Hemodynamic implications of left bundle branch block

Natural increase in the efficiency of ablation of ventricular tachyarrhythmias using high-density mapping in patients with non-ischemic etiology

OBJECTIVE

This research is aimed at evaluating the efficacy and safety of ablation of ventricular tachyarrhythmias using high-density mapping in patients with non-ischemic etiology.

MATERIAL AND METHODS

This study analyzed 60 patients with ventricular tachyarrhythmias, using diagnostic tools like electrocardiography and MRI. Treatment involved epicardial ablation following the E. Sosa method, with efficacy evaluated through the SF-36 survey and MRI. Success rates were categorized, and post-treatment care included troponin monitoring and aspirin. Data was analyzed using Excel and Statistika 11.0.

RESULTS

Of the 60 patients, 30 underwent surgery at the City Cardiological Center in Almaty and 30 patients were operated on at the National Research Cardiac Surgery Center in Astana. Prior to surgery, all patients underwent a standard clinical diagnostic examination followed by ablation of ventricular tachyarrhythmias using high-density mapping. After six and 12 months from the beginning of the study, all patients underwent a follow-up examination, with an assessment of the effectiveness of the above treatment. After 12 months, follow-up examination of patients showed good results. Left ventricular ejection fraction in patients after 12 months increased from 47 ± 2.4 to 58 ± 4.5%. The end-diastolic diameter of the left ventricle decreased from 61.2 ± 2.31 to 50.1 ± 1.9 mm.

CONCLUSION

In summary, the study highlights the efficacy and safety of high-density mapping ablation in treating ventricular tachyarrhythmias, especially from the right ventricular outflow tract in patients with reduced left ventricular ejection fraction. The success rate of the procedure was 95%. This approach proves beneficial for patients unresponsive to antiarrhythmic therapy, enhancing both the quality of life and potentially reducing mortality in patients with ventricular arrhythmias.

A porcine large animal model of radiofrequency ablation-induced left bundle branch block

Background

Electrocardiographic (ECG) features of left bundle branch (LBB) block (LBBB) can be observed in up to 20%-30% of patients suffering from heart failure with reduced ejection fraction. However, predicting which LBBB patients will benefit from cardiac resynchronization therapy (CRT) or conduction system pacing remains challenging. This study aimed to establish a translational model of LBBB to enhance our understanding of its pathophysiology and improve therapeutic approaches.

Methods

Fourteen male pigs underwent radiofrequency catheter ablation of the proximal LBB under fluoroscopy and ECG guidance. Comprehensive clinical assessments (12-lead ECG, bloodsampling, echocardiography, electroanatomical mapping) were conducted before LBBB induction, after 7, and 21 days. Three pigs received CRT pacemakers 7 days after LBB ablation to assess resynchronization feasibility.

Results

Following proximal LBB ablation, ECGs displayed characteristic LBBB features, including QRS widening, slurring in left lateral leads, and QRS axis changes. QRS duration increased from 64.2 ± 4.2 ms to 86.6 ± 12.1 ms, and R wave peak time in V6 extended from 21.3 ± 3.6 ms to 45.7 ± 12.6 ms. Echocardiography confirmed cardiac electromechanical dyssynchrony, with septal flash appearance, prolonged septal-to-posterior-wall motion delay, and extended ventricular electromechanical delays. Electroanatomical mapping revealed a left ventricular breakthrough site shift and significantly prolonged left ventricular activation times. RF-induced LBBB persisted for 3 weeks. CRT reduced QRS duration to 75.9 ± 8.6 ms, demonstrating successful resynchronization.

Conclusion

This porcine model accurately replicates the electrical and electromechanical characteristics of LBBB observed in patients. It provides a practical, cost-effective, and reproducible platform to investigate molecular and translational aspects of cardiac electromechanical dyssynchrony in a controlled and clinically relevant setting.

[Left bundle branch block - dilated cardiomyopathy - heart failure: common links in the closed pathogenetic chain]

This review summarizes the available information on the epidemiology and prognosis of patients with left bundle branch block (LBBB), morphological alterations of the myocardium both resulting in and ensuing LBBB, cardiac biomechanics in LBBB, and possibilities of its correction.

