Biomedical subjects

Norbert M Van Hemel

Publications and source records attributed to Norbert M Van Hemel.

3 recordsLinked to original sources

PubMed2005

A technique of lead insertion for low atrial septal pacing.

BACKGROUND: Pacing in the low right atrial septum (LAS) appears superior to right atrial appendage or free wall stimulation for the prevention of paroxysmal atrial fibrillation. However, insertion of active fixation lead in the low right atrial septal position is difficult and time consuming, inhibiting application of this pacing method in daily practice. METHODS: The technique of handling and positioning of a new "over the wire" lead system is presented with emphasis on electrocardiographic P wave pattern and fluoroscopic landmarks. RESULTS: The initial results demonstrate an acute implantation and short-term success of LAS pacing of >90% in the first 100 patients without major complications. Pacing thresholds at 3 and 6 months were fully comparable with that of the conventional atrial pacing, whereas impedance and atrial sensing signals were significantly higher at 3 and 6 months follow-up. CONCLUSION: These favorable initial results justify recommanding chronic LAS pacing with the active fixation atrial lead and providinge guidelines and fluoroscopic landmarks for the implantation. Insertion of the atrial active fixation lead positioned with the Locatortrade mark tool strongly supports the implantation procedure.

Aged↗

PubMed2004

Paroxysmal atrial fibrillation in male endurance athletes. A 9-year follow up.

AIMS: To study the course and circumstances of atrial fibrillation in endurance sports. BACKGROUND: Atrial fibrillation is the main cause of symptoms in athletes and frequently disturbs the performance during the practising of sport. The course of the arrhythmia is seldom reported in this population. METHODS: In 1993 and 2002 symptoms and clinical presentation of atrial fibrillation were evaluated in 30 well-trained athletes with a specially designed questionnaire. RESULTS: In 1993 paroxysmal atrial fibrillation was present in 30 male athletes at the mean age of 48.1 +/- 7.8, 3 (10%) of them also had paroxysmal atrial flutter. Three (10%) of the athletes died before 2002. In 2002 paroxysmal atrial fibrillation continued in 15 (50%) athletes, permanent atrial fibrillation emerged in 5 (17%) athletes and 7 (23%) of them showed no further atrial fibrillation. In 1993 paroxysms of atrial fibrillation started at a relatively low level of training intensity compared with the mean maximal training intensity of 11 +/- 7 versus 8 +/- 4 h/week (p < 0.05). The first attack of adrenergically induced paroxysmal atrial fibrillation was more often present in younger athletes (p < 0.005) and vagally induced paroxysmal atrial fibrillation was more apparent in older athletes (p < 0.05). In 10 (38%) of the athletes a familiar form of paroxysmal atrial fibrillation was present. CONCLUSION: A small proportion of the athletes (26%) was asymptomatic. Paroxysmal atrial fibrillation remained stable in half of the athletes whereas the arrhythmia changed into permanent atrial fibrillation in a minority of this population.

Adult↗

PubMed2004

Form analysis using digital signal processing reliably discriminates far-field R waves from P waves.

The correct detection of atrial arrhythmias by pacemakers is often limited by the presence of far-field R waves (FFRWs) in the atrial electrogram. Digital signal processing (DSP) of intracardiac signals is assumed to provide improved discrimination between P waves and FFRWs when compared to current methods. For this purpose, 100 bipolar and unipolar intracardiac atrial recordings from 31 patients were collected during pacemaker replacement and used for the off-line application of a novel DSP algorithm. Digital processing of the atrial intracardiac electrogram (IEGM) signals (8 bit, 800 samples/s) included filtering and calculation of the maximum amplitude and slope of the detected events. The form parameter was calculated, being the sum of the most negative value of the amplitude and that of the slope of the detected event. The algorithm collects form parameter data of P waves and FFRWs and composes histograms of these data. A sufficiently large gap between the FFRW and P wave histograms allows discrimination of these two signals based on form parameters. Three independent observers reviewed the reliability of classification with this algorithm. Sensitivity and specificity of FFRW detection were 99.63% and 100%, respectively, and no P waves were falsely classified. It can be concluded that this novel DSP algorithm shows excellent discrimination of FFRWs under off-line conditions and justify the implementation of this algorithm in future pacemakers for real-time discrimination between P waves and FFRWs. This method prevents false mode switching and allows correct and immediate intervention pacing for atrial tachyarrhythmias.

Algorithms↗