Differential effects of sevoflurane and propofol on swine cardiac conduction system.

Objective: To compare the effects of sevoflurane and propofol on the porcine cardiac conduction system.

Study Design: A prospective, comparative study of electrophysiological properties of anaesthetics agents in an experimental porcine model.

Animals: A total of 36 hybrid Landrace-Large White pigs.

Effects of angiotensin-neprilysin inhibition compared to angiotensin inhibition on ventricular arrhythmias in reduced ejection fraction patients under continuous remote monitoring of implantable defibrillator devices.

Background: Angiotensin-neprilysin inhibition compared to angiotensin inhibition decreased sudden cardiac death in patients with reduced ejection fraction heart failure (rEFHF). The precise mechanism remains unclear.

Objective: The purpose of this study was to explore the effect of angiotensin-neprilysin inhibition on ventricular arrhythmias compared to angiotensin inhibition in rEFHF patients with an implantable cardioverter-defibrillator (ICD) and remote monitoring.

Treating Refractory Hypertension: Renal Denervation With High-Resolution 3D-Angiography.

A 53-year-old male was referred to our Department for refractory primary hypertension. Despite high doses of 6 anti-hypertensive drugs, ambulatory monitoring of blood pressure (BP) revealed a mean BP of 160/90 mmHg. Under local anaesthesia, renal denervation with radiofrequency was performed supported by high-resolution 3D angiography, which helped confirm the position of the applications in a spiroid fashion.

Relationship between mechanical and electrical remodelling in patients with cardiac resynchronization implanted defibrillators.

Aims: Cardiac resynchronization therapy (CRT) is associated with reverse left ventricular (LV) remodelling. However, the effects of CRT-induced mechanical remodelling on electrical remodelling, and the occurrence of ventricular arrhythmias have not been clearly established. We studied the relationship between mechanical remodelling, electrical remodelling, and the occurrence of appropriate implantable cardioverter-defibrillator (ICD) therapy 1 year after CRT.

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.

Electrophysiological differences between the epicardium and the endocardium of the left atrium.

Background: Electrophysiological properties of the atrial endocardium compared to epicardium are not well understood. The purpose of this study was to compare the electrophysiological properties and vulnerability to arrhythmia induction from these regions.

Methods And Results: Transseptal endocardial and percutaneous epicardial mapping were performed in a porcine model (n = 7).

A simple pacing method to diagnose postero-anterior (clockwise) cavo-tricuspid isthmus block after radiofrequency ablation.

Aims: Bidirectional block of the cavo-tricuspid isthmus (CTI) is a widely accepted endpoint for typical atrial flutter ablation, but its evaluation may be difficult, especially in the postero-anterior (clockwise) direction. The main goal was to evaluate pacing at the septal edge of the ablation line as an indicator of clockwise CTI block and as a predictor for flutter recurrence.

Methods And Results: In 94 patients undergoing flutter ablation, CTI block in the antero-posterior (counterclockwise) direction was determined by differential pacing from several levels of the anterior right atrial (RA).

Atrioventricular conduction and arrhythmias at the initiation of beating in embryonic mouse hearts.

To investigate cardiac physiology at the onset of heart beating in embryonic mouse hearts, we performed optical imaging of membrane potential (Vm) and/or intracellular calcium (Ca(i)). Action potentials and Ca(i) transients were detected in approximately 50% of mouse embryo hearts at E8.5, but in all hearts at E9.

Intrapericardial balloon placement for prevention of collateral injury during catheter ablation of the left atrium in a porcine model.

Background: Catheter ablation of the left atrium (LA) is associated with potential collateral injury to surrounding structures, especially the esophagus and the right phrenic nerve (PN).

Objectives: The purpose of this study was to evaluate the efficacy and feasibility of intrapericardial balloon placement (IPBP) for the protection of collateral structures adjacent to the LA.

Methods: Electroanatomic mapping was performed in porcine hearts using a transseptal endocardial approach in eight swine weighing 40-50 kg.

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.

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.

Muscleblind-like 2 (Mbnl2) -deficient mice as a model for myotonic dystrophy.