Assessment of left ventricular dyssynchrony by speckle tracking echocardiography in children with duchenne muscular dystrophy

Prognosis of Duchenne muscular dystrophy (DMD) is related to cardiac dysfunction. Two dimensional-speckle tracking echocardiography (2D-STE) has recently emerged as a non-invasive functional biomarker for early detection of DMD-related cardiomyopathy. This study aimed to determine, in DMD children, the existence of left ventricle (LV) dyssynchrony using 2D-STE analysis. This prospective controlled study enrolled 25 boys with DMD (mean age 11.0 ± 3.5 years) with normal LV ejection fraction and 50 age-matched controls. Three measures were performed to assess LV mechanical dyssynchrony: the opposing-wall delays (longitudinal and radial analyses), the modified Yu index, and the time-to-peak delays of each segment. Feasibility and reproducibility of 2D-STE dyssynchrony were evaluated. All three mechanical dyssynchrony criteria were significantly higher in the DMD group than in healthy subjects: (1) opposing-wall delays in basal inferoseptal to basal anterolateral segments (61.4 ± 45.3 ms vs. 18.3 ± 50.4 ms, P < 0.001, respectively) and in mid inferoseptal to mid anterolateral segments (58.6 ± 35.3 ms vs. 42.4 ± 36.4 ms, P < 0.05, respectively), (2) modified Yu index (33.3 ± 10.1 ms vs. 28.5 ± 8.1 ms, P < 0.05, respectively), and (3) most of time-to-peak values, especially in basal and mid anterolateral segments. Feasibility was excellent and reliability was moderate to excellent, with ICC values ranging from 0.49 to 0.97. Detection of LV mechanical dyssynchrony using 2D-STE analysis is an easily and reproducible method in paediatric DMD. The existence of an early LV mechanical dyssynchrony visualized using 2D-STE analysis in children with DMD before the onset of cardiomyopathy represents a perspective for future paediatric drug trials in the DMD-related cardiomyopathy prevention.Clinical Trial Registration Clinicaltrials.gov NCT02418338. Post-hoc study, registered on April 16, 2015.

Implantable cardiac electronic device therapy for patients with a systemic right ventricle

The systemic right ventricle (SRV), defined as the morphological right ventricle supporting the systemic circulation, is relatively common in congenital heart disease (CHD). Our review aimed at examining the current evidence, knowledge gaps and technical considerations regarding implantable cardiac electronic device therapy in patients with SRV. The risk of sinus node dysfunction (SND) after atrial switch repair and/or complete heart block in congenitally corrected transposition of great arteries requiring permanent pacing increases with age. Similar to acquired heart disease, indication for pacing includes symptomatic bradycardia, SND and high degree atrioventricular nodal block. Right ventricular dysfunction and heart failure also represent important complications in SRV patients. Cardiac resynchronisation therapy (CRT) has been proposed to improve systolic function in SRV patients, although indications for CRT are not well defined and its potential benefit remains uncertain. Amongst adult CHD, patients with SRV are at the highest risk for sudden cardiac death (SCD). Nevertheless, risk stratification for SCD is scarce in this cohort and implantable cardioverter-defibrillator indication is currently limited to secondary prevention. Vascular access and the incidence of device-related complications, such as infections, inappropriate shocks and device system failure, represent additional challenges to implantable cardiac electronic device therapy in patients with SRV. A multidisciplinary approach with tertiary expertise and future collaborative research are all paramount to further the care for this challenging nonetheless ever increasing cohort of patients.

Left Bundle Branch Block: Current and Future Perspectives

Left bundle branch block may be due to conduction system degeneration or a reflection of myocardial pathology. Left bundle branch block may also develop following aortic valve disease or cardiac procedures. Patients with heart failure with reduced ejection fraction and left bundle branch block may respond positively to cardiac resynchronization therapy. Lead placement via the coronary sinus is the mainstay approach of cardiac resynchronization therapy. However, other options, including physiological pacing, are being explored. In this review, we summarize the salient pathophysiologic and clinical aspects of left bundle branch block, as well as current and future strategies for management.

Relationships between electrical and mechanical dyssynchrony in patients with left bundle branch block and healthy controls

BACKGROUND

Abnormal electrical activation may cause dyssynchronous left ventricular (LV) contraction. In this study, we characterized and analyzed electrical and mechanical dyssynchrony in patient with left bundle branch block (LBBB) and healthy controls.

