Effects of adenotonsillectomy on R-R interval and brain natriuretic peptide levels in children with sleep apnea: a preliminary report.

OBJECTIVES

Obstructive sleep apnea is associated with decreased R-R interval length and overall R-R interval variability in the electrocardiogram along with increased morning brain natriuretic peptide (BNP) blood levels. These findings indicate enhanced sympathetic tone and cardiac strain. In this study, it was hypothesized that adenotonsillectomy (AT) in children with sleep apnea is accompanied by improvement in polysomnography indices, increase in length and variability of R-R interval, and reduction in BNP levels.

METHODS

Polysomnography and measurements of morning BNP levels were performed before and 4-6months after AT. Mean and standard deviation of R-R interval were calculated from polysomnography electrocardiogram recordings.

RESULTS

Twenty-one children were studied. Apnea-hypopnea index and log-transformed BNP levels decreased postoperatively from 8.4±7.6 episodes/h and 2.2±0.7, to 1.8±1.4 episodes/h and 1.9±0.3, respectively (p<0.05). Mean R-R interval increased from 703.2±137.4ms (Stage 2), 699.3±135.8ms (Stage 3), 707.4±128.9ms (Stage 4) and 660.5±140.1ms (Stage REM), to 773.5±122.7ms (Stage 2), 765.7±73.7ms (Stage 3), 771.2±71.6ms (Stage 4), and 738.6±81.7ms (Stage REM), respectively (p<0.05 for comparisons pre- vs. post-operatively). Standard deviation of R-R in Stage 2 increased from 88.5±29.6 to 122.7±67ms (p=0.045).

CONCLUSIONS

Increase in nocturnal length of R-R interval and decrease in BNP levels after AT for sleep apnea may reflect postoperative reduction in sympathetic tone and cardiac strain.