Copyright © Françoise Herrmann
A normal heart weighs approximately 300 grams, with slightly smaller hearts on average for women, and slightly larger hearts on average for men. A sick and older heart, or the heart of heavier folks, weighs considerably more as the heart enlarges to work twice as hard.
The CARMAT heart weighs 900 grams with all components embedded inside the pericardial cavity. The search for solutions to the anatomical constraints of the available pericardial space for a heart prosthesis invoked the miniaturization of components. Thus, the patent US2009132038 concerning a Rotary displacement pump with smaller radial dimensions, discloses one of the miniaturized components of the CARMAT heart.
The rotary pump of this patent is designed to handle the fluid hydraulics of the two heart ventricles of a cardiac prosthesis. These fluid actuators are driven by sophisticated hydraulic sensors which determine the amount of blood flow within each ventricle that is pumped to the aorta and pulmonary artery.
Below appears the abstract of US2009132038 and a patent drawing. Another drawing illustrating the green-colored fluid actuator pumps inside the ventricles is also included. This illustration is extracted from the French press (Le Monde, 23-12-2013).
Abstract of US2009132038
According to the invention the rotary pump consists of an external gear (13) with internal teeth (16) in the form of a squirrel cage, and an internal gear (9), housed in an off-centre manner in the interior of said external gear (13) and fitted with external teeth (9D) intermeshing with said internal teeth (16) and consisting of a number of inferior teeth of a unit with the number of teeth of the later. The rotation means of said external teeth (13) comprise at least a bearing (11, 12) centrally laid out in a flange end (14,15) of said aforementioned external gear (13) and the aforementioned external gear (13) is at least partly dismantled in order to introduce said internal gear (9).
If a natural heart "beats", what does CARMAT heart sound like? Does it beep?