METHODS

Myocardial perfusion imaging (MPI) data from 994 patients were analyzed. Forty-three patient fulfilled criteria for LBBB and 24 for controls. Electrical activation was characterized with vector electrocardiography (VECG) and LV function including mechanical dyssynchrony with ECG-gated MPI phase analysis.

RESULTS

QRS duration (QRSd; r = 0.69, P < .001) and a few other VECG parameters correlated significantly with phase bandwidth (phaseBW) representing mechanical dyssynchrony. End-diastolic volume (EDV; r = 0.59, P < .001), ejection fraction and end-systolic volume correlated also with phaseBW. QRSd (β = 0.47, P < .001) and EDV (β = 0.36, P = .001) were independently associated with phaseBW explaining 55% of its variation. Sixty percent of patients with LBBB had significant mechanical dyssynchrony. Those patients had wider QRSd (159 vs 147 ms, P = .013) and larger EDV (144 vs 94 mL, P = .008) than those with synchronous LV contraction. Cut-off values for mechanical dyssynchrony seen in patients with LBBB were QRSd ≥ 165 ms and EDV ≥ 109 mL.

CONCLUSIONS

Despite obvious conduction abnormality, LBBB is not always accompanied by mechanical dyssynchrony. QRSd and EDV explained 55% of variation seen in phaseBW. These two parameters were statistically different between LBBB cases with and without mechanical dyssynchrony.

Prognostic utility of electrocardiograms in patients with hypertension older than 65 years. The PAFRES study

OBJECTIVE

Left ventricular hypertrophy is the most common marker of target organ damage in arterial hypertension. Electrocardiograms are typically performed to identify left ventricular hypertrophy. The aim of this study was to analyse the prognostic utility of other electrocardiographic abnormalities in patients with arterial hypertension, beyond ventricular hypertrophy.

MATERIALS AND METHODS

The study included 1003 patients older than 65years with arterial hypertension. We recorded risk factors, previous cardiovascular history and medical treatment and analysed various electrocardiographic abnormalities including the Sokolow-Lyon index, the Cornell index, ventricular overload and branch blocks. The study conducted a 2-year follow-up, recording the major cardiovascular events (mortality, myocardial infarction, stroke and hospitalisation for heart failure).

RESULTS

The study population's mean age was 72.9±5.8years, 47.5% of whom were men. During the follow-up, 13.9% of the patients experienced a major cardiovascular event. These patients were older, more often smokers and engaged in less physical exercise, without presenting differences in the antihypertensive therapy or blood pressure control. The ventricular overload pattern (HR: 1.93; 95%CI: 1.160-3.196; P=.011) and the complete left bundle branch block (HR: 2.27; 95%CI: 1.040-4.956; P=.040) behaved as independent electrocardiographic predictors of major cardiovascular events; however, left ventricular hypertrophy using the Sokolow and/or Cornell index did not behave as such.

CONCLUSIONS

For patients with hypertension, the presence in the baseline electrocardiogram of complete left bundle branch block or a pattern of ventricular overload identifies a population at increased cardiovascular risk.

True complete left bundle branch block reveals dyssynchrony evaluated by semiconductor single-photon emission computed tomography

BACKGROUND

Conventional complete left bundle branch block (CLBBB) criteria sometimes result in a false-positive diagnosis that does not represent dyssynchrony. Recently, true CLBBB criteria have been proposed to detect responders to cardiac resynchronization therapy (CRT), although their correlation with severity of dyssynchrony or natural prognosis is unclear.

METHODS

Ninety-four consecutive patients (74 ± 9 years, 63 men) with conventional CLBBB during sinus rhythm underwent semiconductor SPECT. They were divided into two groups: patients with true CLBBB and others. True CLBBB was characterized by the mid-QRS notching/slurring and wide QRS duration (male, ≥140 milliseconds; female, ≥130 milliseconds). Multivariate analysis was performed to detect left ventricular dyssynchrony (LVD), defined as bandwidth ≥145° and/or phase standard deviation (SD) ≥43°. Primary endpoints (hospitalization for heart failure or cardiac death) were evaluated.

