Effect of right ventricular apex pacing on the Tei index and brain natriuretic peptide in patients with a dual-chamber pacemaker.
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.
Ichiki
Hitoshi
H
Department of Cardiovascular, Respiratory, and Metabolic Medicine, Graduate School of Medicine, Kagoshima University, Kagoshima, Japan.
Oketani
Naoya
N
Hamasaki
Shuichi
S
Ishida
Sanemasa
S
Kataoka
Tetsuro
T
Ogawa
Masakazu
M
Saihara
Keishi
K
Okui
Hideki
H
Fukudome
Tsuyoshi
T
Shinasato
Takuro
T
Kubozono
Takuro
T
Ninomiya
Yuichi
Y
Matsushita
Takehiko
T
Otsuji
Yutaka
Y
Tei
Chuwa
C
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*
D020097:Natriuretic Peptide, Brain