title: Effect of right ventricular apex pacing on the Tei index and brain natriuretic peptide in patients with a dual-chamber pacemaker.
abstract: BACKGROUND
  Asynchronous electrical activation induced by right ventricular apex (RVA) pacing can cause various abnormalities in left ventricular (LV) function, particularly in the context of severe LV dysfunction or structural heart disease. However, the effect of RVA pacing in patients with normal LV and right ventricular (RV) function has not been fully elucidated. The aim of this study was to characterize the effects of RVA pacing on LV and RV function by assessing isovolumic contraction time and isovolumic relaxation time divided by ejection time (Tei index) and by assessing changes in plasma brain natriuretic peptide (BNP).
  
  
  METHODS
  Doppler echocardiographic study and BNP measurements were performed at follow-up (mean intervals from pacemaker implantation, 44+/-75 months) in 76 patients with dual chamber pacemakers (sick sinus syndrome, n=30; atrioventricular block, n=46) without structural heart disease. Patients were classified based on frequency of RVA pacing, as determined by 24-hour ambulatory electrocardiogram (ECG) that was recorded just before echocardiographic study: pacing group, n=46 patients with RVA pacing>or=50% of the time, percentage of ventricular paced 100+/-2%; sensing group, n=30, patients with RVA pacing<50% of the time, percentage of ventricular paced 3+/-6%.
  
  
  RESULTS
  There was no significant difference in mean heart rate derived from 24-hour ambulatory ECG recordings when comparing the two groups (66+/-11 bpm vs 69+/-8 bpm). LV Tei index was significantly higher in pacing group than in sensing group (0.67+/-0.17 vs 0.45+/-0.09, P<0.0001), and the RV Tei index was significantly higher in pacing group than in sensing group (0.34+/-0.19 vs 0.25+/-0.09, P=0.011). Furthermore, BNP levels were significantly higher in pacing group than in sensing group (40+/-47 pg/mL vs 18+/-11 pg/mL, P=0.017). With the exception of LV diastolic dimension (49+/-5 mm vs 45+/-5 mm, P=0.012), there were no significant differences in other echocardiographic parameters, including left atrium (LA) diameter (35+/-8 mm vs 34+/-5 mm), LA volume (51+/-27 cm3 vs 40+/-21 cm3), LV systolic dimension (30+/-6 mm vs 29+/-7 mm), or ejection fraction (66+/-9% vs 63+/-11%), when comparing the two groups.
  
  
  CONCLUSIONS
  These findings suggest that the increase of LV and RV Tei index, LVDd, and BNP are highly correlated with the frequency of the RVA pacing in patients with dual chamber pacemakers.
authors.affiliation: Department of Cardiovascular, Respiratory, and Metabolic Medicine, Graduate School of Medicine, Kagoshima University, Kagoshima, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ichiki
authors.forename: Naoya
authors.initials: N
authors.lastname: Oketani
authors.forename: Shuichi
authors.initials: S
authors.lastname: Hamasaki
authors.forename: Sanemasa
authors.initials: S
authors.lastname: Ishida
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Kataoka
authors.forename: Masakazu
authors.initials: M
authors.lastname: Ogawa
authors.forename: Keishi
authors.initials: K
authors.lastname: Saihara
authors.forename: Hideki
authors.initials: H
authors.lastname: Okui
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Fukudome
authors.forename: Takuro
authors.initials: T
authors.lastname: Shinasato
authors.forename: Takuro
authors.initials: T
authors.lastname: Kubozono
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ninomiya
authors.forename: Takehiko
authors.initials: T
authors.lastname: Matsushita
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Otsuji
authors.forename: Chuwa
authors.initials: C
authors.lastname: Tei
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects*; D004868:Equipment Failure; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D010138:Pacemaker, Artificial / Q000009:adverse effects*; D013318:Stroke Volume; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology*; D018497:Ventricular Dysfunction, Right / Q000175:diagnosis* / Q000517:prevention & control*
chemical_list: D020097:Natriuretic Peptide, Brain