RESULTS

True CLBBB had wider bandwidth (145 ± 83° vs 110 ± 64°, P = 0.024) and higher phase SD (48 ± 26° vs 35 ± 19°, P = 0.007). Ejection fraction (EF), end-diastolic volume (EDV), summed rest score (SRS), and the presence of ischemic heart disease (IHD) showed no differences between groups (P = 0.401, 0.591, 0.165, and 0.212, respectively). Multivariate analysis revealed that true CLBBB, EF, and EDV were significant predictors of LVD (odds ratio, 12.6, 0.90, 1.03; P = 0.003, 0.002, 0.022, respectively). At 3-year follow-up (median 667 days), primary endpoints were comparable in both groups (log-rank, P = 0.92).

CONCLUSIONS

Patients with true CLBBB had more severe dyssynchrony on single-photon emission computed tomography than patients with nontrue CLBBB. On the other hand, the two groups showed no differences in EF, EDV, the presence of IHD, hospitalization for heart failure, and cardiac death.

Rate-dependent Left Bundle Branch Block during Anaesthesia

Rate-dependent left bundle branch block during general anaesthesia is rare. Its occurrence makes electrocardiographic diagnosis of acute myocardial ischaemia or infarction difficult. It can also be confused with a slow rate ventricular tachycardia. We present a case of rate-dependent left bundle branch block in a patient with no previous history of ischaemic heart disease. Carotid sinus massage resulted in a decrease in heart rate and reversion to normal sinus rhythm.

Clinical assessment of intraventricular blood transport in patients undergoing cardiac resynchronization therapy

In the healthy heart, left ventricular (LV) filling generates different flow patterns which have been proposed to optimize blood transport by coupling diastole and systole. This work presents a novel image-based method to assess how different flow patterns influence LV blood transport in patients undergoing cardiac resynchronization therapy (CRT). Our approach is based on solving the advection equation for a passive scalar field from time-resolved blood velocity fields. Imposing time-varying inflow boundary conditions for the scalar field provides a straightforward method to distinctly track the transport of blood entering the LV in the different filling waves of a given cardiac cycle, as well as the transport barriers which couple filling and ejection. We applied this method to analyze flow transport in a group of patients with implanted CRT devices and a group of healthy volunteers. Velocity fields were obtained using echocardiographic color Doppler velocimetry, which provides two-dimensional time-resolved flow maps in the apical long axis three-chamber view of the LV. In the patients under CRT, the device programming was varied to analyze flow transport under different values of the atrioventricular conduction delay, and to model tachycardia (100 bpm). Using this method, we show how CRT influences the transit of blood inside the left ventricle, contributes to conserving kinetic energy, and favors the generation of hemodynamic forces that accelerate blood in the direction of the LV outflow tract. These novel aspects of ventricular function are clinically accessible by quantitative analysis of color-Doppler echocardiograms.

Conduction Abnormalities after Transcatheter Aortic Valve Implantation and Diastolic Dysfunction

OBJECTIVES

Transcatheter aortic valve implantation (TAVI) is frequently associated with the development of conduction abnormalities. We assessed the effect of conduction abnormalities on diastolic function following TAVI.

METHODS

In total, 101 consecutive post-TAVI patients were included, each with echocardiographic follow-up at 1 and 6 months. Diastolic properties were correlated with the occurrence of a long PR interval and wide QRS, and their change from baseline. The measured diastolic parameters included E/A ratio, E wave deceleration time, E wave to e' ratio, left atrial (LA) volume, and systolic pulmonary artery pressure (SPAP). The clinical outcome was all-cause mortality.

RESULTS

Overall, TAVI was associated with a consistent decrease in SPAP at the 1- and 6-month follow-up. LA volumes were increased at 1 month post-TAVI in patients with a wide compared to normal QRS (p = 0.03) and at 6 months in patients with a normal compared to prolonged PR (p = 0.03). PR prolongation above 40 ms was associated with lower SPAP at the 1- but not 6-month follow-up. Survival was not influenced by conduction abnormalities.

