Search Results
Results 301 - 350 of 2022
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Herman Dalibor - - 2007
This research is aimed to the determination of the changes in the cardiac energetic output for three different modes of cardiac rhythm pacing. The clinical investigation of thirteen patients with the permanent dual-chamber pacemaker implantation was carried out. The patients were taken to echocardiography examination conducted by way of three ...
Kilic Harun - - 2008
BACKGROUND: Twelve-lead electrocardiography (ECG) is the most important source for the early diagnosis of an acute myocardial ischemia. However, its diagnostic value when the sequence of ventricular activation is altered by ventricular pacing is unknown. The aim of the study was to evaluate the ECG changes on the paced ECG ...
Colombowala Ilyas K - - 2008
INTRODUCTION: Knowledge of the global atrial activation pattern is critical to ablation of an atrial arrhythmia. We hypothesized that the variability in post-pacing intervals (PPIs) with pacing at different cycle lengths (CLs) from the same pacing site, regardless of distance to the circuit, can be used to identify atrial activation ...
Kachboura S - - 2008
BACKGROUND: There is an accumulating data suggesting the deleterious effects of right ventricular pacing on left ventricular performance. Such pacing mimics left bundle branch block resulting in a prolonged QRS duration and causes ventricular asynchrony. AIMS: The purpose of this study is to assess heart failure and left ventricular systolic ...
Ahlberg Sarah E - - 2008
AIMS: The determination of dynamic changes in ventricular repolarization may provide insight into arrhythmogenic mechanisms as a consequence of pacing site. This study investigated acute pacing site effects on global characteristics of electrical restitution using high resolution, non-contact mapping (NCM). METHODS AND RESULTS: Activation-recovery intervals (ARIs) were determined from reconstructed ...
Bogun Frank - - 2008
BACKGROUND: Pace mapping has been used to identify the site of origin of focal ventricular arrhythmias. The spatial resolution of pace mapping has not been adequately quantified using currently available three-dimensional mapping systems. OBJECTIVE: The purpose of this study was to determine the spatial resolution of pace mapping in patients ...
Zhang Xue-Hua - - 2008
INTRODUCTION: Emerging data have suggested that right ventricular (RV) apical pacing results in progressive left ventricular (LV) dysfunction and contributes to the development of heart failure (HF). This study aimed to investigate the prevalence and clinical predictors for the development of new-onset HF after long-term RV apical pacing in patients ...
Shannon Heather Joanne - - 2007
BACKGROUND: Noncontact endocardial mapping allows accurate beat-to-beat reconstruction of the reentrant pathway of ventricular tachycardia and improves outcomes after ablation. Several studies support electrocardiographic imaging (ECGI) as a means of noninvasively outlining epicardial activation despite constraints of internal geometry. However, few have explored its clinical application. This study aims to ...
Giudici Michael C - - 2007
BACKGROUND: The electrocardiogram (ECG) patterns during pacing from the great cardiac vein (GCV) and the middle cardiac vein (MCV) are not well known. METHODS: We recorded 12-lead ECGs during GCV and MCV pacing in 26 patients undergoing implantation of a cardiac resynchronization device. The left ventricular (LV) lead was passed ...
Lloyd Michael S - - 2007
BACKGROUND: Myocardial depolarization can be achieved with currents of either anodal or cathodal polarity. In contrast to conventional cathodal pacing, anodal pacing initially hyperpolarizes tissue and improves myocardial contractility in animal models. METHODS AND RESULTS: In 13 patients undergoing cardiac resynchronization therapy (CRT) device implantation, we compared the mean left ...
Ehrlich Joachim R - - 2008
BACKGROUND: Microvolt T-wave alternans (MTWA) is a valuable tool for stratification of patients at risk for sudden death and has recently been approved for this purpose by Medicare. Although right atrial (RA) pacing has been applied for MTWA testing, the effects of other pacing modalities on MTWA have not been ...
Biffi Mauro - - 2007
AIMS: To investigate the feasibility of transvenous left ventricular (LV) pacing by autocapture at long term. A reliable measurement of LV evoked response (ER) is the pivotal requirement for beat-to-beat detection of ventricular capture and automatic output adjustment. METHODS AND RESULTS: Seven patients with accepted class I indication to permanent ...
Kimmel Michael W - - 2007
Aims Cardiac resynchronization therapy with biventricular pacing has proved beneficial in symptomatic heart failure patients, yet the effects in patients with structurally normal hearts remain unknown. We hypothesized that, in an acute swine model with normal anatomy and function, single-site right ventricular (RV) pacing would better preserve haemodynamic function and ...
