Biventricular Pacing Therapy Research Articles

Understanding the modern-era management of cardiac tachyarrhythmias

Diagnosis and treatment modalities of supraventricular arrhythmias have been changed over the past decade. This article mainly outlines advances in diagnosis and modern-day management of supraventricular tachycardia as well as an overview of the management of wide complex tachyarrhythmias. The role of cardiac electrophysiology study and radiofrequency catheter ablation in the diagnosis and management of a wide variety of supraventricular arrhythmias is also discussed. This article also emphasizes the current evidence-based management of atrial-origin tachyarrhythmias such as atrial flutter and fibrillation.The management of cardiac arrhythmias has changed over the past decade, which is mainly due to improvements in catheter ablation including 3D mapping catheter ablation, improvements in device therapy such as implantable cardioverter defibrillator (ICD) and biventricular pacing therapy (CRT) which have evolved to treat many conditions. Catheter ablation has moved from being a treatment considered only for patients with refractory arrhythmias to a first-line treatment. In the new era, catheter ablation is also used to treat atrial origin tachyarrhythmias such as atrial fibrillation (AF) and atrial flutter as well as ventricular tachycardia (epicardial VT ablation). Improvement of imaging modalities such as 2D/3D echocardiogram and cardiac MRI also play a vital role in the prognosis of ablation particularly in AF and epicardial VT ablation. Improvement in device implantation such as ICD and biventricular pacing also helpful in managing tachyarrhythmia. Modern advancements in cardiac electrophysiology help patients to improve their quality of life and prevent sudden cardiac deaths due to cardiac arrhythmia.

A New Electromechanical Wave Imaging Dispersion Metric for the Characterization of Ventricular Activation in Different Cardiac Resynchronization Therapy Pacing Schemes.

Conventional biventricular (BiV) pacing cardiac resynchronization therapy (CRT) is an established treatment for heart failure patients. Recently, multiple novel CRT delivering technologies such as His-Bundle pacing have been investigated as alternative pacing strategies for optimal treatment benefit. Electromechanical Wave Imaging (EWI), a high frame-rate echocardiography-based modality, is capable of visualizing the change from dyssynchronous activation to resynchronized BiV-paced ventricles in 3D. This proof-of-concept study introduces a new EWI-based dispersion metric to further characterize ventricular activation. Patients with His-Bundle device implantation (n = 4), left-bundle branch block (n = 10), right-ventricular (RV) pacing (n = 10), or BiV pacing (n = 15) were imaged, as well as four volunteers in normal sinus rhythm (NSR). EWI successfully mapped the ventricular activation resulting from His-Bundle pacing. Additionally, very similar activation patterns were obtained in the NSR subjects, confirming recovery of physiological activation with His pacing. The dispersion metric was the most sensitive EWI-based metric that identified His pacing as the most efficient treatment (lowest activation time spread), followed by BiV and RV pacing. More specifically, the dispersion metric significantly (p < 0.005) distinguished His pacing from the other two pacing schemes as well as LBBB. The initial findings presented herein indicate that EWI and its new dispersion metric may provide a useful resynchronization evaluation clinical tool in CRT patients under both novel His-Bundle pacing and more conventional BiV pacing strategies.

9 Identification of a potential cause of non-response to biventricular pacing using intravenous adenosine

Aim We aim to evaluate the efficacy and safety of determining the presence of true biventricular pacing by administration of intravenous adenosine. This aims to determine whether non-response to biventricular pacing therapy is partially explained by over-counting of the percentage of pacing therapy by the presence of fusion beats. We compared the proportion of patients with fusion beats in non-responders compared to responders Methods This will be a single centre, prospective, cohort study. 71 consecutive patients with implanted cardiac resynchronisation devices between July 2006 and November 2015 were identified. Patients underwent the adenosine trial at least 12 months post CRT device implantation to detect the presence of potentially ineffective biventricular pacing. This was compared with the recorded percentage of biventricular pacing reported during device interrogation. Correlation was made between response to CRT therapy and presence of effective biventricular pacing. Results Preliminary results from 24 patients demonstrate that symptomatic adenosine administration was successful in identifying true effective biventricular paced beats. This has allowed us to identify patients with fusion beats. 8 patients were non-responders to CRT, whereas 16 patients were responders. 50% (n=4) of non-responders and 12.5% (n=2) of responders had definite electrocardiography (ECG) changes through the symptomatic adenosine administration, showing that a percentage of the paced beats counted by the CRT device may in fact be fusion beats. Figure 1 shows the clear change in the morphology of the QRS complex in one of the non-responders. Figure 1 Electrocardiogram of a non-responder during symptomatic adenosine administration Conclusion Preliminary results suggest that symptomatic adenosine administration is successful in identifying true effective biventricular paced beats which may be overestimated by CRT device interrogation. Correlation with response to CRT is yet to be established, but in 50% of the non-responders we identified a definite change in the morphology of the paced rhythm during the symptomatic response to adenosine. This raises a question of whether the poor response to CRT for these patients is actually due to the insufficient percentage of effective biventricular pacing (

