Techniques are provided for detecting heart failure or other medical conditions within a patient using an implantable medical device, such as pacemaker or implantable cardioverterdefibrillator, or external system. The system is configured for enabling one or more arterial devices to be accommodated in the aorta of the patient in use of the system, and a perfusion lumen arrangement provides therethrough a target perfusion flow into the aorta having a target perfusion flow rate that is significantly greater than a nominal perfusion flow rate, by an excess perfusion flow rate. Rotations of the motor are reduced by the reducer and transmitted to the roller body.