Key result
In patients with typical atrial flutter, administration of 1 mg/kg pilsicainide and higher pacing rates significantly extended the length of the conduction block at the posterior right atrium.
Why the study?
Does pacing rate, pacing site, and pilsicainide administration alter the conduction block line in the posterior right atrium in patients with typical atrial flutter?
Observational (n=40)
Does pacing rate, pacing site, and pilsicainide administration alter the conduction block line in the posterior right atrium in patients with typical atrial flutter?
Pacing rate, pacing site, and sodium channel blockade with pilsicainide significantly extend the conduction block line in the posterior right atrium, providing a mechanistic explanation for the predominance of counterclockwise atrial flutter and class IC flutter.
Answers are grounded in this paper and cite their sources.
Supports mechanistic basis for counterclockwise flutter predominance; hypothesis-generating for class IC effects, should not yet change practice.
INTRODUCTION: Conduction block in the posterior right atrium (RA) plays an important role in perpetuating atrial flutter (AFL). Although conduction blocks have functional properties, it is not clear how the block line changes with the pacing rate, pacing site, and administration of antiarrhythmic drugs. METHODS AND RESULTS: Forty patients with typical AFL were enrolled. Pacing (110, 170, 230 ppm) from the coronary sinus ostium (CSo) and low lateral RA was performed. After 1 mg/kg pilsicainide (pure sodium channel blockade) administration, the pacing protocol was repeated. Conduction block was assessed based on a color-coded isopotential map and 20 points of virtual unipolar electrograms in the posterior RA using noncontact mapping. Block line proportion was defined as the percentage of length of the block line between the superior and inferior vena cava. The pacing rate-dependent extension of the block proportion was significant during pacing from both sides (pacing from the CSo: 59 ± 17% at 110 ppm, 69 ± 16% at 230 ppm, P < 0.05; pacing from the low lateral RA: 43 ± 19% at 110 ppm, 55 ± 22% at 230 ppm, P < 0.05). The block line was significantly longer during CSo pacing than during low lateral RA pacing at each rate (all P < 0.05). After pilsicainide administration, the block line extended further. CONCLUSION: In addition to pacing rate-dependent and site-dependent changes in the block line, pilsicainide further extended the block line length. This phenomenon explains the clinical observation that counterclockwise AFL occurs more frequently than clockwise AFL, and the mechanism of class IC AFL.
No takes yet. Share an insight, caveat, or question.
Takami et al. (2012) conducted an observational in Typical Atrial Flutter (n=40). Pilsicainide vs. Baseline was evaluated on Length of conduction block at the posterior right atrium. In patients with typical atrial flutter, administration of 1 mg/kg pilsicainide and higher pacing rates significantly extended the length of the conduction block at the posterior right atrium.
Synapse has enriched 10 related papers. Consider them for comparative context: