Vena-caval device
Apparatus and method are described including identifying a subject as suffering from a condition that causes the subject to have elevated central venous pressure. In response thereto, a device is placed inside the subject's vena cava such that an upstream end of the device is placed at a location upstream of junctions of the vena cava with all of the subject's renal veins. The device defines a passage through the device, at least a portion of the passage converging in a direction from an upstream end of the device to downstream end of the device. Other applications are also described.
1. Apparatus for use with renal veins and a vena cava of a subject, the apparatus comprising:
a vena-caval device consisting of a nozzle having an upstream end and a downstream end, the device configured to be placed inside the vena cava such that an upstream end of the device is placed at a location upstream of junctions of the vena cava with the subject's renal veins, the device comprising:
an upstream end, comprising the upstream end of the nozzle;
a downstream end, comprising the downstream end of the nozzle;
an outer wall shaped to, at least partially, directly couple to the vena cava; and
an inner wall shaped to define a passage through the device, at least a portion of the passage converging in a direction from the upstream end of the device to the downstream end of the device;
the device:
(i) configured to be placed inside the vena cava such that all the blood flow through the vena cava flows directly into the upstream end of the device and directly out of the downstream end of the device; and
(ii) shaped to direct, in a passive manner, antegrade blood flow through the vena cava past the renal veins; and
a valve configured to be placed inside the subject's vena cava at a location that is downstream of the junctions of the vena cava with the subject's renal veins, the valve being configured to allow antegrade blood flow therethrough and to prevent retrograde blood flow therethrough, to thereby protect the subject's renal veins from backflow and pressure of blood from a portion of the vena cava that is downstream of the renal veins.