Event Title

Proposition of Novel Frequency Bands for HRV Assessment in Isolated Denervated Guinea Pig Hearts

Location

Steelcase Lecture Hall

Start Date

3-2011 4:30 PM

Description

INTRODUCTION: This study aims to analyze the myogenic component of heart rate variability (HRV) in the frequency domain in denervated and isolated guinea pig hearts. In previous studies on human subjects, HRV has been analyzed in low frequency (LF) and high frequency (HF) bands, where they are modulated by sympathetic (S) and parasympathetic (P) systems respectively. This research proposes new frequency bands (0.15HzMETHODS: Four groups of guinea pig isolated hearts (n=6 each) were perfused wth Kreb’s-Ringers (KR) solution. After 30 min stabilization, hearts were perfused continuously either with KR (CON), KR + 1 µM atropine (ATR; P receptor blocker), Kr + 5 µM esmolol (ESM; S receptor blocker), or both ATR and ESM (ESAT) for 30 min followed by 30 min global ischemia and 120 min reperfusion (REP). Bipolar electrograms were recorded from the right ventricle (V) at baseline (BL), 20 min after KR, ATR, ESM and ESAT perfusion, and at various times during the reperfusion period. VV tachograms (beat-to-beat interval vs. time) were analyzed in the frequency domain and the following indices were computed: normalized LF power (LFN=100 * LF / (LF + HF)), normalized HF power (HFN= 100 * HF / (LF + HF)) and the power-ratio (LF/HF). RESULTS: ATR indicated statistically higher LFN and LF/HF, and lower HFN compared to CON. ESM and ESAT did not show statistically different values for any of the indices vs. CON. CONCLUSION: The observations using the new frequency bands were corroborated by findings from in-vivo studies confirming the suitability of tailoring frequency domain analysis of HRV to species-related differences in intrinsic heart rate.

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Mar 1st, 4:30 PM

Proposition of Novel Frequency Bands for HRV Assessment in Isolated Denervated Guinea Pig Hearts

Steelcase Lecture Hall

INTRODUCTION: This study aims to analyze the myogenic component of heart rate variability (HRV) in the frequency domain in denervated and isolated guinea pig hearts. In previous studies on human subjects, HRV has been analyzed in low frequency (LF) and high frequency (HF) bands, where they are modulated by sympathetic (S) and parasympathetic (P) systems respectively. This research proposes new frequency bands (0.15HzMETHODS: Four groups of guinea pig isolated hearts (n=6 each) were perfused wth Kreb’s-Ringers (KR) solution. After 30 min stabilization, hearts were perfused continuously either with KR (CON), KR + 1 µM atropine (ATR; P receptor blocker), Kr + 5 µM esmolol (ESM; S receptor blocker), or both ATR and ESM (ESAT) for 30 min followed by 30 min global ischemia and 120 min reperfusion (REP). Bipolar electrograms were recorded from the right ventricle (V) at baseline (BL), 20 min after KR, ATR, ESM and ESAT perfusion, and at various times during the reperfusion period. VV tachograms (beat-to-beat interval vs. time) were analyzed in the frequency domain and the following indices were computed: normalized LF power (LFN=100 * LF / (LF + HF)), normalized HF power (HFN= 100 * HF / (LF + HF)) and the power-ratio (LF/HF). RESULTS: ATR indicated statistically higher LFN and LF/HF, and lower HFN compared to CON. ESM and ESAT did not show statistically different values for any of the indices vs. CON. CONCLUSION: The observations using the new frequency bands were corroborated by findings from in-vivo studies confirming the suitability of tailoring frequency domain analysis of HRV to species-related differences in intrinsic heart rate.