High mechanical efficiency of left ventricular arrhythmic contractions during atrial fibrillation

Juichiro Shimizu, Satoshi Mohri, Haruo Ito, Hiroki Yamaguchi, Shunji Sano, Miyako Takaki, Hiroyuki Suga

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We analyzed the frequency distribution of the left ventricular (LV) mechanical efficiency of individual arrhythmic beats during electrically induced atrial fibrillation (AF) in normal canine hearts. This efficiency is the fraction of the external mechanical work (EW) in the total mechanical energy measured by the systolic pressure-volume area (PVA). The mean, median, and mode of this efficiency (EW/PVA) were as high as 78%, 80%, and 81%, respectively, on average in six hearts. These high efficiencies were comparable to that of the regular beats in these hearts. The frequency distribution of the EW/PVA during AF tended to skew to the higher side in all the hearts. Since the EW/PVA is directly related to both the ventriculo-arterial (or afterload) coupling ratio (Ea/Emax; Ea = effective arterial elastance, Emax = end-systolic ventricular elastance) and the ejection fraction on a per-beat basis, we also analyzed their frequency distributions. We found them to skew enough to account for the rightward skewed frequency distribution of the EW/PVA during AF with the unexpectedly high mean EW/PVA. These results indicate that the LV arrhythmia during AF per se does not directly suppress the mean level of LV mechanical efficiency in normal canine hearts.

Original languageEnglish
Pages (from-to)269-274
Number of pages6
JournalJournal of Physiological Sciences
Volume56
Issue number4
DOIs
Publication statusPublished - Aug 2006

Keywords

  • Arrhythmia
  • External work
  • Heart
  • Pressure-volume area

ASJC Scopus subject areas

  • Physiology

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