Biomedical subjects

Viveka Frykman

Publications and source records attributed to Viveka Frykman.

2 recordsLinked to original sources

PubMed2003

Rapid atrial pacing does not decrease the atrial defibrillation threshold.

The aim of the study was to evaluate the effect of preshock atrial pacing on the atrial defibrillation threshold (DFT) during internal cardioversion of AF. The implantable atrial defibrillator has been added to the therapeutic options for patients with recurrent episodes of persistent AF. Although the device is efficient in restoring sinus rhythm, patient discomfort is a limitation. Methods that lower the ADFT are needed. Eleven patients with AF underwent internal cardioversion. In a randomized, crossover design, ADFT testing was performed, applying a step-up protocol starting at 100 V. Rapid atrial pacing was performed with a right atrial catheter for 20 seconds at 90% of the average cycle length of the fibrillatory waves and was immediately followed by a biphasic defibrillation shock. At each energy level, pacing + shock was compared to shock only, until the level at which sinus rhythm was restored by both modes. The step-up protocol was thereafter repeated using the inverse sequence of the two modes. A total of 19 ADFTs were obtained. For 10 the ADFT was lower with pacing + shock, in 4 equal and in 5 higher, than with shock only. The ADFT (mean +/- SD) with pacing + shock was 260 +/- 84 V(3.4 +/- 2.9 J) and did not differ from shock only: 268 +/- 85 V(3.8 +/- 3.0 J) (P > 0.05). The coefficient of variation and the coefficient of reproducibility for pacing + shock was 16% and 60 V, respectively, and for shock only 17% and 61 V. Rapid atrial pacing did not influence the internal ADFT in AF. The randomized, crossover protocol used was reproducible between different modes, and seems useful when testing the impact of different interventions on the ADFT.

Atrial Fibrillation↗

PubMed2003

What characterizes episodes of atrial fibrillation requiring cardioversion? Experience from patients with an implantable atrial cardioverter.

BACKGROUND: Episodes of paroxysmal atrial fibrillation may cause disabling symptoms. Asymptomatic episodes of paroxysmal atrial fibrillation are, however, more common than symptomatic episodes. The aim of the study was to investigate whether episodes of atrial fibrillation for which the patient requires cardioversion differ from those in which the patient does not seek this therapy. METHODS: We studied 21 patients with atrial fibrillation treated with an implanted atrial cardioverter. The device displayed intracardiac electrograms from episodes of atrial fibrillation in which the patient received cardioversion and from episodes that did not lead to a hospital visit or cardioversion. The heart rate (mean, highest, and lowest) and the degree of ventricular interval irregularity were analyzed with these electrograms. RESULTS: There were 132 episodes of atrial fibrillation available for analysis, of which 73 led to cardioversion and 58 did not. Episodes leading to hospital/clinic visits and therapy had a higher maximum ventricular rate (130 vs 115/min, P =.0004) than episodes that did not cause the patients to seek therapy. This difference in heart rate was most prominent at the beginning of the episode, but tended to become more similar during the episode. There were no differences in ventricular cycle length irregularity between the 2 types of episodes. Moreover, treated episodes also had a significantly longer duration (mean duration 33 vs 9 hours, P =.002). CONCLUSIONS: Episodes of atrial fibrillation that cause the patient to seek cardioversion are characterized by a high initial ventricular rate and a longer duration than those that go untreated.

Adolescent↗