Effects of cardiac resynchronization therapy on muscle sympathetic nerve activity.

INTRODUCTION: Muscle sympathetic nerve activity (MSNA) is an independent prognostic marker in patients with heart failure (HF). Therefore, its relevance to the treatment of HF patients is unquestionable. OBJECTIVES: In this study, we investigated the effects of cardiac resynchronization therapy (CRT) on MSNA response at rest and during exercise in patients with advanced HF. METHODS: We assessed 11 HF patients (51 ± 3.4 years; New York Heart Association class III-IV; left ventricular ejection fraction 27.8 ± 2.2%; optimal medical therapy) submitted to CRT. Evaluations were made prior to and 3 months after CRT. MSNA was performed at rest and during moderate static exercise (handgrip). Peak oxygen consumption (VO2 ) was evaluated by means of cardiopulmonary exercise test. HF patients with advanced NYHA class without CRT and healthy individuals were also studied. RESULTS: CRT reduced MSNA at rest (48.9 ± 11.1 bursts/min vs 33.7 ± 15.3 bursts/min, P < 0.05) and during handgrip exercise (MSNA 62.3 ± 13.1 bursts/min vs 46.9 ± 14.3 bursts/min, P < 0.05). Among HF patients submitted to CRT, the peak VO2 increased (12.9 ± 2.8 mL/kg/min vs 16.5 ± 3.9 mL/kg/min, P < 0.05) and an inverse correlation between peak VO2 and resting MSNA (r = -0.74, P = 0.01) was observed. CONCLUSIONS: In patients with advanced HF and severe systolic dysfunction: (1) a significant reduction of MSNA (at rest and during handgrip) occurred after CRT, and this behavior was significantly superior to HF patients receiving only medical therapy; (2) MSNA reduction after CRT had an inverse correlation with O2 consumption outcomes.

Global and regional ventricular repolarization study by body surface potential mapping in patients with left bundle-branch block and heart failure undergoing cardiac resynchronization therapy.

BACKGROUND: The controversial effects promoted by cardiac resynchronization therapy (CRT) on the ventricular repolarization (VR) have motivated VR evaluation by body surface potential mapping (BSPM) in CRT patients. METHODS: Fifty-two CRT patients, mean age 58.8 ± 12.3 years, 31 male, LVEF 27.5 ± 9.2, NYHA III-IV heart failure with QRS181.5 ± 14.2 ms, underwent 87-lead BSPM in sinus rhythm (BASELINE) and biventricular pacing (BIV). Measurements of mean and corrected QT intervals and dispersion, mean and corrected T peak end intervals and their dispersion, and JT intervals characterized global and regional (RV, Intermediate, and LV regions) ventricular repolarization response. RESULTS: Global QTm (P < 0.001) and QTc(m) (P < 0.05) were decreased in BIV; QTm was similar across regions in both modes (P = ns); QTc(m) values were lower in RV/LV than in Intermediate region in BASELINE and BIV (P < 0.001); only RV/Septum showed a significant difference (P < 0.01) in the BIV mode. QTD values both of BASELINE (P < 0.01) and BIV (P < 0.001) were greater in the Intermediate than in the LV region. CRT effect significantly reduced global/regional QTm and QTc(m) values. QTD was globally decreased in RV/LV (Intermediate: P = ns). BIV mode significantly reduced global T peak end mean and corrected intervals and their dispersion. JT values were not significant. CONCLUSIONS: Ventricular repolarization parameters QTm, QTc(m), and QTD global/regional values, as assessed by BSPM, were reduced in patients under CRT with severe HF and LBBB. Greater recovery impairment in the Intermediate region was detected by the smaller variation of its dispersion.

Cardiac resynchronization therapy evaluated by myocardial scintigraphy with 99mTc-MIBI: changes in left ventricular uptake, dyssynchrony, and function.

