Abstract: A method for controlling the systemic pressure at the end of a cardiac operation wherein a double-balloon catheter is brought, along a single path, close to the junction of a right atrium with a superior and inferior venacavae. The distance between a first and a second balloon is then adjusted so that they are placed at an adequate position in the superior and inferior venacavae respectively. The balloons are inflated and one checks whether a balance between the outputs of the two sides of the heart has been restored. The balloons are deflated when a new equilibrium is established and the catheter is removed along the same path. A double balloon occlusion device especially designed to perform said operation is also described.