Evaluation of super-responders to cardiac resynchronization therapy in the presence of left bundle branch block and absence of scar in the posterolateral wall of the left ventricle

Patients with heart failure (HF) undergoing cardiac resynchronization therapy (CRT) who exhibit above-expected improvement are known as super-responders. We assessed the rate of super-responders in a population with left bundle branch block (LBBB) > 150 ms in the absence of scar tissue in the left ventricular posterolateral wall as well as prognostic variables. In this prospective observational cohort study (n=20) an electrocardiogram (ECG) was performed pre- and post-CRT. The classic and Strauss LBBB criteria were adopted (> 150 ms). The percent (%) reduction of the QRS was calculated after implantation. All patients responded to the Minnesota Living with Heart Failure questionnaire and underwent an echocardiogram to measure left ventricular ejection function (LVEF), left atrium (LA) diameter, left ventricular end-systolic volume (LVEDV), left ventricular end-diastolic volume (LVESV), and left ventricular end-diastolic diameter (LVEDD) pre- and 6 months post-CRT. Cardiac magnetic resonance imaging (MRI) measured the presence of scar tissue in the posterolateral LV wall and the total scar burden (% LV mass). Fisher's exact test and the Mann-Whitney test were performed to evaluate possible prognostic variables. The mean age was 58.20±8.79 years old, 60% female, with a mean LVEF of 28.15±5.10%, ECG with LBBB mean QRS of 162.15±7.86 ms, LBBB > 150 ms with Strauss standard in 90% of cases, and 90% with non-ischemic cardiomyopathy. Twelve cases (60%) of super-responders (reduction > 30% LVESV after 6 months) were observed. Super-responders did not present a difference in response in sex (12 vs 8 P=0.67), age (58.67 vs 57.7 P=087), Minnesota quality of life (55.50 vs 67.70 P=0.2), % initial QRS reduction (21.16 vs 18.69 P=0.21), LVEF (29.25 vs 26.5 P=0.38), LVEDD (66.33 vs 67.67 P=0.83), LVEDV (211.16 vs 228.53 P=0.75), LVESV (145.83 vs 167.00 P=0.75), or LA diameter (41.58 vs 43.63 P=0.45). The presence of LBBB > 150 ms, using the Strauss standard (90%) and the absence of scar in the posterolateral wall may account for these positive results. Super-responders benefit the most from CRT, and the results of this study can contribute to a better selection of CRT candidates.

Simplified method for esophagus protection during radiofrequency catheter ablation of atrial fibrillation--prospective study of 704 cases

Introduction

Although rare, the atrioesophageal fistula is one of the most feared complications in radiofrequency catheter ablation of atrial fibrillation due to the high risk of mortality.

Objective

This is a prospective controlled study, performed during regular radiofrequency catheter ablation of atrial fibrillation, to test whether esophageal displacement by handling the transesophageal echocardiography transducer could be used for esophageal protection.

Methods

Seven hundred and four patients (158 F/546M [22.4%/77.6%]; 52.8±14 [17-84] years old), with mean EF of 0.66±0.8 and drug-refractory atrial fibrillation were submitted to hybrid radiofrequency catheter ablation (conventional pulmonary vein isolation plus AF-Nests and background tachycardia ablation) with displacement of the esophagus as far as possible from the radiofrequency target by transesophageal echocardiography transducer handling. The esophageal luminal temperature was monitored without and with displacement in 25 patients.

Results

The mean esophageal displacement was 4 to 9.1cm (5.9±0.8 cm). In 680 of the 704 patients (96.6%), it was enough to allow complete and safe radiofrequency delivery (30W/40ºC/irrigated catheter or 50W/60ºC/8 mm catheter) without esophagus overlapping. The mean esophageal luminal temperature changes with versus without esophageal displacement were 0.11±0.13ºC versus 1.1±0.4ºC respectively, P<0.01. The radiofrequency had to be halted in 68% of the patients without esophageal displacement because of esophageal luminal temperature increase. There was no incidence of atrioesophageal fistula suspected or confirmed. Only two superficial bleeding caused by transesophageal echocardiography transducer insertion were observed.

Conclusion

Mechanical esophageal displacement by transesophageal echocardiography transducer during radiofrequency catheter ablation was able to prevent a rise in esophageal luminal temperature, helping to avoid esophageal thermal lesion. In most cases, the esophageal displacement was sufficient to allow safe radiofrequency application without esophagus overlapping, being a convenient alternative in reducing the risk of atrioesophageal fistula.

Comparison of electrophysiological parameters of septal and apical endocardial cardiac stimulation

BACKGROUND

The conventional right ventricle (RV) endocardial pacing leads QRS widening and desynchronization myocardial compromising ventricular function. With the need for stimulation less deleterious, RV septal pacing has been used more. Eventually have been reported higher thresholds and smaller R waves in the septal stimulation.

OBJECTIVE

To compare the parameters of the septal and apical stimulation, intra-patient, if there are any differences that may affect the choice of the point of stimulation.

