The signals shown are a two-second snippet of an electrocardiogram (ECG) and a simultaneously recorded continuous blood pressure signal. The blue markers are annotations that mark the heart beats. Even this small excerpt contains a wealth of information that is not usually given attention; for example, the time interval from the electrical activation of the ventricles (marked by the annotations) to the peak of the blood pressure signal varies from beat to beat, reflecting the degree of filling of the ventricles, their contractility, the pulse wave velocity and its modulation by arterial compliance and peripheral resistance, and much more. A thorough analysis of these variables requires more and longer signals.