Interface Electrocardiogram

interface Electrocardiogram {
    $type$: "Electrocardiogram";
    averageHeartRateBPM?: number;
    classification?: string;
    endTimestamp?: number;
    readings?: ElectrocardiogramReadings[];
    samplingFrequencyHz?: number;
    startTimestamp?: number;
    symptoms?: string;
    typeDescription?: string;
    voltageMeasurements: number;
}