Cardiac resynchronization therapy: past, present, and future.

Cardiac resynchronization therapy (CRT), or biventricular pacing, has become a standard therapeutic modality for patients with symptomatic heart failure (HF), depressed left ventricular (LV) function, and electrical dyssynchrony. Despite the overall success of CRT in improving morbidity and mortality in selected patients with HF, a significant minority demonstrates nonresponse. This review describes the electrical and physiologic rationale for biventricular pacing therapy, summarizes landmark clinical trials assessing CRT efficacy, highlights strategies to optimize the response to CRT, and frames future challenges in the use, delivery, and care of patients undergoing CRT.

GW24-e3774 Therapeutic effect of cardiac resynchronisation therapy about congestive heart failure

ObjectivesThe aim of this study is to observe the effect of 12 months after therapy of CRT in patients with congestive heart failure, to investigate the change of serum inflammation...

Loss of Biventricular Pacing and Inappropriate Therapy by a Cardiac Resynchronization Implantable Defibrillator

Pacing and Clinical ElectrophysiologyVolume 36, Issue 8 p. 1030-1031 DEVICE ROUNDS Loss of Biventricular Pacing and Inappropriate Therapy by a Cardiac Resynchronization Implantable Defibrillator RÓBERT PAP M.D., Ph.D., Corresponding Author RÓBERT PAP M.D., Ph.D. 2nd Department of Medicine and Cardiology Centre, University of Szeged, Szeged, HungaryAddress for reprints: Róbert Pap, M.D., Ph.D., 2nd Department of Medicine and Cardiology Centre, University of Szeged, 6720 Szeged, Korányi fasor 6, Hungary. Fax: 36-62-544-568; e-mail: pap.paprobert@gmail.comSearch for more papers by this authorGERGELY KLAUSZ M.D., Ph.D., GERGELY KLAUSZ M.D., Ph.D. 2nd Department of Medicine and Cardiology Centre, University of Szeged, Szeged, HungarySearch for more papers by this authorTIBOR BALÁZS, TIBOR BALÁZS Biotronik, Budapest, HungarySearch for more papers by this authorLÁSZLÓ SÁGHY M.D., LÁSZLÓ SÁGHY M.D. 2nd Department of Medicine and Cardiology Centre, University of Szeged, Szeged, HungarySearch for more papers by this author RÓBERT PAP M.D., Ph.D., Corresponding Author RÓBERT PAP M.D., Ph.D. 2nd Department of Medicine and Cardiology Centre, University of Szeged, Szeged, HungaryAddress for reprints: Róbert Pap, M.D., Ph.D., 2nd Department of Medicine and Cardiology Centre, University of Szeged, 6720 Szeged, Korányi fasor 6, Hungary. Fax: 36-62-544-568; e-mail: pap.paprobert@gmail.comSearch for more papers by this authorGERGELY KLAUSZ M.D., Ph.D., GERGELY KLAUSZ M.D., Ph.D. 2nd Department of Medicine and Cardiology Centre, University of Szeged, Szeged, HungarySearch for more papers by this authorTIBOR BALÁZS, TIBOR BALÁZS Biotronik, Budapest, HungarySearch for more papers by this authorLÁSZLÓ SÁGHY M.D., LÁSZLÓ SÁGHY M.D. 2nd Department of Medicine and Cardiology Centre, University of Szeged, Szeged, HungarySearch for more papers by this author First published: 10 January 2013 https://doi.org/10.1111/pace.12076Citations: 4Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume36, Issue8August 2013Pages 1030-1031 RelatedInformation

A Study of Mechanical Optimization Strategy for Cardiac Resynchronization Therapy Based on an Electromechanical Model