CONCLUSIONS

TAVI is associated with a reduction in SPAP. A postprocedural wide QRS and normal PR interval may unfavorably influence the left-sided filling performance, resulting in an increased LA volume. Other diastolic parameters, as well as survival, are not significantly affected by postprocedural conduction abnormalities.

Ventricular pacing - Electromechanical consequences and valvular function

Although great strides have been made in the areas of ventricular pacing, it is still appreciated that dyssynchrony can be malignant, and that appropriately placed pacing leads may ameliorate mechanical dyssynchrony. However, the unknowns at present include: 1. The mechanisms by which ventricular pacing itself can induce dyssynchrony; 2. Whether or not various pacing locations can decrease the deleterious effects caused by ventricular pacing; 3. The impact of novel methods of pacing, such as atrioventricular septal, lead-less, and far-field surface stimulation; 4. The utility of ECG and echocardiography in predicting response to therapy and/or development of dyssynchrony in the setting of cardiac resynchronization therapy (CRT) lead placement; 5. The impact of ventricular pacing-induced dyssynchrony on valvular function, and how lead position correlates to potential improvement. This review examines the existing literature to put these issues into context, to provide a basis for understanding how electrical, mechanical, and functional aspects of the heart can be distorted with ventricular pacing. We highlight the central role of the mitral valve and its function as it relates to pacing strategies, especially in the setting of CRT. We also provide future directions for improved pacing modalities via alternative pacing sites and speculate over mechanisms on how lead position may affect the critical function of the mitral valve and thus overall efficacy of CRT.

Ablation of frequent premature ventricular complex in an athlete

Premature ventricular complex are common findings in the exam of many athletes. There is no extensive scientific evidence in the management of this situation particularly when associated with borderline contractile function of the left ventricle. In this case report, we present a 35-year-old asymptomatic healthy athlete with high incidence (over 10,000 beats in 24 h) of premature ventricular complex and left ventricular dilatation with dysfunction, which persisted after a resting period of 6 months without training. We performed radiofrequency ablation of the premature ventricular complex focus. After 1-year follow-up, he was asymptomatic without arrhythmia and the left ventricle normalized its size and function as shown by echocardiogram and cardiac magnetic resonance.

Mechanical discoordination increases continuously after the onset of left bundle branch block despite constant electrical dyssynchrony in a computational model of cardiac electromechanics and growth

AIMS

To test whether a functional growth law leads to asymmetric hypertrophy and associated changes in global and regional cardiac function when integrated with a computational model of left bundle branch block (LBBB).

METHODS AND RESULTS

In recent studies, we proposed that cardiac myocytes grow longer when a threshold of maximum fibre strain is exceeded and grow thicker when the smallest maximum principal strain in the cellular cross-sectional plane exceeds a threshold. A non-linear cardiovascular model of the beating canine ventricles was combined with the cellular growth law. After inducing LBBB, the ventricles were allowed to adapt in shape over time in response to mechanical stimuli. When subjected to electrical dyssynchrony, the combined model of ventricular electromechanics, haemodynamics, and growth led to asymmetric hypertrophy with a faster increase of wall mass in the left ventricular (LV) free wall (FW) than the septum, increased LV end-diastolic and end-systolic volumes, and decreased LV ejection fraction. Systolic LV pressure decreased during the acute phase of LBBB and increased at later stages. The relative changes of these parameters were similar to those obtained experimentally. Most of the dilation was due to radial and axial fibre growth, and hence altered shape of the LVFW.

CONCLUSION

Our previously proposed growth law reproduced measured dyssynchronously induced asymmetric hypertrophy and the associated functional changes, when combined with a computational model of the LBBB heart. The onset of LBBB leads to a step increase in LV mechanical discoordination that continues to increase as the heart remodels despite the constant electrical dyssynchrony.

Clinical Impact of Persistent Left Bundle-Branch Block After Transcatheter Aortic Valve Implantation With CoreValve Revalving System

Background—

Conduction disturbances are relatively common after transcatheter aortic valve implantation. Previous data demonstrated an adverse impact of persistent left bundle-branch block (LBBB) after surgical aortic valve replacement. It is unclear whether new-onset LBBB may also impact the prognosis of patients after transcatheter aortic valve implantation.

