Abstract: The present invention is directed to a method of preventing or alleviating high venous pressure in a patient, the method comprising the steps of implanting a first biocompatible scaffold into the lumen of the vena cava inferior (VCI) of the patient, preferably at a site between the right atrium and the ostium of the hepatic veins; optionally implanting a second biocompatible scaffold into the lumen of the first biocompatible scaffold; and placement of a first valve into the lumen of the first or second biocompatible scaffold; wherein the biocompatible scaffolds and the first valve are configured and arranged to permit blood flow towards a right atrium of the patient and to prevent blood flow in an opposite direction.

Abstract: In a method and apparatus for operating an implantable cardiac pacemaker, the stimulation rate is modulated, while a patient in whom the pacemaker is implanted is experiencing a number of different levels of physical stress, and a number of signal sequences corresponding to a non-mechanical physiological characteristic are obtained, one sequence being obtained for each physical stress level. These signal sequences form a reference field, which is stored in the pacemaker. A current signal sequence of the non-mechanical physiological characteristic is subsequently obtained, and this signal sequence is compared to all of the signal sequences in the stored reference field, and one of the reference field signal sequences having the highest correlation with the current signal sequence is selected. The stimulation rate is then set at a rate equal to the basic stimulation rate for the modulation which produced the highest correlating sequence in the reference field.