An optimal electrode position and interventricular (VV) delay in cardiac resynchronization therapy (CRT) improves its success. However, the precise quantification of cardiac dyssynchrony and magnitude of resynchronization achieved by biventricular (BiV) pacing therapy with mechanical optimization strategies based on computational models remain scant. The maximum circumferential uniformity ratio estimate (CURE) was used here as mechanical optimization index, which was automatically computed for 6 different electrode positions based on a three-dimensional electromechanical canine model of heart failure (HF) caused by complete left bundle branch block (CLBBB). VV delay timing was adjusted accordingly. The heart excitation propagation was simulated with a monodomain model. The quantification of mechanical intra- and interventricular asynchrony was then investigated with eight-node isoparametric element method. The results showed that (i) the optimal pacing location from maximal CURE of 0.8516 was found at the left ventricle (LV) lateral wall near the equator site with a VV delay of 60 ms, in accordance with current clinical studies, (ii) compared with electrical optimization strategy of E RMS, the LV synchronous contraction and the hemodynamics improved more with mechanical optimization strategy. Therefore, measures of mechanical dyssynchrony improve the sensitivity and specificity of predicting responders more. The model was subject to validation in future clinical studies.

Rhythm Control Should Be Better for the Management of Patients With Atrial Fibrillation and Heart Failure - Rhythm Control vs. Rate Control: Which Is Better in the Management of Atrial Fibrillation? (Rhythm-Side) -

The incidence of atrial fibrillation (AF) increases with advancing NHYA cardiac functional class, and it significantly affects the cardiac function of a failing heart. In such situations, clinicians should aim to maintain sinus rhythm in these patients with heart failure (HF) in order to improve their prognosis. However, according to various randomized clinical studies demonstrating the non-superiority of rhythm control over rate control, many clinicians seem to prefer to take the line of least resistance (ie, rate control). Curative catheter ablation mainly based on isolation procedure of the pulmonary veins in patients with AF and HF has demonstrated a significant improvement in left ventricular function, even in the presence of adequate ventricular rate control before the ablation. On the other hand, ablation and biventricular pacing therapy, which is an extreme rate control strategy, has not shown any beneficial effects for these patients. Therefore, a regular RR interval with an appropriate cycle length only is not sufficient to improve cardiac performance, and maintenance of sinus rhythm, which restores atrial contraction and the atrioventricular synchrony, is thought to be essential for an improvement in HF. Thoughtful clinicians should do their best to find a way to keep HF patients in sinus rhythm.

Echocardiography, dyssynchrony, and the response to cardiac resynchronization therapy

Biventricular pacing or cardiac resynchronization therapy (CRT) has been a considerable advance in the therapy of chronic heart failure. However, it is clear that not all patients benefit either in terms of symptoms or cardiac function, and some may be worsened by CRT. In this review, we consider the arguments, both clinical and economical, in favour of improved selection of patients for CRT other than those in current guidelines. It also seems clear that the fundamental mechanism of CRT is correction of dyssynchrony, and we review the various methodologies available to detect dyssynchrony. Other factors are probably also important in determining outcomes such as lead position, the extent and form of myocardial damage, optimizing pacemaker performance, and clinical expertise. The potential costs of inappropriate CRT implantation are high to our patients and to the health economy, and it behooves the cardiology community to develop better selection criteria. The current guidelines can and should be improved.

Does Biventricular Pacing Improve Hemodynamics in Children Undergoing Routine Congenital Heart Surgery?

