Intrathoracic impedance monitoring to detect chronic heart failure deterioration: relationship to changes in NT-proBNP.

BACKGROUND: An alert algorithm, based on intrathoracic impedance monitoring, has been incorporated into a cardiac resynchronisation device (CRT) to detect pulmonary fluid accumulation, and to audibly alert patients to decompensating chronic heart failure (CHF). AIMS: To evaluate this algorithm, alert events were correlated with changes in NT-proBNP concentration and CHF status. METHODS AND RESULTS: In a prospective observational study of 62 patients (89% male, aged 67+/-1 year), NT-proBNP plasma concentrations, clinical CHF status, and device data were collected at enrolment, during regular follow-up and at device alerts. Over a mean follow-up of 27+/-2 weeks, pooled data indicated a weak, but significant inverse relationship between relative changes in intrathoracic impedance and NT-proBNP (r=-0.3; p<0.001). In 52 device alerts from 35 patients, NT-proBNP increased by 66+/-19% from 2039+/-331 pg/ml (p<0.001). The increase in NT-proBNP was higher in alerts with clinical signs of CHF deterioration (n=30, 89+/-25%; p<0.001) than in alert events without clinical signs (n=22, 25+/-15%; p=n.s.). CONCLUSION: Intrathoracic impedance based alert events are associated with a significant increase in NT-proBNP concentration. These data indicate that intrathoracic impedance monitoring might facilitate the outpatient management of CHF patients with implanted CRT devices.

Worldwide evaluation of a defibrillation lead with a small geometric electrode surface for high-impedance pacing.

BACKGROUND: Pacing leads with a small electrode surface for high-impedance stimulation have been shown to prolong pacemaker longevity, but no sufficient data is available on the safety and feasibility of a defibrillation lead with this novel design. METHODS: We evaluated the clinical performance of a tined, steroid-eluting defibrillation lead with a small electrode surface area (model 6944) in a prospective multicenter study. A total of 542 patients with conventional indications for an implantable cardioverter defibrillator were randomized 1:1 to receive either the model 6944 or a tined, steroid-eluting defibrillation lead with a conventional sized electrode surface area (model 6942). Device performance and electrical parameters were evaluated at implant and 1, 3, 6, and 12 months thereafter (mean follow-up 11.3 +/- 5.6 months). RESULTS: Baseline characteristics, lead implant success rates, and defibrillation thresholds did not differ significantly between the 2 groups. While pacing thresholds did not differ significantly during follow-up, pacing impedance was approximately twice as high in the model 6944 as in the model 6942 lead (P <.0001). Mean R-wave amplitudes were smaller in patients with a 6944 (9.1 +/- 3.1 mV vs 9.8 +/- 3.6 mV for model 6942, P <.05), but remained stable within both groups throughout the observation period. The total number of ventricular lead-related adverse events and patient survival did not differ significantly between the 2 groups. CONCLUSIONS: The use of a defibrillation lead with a small electrode surface for high-efficiency pacing is safe and feasible and increases pacing impedance without significantly compromising clinical performance.

The total right/left-volume index: a new and simplified cardiac magnetic resonance measure to evaluate the severity of Ebstein anomaly of the tricuspid valve: a comparison with heart failure markers from various modalities.

BACKGROUND: The classification of clinical severity of Ebstein anomaly still remains a challenge. The aim of this study was to focus on the interaction of the pathologically altered right heart with the anatomically-supposedly-normal left heart and to derive from cardiac magnetic resonance (CMR) a simple imaging measure for the clinical severity of Ebstein anomaly. METHODS AND RESULTS: Twenty-five patients at a mean age of 26±14 years with unrepaired Ebstein anomaly were examined in a prospective study. Disease severity was classified using CMR volumes and functional measurements in comparison with heart failure markers from clinical data, ECG, laboratory and cardiopulmonary exercise testing, and echocardiography. All examinations were completed within 24 hours. A total right/left-volume index was defined from end-diastolic volume measurements in CMR: total right/left-volume index=(RA+aRV+fRV)/(LA+LV). Mean total right/left-volume index was 2.6±1.7 (normal values: 1.1±0.1). This new total right/left-volume index correlated with almost all clinically used biomarkers of heart failure: brain natriuretic peptide (r=0.691; P=0.0003), QRS (r=0.432; P=0.039), peak oxygen consumption/kg (r=-0.479; P=0.024), ventilatory response to carbon dioxide production at anaerobic threshold (r=0.426; P=0.048), the severity of tricuspid regurgitation (r=0.692; P=0.009), tricuspid valve offset (r=0.583; P=0.004), and tricuspid annular plane systolic excursion (r=0.554; P=0.006). Previously described severity indices ([RA+aRV]/[fRV+LA+LV]) and fRV/LV end-diastolic volume corresponded only to some parameters. CONCLUSIONS: In patients with Ebstein anomaly, the easily acquired index of right-sided to left-sided heart volumes from CMR correlated well with established heart failure markers. Our data suggest that the total right/left-volume index should be used as a new and simplified CMR measure, allowing more accurate assessment of disease severity than previously described scoring systems.

