Using Holter ECG and Heart Rate Variability to Detect Sleep-Disordered Breathing Phyllis K Stein, Ph.D. Heart Rate Variability Laboratory Washington University School of Medicine St. Louis, MO

Background When patients with sleep-disordered breathing have an event, there is an autonomic arousal associated with a brief awakening, they then resume normal breathing, and fall back asleep. This repeated awakening is associated with a repeated increase in heart rate which return to baseline when the patient falls back asleep.

Sleep Apnea Clarified

Heart-Rate-Based Graphical Method for Detecting Sleep-Disordered Breathing 1. Sequence of unedited beat-to-beat R-R (or preferable edited N-N) intervals. 2. Convert R-R intervals to instantaneous HR (60,000/R-R interval in ms). 3. Plot tachogram of HR vs. time on 6 parallel 10-min plots (one hr/page).

Tachogram Axes x-axis = time in minutes (0-10 minutes) 0-100 bpm “x-axis” x-axis = time in minutes (0-10 minutes) y-axis for each 10-min plot is H (0-100 bpm in 5 cm) “x-axis” is mean HR for that 10-min segment

Sleep Onset in a Patient Without OSAHS To bed

Onset of OSAHS Patient falls asleep

Tachograms From the Computers In Cardiology Sleep Apnea Contest Data based on R-R intervals using simple QRS detection algorithm and not edited. 35 tachograms blindly scored for OSA, no OSA and indeterminate. # each category known. Graphical method, 1 pair wrong, severe sleep-disordered breathing but hypopneas not OSA.

CVHR Subject 2 Brady-tachy pattern not seen

CVHR Subject 5 Tachycardia during OSA

CVHR Subject 7

CVHR Subject 8

CVHR and Normal Sleep or Quiet Rest Subject 9 Probable change in position resulting in OSA

CVHR Subject 13

CVHR Subject 16 (Hypopneas)

CVHR Subject 19

CVHR Subject 20

CVHR Subject 21

CVHR Subject 23

Apnea Appears to be Positional in Subject 23 Change in position terminates apnea

CVHR Subject 25

CVHR Subject 26

CVHR Subject 27

CVHR Subject 28

CVHR Subject 30 Probable change in position-apnea more severe earlier

Severe Sleep Apnea Subject 31 Magnitude of RSA declines during some but not all events

Severe Sleep Apnea Subject 32 Probable change in position or sleep stage. RSA is reduced.

Tachogram Evaluation Identify epochs of CVHR (cyclic variation of heart rate) Quantify CVHR by by total number of minutes (to nearest 30s) with CVHR. If CVHR is predominant, no need to quantify.

CVHR Definition At least 3 consecutive cycles of rising and falling heart rate. A visible rise in heart rate (5 bpm). A return to baseline. Each cycle 10 s duration. At least 20s but less than 2 min between cycles.

CVHR Criteria for Significantly Abnormal Sleep 20% of time in CVHR of any type High amplitude regular CVHR pathomnemonic for OSA Lower amplitude or irregular CVHR may be associated with apneas, hypopneas, periodic limb movements or arousals for no apparent reason.

Results of Sleep Lab Validation of CVHR Tachogram Method 100% detection of significantly abnormal sleep. High amplitude regular CVHR always sleep apnea. Lower amplitude or irregular CVHR could be apneas or hypopneas or leg movements, a mixture or arousals for no apparent reason. Non-diagnostic for flat tachograms (extremely low HRV) or atrial fibrillation.

Heart Rate Patterns on Tachograms Can Detect More Than Just Sleep Apnea

HR Patterns During Central Apneas

HR Patterns During Severe De-Saturation O2 Sat = 65% Irregular Low Amplitude CVHR

Low Amplitude CVHR Possibly Associated with Mixed Events

HR Patterns Associated with Periodic Limb Movements

Cheyne-Stokes Breathing

Cheyne-Stokes Breathing

Blown Up Section of Prior Tachogram Showing RSA During Cheyne-Stokes Respiration

Power Spectral Analysis of Heart Rate Variability to Detect Sleep-Disordered Breathing

HRV power spectral plot quantifies the underlying periodicities in heart rate. CVHR is a periodic change in heart rate which should be reflected in the HRV power spectrum

Normal-Appearing Nighttime Power Spectral Plot HF Peak Due to RSA

Onset of OSAHS Patient falls asleep

Power Spectral Plot for Previous Tachogram Showing OSAHS Pattern VLF Peak Associated with Sleep Apnea HF Peak Due to RSA 0.8 Hz

HR Patterns During Central Apneas

Power Spectral Plot for Previous Tachogram Showing HRV Pattern for Central Apneas 0.8 Hz VLF Peak Associated with Central Apneas Little or no HF power

HR Patterns During Severe De-Saturation O2 Sat =65% Irregular Low Amplitude CVHR

Power Spectral Plot for Previous Tachogram Diffuse HF Peak Reflecting Irregular Respiration or Heart Rate Pattern VLF Peak Associated with OSAHS 0.8 Hz

Cheyne-Stokes Breathing

2-Min Averaged HRV Pattern for Cheyne-Stokes Respiration Hard to see CSR peak

Hourly HRV Power Spectral Plots for Cheyne-Stokes Breathing

HR Patterns Associated with PLMs

Power Spectral Plot for Previous Tachogram Showing Periodic Limb Movements VLF Peak Due to PLMS (0.04 Hz) HF Peak Due to RSA 0.8 Hz

Conclusions Sleep apnea and other sleep-disturbing syndromes can easily be identified from heart rate tachograms generated from routine Holter recordings Visual examination of HRV patterns generated from hourly power spectral plots often available on commercial Holter scanners may help identify patients with CVHR. Method is not valid for patients with significant autonomic dysfunction resulting in flat tachograms or in patients with atrial fibrillation