Biventricular (BiV) pacing or cardiac resynchronization therapy (CRT) is an established therapy for heart failure in adults. In children, cardiac dyssynchrony occurs most commonly following repair of congenital heart disease (CHD) where multisite pacing has been shown to improve both hemodynamics and ventricular function. Determining which patient types would specifically benefit has not yet been established. A prospective, repeated measures design was undertaken to evaluate BiV pacing in a cohort of children undergoing biventricular repair for correction of their CHD. Hemodynamics, arterial blood gas, electrocardiographic (ECG), and echocardiographic data were collected. Pacing protocol was undertaken prior to the patient's extubation with 20 min of conventional right ventricular (RV) or BiV pacing, preceded and followed by 10 min of recovery time. Multivariate statistics were used to analyze the data with p values <0.05 considered significant. Twenty-five (14 female) patients underwent surgery at a median (range) age of 5.2 (0.1-37.4) months with no early mortality. The Risk-adjusted classification for Congenital Heart Surgery (RACHS) scores were 2 in 14 patients, 3 in eight patients, and 4 in three patients. None had pre-existing arrhythmias, dyssynchrony, or required pacing pre-operatively. No patient required implantation of a permanent pacemaker post-operatively. The median cardio-pulmonary bypass time was 96 (55-236) min. RV and BiV pacing did not improve cardiac index from baseline (3.23 vs. 3.42 vs. 3.39 L/min/m2; p > 0.05). The QRS duration was not changed with pacing (100 vs. 80 vs. 80 ms; p > 0.05). On echocardiography, the time-to-peak velocity difference between the septal and posterior walls (synchrony) during pacing was similar to baseline and was also not statistically significant. BiV pacing did not improve cardiac output when compared to intrinsic sinus rhythm or RV pacing in this cohort of patients. Our study has shown that BiV pacing is not indicated in children who have undergone routine BiV congenital heart surgery. Further prospective studies are needed to assess the role of multisite pacing in children with ventricular dyssynchrony such as those with single ventricles, those undergoing reoperation or those with high RACHS scores.

Role of echocardiography in selection of patients for biventricular pacing therapy

Cardiac resynchronization therapy (CRT) has demonstrated improved quality of life, New York Heart Association class, left ventricular ejection fraction, and survival in patients with moderate to severe heart failure, left ventricular ejection fraction less than or equal to 35%, and a prolonged QRS duration. QRS duration remains the primary surrogate for mechanical dyssynchrony, defining the pathophysiology of abnormal regional mechanical activation. Studies have demonstrated that 30% to 40% of patients who meet current criteria for CRT are nonresponders. Therefore, there is great interest in the relationship between electrical and mechanical dyssynchrony, and the ability of each alone or together to predict response remains unknown. Echocardiographic approaches have emerged to quantify mechanical dyssynchrony with greater specificity than QRS duration alone. Although these methods are complex, exciting, and highly accurate for predicting response to CRT in single-center studies, they lack widespread applicability and validation to replace current criteria for device implantation. Use of echocardiography to define dyssynchrony and the impact of promising imaging methods for future patient selection for CRT are discussed.

Reversal of Right Ventricular Apex Pacing-Induced Left Ventricular Apical Dyskinesis

Right ventricular apical (RVA) pacing is known to cause left ventricular (LV) dysfunction, myocardial perfusion defects, abnormal septal contractility, asymmetrical septal hypertrophy, and heart failure in some patients.1–2 However, RV pacing-induced LV apical dyskinesis has not been previously described in the literature. We report a case of RVA pacing-induced LV apical dyskinesis that resolved acutely and was accompanied by a global improvement in LV systolic function after biventricular (BiV) pacing therapy with relocation of the RV lead. Intraoperative real-time 3D echocardiography was used for the optimal RV and LV pacing site selection. The case is a 73-year-old patient with complete heart block who underwent dual-chamber pacing (right atrial appendage and RVA pacing) for complete heart block, 3 years before the presentation. At baseline, she had normal ventricular function with an ejection fraction (EF) of 65%; however over the last 2 years, she had progressive LV dysfunction and worsening symptoms of congestive heart failure. A follow-up echocardiogram at this time showed an ejection fraction of 15% and marked dyskinesis of the LV apex. Based on a presumptive diagnosis of RVA …

Atrioventricular Nodal Ablation and Biventricular Pacing Therapy with Coronary Venoplasty for Severe Heart Failure with Drug Refractory Atrial Tachycardia

A 53-year-old man was admitted to our hospital for dyspnea, associated with atrial tachycardia. He underwent mitral valve replacement and Maze operation for mitral regurgitation and atrial fibrillation and since then he suffered from drug refractory atrial tachycardia followed by cardiogenic shock with systolic heart failure. Atrial tachycardia with rapid ventricular response was medically refractory, and radical catheter ablation was thought to be very difficult due to post Maze operation, mitral mechanical valve replacement and unstable hemodynamics. Thus, atrioventricular nodal ablation, which was s safe procedure compared to the radical ablation for this patient, and biventricular pacemaker implantation, which required coronary venoplasty, were performed. Combination therapy may be one of the treatments for heart failure patients with drug refractory tachyarrhythmias.