Comparison of immediate and delayed automatic antitachycardia pacing for the termination of atrial tachyarrhythmias.

AIMS: Automatic atrial antitachycardia pacing (ATP) can terminate atrial tachyarrhythmias (ATs) in patients with an implanted device. We investigated if the programmable delay between AT onset and ATP influences therapy efficacy. METHODS: Patients with intermittent ATs and an implanted DDDRP pacemaker were randomized to receive ATP either immediately or 30min after AT detection. After four months stored data were interrogated, AT-related symptoms were assessed, and patients crossed over to the alternative treatment arm for another four months. Stored atrial electrograms were analyzed for degree of AT organization and ATP success. RESULTS: In 22 patients (64% male; 72+/-7 years), ATP success rates were higher during immediate than during delayed ATP (device classification: 59+/-7% vs. 22+/-5%, P<0.01; manual analysis: 36+/-6% vs. 12+/-5%, P<0.01). Higher efficacy of immediate ATP was associated with a larger proportion of organized (Type I) AT prior to therapy (71% vs. 44% during delayed ATP). No difference was found in total AT numbers and duration, AT burden or related symptoms. CONCLUSIONS: The programmable delay between arrhythmia onset and therapy delivery significantly influences the success-rate of ATP. However, a higher efficacy of immediate compared with delayed ATP does not translate into a reduction of AT burden or related symptoms.

Atrial overdrive pacing compared to CPAP in patients with obstructive sleep apnoea syndrome.

AIMS: Obstructive sleep apnoea (OSA) is associated with oxygen desaturation, blood pressure increase, and neurohumoral activation, resulting in possible detrimental effects on the cardiovascular system. Continuous positive airway pressure (CPAP) is the therapy of choice for OSA. In a recent study, nocturnal atrial overdrive pacing (pacing) reduced the severity of sleep apnoea in pacemaker patients. We compared the effects of CPAP with those of pacing in patients with OSA but without pacemaker indication or clinical signs of heart failure. METHODS AND RESULTS: Ten patients with OSA on CPAP therapy were studied for three nights by polysomnography. During the nights that followed a night without any treatment (baseline), the patients were treated with CPAP or pacing in a random order. Pacing was performed with a temporary pacing lead. The pacing frequency was 15 b.p.m. higher than the baseline heart rate. The apnoea-hypopnoea index was 41.0 h(-1) (12.0-66.6) at baseline and was significantly lower during CPAP [2.2 h(-1) (0.3-12.4)] compared with pacing [39.1 h(-1) (8.2-78.5)]. Furthermore, duration and quality of sleep were significantly improved during CPAP when compared with pacing. CONCLUSION: Nocturnal atrial overdrive pacing is no alternative therapeutic strategy to CPAP for the treatment of OSA in patients without clinical signs of heart failure and without conventional indication for anti-bradycardia pacing.

Inhibition of bradycardia pacing and detection of ventricular fibrillation due to far-field atrial sensing in a triple chamber implantable cardioverter defibrillator.

Oversensing of intracardiac signals or myopotentials may cause inappropriate ICD therapy. Reports on far-field sensing of atrial signals are rare, and inappropriate ICD therapy due to oversensing of atrial fibrillation has not yet been described. This report presents a patient with a triple chamber ICD and a history of His-bundle ablation who experienced asystolic ventricular pauses and inappropriate detection of ventricular fibrillation due to far-field oversensing of atrial fibrillation. Several factors contributed to the complication, which resolved after reduction of the ventricular sensitivity.

1-year performance of a defibrillation lead with a small electrode surface for high impedance pacing: a randomized, controlled study.

