Heart Rate Variability (HRV) is the variation in time between consecutive heartbeats, measured in milliseconds. A higher HRV generally reflects a healthy and adaptable autonomic nervous system, indicating the heart can respond flexibly to physical and emotional demands. Reduced HRV is associated with cardiovascular risk and may indicate autonomic dysfunction following cardiac arrest or in the context of heart failure.
HRV is measured using ECG analysis or consumer wearable devices. Clinical-grade measurement requires a validated 24-hour Holter recording for accuracy. Consumer wearables can give indicative trends but vary in precision.
In recovery, HRV monitoring is sometimes used to guide exercise intensity and track physiological adaptation during cardiac rehabilitation. Survivors interested in tracking HRV should discuss its relevance to their specific condition with their cardiologist, as interpretations differ depending on underlying diagnosis and device type.
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