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. The control unit is sensitive to said flow-meter
signal and utilises that signal to control the pumping unit, for example
to cause the pumping unit to operate in a condition of synchronous
counterpulsation with regard to the natural heart, that is with the
variable-volume chamber capable of receiving blood from the assisted
heart when it is in a systolic phase and the variable-volume chamber that
expels the blood collected in the chamber, when the assisted heart is in
a diastolic phase.