PURPOSE: (99m)Tc-MIBI gated myocardial scintigraphy (GMS) evaluates myocyte integrity and perfusion, left ventricular (LV) dyssynchrony and function. Cardiac resynchronization therapy (CRT) may improve the clinical symptoms of heart failure (HF), but its benefits for LV function are less pronounced. We assessed whether changes in myocardial (99m)Tc-MIBI uptake after CRT are related to improvement in clinical symptoms, LV synchrony and performance, and whether GMS adds information for patient selection for CRT. METHODS: A group of 30 patients with severe HF were prospectively studied before and 3 months after CRT. Variables analysed were HF functional class, QRS duration, LV ejection fraction (LVEF) by echocardiography, myocardial (99m)Tc-MIBI uptake, LV end-diastolic volume (EDV) and end-systolic volume (ESV), phase analysis LV dyssynchrony indices, and regional motion by GMS. After CRT, patients were divided into two groups according to improvement in LVEF: group 1 (12 patients) with increase in LVEF of 5 or more points, and group 2 (18 patients) without a significant increase. RESULTS: After CRT, both groups showed a significant improvement in HF functional class, reduced QRS width and increased septal wall (99m)Tc-MIBI uptake. Only group 1 showed favourable changes in EDV, ESV, LV dyssynchrony indices, and regional motion. Before CRT, EDV, and ESV were lower in group 1 than in group 2. Anterior and inferior wall (99m)Tc-MIBI uptakes were higher in group 1 than in group 2 (p<0.05). EDV was the only independent predictor of an increase in LVEF (p=0.01). The optimal EDV cut-off point was 315 ml (sensitivity 89%, specificity 94%). CONCLUSION: The evaluation of EDV by GMS added information on patient selection for CRT. After CRT, LVEF increase occurred in hearts less dilated and with more normal (99m)Tc-MIBI uptake.

Cardiac sympathetic activity pre and post resynchronization therapy evaluated by 123I-MIBG myocardial scintigraphy.

BACKGROUND: Imaging with (123)I-metaiodobenzylguanidine (MIBG) is used for the assessment of cardiac sympathetic activity (CSA). We analyzed CSA before and after cardiac resynchronization therapy (CRT), and correlated these data with CRT response. METHODS AND RESULTS: Thirty patients with chronic heart failure and classic indications for CRT were prospectively studied before and at least 3 months after CRT. The variables analyzed were: QRS width, left-ventricular ejection fraction (LVEF), left-ventricular end-diastolic diameter (LVEDD), heart/mediastinum MIBG uptake ratio (H/M), and washout rate (WR). After CRT, patients were divided into two groups: group 1 (21 patients), responders improving to functional class (FC) I or II; and group 2 (9 patients), nonresponders remaining in FC III or IV. After CRT, only group 1 showed favorable changes in QRS width (P =.003), LVEF (P =.01), LVEDD (P =.04), and H/M ratio (P =.003). The H/M ratio and WR were associated with CRT response (P =.005 and P =.04, respectively). The H/M ratio was the only independent predictor of CRT response (P =.01). Receiver operating characteristic curves showed that the optimal H/M ratio cutoff point was 1.36 (sensitivity, 75%; specificity, 71%). CONCLUSIONS: Improvement in CSA correlated with a positive CRT response. Lower MIBG uptake before therapy was associated with CRT nonresponse. The H/M ratio could be helpful in selecting patients for CRT.

Is isolated congenital heart block associated to neonatal lupus requiring pacemaker a distinct cardiac syndrome?

Isolated congenital heart block (ICHB) is frequently associated with neonatal lupus syndrome (NLS). Therefore few data are available regarding the long-term cardiac outcome of newborns with ICHB and the pathogenic mechanisms are not yet defined. In order to compare demographic features and cardiological outcome of patients with ICHB submitted to pacemaker (PM) implantation with and without NLS, forty ICHB patients were evaluated pre- and post-PM implantation, by clinical, electrocardiogram, Holter Monitoring, treadmill test, and electrophysiological study. According to the presence of antibodies to 52 and 60 kDa Ro/SSA and La/SSB proteins in mother's sera, it was found that 60% (24/40) of patients had ICHB associated to NLS (ICHB/NL+). Twenty-three of 24 ICHB/NL+ patients were asymptomatic, and 16 (67%) were female (P = 0.013). The frequency of syncope, mitral insufficiency (MI), and congestive heart failure (CHF) was similar pre-PM implantation in both ICHB/NL+ and ICHB/NL- groups (P > 0.05). After PM implantation, MI and CHF were only observed in ICHB/NL+ patients, although not statistically significant. Interestingly, 67% of ICHB/NL+ were noticed before one year of age while only one fourth of ICHB/NL- was diagnosed in this period (P = 0.024). Almost half (46%) of ICHB/NL+ patients required PMs in the first 24 months of life, whereas only one in the ICHB/NL- received a PM at the same age (P = 0.02). In ICHB patients requiring PM implantation, the antibody-mediated lesion seems to be associated with an earlier onset and a more severe heart disease, in spite of the uniform criteria for PM indication.

