THE BIG PICTURE ABOUT 'BIG DATA'.

Physician leaders and their organizations need a strong understanding of the benefits of harvesting and analyzing information about their patients - from cost savings to better individual treatment.

Anisotropic conduction block and reentry in neonatal rat ventricular myocyte monolayers.

Anisotropy can lead to unidirectional conduction block that initiates reentry. We analyzed the mechanisms in patterned anisotropic neonatal rat ventricular myocyte monolayers. Voltage and intracellular Ca (Ca(i)) were optically mapped under the following conditions: extrastimulus (S1S2) testing and/or tetrodotoxin (TTX) to suppress Na current availability; heptanol to reduce gap junction conductance; and incremental rapid pacing.

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.

Electrophysiological consequences of acute regional ischemia/reperfusion in neonatal rat ventricular myocyte monolayers.

Background: Electrophysiological changes promoting arrhythmias during acute regional ischemia/reperfusion are challenging to study in intact cardiac tissue because of complex 3-dimensional myocardial and vascular geometry. We characterized electrophysiological alterations and arrhythmias during regional ischemia/reperfusion in a simpler 2-dimensional geometry of cultured neonatal rat ventricular myocyte monolayers.

Methods And Results: Optical mapping of intracellular Ca (Ca(i)) and voltage was performed with the use of Rhod 2-AM and Rh-237, respectively.

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.

Spatially discordant alternans in cardiomyocyte monolayers.

Repolarization alternans is a harbinger of sudden cardiac death, particularly when it becomes spatially discordant. Alternans, a beat-to-beat alternation in the action potential duration (APD) and intracellular Ca (Cai), can arise from either tissue heterogeneities or dynamic factors. Distinguishing between these mechanisms in normal cardiac tissue is difficult because of inherent complex three-dimensional tissue heterogeneities.

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.

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.

The use of the Doppler pulmonary artery velocity time integral to optimize placement of a ventricular pacing lead in a patient with Ebstein's anomaly.

Ebstein's anomaly is a rare congenital heart defect. Patients with severe symptomatic tricuspid regurgitation requiring surgical correction often have conduction system disease. We present a case of a 14 year-old girl with Ebstein's malformation and bioprosthetic tricuspid valve who required permanent pacing for symptomatic bradycardia.

Pacemaker lead infection secondary to Haemophilus parainfluenzae.

Cardiac device infections are a rare complication of pacing and defibrillator therapy. The number of implanted devices will likely continue to rise with increasing implantation of the cardioverter defibrillator and cardiac resynchronization devices. This report describes a case of an uncommon pathogen for device-associated endocarditis.