A small electrode surface reduces pacing current drain and can extend generator longevity. The study evaluated the performance of a tined, quadripolar defibrillation lead (model 6944) that has a small-surfaced, steroid-eluting electrode tip for high impedance pacing. In a prospective, controlled study, 34 patients with conventional ICD indications were randomized one to one to receive the high impedance model 6944 or a tined defibrillation lead with a conventional sized, steroid-eluting electrode tip model 6942. Lead performance was evaluated at implant, prior to hospital discharge, and 1, 3, 6, and 12 months thereafter. Baseline characteristics did not differ significantly between patients implanted with lead model 6942 (n = 16) or model 6944 (n = 17). One patient randomized to receive the model 6942 was excluded from the study and was implanted with an active-fixation lead after stable lead positioning was neither possible with the 6942 nor with the 6944 electrode. No other lead related adverse events were observed. At implant, there were no significant differences between pacing thresholds, sensing performance, defibrillation impedances, and defibrillation thresholds in both groups, but pacing impedance of the model 6944 (988.6 +/- 217.7 omega) was approximately twice as high as high as in the model 6942 (431.7 +/- 83.7 omega; P < 0.0001). This difference remained highly significant throughout the observation period of 12 months, while R wave amplitudes and pacing thresholds remained equal in both lead models. The use of a tined defibrillation lead with a small, steroid-eluting electrode tip appears safe and results in a high pacing impedance without compromising system performance.

Subthreshold test pulses versus low energy shock delivery to estimate high energy lead impedance in implanted cardioverter defibrillator patients.

The high energy lead impedance is valuable for detecting lead failure in ICDs, but until recently shock delivery was necessary for high energy impedance measurement. This study compared the use of subthreshold test pulses and low energy test shocks to estimate the high energy impedance. Immediately after implantation of Ventak Prizm ICDs in 29 patients, the lead impedance was measured with five subthreshold (0.4 microJ) test pulses, 5 low energy (1.1 J) shocks, and two to three high energy (16 +/- 4.5 J) shocks. The mean impedances measured using high energy shocks, low energy shocks, and subthreshold pulses were 42.0 +/- 7.3 omega, 46.5 +/- 8.1 omega, and 42.4 +/- 7.1 omega, respectively. The impedances measured using high and low energy shocks differed significantly (P < 0.0001), while those obtained by high energy shocks and low energy pulses did not (P = 0.63). According to the Pearson correlation coefficient, the impedance measurements with subthreshold pulses and low energy shocks were both closely correlated (P < 0.0001) with impedance values determined with high energy shocks. However, while the impedance values tended to be higher when measured with low energy shocks, the concordance correlation coefficient (c) was higher for subthreshold test pulse versus high energy shock (c = 0.92) than for low versus high energy shock (c = 0.73). Furthermore, the intraindividual variability of impedance measurements was lower with subthreshold pulse measurements than with low energy shocks. Compared with low energy shocks, impedance measurement with subthreshold pulses has higher reproducibility and a higher correlation with the impedance obtained by high energy shock delivery. Safe and painless high energy impedance estimation with subthreshold pulses might, therefore, help to detect ICD lead failure during routine follow-up.

[Evaluation of the German Type D Scale (DS14) and prevalence of the Type D personality pattern in cardiological and psychosomatic patients and healthy subjects]. / Evaluation der deutschen Typ-D-Skala (DS14) und Prävalenz der Typ-D-Persönlichkeit bei kardiologischen und psychosomatischen Patienten sowie Gesunden.

The Type D personality pattern, consisting of negative affectivity and social inhibition, has been shown by Denollet et al. to predict adverse prognosis in patients with coronary heart disease. For measuring the Type D characteristics, Denollet has devised the 14 item Type D scale (DS14). In the present study, this instrument was translated into German. The validity, reliability and adequacy of the German DS14 were then tested in 2421 persons, including cardiological and psychosomatic patients as well as healthy factory workers. The results document sound psychometric properties of the scale. Cronbach's alpha was 0.87 for the negative affectivity subscale and 0.86 for social inhibition. The two-factor structure of the original instrument could be clearly replicated. The prevalence rates of the Type D pattern were lowest in cardiological patients (25 %) and highest in psychosomatic patients (62 %). The prevalence in this German sample of cardiology patients was also lower than the one observed in healthy factory workers (32.5 %) and in CHD samples reported in the literature. These group differences could not be accounted for by differences in age and sex distribution. In conclusion, the DS14 is a valid and reliable instrument that can be used for an economic evaluation of the Type D characteristics in patients and healthy persons. The possible meaningfulness of the low Type D prevalence in cardiac patients and the prognostic relevance of this pattern require further study.