Effect of pacing-induced ventricular dyssynchrony on right ventricular function.

BACKGROUND: Asynchronous electrical activation induced by right ventricular (RV) pacing can cause several abnormalities in left ventricular (LV) function. However, the effect of ventricular pacing on RV function has not been well established. We evaluated RV function in patients undergoing long-term RV pacing. METHODS: Eighty-five patients and 24 healthy controls were included. After pacemaker implantation, conventional echocardiography and strain imaging were used to analyze RV function. Strain imaging measurements included peak systolic strain and strain rate. LV function and ventricular dyssynchrony by tissue Doppler imaging (TDI) were assessed. Intra- and interobserver variabilities of TDI parameters were tested on 15 randomly selected cases. RESULTS: All patients were in New York Heart Association functional class I or II and percentage of ventricular pacing was 96 ± 4%. RV apical induced interventricular dyssynchrony in 49 patients (60%). LV dyssynchrony was found in 51 patients (60%), when the parameter examined was the standard deviation of the time to peak myocardial systolic velocity of all 12 segments greater than 34 ms. Likewise, septal-to-lateral delay ≥ 65 ms was found in 31 patients (36%). All echocardiographic indexes of RV function were similar between patients and controls (strain: -22.8 ± 5.8% vs -22.1 ± 5.6%, P = 0.630; strain rate: -1.47 ± 0.91 s(-1) vs -1.42 ± 0.39 s(-1) , P = 0.702). Intra- and interobserver variability for RV strain was 3.1% and 5.3%, and strain rate was 1.3% and 2.1%, respectively. CONCLUSIONS: In patients with standard pacing indications, RV apical pacing did not seem to affect RV systolic function, despite induction of electromechanical dyssynchrony.

Health-related quality of life in Brazilian pacemaker patients.

BACKGROUND: Most quality of life (QoL) studies of pacemaker patients have been conducted in either North America or Europe and their applicability to Latin American populations is largely unknown. Our aim is to study health-related QoL indices in Brazilian pacemaker patients and their determinants using both a generic (SF-36) and a disease-specific questionnaire (AQUAREL). METHODS: The study enrolled 139 clinically stable patients (aged 59 +/- 14, 60.4% female) without any communication or cognitive impairments who went to the Pacemaker Laboratory for postimplantation follow-up. All patients were submitted to a standard protocol, which included an interview, functional class assessment, and QoL questionnaires. Additionally, 74 patients were requested to perform a 6-minute walk test. RESULTS: Female patients and patients without a partner displayed low QoL scores in both the SF-36 mental component summary and the AQUAREL arrhythmia domain. Chagas disease patients displayed low scores only in AQUAREL domains. All health-related QoL scores were low in patients with the worst, high-numbered functional classes, the strongest determinant of low QoL scores in multivariate analysis. CONCLUSION: In this first systematic study of QoL in a Latin American pacemaker population, AQUAREL detected well-impaired health-related QoL scores in different groups of patients, particularly in those with Chagas disease. Heart failure, evaluated by functional class, was the strongest predictor of low QoL in pacemaker patients.

Automatic adjustment of pacing output in the clinical setting.

BACKGROUND: AutoCapture (AC) is a programmable feature that enables the pacemaker to both track the capture threshold and automatically adjust the output on a beat-by-beat basis. Although AC safely and significantly reduces the current drainage, some authors have argued that the longevity benefit of such a system is overstated. This study aims to estimate the longevity extension that can be obtained, in the clinical routine, by turning the AC on in comparison to pacemakers programmed to operate at the shipped and manually optimized output. METHODS: We selected 83 consecutive patients who received implanted St Jude's Affinity pacemakers >6 months earlier. Eight patients died or were lost to follow-up and in 9 subjects the AC could not be turned on. In the remaining 66 patients, current drain and estimated longevity were compared in 3 situations: (1) AC on; (2) AC off, optimized programming (100%-150% voltage threshold); (3) AC off, shipped output (3.5 V). RESULTS: Five patients had large variations (>1 V) of the AC threshold. Current drainage was 8.0 +/- 0.9 mA in the AC group, 8.7 +/- 1.8 mA with AC off and optimized programming, and 11.3 +/- 2.3 mA at shipped output (P <.01). Estimated longevity was significantly extended (P <.01) by AC (12.1 +/- 1.0 years) when compared to shipped (8.9 +/- 1.7 years) and optimized programming (11.3 +/- 1.4 years). CONCLUSION: Reprogramming the pacemaker output significantly enhanced its estimated longevity; AC added a moderate but significant extension over manual reprogramming and was associated with increased safety in patients with large ventricular threshold variations.