Cardiac damage from chronic use of chloroquine: a case report and review of the literature.

Chloroquine has been widely used in rheumatological treatment, but potential severe side effects require careful follow-up. Cardiac damage is not a common consequence, but its clinical relevance has not yet been described. We report the case of a 58-year-old woman with rheumatoid arthritis, in whom chronic chloroquine use resulted in major irreversible cardiac damage. She presented with syncopal episodes due to complete atrioventricular block confirmed by electrophysiological study whose changes were concluded to be irreversible and a permanent pacemaker was indicated. Endomyocardial biopsy was also performed to search for histopathological and ultrastructural cardiac damage. We also reviewed the 22 cases of chloroquine-induced cardiopathy described to date as well as its pathophysiology.

Cardiac damage from chronic use of chloroquine: a case report and review of the literature

Chloroquine has been widely used in rheumatological treatment, but potential severe side effects require careful follow-up. Cardiac damage is not a common consequence, but its clinical relevance has not yet been described. We report the case of a 58-year-old woman with rheumatoid arthritis, in whom chronic chloroquine use resulted in major irreversible cardiac damage. She presented with syncopal episodes due to complete atrioventricular block confirmed by electrophysiological study whose changes were concluded to be irreversible and a permanent pacemaker was indicated. Endomyocardial biopsy was also performed to search for histopathological and ultrastructural cardiac damage. We also reviewed the 22 cases of chloroquine-induced cardiopathy described to date as well as its pathophysiology

Biventricular pacing improves clinical behavior and reduces prevalence of ventricular arrhythmia in patients with heart failure.

PURPOSE: To analyze the influence of biventricular pacing (BP) on clinical behavior, ventricular arrhythmia (VA) prevalence, and left ventricular ejection fraction (LV EF) by gated ventriculography. METHODS: Twenty-four patients with left bundle branch block (LBBB) and NYHA class III and IV underwent pacemaker implantation and were randomized either to the conventional or BP group, all receiving BP after 6 months. RESULTS: Sixteen patients were in NYHA class IV (66.6%) and 8 were in class III (33.4%). After 1-year follow-up, 14 patients were in class II (70%) and 5 were in class III (25%). Two sudden cardiac deaths occurred. A significant reduction in QRS length was found with BP (p=0.006). A significant statistical increase, from a mean of 19.13 +/- 5.19% (at baseline) to 25.33 +/- 5.90% (with BP) was observed in LVEF Premature ventricular contraction prevalence decreased from a mean of 10,670.00 +/- 12,595.39 SD or to a mean of 3,007.00 +/- 3,216.63 SD PVC/24 h with BP (p<0.05). Regarding the hospital admission rate over 1 year, we observed a significant reduction from 60. To 16 admissions with BP (p<0.05). CONCLUSION: Patients with LBBB and severe heart failure experienced, with BP, a significant NYHA class and LVEF improvement. A reduction in the hospital admission rate and VA prevalence also occurred.

Biventricular pacing improves clinical behavior and reduces prevalence of ventricular arrhythmia in patients with heart failure

PURPOSE: To analyze the influence of biventricular pacing (BP) on clinical behavior, ventricular arrhythmia (VA) prevalence, and left ventricular ejection fraction (LV EF) by gated ventriculography. METHODS: Twenty-four patients with left bundle branch block (LBBB) and NYHA class III and IV underwent pacemaker implantation and were randomized either to the conventional or BP group, all receiving BP after 6 months. RESULTS: Sixteen patients were in NYHA class IV (66.6 per cent) and 8 were in class III (33.4 per cent). After 1-year follow-up, 14 patients were in class II (70 per cent) and 5 were in class III (25 per cent). Two sudden cardiac deaths occurred. A significant reduction in QRS length was found with BP (p=0.006). A significant statistical increase, from a mean of 19.13 ñ 5.19 per cent (at baseline) to 25.33 ñ 5.90 per cent (with BP) was observed in LVEF Premature ventricular contraction prevalence decreased from a mean of 10,670.00 ñ 12,595.39 SD or to a mean of 3,007.00 ñ 3,216.63 SD PVC/24 h with BP (p<0.05). Regarding the hospital admission rate over 1 year, we observed a significant reduction from 60. To 16 admissions with BP (p<0.05). CONCLUSION: Patients with LBBB and severe heart failure experienced, with BP, a significant NYHA class and LVEF improvement. A reduction in the hospital admission rate and VA prevalence also occurred.