Sauer William H - - 2008
BACKGROUND: Transient VA block can be created in the AV node (AVN) when an atrial extrastimulus is delivered at the AVN effective refractory period (ERP) due to anterograde concealed conduction. OBJECTIVE: We hypothesized that ventricular stimulation during pacing-induced AVN refractoriness could identify concealed accessory pathways (APs) that remain hidden with ...
Yamada Takumi - - 2008
BACKGROUND: Ventricular arrhythmias (VAs) may arise from the aortic sinuses and have electrocardiographic and electrophysiological characteristics that suggest a left (LCC) or right coronary cusp (RCC) origin. However, VAs that arise near the junction of those two cusps (L-RCC) may have unusual features. OBJECTIVES: The purpose of this study was ...
Sankaranarayanan Rajiv - - 2007
Although transvenous access to the coronary veins has considerably simplified left ventricular (LV) pacing, it can remain a time consuming and arduous task achieving satisfactory pacing positions for the LV electrode. Common problems include negotiating small veins with adequate guide catheter stability, pacing electrode stability once positioned, and phrenic nerve ...
Fuller Geraldine A - - 2007
BACKGROUND: Dilated cardiomyopathy is a naturally occurring disease in humans and dogs. Human studies have shown increased levels of myosin heavy chain (MHC)-beta in failing ventricles and the left atria (LA) and of ventricular light chain (VLC)-2 in the right atria in dilated cardiomyopathy. METHODS AND RESULTS: This study evaluates ...
Berger Carolyn M - - 2007
Experimental studies have linked alternans, an abnormal beat-to-beat alternation of cardiac action potential duration, to the genesis of lethal arrhythmias such as ventricular fibrillation. Prior studies have considered various closed-loop feedback control algorithms for perturbing interstimulus intervals in such a way that alternans is suppressed. However, some experimental cases are ...
Liu Wen-Hao - - 2008
BACKGROUND: Chronic right ventricular apical (RVA) pacing can lead to an increased risk of heart failure. However, assessment of left ventricular mechanical dyssynchrony in the whole left ventricle simultaneously with acute RVA pacing has never been investigated. METHODS AND RESULTS: This study included 35 patients with sick sinus syndrome and ...
Sosunov Eugene A - - 2008
BACKGROUND: Cardiac memory is a change in T-wave morphology induced by ventricular pacing or arrhythmias that persist after resumption of normal AV conduction. Changing the pacemaker site from atrium to ventricle alters ventricular activation and the mechanical pattern of ventricular contraction. Either or both alterations affect T-wave configuration. OBJECTIVE: The ...
Carbone Vincenzo - - 2008
This report deals with a patient with single-lead VDD pacemaker and intermittent atrial sensing failure. At first glance, the electrocardiogram suggested a VVI mechanism of pacing, being paced QRS complexes dissociated from sinus P waves: this revealed that intracardiac atrial electrograms were too small to reach the sensing threshold. At ...
Sweeney Michael O - - 2007
BACKGROUND: Conventional dual-chamber pacing maintains atrioventricular synchrony but results in high percentages of ventricular pacing, which causes ventricular desynchronization and has been linked to an increased risk of atrial fibrillation in patients with sinus-node disease. METHODS: We randomly assigned 1065 patients with sinus-node disease, intact atrioventricular conduction, and a normal ...
Berberian George - - 2007
OBJECTIVES: Biventricular pacing is important therapy for congestive heart failure, reversing left ventricular dysfunction in dilated cardiomyopathy. Although left ventricular lead location and right ventricular-left ventricular delay are believed to be critical in biventricular pacing, there is no established technique for optimizing pacing site and timing. METHODS: After median sternotomy ...
Reynolds Dwight W - - 2007
Physiologic pacing is an evolving term used to describe different concepts and technologic developments in implantable devices (including pacemakers and defibrillators) over the past several decades. Currently much of the discussion about optimal physiologic pacing involves fairly recently appreciated deleterious effects of traditional right ventricular pacing. Technologic solutions to the ...
Ahlberg Sarah E - - 2007
INTRODUCTION: Pacing site is known to influence the contractile state of the ventricle. Non-physiologic pacing sites such as the right ventricular apex (RVA) or left ventricular freewall (LVFW) have been shown to decrease the contractile state of normal myocardium, due to abnormal electrical propagation. The impact of pacing at these ...
