Echocardio-variability - Low and high frequency beat-to-beat variability in echocardiographic signals

Measurement signals originating from the cardiovascular system are known to comprise oscillating components and beat-to-beat variability, e.g., heart-rate variability and blood pressure variability. In clinical echocardiographic procedures, typically only a few cardiac cycles are acquired. This pilot study analyses the beat-to-beat variability of echocardiographic variables (echocardio-variability) in minute long acquisitions. Simultaneous echocardiography, including electrocardiography and respiration, and continuous blood pressure measurement were acquired from seven healthy subjects and two patients with cardiac disease. Variability of echocardiographic variables and their coupling to respiration, heart rate variability and blood pressure was analyzed. Results showed that healthy subjects had higher variability (30%), compared to patients (10%). The variability in a high frequency band was similar in a low frequency band. Patients had lower coupling to heart rate variability than to blood pressure variations. Analyzing the echocardio-variability and its coupling strength to additional physiological signals, may serve as the basis for the development of novel diagnostic indices.