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Ventricular Premature Complexes (ventricular + premature_complex)
Selected AbstractsMechanisms of Ventricular Fibrillation Initiation in MADIT II Patients with Implantable Cardioverter DefibrillatorsPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2008RYAN ANTHONY M.D. Background:The availability of stored intracardiac electrograms from implantable defibrillators (ICDs) has facilitated the study of the mechanisms of ventricular tachyarrhythmia onset. This study aimed to determine the patterns of initiation of ventricular fibrillation (VF) in Multicenter Automatic Defibrillator Implantation Trial (MADIT) II patients along with associated electrocardiogram (ECG) parameters and clinical characteristics. Methods:Examination of stored electrograms enabled us to evaluate the rhythm preceding each episode of VF and to calculate (intracardiac) ECG parameters including QT, QT peak (QTp), coupling interval, and prematurity index. Results:Sixty episodes of VF among 29 patients (mean age 64.4 ± 2.5 years) were identified. A single ventricular premature complex (VPC) initiated 46 (77%) episodes whereas a short-long-short (SLS) sequence accounted for 14 (23%) episodes. Of the 29 patients studied, 23 patients had VF episodes preceded by a VPC only, two patients with SLS only, and four patients with both VPC and SLS-initiated episodes. There were no significant differences between initiation patterns in regards to the measured ECG parameters; a faster heart rate with SLS initiation (mean RR prior to VF of 655 ± 104 ms for SLS and 744 ± 222 ms for VPC) approached significance (P = 0.06). The two patients with SLS only were not on ,-blockers compared to 83% of the VPC patients. Conclusion:Ventricular fibrillation is more commonly initiated by a VPC than by a SLS sequence among the MADIT II population. Current pacing modes designed to prevent bradycardia and pause-dependent arrhythmias are unlikely to decrease the incidence of VPC-initiated episodes of VF. [source] Arrhythmogenesis of T Wave Alternans Associated with Surface QRS Complex Alternans and the Role of Ventricular Prematurity: Observations from a Canine Model of LQT3 SyndromeJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2002MASAOMI CHINUSHI M.D. Intramural TWA and Its Arrhythmogenesis.Introduction: T wave alternans (TWA) is characterized by cycle-to-cycle changes in the QT interval and/or T wave morphology. It is believed to amplify the underlying dispersion of ventricular repolarization. The aim of this study was to examine the mechanisms and arrhythmogenesis of TWA accompanied by QRS complex and/or blood pressure (BP) waveform alternans, using transmural ventricular electrogram recordings in an anthopleurin-A model of long QT syndrome. Methods and Results: The cardiac cycle length was gradually shortened by interruption of vagal stimulation, and TWA was induced in six canine hearts. Transmural unipolar electrograms were recorded with plunge needle electrodes from endocardial (Endo), mid-myocardial (Mid), and epicardial (Epi) sites, along with the surface ECG and BP. The activation-recovery interval (ARI) was measured to estimate local refractoriness. During TWA, ARI alternans was greater at the Mid than the Epi/Endo sites, and it was associated with the development of marked spatial dispersion of ventricular repolarization. As TWA increased, ventricular activation of the cycles associated with shorter QT intervals displayed delayed conduction at the Mid sites as a result of a critically longer ARI of the preceding cycle and longer QT interval, while normal conduction was preserved at the Epi site. Delayed conduction at the Mid sites manifested as surface ECG QRS and BP waveform alternans, and spontaneous ventricular tachyarrhythmias developed in absence of ventricular prematurity. In other instances, in absence of delayed conduction during TWA, ventricular premature complexes infringed on a prominent spatial dispersion of ventricular repolarization of cycles with long QT intervals and initiated ventricular tachyarrhythmia. Conclusion: TWA accompanied by QRS alternans may signal a greater ventricular electrical instability, since it is associated with intramural delayed conduction, which can initiate ventricular tachyarrhythmia without ventricular premature complexes. [source] Myocardial perforation by a stick foreign body in a dogJOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 2 2008Augusta Pelosi DVM, DACVS Abstract Objective: To report a case of myocardial perforation by a stick foreign body in a dog. Case Summary: A 3-year-old castrated male Labrador Retriever was examined because of a puncture wound seen after an unsupervised run in the woods. The wound was suspected to penetrate into the thoracic cavity on the basis of physical exam and radiographs. Uniform ventricular premature complexes (VPCs) and junctional beats were noted on electrocardiogram (ECG). Thoracotomy was performed and a 6-cm wooden stick was seen protruding from the right ventricle through the pericardium toward the sternum. The stick was removed while purse string sutures were tied around the resultant myocardial defect. Follow-up echocardiography revealed intact intracardiac structures. VPCs were treated with lidocaine and resolved completely within 24 hours of presentation. New or Unique Information Provided: Thoracic trauma can result in myocardial injury; penetration into the myocardium represents a life-threatening situation for the emergency clinician. Cardiac injury should be included in the differential diagnoses of penetrating thoracic foreign bodies. [source] Increased Ventricular Ectopic Activity in Relation to C-Reactive Protein, and NT-Pro-Brain Natriuretic Peptide in Subjects With No Apparent Heart DiseasePACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 11 2006AHMAD SAJADIEH M.D. Background: Subjects with frequent ventricular premature complexes (VPC) and no apparent heart disease make a heterogenic group with regard to prognosis. Some biomarkers have recently proved useful in risk stratification in different heart diseases. We examined prognostic impact of NT-Pro-brain natriuretic peptide (NT-Pro BNP), and C-reactive protein (CRP) in relation to frequent VPC in subjects with no apparent heart disease. Methods: Six hundred seventy-eight healthy subjects between 55 and 75 years of age with no history of cardiovascular disease were included in the study. All were tested with fasting laboratory testing and 48-hour ambulatory ECG monitoring. Frequent VPC was defined as VPC ,30/hour. Results: In 56 subjects (8%) with frequent VPC the prognosis was much poorer compared to those without frequent VPC (Hazard ratio and 95% CI: 2.3;1.2,4.4, P = 0.01), after adjustment for conventional risk factors. In subjects with frequent VPC increased levels of CRP (above 2.5 ,g/mL) was the only factor among the tested biomarkers, which was associated with a poor prognosis. Taking subjects without frequent VPC as reference, the hazard ratio and 95% CI for subjects with frequent VPC and increased CRP was 3.6;1.8,7.1, P = 0.0004, and for those with frequent VPC and normal CRP 0.8;0.2,3.5, P = 0.83, after correction for conventional risk factors. Conclusions: Among middle-aged and elderly subjects with no apparent heart disease and frequent VPCs, a CRP value ,2.5 ,g/mL is associated with a significantly higher risk of death and acute myocardial infarction. These subjects deserve primary prevention measures and further work up for structural heart disease. [source] | ||||||||||