What is the clinical evidence from this study?

Study design: Other. Population: Healthy (n=5). Intervention: Autonomic perturbations (atropine, head-up tilt, scopolamine) vs. Baseline. Primary outcome: Change in Complex Correlation Measure (CCM) from baseline (p=<0.01).

March 3, 2011Open Access

Sensitivity of temporal heart rate variability in Poincaré plot to changes in parasympathetic nervous system activity

Q: What are the key findings of this study?

The Complex Correlation Measure (CCM) was significantly more sensitive to changes in parasympathetic activity during autonomic perturbations than standard descriptors SD1 and SD2 (p<0.01).

Key Result

The Complex Correlation Measure (CCM) was significantly more sensitive to changes in parasympathetic activity during autonomic perturbations than standard descriptors SD1 and SD2 (p<0.01).

Structured PICO

Do autonomic perturbations (atropine, tilt, scopolamine) alter the Complex Correlation Measure (CCM) of heart rate variability in healthy subjects?

Population

5 healthy adults aged 20 to 40 years underwent autonomic perturbations to assess the sensitivity of temporal heart rate variability descriptors.

Intervention

Autonomic perturbations including 70° head-up tilt, intravenous atropine infusion (1.2 mg bolus followed by 0.12-0.24 mg/min), and transdermal scopolamine (1.5 mg patch overnight).

Comparator

Baseline resting state (supine position for 10 minutes).

Outcome

Changes in the temporal structure of the Poincaré plot as measured by the Complex Correlation Measure (CCM), SD1, and SD2.surrogate

The Complex Correlation Measure (CCM) is a highly sensitive metric for detecting changes in parasympathetic nervous system activity via heart rate variability.

Main Result

p-value: p=<0.01

Limitations

Small sample size of 5 subjects
CCM fails if RR intervals are perfectly aligned on a line
Further studies needed to investigate sympathetic activity changes
Gender and age effects were not investigated

Abstract

BACKGROUND: A novel descriptor (Complex Correlation Measure (CCM)) for measuring the variability in the temporal structure of Poincaré plot has been developed to characterize or distinguish between Poincaré plots with similar shapes. METHODS: This study was designed to assess the changes in temporal structure of the Poincaré plot using CCM during atropine infusion, 70° head-up tilt and scopolamine administration in healthy human subjects. CCM quantifies the point-to-point variation of the signal rather than gross description of the Poincaré plot. The physiological relevance of CCM was demonstrated by comparing the changes in CCM values with autonomic perturbation during all phases of the experiment. The sensitivities of short term variability (SD1), long term variability (SD2) and variability in temporal structure (CCM) were analyzed by changing the temporal structure by shuffling the sequences of points of the Poincaré plot. Surrogate analysis was used to show CCM as a measure of changes in temporal structure rather than random noise and sensitivity of CCM with changes in parasympathetic activity. RESULTS: CCM was found to be most sensitive to changes in temporal structure of the Poincaré plot as compared to SD1 and SD2. The values of all descriptors decreased with decrease in parasympathetic activity during atropine infusion and 70° head-up tilt phase. In contrast, values of all descriptors increased with increase in parasympathetic activity during scopolamine administration. CONCLUSIONS: The concordant reduction and enhancement in CCM values with parasympathetic activity indicates that the temporal variability of Poincaré plot is modulated by the parasympathetic activity which correlates with changes in CCM values. CCM is more sensitive than SD1 and SD2 to changes of parasympathetic activity.

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