Estner Heidi Luise - - 2008
We report on a 32-year-old man with tricuspid atresia, pulmonary stenosis and hypoplastic right ventricle. He had received a Fontan-Kreutzer procedure (anastomosis between the right atrial appendage and the pulmonary artery) at the age of 14 years. At the age of 2 years, an abdominal VVI-pacemaker with an epicardial ventricular ...
Shuros Allan C - - 2007
BACKGROUND: Myocardial infarction modifies the distribution of stress within the heart, increasing wall stress in ischemic and surrounding tissue, which often leads to adverse left ventricular remodeling. Electrical preexcitation pacing with appropriate timing of high-stress regions can reduce local strain and may attenuate global remodeling. METHODS AND RESULTS: Myocardial infarction ...
Tomaske Maren - - 2007
AIMS: Permanent ventricular pacing in children is associated with ventricular dysfunction due to asynchronous activation. It is unclear whether paced QRS intervals increase disproportionately over time, which could potentially cause ventricular dysfunction. METHODS: A total of 52 children, with bipolar steroideluting epicardial leads implanted at a median age of 5.6 ...
Lee Kathy L - - 2007
OBJECTIVES: The purpose of this study was to evaluate the feasibility and safety of a novel technology that uses energy transfer from an ultrasound transmitter to achieve cardiac stimulation without the use of a pacing lead in humans. BACKGROUND: To overcome the limitations of pacemaker leads, a new technology enabling ...
Wecke Liliane - - 2007
BACKGROUND: Right ventricular apical (RVA) pacing induces electrophysiological and structural remodeling. Cardiac memory (CM) evolves during the course of pacing and is readily apparent on electrocardiography (ECG) or vectorcardiography (VCG) when normal ventricular activation resumes. OBJECTIVE: This study sought to assess ventricular repolarization (VR) changes during pacing and intermittent normal ...
Sirker Alexander - - 2007
AIMS: Biventricular (BiV) pacing and left univentricular (LUV) pacing can each produce clinical benefits in heart failure. The impact of modern refinements in pacing optimization on the relative benefits of these two modes is unknown. We aimed to compare these two modes in patients with heart failure, using Echo-based optimization ...
Yoda Masataka - - 2007
Coronary sinus (CS) dissection during biventricular pacing electrode implantation is a complication that rarely develops. A 71-year-old female with recurrent ventricular tachycardia, heart decompensation, and poor left ventricular function because of dilated cardiomyopathy was admitted for the implantation of a cardioverter-defibrillator for biventricular pacing. During the operation, we experienced a ...
Chen Tien-En - - 2007
A 53-year-old woman with sinus node dysfunction underwent dual-chamber pacemaker implantation through a persistent left superior vena cava draining into the coronary sinus, which was detected at the time of implantation. We managed to fix the ventricular lead in the right ventricular (RV) apex by forming a clockwise loop in ...
Sweeney Michael O - - 2007
OBJECTIVES: The purpose of this study was to characterize interactions between normal pacing system operation and the initiating sequence of ventricular tachycardia (VT)/ventricular fibrillation (VF). BACKGROUND: Abrupt changes in ventricular cycle lengths (short-long-short, S-L-S) might initiate VT/VF. The S-L-S sequences might be passively permitted or actively facilitated by bradycardia pacing. ...
Curtis Anne B - - 2007
BACKGROUND: Right ventricular (RV) pacing restores ventricular systole in patients with atrioventricular (AV) block, yet recent studies have suggested that in patients with AV block and left ventricular (LV) dysfunction, RV pacing may exacerbate the progression to heart failure (HF). BLOCK HF is a prospective, multi-center, randomized, double-blind, controlled trial ...
Katritsis Demosthenes G - - 2007
A new technique for the placement of left ventricular pacing leads in the tributaries of the coronary sinus (CS) is described. Antegrade visualization of the CS is accomplished by selective coronary angiography, and a hydrophilic 0.032 in. wire is advanced along the CS. This facilitates the advancement of a CS ...
Cleland John G F - - 2007
This article provides information and a commentary on trials relevant to the pathophysiology, prevention and treatment of heart failure, presented at Heart Rhythm 2007 organised by the Heart Rhythm Society which was held in Denver, USA and Heart Failure 2007 organised by the Heart Failure Association of the European Society ...
Hafid Kebbati A - - 2007
OBJECTIVE: Pulmonary veins (PVs) are important sources of paroxysmal atrial fibrillation (AF). Rapid atrial pacing changes atrial electrophysiology, and facilitates the induction and maintenance of AF. The purpose of our study was to evaluate the changes in atrial effective refractory period (AERP) proprieties and in ionic currents in PVs myocytes ...
