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[Spectrum analysis of heart rate variability in obstructive hypertrophic myocardiopathy. Evidence of altered
U Limbruno1, G Strata, G Mengozzi
1Istituto di Cardiologia, Università degli Studi, Pisa.
Insights
Patients with hypertrophic obstructive cardiomyopathy (HOCM) exhibit altered sympathetic activity. Heart rate variability analysis reveals blunted sympathetic response to tilt in HOCM patients compared to controls.
Area of Science:
- Cardiology
- Autonomic Nervous System Function
Context:
- Hypertrophic obstructive cardiomyopathy (HOCM) is a condition where altered sympathetic activity may contribute to its development.
- Assessing sympatho-vagal balance is crucial for understanding cardiovascular regulation in HOCM.
Purpose:
- To evaluate sympatho-vagal function and balance in patients with HOCM using spectral analysis of heart rate variability.
- To compare autonomic responses during rest and passive tilt between HOCM patients and healthy controls.
Summary:
- Heart rate variability (HRV) spectral analysis was performed on 18 HOCM patients and 15 controls at rest and during passive tilt.
- HOCM patients showed reduced low-frequency (LF) HRV at rest. During tilt, controls exhibited expected increases in LF and LF/HF ratio, while HOCM patients showed a blunted or reversed response.
- High-frequency (HF) HRV, an index of vagal activity, was reduced in controls during tilt but not significantly different between groups at rest or during tilt.
Impact:
- This study highlights a potential impairment in baroreflex-mediated sympathetic modulation in HOCM patients.
- Findings suggest that autonomic dysfunction, specifically blunted sympathetic reactivity, may play a significant role in the pathophysiology of HOCM.
- Understanding these autonomic alterations could inform future therapeutic strategies for managing HOCM.
Abstract:
Altered sympathetic activity may play an important role in the pathogenesis of hypertrophic obstructive cardiomyopathy (HOCM). Spectral analysis of heart rate variability was employed to assess the sympatho-vagal function and balance in 18 patients with HOCM (11 males, 7 females, mean age 42 years, range 19-59) and in 15 healthy control subjects (9 males, 6 females, mean age 44 years, range 18-65). Electrocardiographic recordings obtained both at rest and during 60 degrees passive tilt, were digitized and analyzed by fast Fourier transform in order to obtain the power spectrum of heart rate variability. The low-frequency band (LF: 0.05-0.17 Hz) and the high-frequency band (HF: 0.18-0.34) of power spectrum were considered as indexes of sympathetic and vagal activities respectively. A semiquantitative two-dimensional echocardiographic score (SES) was used to assess the entity of myocardial hypertrophy whereas the entity of the intraventricular gradient was determined by continuous wave Doppler. Low-frequency band at rest was slightly but significantly reduced in HOCM group with respect to controls (35.2 +/- 2.0 vs 45.0 +/- 2.5 nu, respectively; p < 0.01), whereas the HF band and the LF/HF ratio were not different in the 2 groups. During tilt, control subjects showed a significant reduction of the HF band (-35%, p < 0.001), an increase in the LF band (+36%, p < 0.001) and a sharp increase in the LF/HF ratio (+105%, p < 0.001). On the contrary the baroreflex increase in the LF band and LF/HF ratio during tilt was markedly blunted, or even reverted, in patients with HOCM (-9%, NS and +5%, NS, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)