Segmentation-based algorithms to quantify nonviable myocardium after delayed contrast-enhanced computed tomography: defining what’s dead

The ability to distinguish dysfunctional but viable myocardium from nonviable tissue after acute or chronic ischemia has important implications for the therapeutic management of patients with coronary artery disease. In the acute phase, myocardial revascularization in patients with viable myocardium can improve ventricular dysfunction 1 Alderman E.L. Fisher L.D. Litwin P. Kaiser G.C. Myers W.O. Maynard C. Levine F. Schloss M. Results of coronary artery surgery in patients with poor left ventricular function (CASS). Circulation. 1983; 68: 785-795 Crossref PubMed Scopus (698) Google Scholar and long-term survival, 2 Pagley P.R. Beller G.A. Watson D.D. Gimple L.W. Ragosta M. Improved outcome after coronary bypass surgery in patients with ischemic cardiomyopathy and residual myocardial viability. Circulation. 1997; 96: 793-800 Crossref PubMed Scopus (358) Google Scholar whereas image-based characterization of myocardial scar structure in the setting of chronic ischemia can identify those patients with hibernating myocardium who may achieve functional systolic recovery with revascularization. 3 Wakimoto H. Maguire C.T. Kovoor P. Hammer P.E. Gehrmann J. Triedman J.K. Berul C.I. Induction of atrial tachycardia and fibrillation in the mouse heart. Cardiovasc Res. 2001; 50: 463-473 Crossref PubMed Scopus (78) Google Scholar The assessment of both acute and chronic myocardial viability using delayed enhanced magnetic resonance imaging (de-MRI) is considered the standard for myocardial viability assessment. As the clinical indications for implantable cardiac defibrillators and biventricular pacing therapy continue to expand, however, development and validation of alternative imaging methods with similar anatomic, functional, and viability imaging capabilities are needed to accommodate this growing population of patients.

Effect of triangle ventricular pacing on haemodynamics and dyssynchrony in patients with advanced heart failure: a comparison study with conventional bi-ventricular pacing therapy

This study examined the impact of cardiac resynchronization therapy (CRT) by triangle ventricular pacing (Tri-V) on left ventricular (LV) function and dyssynchrony. Twenty-one patients with NYHA class III or IV heart failure were studied. For Tri-V, two right ventricular (RV) leads were connected to the CRT device via a Y-connector with one lead anchored at the RV apex and the other at the RV outflow tract. The LV lead was positioned in the posterolateral or lateral cardiac vein. CRT with standard bi-ventricular pacing (Bi-V) was performed with the RV apical and LV leads. LV function was assessed by the measurement of LV positive dp/dt (dP/dt(max)) and cardiac output (CO). LV dyssynchrony was assessed using the standard deviation of the time to peak myocardial velocity during the systolic phase in 12 LV segments (Ts-SD) derived from tissue Doppler images. In comparison to Bi-V, Tri-V increased dP/dt(max) (baseline, 746 +/- 165; Bi-V, 909 +/- 186; Tri-V, 959 +/- 195 mmHg/s, P = 0.04) and CO (baseline, 3.1 +/- 1.0; Bi-V, 3.4 +/- 1.1; Tri-V, 3.8 +/- 1.2 L/min, P < 0.001), decreased Ts-SD (baseline, 54.0 +/- 35.0; Bi-V, 33.6 +/- 15.3; Tri-V, 22.4 +/- 8.1 ms, P = 0.02). The acute beneficial effects of Tri-V on LV function and dyssynchrony were greater than those of Bi-V.

Regression of dilated-hypokinetic hypertrophic cardiomyopathy by biventricular cardiac pacing

The evolution of hypertrophic cardiomyopathy (HCM) towards dilatation and hypokinesis is an increasingly recognized complication with a high incidence of adverse outcomes, including sudden cardiac death, requiring defibrillator implantation and cardiac transplantation. It is generally regarded as the irreversible 'burnt-out' end-stage manifestation of HCM. We report one of the first cases of profound regression of the dilated-hypokinetic state by the application of biventricular pacing and cardiac resynchronization therapy (CRT). Reviewing the literature on the role of pacing in HCM and the energetic rationale for CRT in HCM prompts us to suggest that further systematic studies are needed urgently to assess the role of CRT in HCM variants.

