Abstract: A cardiac ventricular assist device or VAD includes a pumping unit with a variable-volume chamber capable of receiving a mass of blood, and a control unit to control the pumping unit to obtain contraction of the variable-volume chamber, with consequent expulsion of the blood collected in the chamber, and expansion of the variable-volume chamber consequent on the flow of blood into the chamber. A flow line is included, such as a transcutaneous line, for a gaseous flow caused by the contraction and expansion of the variable-volume chamber. A sensor sensitive to the gaseous flow in the flow line generates a flow-meter signal that is indicative of the expulsion and inflow of blood with regard to the variable-volume chamber.