Methods and Results—

Among 1060 patients treated with a CoreValve Revalving System transcatheter aortic valve implantation between October 2007 and April 2011 in high-volume centers in Italy, we analyzed those without LBBB or pacemaker at admission (879 patients [82.9%]). We further excluded those who underwent permanent pacemaker implantation within 48 hours after the procedure (61 patients [7%]), for a final study population of 818 patients. Among them, 224 patients (group A; 27.4%) developed a persistent LBBB and the remaining 594 (group B; 72.6%) did not. Clinical characteristics were similar between groups. A low implantation was significantly more frequent in group A (15% versus 9.8%, P =0.02). No patients were censored before 1 year (median follow-up period 438 days, interquartile range 174–798 days). Survival analyses and inherent log-rank tests showed that LBBB was not associated with higher all-cause mortality, cardiac mortality, or hospitalization for heart failure at 30 days or 1 year. At 30 days, but not at 1 year, group A had a significantly higher rate of pacemaker implantation.

Conclusions—

In this registry of high-volume centers, persistent LBBB after CoreValve Revalving System transcatheter aortic valve implantation showed no effect on hard end points. On the other hand, LBBB was associated with a higher short-term rate of pacemaker implantation.

Asymptomatic Left Bundle Branch Block Predicts New-Onset Congestive Heart Failure and Death From Cardiovascular Diseases

Background

Left bundle branch block (LBBB) has been proposed as a risk factor for cardiovascular morbidity and mortality. We sought to characterize the strength of these associations in a population without preexisting clinical heart disease.

Methods

The association between LBBB and new-onset congestive heart failure (CHF) or death from cardiovascular diseases was examined in 1,688 participants enrolled in the SPPARCS study who were free of known CHF or previous myocardial infarction. SPPARCS is a community-based cohort study in residents of Sonoma, California that are > 55 years. Medical history and 12-lead ECGs were obtained every 2 years for up to 6 years of follow-up. LBBB at enrollment or year 2 was considered “baseline” and assessed as a predictor of CHF and cardiovascular death ascertained at years 4 and 6.

Results

The prevalence of LBBB at baseline was 2.5% (n = 42). During 6 years of follow-up, 70 (4.8%) people developed new CHF. Incidence of CHF was higher in patients with LBBB than in participants without LBBB. This association persisted after controlling for potential confounders (odds ratio (OR): 2.85; 95% confidence interval (CI): 1.01 - 8.02; P = 0.047). A higher mortality from cardiovascular diseases was also found in participants with LBBB after adjusting for potential confounders (OR: 2.35, 95%CI: 1.02 - 5.41; P = 0.044).

Conclusions

LBBB in the absence of a clinically detectable heart disease is associated with new-onset CHF and death from cardiovascular diseases. Further study is warranted to determine if additional diagnostic testing or earlier treatment in patients with asymptomatic LBBB can decrease cardiovascular morbidity or mortality.

Treatment options in end-stage heart failure: where to go from here?

Chronic heart failure is a major healthcare problem associated with high morbidity and mortality. Despite significant progress in treatment strategies, the prognosis of heart failure patients remains poor. The golden standard treatment for heart failure is heart transplantation after failure of medical therapy, surgery and/or cardiac resynchronisation therapy. In order to improve patients’ outcome and quality of life, new emerging treatment modalities are currently being investigated, including mechanical cardiac support devices, of which the left ventricular assist device is the most promising treatment option. Structured care for heart failure patients according to the most recent international heart failure guidelines may further contribute to optimal decision-making. This article will review the conventional and novel treatment modalities of heart failure.

A man awaiting a double transplant

A 40-year-old gentleman previously fit and well presented to hospital on Christmas day in 2003 with dyspnoea, indigestion and 'pins and needles' down his left arm. Investigations in the emergency department were normal, so the patient was discharged from hospital with a diagnosis of panic attacks. A month later he re-presented to hospital, again with an indigestion-like pain in the chest, worsening dyspnoea, poor exercise tolerance and paroxysmal nocturnal dyspnoea. Myocardial infarction was diagnosed, as well as dilated cardiomyopathy. The patient was subsequently put on the heart transplant register. First he had a pacemaker put in, and 4 months later a defibrillator was inserted which dramatically improved the patient's signs and symptoms. He felt well in himself for 7 years; however began to deteriorate in August 2010. No heart transplants were available at the time, so the patient was offered a ventricular assist device in September 2010. The patient went into kidney failure in December 2010 and haemodialysis was commenced in January 2011. He is currently at home awaiting a double heart and kidney transplant.