Myotonic dystrophy (DM), the most common adult-onset muscular dystrophy, is caused by CTG or CCTG microsatellite repeat expansions. Expanded DM mRNA microsatellite repeats are thought to accumulate in the nucleus, sequester Muscleblind proteins, and interfere with alternative mRNA splicing. Muscleblind2 (Mbnl2) is a member of the family of Muscleblind RNA binding proteins (that also include Mbnl1 and Mbnl3) that are known to bind CTG/CCTG RNA repeats.

Cardiac alternans in embryonic mouse ventricles.

T-wave alternans, an important arrhythmogenic factor, has recently been described in human fetuses. Here we sought to determine whether alternans can be induced in the embryonic mouse hearts, despite its underdeveloped sarcoplasmic reticulum (SR) and, if so, to analyze the response to pharmacological and autonomic interventions. Immunohistochemistry confirmed minimal sarcoplasmic-endoplasmic reticulum Ca-ATPase 2a expression in embryonic mouse hearts at embryonic day (E) 10.

Cardiac resynchronization therapy response is associated with shorter duration of atrial fibrillation.

Background: Atrial fibrillation (AF) is commonly associated with heart failure. The benefit of cardiac resynchronization therapy (CRT) on atrial remodeling has been demonstrated. However, biventricular pacing did not reduce the global incidence of AF.

Left ventricular apical wall motion abnormality is associated with lack of response to cardiac resynchronization therapy in patients with ischemic cardiomyopathy.

Background: Many patients with appropriate indications fail to respond to cardiac resynchronization therapy (CRT).

Objective: The purpose of our study was to determine the relationship between CRT response and preimplantation apical wall motion abnormality.

Methods: We analyzed data from 83 patients with ischemic cardiomyopathy who underwent CRT.

Changes and predictive value of dispersion of repolarization parameters for appropriate therapy in patients with biventricular implantable cardioverter-defibrillators.

Background: The impact of cardiac resynchronization therapy (CRT) on dispersion of repolarization is controversial. The benefit of CRT on sudden cardiac death has been demonstrated only after 3 years follow-up.

Objective: The purpose of this study was to explore the immediate effect of CRT on dispersion of repolarization and to define the value of dispersion of repolarization parameters as predictors of appropriate implantable cardioverter-defibrillator (ICD) therapy.

Functional characterization of atrial electrograms in sinus rhythm delineates sites of parasympathetic innervation in patients with paroxysmal atrial fibrillation.

Objectives: This study sought to characterize left atrial (LA) sinus rhythm electrogram (EGM) patterns and their relationship to parasympathetic responses during atrial fibrillation (AF) ablation.

Background: The mechanistic basis of fractionated LA EGMs in patients with paroxysmal AF is not well understood.

Methods: We analyzed 1,662 LA ablation sites from 30 patients who underwent catheter ablation for paroxysmal AF.

Effects of metabolic inhibition on conduction, Ca transients, and arrhythmia vulnerability in embryonic mouse hearts.

Developing myocardium is more dependent on glycolysis than adult myocardium, yet the effects of selectively inhibiting glycolysis versus oxidative phosphorylation on embryonic heart function have not been well characterized. Accordingly, we investigated how selective metabolic inhibition affects membrane voltage and intracellular Ca (Ca(i)) transients in embryonic mouse hearts, including their susceptibility to arrhythmias. A total of 136 isolated embryonic mouse hearts were exposed to either 1) 2-deoxyglucose (2DG; 10 mM) or iodoacetate (IAA; 0.

Usefulness of preimplantation B-type natriuretic peptide level for predicting response to cardiac resynchronization therapy.

Nearly 1/3 of patients with heart failure (HF) fail to respond to cardiac resynchronization therapy (CRT). The purpose of this study was to evaluate the value of preimplantation brain natriuretic peptide (BNP) in predicting the clinical response to CRT. We retrospectively analyzed 164 patients who underwent CRT.

Incomplete myocardial rupture after coronary embolism of an isolated single coronary artery.

An 82-year-old female was admitted to the coronary care unit with an anterior wall myocardial infarction and cardiogenic shock. She was in chronic atrial fibrillation without oral anticoagulation. Coronary angiography showed occlusion of the left main coronary artery which originated together with a normal right coronary artery from the right sinus of Valsalva.