Economic Analysis of a Randomized Trial of Biventricular Pacing in Canada

Congestive heart failure (CHF) has been shown to affect 5% of the Canadian adult population, and leads to 9.5 deaths per 100 cardiac-related hospitalizations in Canada. The economic outcomes from biventricular pacing for heart failure are not well understood. This study analyzes resource utilization and related costs associated with CHF for patients who receive standard implantable cardiac defibrillators (ICDs) versus those who receive ICD plus biventricular pacing or cardiac resynchronization therapy (CRT). The Canadian analysis of resynchronization therapy in heart failure (CART-HF) study included 72 patients with New York Heart Association class II-IV CHF requiring an ICD. Patients were randomized to receive either ICD + CRT treatment or ICD treatment alone. Medical resource utilization data were collected for 6 months following treatment and were applied to representative costs for the provinces of Quebec and Ontario. Resource utilization was subcategorized into pharmacological therapy, physician visits, hospitalizations, adverse events, and productivity losses. Post-treatment, per patient costs for the CRT + ICD treatment group were less than the follow-up costs for patients receiving ICD treatment only in each province. Mean savings for patients receiving biventricular therapy were CAD 2,420 dollars in Quebec and CAD 2,085 dollars in Ontario during the 6-month follow-up. These analyses indicate that savings in post-implant health-care utilization (hospitalizations and pharmacological therapy) can offset some of the device and procedural costs associated with CRT devices.

Lack of Uniformity in Safety Reporting for CRT Implantation in Randomized Clinical Trials and Pre Market Approval Applications

Background: Biventricular pacing or cardiac resynchronization therapy (CRT-P; CRT-D) is approved in the U.S. for NYHA Class III-IV based on symptom benefit. However, a critical analysis of published complication (Cx) incidence and comparison with data submitted in FDA-mandated PreMarket Approval (PMA) applications has not been performed. Methods: We analyzed (1) peri-procedural Cxs by category in multicenter randomized clinical trials (RCTs) of CRT-P (n = 7), CRT-D (n = 3) or both (n = 1) published from 2001-2005 and (2) CRT PMAs accessible on-line (http://www.acessdata.fda.gov/scripts/cdrh/chfdocs/cfPMA/pma.cfm) for “complications”, FDA-defined as adverse events (AEs) that result in invasive intervention or in death/serious injury/explantation or repositioning of the device.

1257: Impaired intrinsic contractility detected by echocardiographic techniques

Speckle images are emerging new techniques for detecting and measuring cardiac mechanical dysfunction. In the past decade, the most commonly used methods to study the interaction between the ultrasound beam and the tissue speckles were the Doppler shift or power reflected from the tissue or blood cells and the radiofrequency ultrasound signal backscattered from the tissue. Ultrasonic tissue characterization (UTC) with cardiac cycle-dependent variation of integrated backscatters (IBS) has been shown as the intrinsic myocardial contractility and a potential indicator for early systolic dysfunction. Normal myocardium exhibits a cycle-dependent variation of IBS that will be blunted in the amplitude and have a temporal shift in the nadir by experimental ischemia. Reperfusing the acutely infarcted myocardium will restore the cyclic variation before the wall motion recovery, suggesting the detection of stunned myocardium. In hibernating myocardium, recent investigations have shown that the intramural contractility is relatively independent of resting wall motion and parallels contractile reserve. Using this technique, it has been demonstrated that diastolic abnormalities of left ventricular (LV) function, in arterial hypertension, are related and progress with systolic intrinsic dysfunction. Doppler tissue imaging (DTI) is another new objective method that accurately quantifies myocardial tissue velocities, deformation, time intervals and LV filling pressure. It has also been widely used for evaluating intrinsic contractility during myocardial ischemia, the reverse remodeling and improved synchronicity by simultaneously delaying regional contraction after biventricular pacing therapy in heart failure, and the assessment of LV function in different stages of chronic renal disease. In conclusion, speckle image represents a relatively new diagnostic tool, which allows integration of the conventional echocardiographic evaluation, in order to obtain specific textural parameters that reflect the myocardial ultrastructural texture and intrinsic contractility.

AB40-4: Increased global dispersion of ventricular repolarization during left ventricular epicardial pacing: In vivo evaluation by monophasic action potential mapping in swine

Recent studies have highlighted the benefits of biventricular pacing therapy for patients with congestive heart failure, but latest in vitro studies suggested that epicardial pacing might lead to a prominent increase in transmural dispersion, which may be linked to the reported malignant ventricular arrhythmias in patients with biventricular pacing. However, the dispersion of global repolarization under epicardial pacing has never been in vivo evaluated.