Effects of right ventricular septal versus apical pacing on plasma natriuretic peptide levels

Background:

To investigate the contribution of right ventricular (RV) pacing sites to the cardiac function, this study compares plasma B-type natriuretic peptide (BNP) levels during RV septal and apical pacing in patients implanted with a pacemaker.

Materials and Methods and Results:

Seventy-four consecutive patients with indication for permanent pacing were included. To provide for the possibility of appropriate subgroup analyses, patients were stratified according to their pacing mode into two groups: Those with dual chamber DDD(R)/VDD pacemakers (41 patients, mean age 54.1±18.4 years), and those with single chamber VVI pacemakers (33 patients, mean age 60.6±18.4 years). A prospective single-blinded randomized design was used. Randomization (1:1 way) was between lead placement on the RV septum or RV apex and occurred during the implant in both groups. Compared to baseline, a significant decrease in BNP (429.8±103 pg/ml and 291.7±138 pg/ml, respectively) levels was observed during DDD(R) /VDD pacing after two months. In contrast, during VVI (R) pacing, a significant increase in BNP levels was observed (657.5±104 pg/ml and 889.5±139 pg/ml, respectively). To determine the impact of pacing sites on cardiac function, we assessed the changes in BNP levels in each group separately. Despite the significant difference in the pattern of changes between the two groups (P < 0.02), no significant changes were observed within groups regarding the acute effect of the pacing site (RV apex vs. RV septal) on BNP levels (P=NS).

Conclusions:

Our main result showed no significant differences between pacing sites and concluded that hemodynamic improvement could be substantially influenced by pacing mode, more than by pacing site.

Effect of right ventricular pacing site on QRS Width

To assess the effect of various right ventricular pacing sites on QRS duration, we enrolled 50 patients (mean age, 64 ± 13 years; 36 men); 16 had bradycardia and 34 had tachycardia. The right ventricle was arbitrarily divided into 5 sections: high and low right ventricular outflow tract, mid septum, low septum, and apex. Right ventricular pacing was performed using an electrode catheter at each of the 5 sites. QRS duration was 162 ± 20 ms during high right ventricular outflow tract pacing, 143 ± 17 ms during low right ventricular outflow tract pacing, 151 ± 20 ms during mid-septal pacing, 163 ± 16 ms during low-septal pacing, and 167 ± 18 ms during apical pacing. Paced QRS duration was shorter during low right ventricular outflow tract and mid-septal pacing compared to apical pacing in 34 patients. There was a difference of 10 ms or less in the paced QRS duration between these pacing sites in the other 16 patients. QRS duration was shortest when the septum was paced in the right ventricle. However, QRS duration was similar during pacing in the septum and the apex in 32% of patients.

Reversal of ventricular premature beat induced cardiomyopathy by radiofrequency catheter ablation

Frequent monomorphic ventricular premature beats (VPBs) may lead to left ventricular dysfunction. We describe two patients with frequent monomorphic VPBs and dilated cardiomyopathy in whom left ventricular function normalised after elimination of the VPBs by radiofrequency catheter ablation. The recent literature on this topic is summarised and potential candidates for catheter ablation are discussed. (Neth Heart J 2010;18:493-8.).

Concordant versus discordant left bundle branch block in heart failure patients: novel clinical value of an old electrocardiographic diagnosis

BACKGROUND

Over the last 50 years left bundle branch block (LBBB) has been defined as homophasic (concordant: cLBBB) or heterophasic (discordant: dLBBB) when associated with a positive or negative T wave in leads I and V5-V6, respectively. LBBB is recognized as an adverse prognostic factor in heart failure (HF). The prevalence and clinical significance of cLBBB and dLBBB in HF patients are unknown.