METHODS

A prospective controlled study. We included 25 patients, 67.2±9 years, 10 (40%) women with indications for pacemaker for bradyarrhythmias. Etiologies were degenerative in nine (36%), Coronary disease in eight (32%), Chagas disease in seven (28%), and valve disease in one (4%) patient. Electrodes were active fixation and assessed the thresholds of command, impedance and R wave in uniand bipolar implant and after six months.

RESULTS

The average acute threshold command, R wave and impedance unipolar / bipolar septais x apicais were respectively 0.73 x 0.73V and 0,74V x 0,78V; 10 x 9,9mV and 12,3 x 12,4mV; 579 x 621Ω and 611 x 629Ω. Comparisons between parameters with septal and apical two-tailed paired t-test showed a P > 0.1. After six months, the mean control thresholds, R wave impedances and unipolar/bipolar septais x apicais were respectively 0.5V x 0 72V and 0.71V x 0,87V; 11.4 x 9,5mV and 12x11,2mV; 423x426 Ω and 578x550 Ω, with P > 0.05, except compared to unipolar pacing threshold septal apical unipolar P 0.02.

CONCLUSION

Using intra-patient comparisons, no significant differences between electrophysiological parameters septal and apical pacing and there are no restrictions for choosing the right ventricular septal pacing.

Association of Bartonella spp bacteremia with Chagas cardiomyopathy, endocarditis and arrhythmias in patients from South America

Infection with Bartonella spp may cause cardiac arrhythmias, myocarditis and endocarditis in humans. The aim of the present study was to evaluate a possible association between Bartonella spp bacteremia and endocarditis, arrhythmia and Chagas cardiomyopathy in patients from Brazil and Argentina. We screened for the presence of bacterial 16S rRNA in human blood by PCR using oligonucleotides to amplify a 185-bp bacterial DNA fragment. Blood samples were taken from four groups of subjects in Brazil and Argentina: i) control patients without clinical disease, ii) patients with negative blood-culture endocarditis, iii) patients with arrhythmias, and iv) patients with chronic Chagas cardiomyopathy. PCR products were analyzed on 1.5% agarose gel to visualize the 185-bp fragment and then sequenced to confirm the identity of DNA. Sixty of 148 patients (40.5%) with cardiac disease and 1 of 56 subjects (1.8%) from the control group presented positive PCR amplification for Bartonella spp, suggesting a positive association of the bacteria with these diseases. Separate analysis of the four groups showed that the risk of a Brazilian patient with endocarditis being infected with Bartonella was 22 times higher than in the controls. In arrhythmic patients, the prevalence of infection was 45 times higher when compared to the same controls and 40 times higher for patients with Chagas cardiomyopathy. To the best of our knowledge this is the first report of the association between Bartonella spp bacteremia and Chagas disease. The present data may be useful for epidemiological and prevention studies in Brazil and Argentina.

Right ventricular apical pacing: the unwanted model of cardiac stimulation?

Despite having a huge benefit in enabling heart rate control, cardiac pacing by stimulating the right ventricular apex causes an artificial iatrogenic left bundle-branch block-like syndrome. As a result, QRS widening and cardiac wall desynchronization occurs. The problems caused by this undesirable pacemaker side effect have been ignored, as they are counteracted by the great benefit of cardiac rate correction. However, the compelling evidence about its harmful effect presented in this article cannot be disregarded and should start an attitude change toward alternate sites of ventricular pacing and preclusion of the right ventricular apex stimulation.

Ablação da fibrilação atrial por cateter com radiofreqüência guiada por mapeamento espectral endocárdico dos "ninhos de FA" em ritmo sinusal

BACKGROUND

Two types of myocardia can be observed through the endocardial spectral mapping (SM) in sinus rhythm: the compact type with a smooth spectrum and the fibrillar type with a segmented spectrum (atrial fibrillation nests). During the atrial fibrillation (AF), the compact type has an organized activation and low frequency (passive), whereas the fibrillar type has a rather disorganized activation and high frequency (active/resonant), with both being activated by high-frequency sustained tachycardia--the background tachycardia (BT).

OBJECTIVE

To describe the treatment of AF by the ablation of the AF nests and BT.

METHODS

1) Catheter ablation of the AF nests with RF [4/8 mm-60 masculine/30-40 J/30s] guided by SM in sinus rhythm, outside the pulmonary vein; 2) atrial stimulation -300 ppm; 3) Additional ablation of the AF nests if AF is induced; 4) Focal ablation if BT and/or Flutter is induced; 5) Clinical follow-up+ ECG+ Holter.

RESULTS

A total of 50+/-18 AF nests/patient were treated. After 11.3+/-8 m, 81 patients (88%) did not present AF (28.3% with antiarrhythmic drugs). After the ablation of the AF nests, AF was not reinduced in 61 patients (71%) and BT was induced and treated in 24 patients (26%). There were two episodes of pericardial bleeding (1 treated clinically and 1 surgically), caused by sheaths that are no longer used

CONCLUSION

The SM in sinus rhythm can be used in the ablation of AF nests. During the AF, the AF nests present a reactive-resonant pattern and the compact myocardium is passive, stimulated by the high frequency of the BT. After the ablation of the AF nests and the BT, it was not possible to reinduce the sustained AF. The Ablation of AF nests outside the pulmonary veins showed to be safe and highly effective in the cure and/or clinical control of the AF.