Rumeau P - - 2007
An infant with a congenital auriculoventricular block (CAVB) of immunological origin was diagnosed prenatally. The mother had Gougerot-Sjögren disease with positive anti-Sjogren's Syndrome A (SSA) and Sjogren's Syndrome B (SSB) serologies. Cardiac pacing was necessary and the epicardial route was chosen. Considering the left ventricular (LV) dilatation, bi-ventricular (BiV) stimulation ...
Naqvi Tasneem Z - - 2007
BACKGROUND: Normalization of heart rate post-pacing stress echocardiography (PASE) could enable evaluation of effect of ischemia on diastolic function. METHODS: We examined the effect of pacing on left ventricular (LV) filling in 55 patients who underwent a transesophageal PASE. Pulse wave Doppler of mitral inflow was obtained at baseline and ...
Sukhija Rishi - - 2007
We investigated left ventricular ejection fraction and new left ventricular wall motion abnormality before pacemaker implantation and at follow-up and mortality at long-term follow-up in 81 patients with implantable cardioverter defibrillators treated with biventricular pacing and in 80 patients with implantable cardioverter defibrillators treated with DDDR-70 right ventricular pacing. At ...
Kharin Sergey - - 2007
OBJECTIVE: This study was planned to investigate ventricular myocardial excitation in birds in which Purkinje fibres penetrate into the ventricular wall and reach the epicardium to advance our knowledge about the evolution of the ventricular activation process in vertebrates. METHODS: A depolarization pattern of the left ventricular free wall in ...
Jeyaraj Darwin - - 2007
BACKGROUND: Altered electrical activation of the heart by pacing or disease induces profound ventricular electrical remodeling (VER), manifested electrocardiographically as T-wave memory and ultimately as deleterious mechanical remodeling from heterogeneous strain. Although T-wave memory is associated with altered expression of sarcolemmal ion channels, the biophysical mechanisms responsible for triggering remodeling ...
Asirvatham Samuel J - - 2007
BACKGROUND: Intracardiac electrodes create an "antenna" capable of unintentionally recording and stimulating tissue beyond the chamber in which they are positioned, resulting in far-field R wave oversensing in pacemakers and inappropriate detection in defibrillators. This feasibility study sought to determine whether a specially constructed lead with two distal totally intramyocardial ...
Martin Louise - - 2007
PURPOSE: Fast swim times in morning rounds are essential to ensure qualification in evening finals. A significant time-of-day effect in swimming performance has consistently been observed, although physical activity early in the day has been postulated to reduce this effect. The aim of this study was to compare intradaily variation ...
Zilberman Mark V - - 2007
BACKGROUND: Although the right atrial appendage (RAA) is typically used for atrial pacing lead implant, recent studies have shown benefits of alternate site atrial pacing (ASAP) in the elderly. However, comparable studies in the young are lacking. METHODS: To investigate effects of ASAP on cardiac function and atrioventricular mechanical interactions ...
Fung Jeffrey Wing-Hong - - 2007
BACKGROUND: Deleterious effect on left ventricular (LV) function was observed with conventional right ventricular apical (RVA) pacing. Preliminary data suggested that biventricular pacing (BiV) may be superior to RVA pacing in patients with LV systolic dysfunction. However, the optimal pacing mode and site(s) for patients with normal LV systolic function ...
Walker Nicola L - - 2007
INTRODUCTION: This study examines the consequences of a large transmural apical infarct on the epicardial electrical activity in isolated rabbit hearts. METHODS AND RESULTS: Hearts were isolated 8 weeks after coronary artery ligation. Membrane voltage from the epicardial surface of the left ventricle (LV) including the infarct was monitored using ...
Rademaker Miriam T - - 2007
Urocortin 1 (Ucn1) may be involved in the pathophysiology of heart failure (HF), but the impact of Ucn1 administration on progression of the disease is unknown. The aim of this study was to investigate the effects of Ucn1 in sheep from the onset of cardiac overload and during the subsequent ...
Gould Paul A - - 2007
AIMS: We investigated whether biventricular (BiV) pacing favourably affects cardiac sympathetic activity in heart failure (HF). METHODS AND RESULTS: In 10 HF patients treated with BiV pacing, we assessed cardiac sympathetic activity by metaiodobenzylguanidine ((123)I-MIBG) imaging. Patients were randomized in a double-blinded crossover fashion, for two weeks of either inactivation ...
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