METHODS AND RESULTS

A total of 897 consecutive systolic HF patients (age 65 +/- 13 years, left ventricular ejection fraction [LVEF], 34 +/- 10%) underwent clinical characterization, electrocardiographic evaluation for LBBB diagnosis and classification, and follow-up for cardiac events (median 37 months, range 1-84). LBBB was diagnosed in 232 patients (26%), cLBBB in 71 (31%), and dLBBB in 161 (69%). The dLBBB patients were older than those with cLBBB, and presented with lower LVEF, greater left ventricular telediastolic diameter and left ventricular mass index, higher level of brain natriuretic peptide, N-terminal pro-brain natriuretic peptide, renin activity, and norepinephrine (all P < .05). At Kaplan-Meier analysis, LBBB (P = .003) and dLBBB (P = .036) were associated with a worse prognosis when the composite end point of sudden death and implantable cardioverter defibrillator shock was considered.

CONCLUSIONS

In systolic HF, dLBBB is associated with a worse clinical, neurohormonal, and prognostic profile. LBBB classification could represent a useful tool in routine clinical evaluation.

Therapeutic strategies for diastolic dysfunction: a clinical perspective

Diastolic dysfunction, which is increasingly viewed as being influential in precipitating heart failure and determining prognosis, is often unrecognized and has therapeutic implications distinct from those that occur with systolic dysfunction. In this review, several therapeutic modalities including pharmacologic, nonpharmacologic, and surgical approaches for primary diastolic dysfunction and heart failure will be discussed.

Response to cardiac resynchronization therapy: is it time to expand the criteria?

BACKGROUND

Cardiac resynchronization therapy (CRT) is a promising treatment for a subgroup of patients with advanced congestive heart failure and a prolonged QRS interval. Despite the majority of patients benefiting from CRT, 10-40% of patients do not respond to this treatment and are labeled as nonresponders. Given that there is a lack of consensus on how to define response to CRT, the purpose of this viewpoint is to discuss currently used definitions and their shortcomings, and to provide recommendations as to how an expansion of the criteria for CRT response may be useful to clinicians.

METHODS AND RESULTS

Analysis of the literature and case reports indicates that the majority of established measures of CRT response, including New York Heart Association functional class and echocardiographic, hemodynamic, and neurohormonal parameters, are poor associates of patient-reported symptoms and quality of life. Moreover, the potential moderating role of psychological factors in determining health outcomes after CRT has largely been neglected.

CONCLUSIONS

It is recommended to routinely assess health status after CRT with a disease-specific questionnaire in standard clinical practice and to examine its determinants, including psychological factors such as personality traits and depression. This may lead to improved (secondary) treatment and prognosis in CHF patients treated with CRT.

Biventricular pacing: impact on exercise-induced increases in mitral insufficiency in patients with chronic heart failure

INTRODUCTION

Mitral regurgitation (MR) in chronic heart failure (CHF) patients frequently worsens with exercise. Cardiac resynchronization therapy (CRT) reduces MR at rest, but its effects on exercise-induced worsening of MR are incompletely explored. The present study examined the influence of CRT on MR during submaximal exercise in CHF patients.

METHODS

Eleven patients with CHF who were treated with CRT underwent echocardiography while performing steady-state exercise during four conduction modes (intrinsic rhythm, right ventricular [RV], biventricular [BiV] and left ventricular [LV] pacing). Measurements of MR were jet area planimetry, effective regurgitant orifice area, peak MR flow rate and regurgitant volume.

RESULTS

At rest and during exercise, there were no differences in dyssynchrony between intrinsic rhythm and RV pacing. BiV and LV pacing reduced dyssynchrony at rest and during exercise compared with intrinsic conduction and RV pacing, and there were no differences in the magnitude of these effects between these two pacing modes. At rest, RV pacing increased MR compared with intrinsic conduction (MR regurgitant volume; P<0.05), whereas BiV and LV pacing reduced MR (reductions in effective regurgitant orifice area and jet area; P<0.02, and MR flow rate; P<0.05 with BiV pacing from intrinsic conduction). MR significantly increased on exercise with intrinsic rhythm and RV pacing, whereas with LV and BiV pacing, there were no significant exercise-induced increases in any MR variable. There were relationships between changes in measures of dyssynchrony and reductions in MR at rest and during exercise.

CONCLUSIONS

CRT reduces MR at rest and during exercise, and prevents exercise-induced MR. Reductions in MR during exercise correlate with improvements in dyssynchrony.