulmonary reflex. To our knowledge, the role of the arterial baroreflex gain (BRG) during and immediately following termination of ventricular fibrillation (VF) has not been characterized.

Objective: We hypothesized that (1) arterial BRG correlated with sinus node cycle length (SNCL) changes during VF, and that (2) the greater the arterial BRG, the greater the blood pressure (BP) recovery following successful defibrillation.

Inappropriate ICD shocks for inappropriate reasons.

ICD shocks can result from a variety of etiologies; determining the proper etiology of the inappropriate shock is essential for correction of the problem. Electromagnetic interference (EMI) can mimic cardiac signals and cause inappropriate defibrillator shocks. We present two cases of inappropriate ICD shocks due to EMI and reversal of the proximal and distal DF-1 lead terminals of the ICD lead.

Plasma osteoprotegerin levels in the general population: relation to indices of left ventricular structure and function.

Osteoprotegerin, a member of the tumor necrosis factor receptor superfamily, has pleiotropic effects on bone metabolism, endocrine function, and the immune system. Myocardial expression and circulating levels of osteoprotegerin are increased in heart failure. The relationship between osteoprotegerin levels in the general population and indices of left ventricular structure and function is unknown.

Heart rate turbulence parameters correlate with post-premature ventricular contraction changes in muscle sympathetic activity.

Background: Heart rate turbulence (HRT) has been shown to be vagally mediated with a strong correlation to baroreflex indices. However, the relationship between HRT and peripheral sympathetic nerve activity (SNA) after a premature ventricular contraction (PVC) remains unclear.

Objective: We sought to evaluate the relationship between HRT and the changes in peripheral SNA after PVCs.

Relation of osteoprotegerin to coronary calcium and aortic plaque (from the Dallas Heart Study).

Circulating osteoprotegerin (OPG) has been shown to be elevated in patients with vascular disease. The role of OPG as a biomarker for atherosclerosis in a large, unselected population is not well known. Plasma OPG levels were measured in 3,386 subjects in the Dallas Heart Study, a multiethnic, population-based probability sample of adults aged 30 to 65 years.

A novel technique for right ventricular lead placement in a patient with a persistent left superior vena cava.

Persistent left superior vena cava is the most common venous anomaly of the thorax. If unrecognized, it could lead to catheter malplacement and even vascular injuries. We describe a novel use of a Worley sheath for the delivery of a right ventricular (RV) endocardial pacing lead in a 65-year-old male with a persistent left superior vena cava.

The effects of rate and irregularity on sympathetic nerve activity in human subjects.

Background: We have recently shown that atrial fibrillation is associated with an increase in sympathetic nerve activity (SNA) compared with sinus rhythm. It remains unclear, however, whether these findings are true at various rates and whether the magnitude of sympathoexcitation is related to the degree of irregularity.

Objective: To determine the role of irregularity in mediating the SNA changes at various pacing rates.

The magnitude of sinus cycle length change during ventricular tachycardia is predictive of successful antitachycardia pacing.

Background: Despite the wide use of antitachycardia pacing (ATP) in patients with implantable cardioverter defibrillators (ICDs), predictors of ATP success remain poorly understood. We hypothesize that the degree of sympathoexcitation, as measured by the sinus cycle length (SCL) shortening during ventricular tachycardia (VT), is a predictor of ATP success.

Methods And Results: The charts of 462 patients with dual-chamber ICDs were reviewed.

Klebsiella pneumoniae: a rare cause of device-associated endocarditis.

Intravascular infections involving implanted pacemakers and defibrillators are being seen with increasing frequency. This report describes a case of intravascular infection of an implanted defibrillator with Klebsiella pneumoniae, an unusual pathogen for pacemaker or defibrillator infection.

Case report: Radiofrequency catheter ablation of typical atrial flutter and the atrioventricular junction via the superior vena caval approach in a patient with a congenital absence of an inferior vena cava.

The absence of an inferior vena cava is a rare congenital condition often without clinical significance. Alternative venous approaches are often needed to treat these patients. We report a case of successful ablation of both isthmus dependent flutter and the AV junction using the superior vena cava in a patient with an inferior vena cava anomaly.

Acute coronary syndrome after infliximab infusion.

The TNFalpha inhibitor infliximab is widely used in the treatment of rheumatoid arthritis and Crohn disease. Mild infusion reactions consisting of low-grade fever, headache, nausea, and fatigue are common, but we describe for the first time the occurrence of an acute coronary syndrome during infliximab administration. This case alerts infusion centers to consider the possibility that chest pain and dyspnea during infliximab infusion can represent a myocardial infarction, even in younger patients without a history of cardiac disease.

Regulation of RANKL-induced osteoclastic differentiation by vascular cells.

Vascular calcification is a regulated process of biomineralization resembling osteogenesis. Many bone-related factors, including resorptive osteoclast-like cells, although in low abundance, have been found in calcified atherosclerotic lesions. The regulatory mechanisms governing them in the vasculature, however, are not clear.

Insulin-like growth factor-I regulates proliferation and osteoblastic differentiation of calcifying vascular cells via extracellular signal-regulated protein kinase and phosphatidylinositol 3-kinase pathways.

Vascular calcification develops within atherosclerotic lesions and results from a process similar to osteogenesis. One of the paracrine regulators of bone-derived osteoblasts, insulin-like growth factor-I (IGF-I), is also present in atherosclerotic lesions. To evaluate its possible role in vascular calcification, we assessed its in vitro effects on proliferation and differentiation in calcifying vascular cells (CVCs), a subpopulation of bovine aortic medial cells.

Mesenchymal stem cells and the artery wall.

The presence of ectopic tissue in the diseased artery wall is evidence for the presence of multipotential stem cells in the vasculature. Mesenchymal stem cells were first identified in the marrow stroma, and they differentiate along multiple lineages giving rise to cartilage, bone, fat, muscle, and vascular tissue in vitro and in vivo. Transplantation studies show that marrow-derived mesenchymal stem cells appear to enter the circulation and engraft other tissues, including the artery wall, at sites of injury.