Differences in the atrial, the ventricular and the digital cardiac rhythm

In 7 healthy young volunteers (3 male, 4 female) an esophageal electrogram, a 3-lead ECG, and continuous finger blood pressure were recorded simultaneously. The onset of the esophageal atrial complex, the onset of the QRS complex in the electrocardiogram and the diastolic point in the finger blood pressure were determined by interactively processing the data with a standard Holter analyzing system. These instances constituted the atrial, the ventricular, and the digital cardiac rhythm. Moving frequency power spectra were computed in a 4-minute time window (step 5 seconds) from the atrial, the ventricular and the digital rhythm. The values obtained from the ventricular rhythm are almost identical to the values obtained from the atrial rhythm. The digital rhythm sometimes yields deviating values. The greatest differences are found in the high frequency powers, where one overestimation of 304% occurred. This makes the digital rhythm less suitable for heart rate variability analysis