title: Strong modulation of ectopic focus as a mechanism of repetitive interpolated ventricular bigeminy with heart rate doubling.
abstract: BACKGROUND
  Repetitive interpolated ventricular bigeminy (RIVB) can introduce a doubling of the ventricular rate.
  
  
  OBJECTIVE
  To clarify the mechanism of RIVB, we hypothesized that it was introduced by a strong modulation of the ventricular automatic focus.
  
  
  METHODS
  RIVB, defined as more than 7 bigeminy events, was detected by instantaneous heart rate and bigeminy interval (BI) tachograms in 1450 successive patients with frequent ventricular premature contractions (≥3000 per day). Postextrasystolic interval bigeminy interval curves were plotted to determine the degree of modulation. Mean sinus cycle length bigeminy interval curves were plotted for selection. RIVB was simulated by using a computer-based parasystole model.
  
  
  RESULTS
  RIVB was observed in 7 patients (age 60 ± 16 years; 2 men and 5 women) with a heart rate of 58.2 ± 6.5 beats/min during a rest period both during the day and at night. The tachograms disclosed the onset of the RIVB with a doubled ventricular rate to 112.3 ± 8.5 beats/min. On the postextrasystolic interval bigeminy interval curves, compensatory bigeminy and interpolated bigeminy constituted overlapping regression lines with slopes close to 1.00 and RIVB was located in the lower left portion. RIVB lasting for up to 3 hours was quickly detected by mean sinus cycle length bigeminy interval curve. The PQ interval immediately after RIVB was prolonged in comparison with baseline (0.18 ± 0.02 to 0.21 ± 0.02 seconds; P < .001). The simulation was able to reproduce RIVB faithfully at a slow heart rate.
  
  
  CONCLUSIONS
  Our findings support the hypothesis that RIVB was introduced by strongly modulated ventricular pacemaker accelerated by an intervening normal QRS.
authors.affiliation: Department of Cardiology, Dokkyo Medical University Koshigaya Hospital, Koshigaya, Japan. Electronic address: tkyng@dokkyomed.ac.jp.
authors.forename: Kan
authors.initials: K
authors.lastname: Takayanagi
authors.forename: Shiro
authors.initials: S
authors.lastname: Nakahara
authors.forename: Noritaka
authors.initials: N
authors.lastname: Toratani
authors.forename: Ryuji
authors.initials: R
authors.lastname: Chida
authors.forename: Sayuki
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Sakai
authors.forename: Akihiro
authors.initials: A
authors.lastname: Takeuchi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ikeda
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003198:Computer Simulation; D015716:Electrocardiography, Ambulatory; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D013610:Tachycardia / Q000150:complications* / Q000503:physiopathology*; D018879:Ventricular Premature Complexes / Q000150:complications* / Q000503:physiopathology*
keywords: AV; Antiphasic tachycardia; BI; ECG; Electrotonic modulation; Interpolation; PBC; PEI; Postextrasystolic interval; RIVB; SCL; VA; VPC; Ventricular premature contraction; Ventricular rate doubling; atrioventricular; bigeminy interval; eHR; electrocardiogram/electrocardiographic; estimated heart rate; mHR; mSBC; mSCL; mean heart rate; mean sinus cycle length; mean sinus cycle length bigeminy interval curve; postextrasystolic interval; postextrasystolic interval bigeminy interval curve; repetitive interpolated ventricular bigeminy; sinus cycle length; ventricular premature contraction; ventriculoatrial