In the human heart there is a sequential contraction of the systemic veins, systemic venous sinus and the pectinated right atrium, ‘the systemic waltz’, and sequential contraction of the pulmonary veins, pulmonary venous sinus and pectinated left atrium, ‘the pulmonary waltz’. The systemic veins contract earlier than the pulmonary veins creating a ‘duet.̊ We hypothesise that this waltz and duet point to a complex extracardiac control of the cardiac rhythm on a beat-to-beat neural basis.