Marcapasso atrioventricular. Incidência e causas de reprogramações em seguimento a longo prazo / Atrioventricular pacemaker. Incidence and causes of reprogramming in long-term follow-up

OBJECTIVE: To assess the incidence of problems requiring reprogramming of atrioventricular pacemakers in a long-term follow-up, and also the causes for this procedure. METHODS: During the period from May '98 to December '99, 657 patients were retrospectively studied, An actuarial curve for the event reprogramming of the stimulation mode was drawn. RESULTS: The follow-up period ranged from 12 to 178 months (mean = 81 months). Eighty-two (12.4 percent) patients underwent reprogramming of the stimulation mode as follows: 63 (9.5 percent) changed to VVI,(R/C); 10 (1.5 percent) changed to DVI,C; 6 (0.9 percent) changed to VDD,C; and 3 (0.5 percent) changed to DOO. The causes for the reprogramming were as follows: arrhythmia conducted by the pacemaker in 39 (37.6 percent) patients; loss of atrial sensitivity or capture, or both, in 39 (38.6 percent) patients; and microfracture of atrial electrode in 5 (4.9 percent) patients. The stimulation mode reprogramming free probability after 15 years was 58 percent. CONCLUSION: In a long-term follow-up, the atrioventricular pacemaker provided a low incidence of complications, a high probability of permanence in the DDD,C mode, and the most common cause of reprogramming was arrhythmia conducted by the pacemaker

Bloqueios divisionais do ramo direito e áreas eletricamente inativas: diagnóstico diferencial eletro-vetocardiográico / Divisional block of the right bundle-branch and electrically inactive areas. Electrovectorcardiographic differential diagnosis

Estudam-se 100 pacientes assintomáticos (idade entre 13 e 56 anos), 82 homens, com características veto-eletrocardiográficos semelhantes, atraso final de conduçäo (AFC), na tentativa de caracterizar padröes no ECG e no VCG para o reconhecimento dos bloqueios divisionais do ramo direito. No bloqueio da divisäo superior do ramo direito (BDSRD), observa-se no ECG: 1) eixo de QRS orientado entre 30.- e 90.- ou indeterminado; 2) duraçäo de QRS normal; 3) onda S de D2 maior ou igual a onda S de D3; 4) onda R empastada em aVR; 5) ondas S presentes nas derivaçöes V5 e V6. No vetocardiograma, nota-se: 1) alça de QRS no plano frontal com orientaçäo inicial esquerda, para cima ou para baixo, rotaçäo anti-horária e morfologia afilada; 2) alça de QRS com rápida mudança de rotaçäo no momento 40 ms tanto no plano frontal quanto no horizontal, orientado para a direita; 3) AFC nos planos (horizontal, frontal e sagital) com 30 ms de duraçäo (12 cometas), orientado no PF entre 210.- e 260.-. Para bloqueio divisional inferior ou médio do ramo direito (BDIRD ou BDMRD) observou-se no ECG: 1) eixo de QRS orientado entre + 60.- - 150.-; 2) duraçäo do complexo QRS normal; 3) onda R em aVR empastada; 4) onda R nas derivaçöes D2 e D3 com baixa voltagem (näo maior que 10mm) e com entalhes na porçäo descendente; 5) ondas S presentes nas derivaçöes V5 e V6. No vetocardiograma, registra-se: 1) a alça de QRS, no PF, com orientaçäo inicial para esquerda, para baixo ou para cima e rotaçäo horária. 2) alça de QRS com rápida mudança de rotaçäo no 40.-, tanto no PF quanto no PH (da esquerda para direita) 3) AFC nos planos com duraçäo de 30 ms (12 cometas), orientado no PF, para o BDIRD, entre 120.- e 150.- para o BDMRD, entre 180.- e 200.-