News Column

Patent Issued for Implantable One-Piece Heart Prosthesis

May 5, 2014



By a News Reporter-Staff News Editor at Cardiovascular Week -- A patent by the inventors Grimme, Marc (Paris, FR); Gourgues, Jean-Elie (Versailles, FR); Carpentier, Alain (Paris, FR); Wartelle, Claude (Gouvieux, FR), filed on January 7, 2009, was published online on April 22, 2014, according to news reporting originating from Alexandria, Virginia, by NewsRx correspondents (see also Carmat).

Patent number 8702793 is assigned to Carmat (Velizy Villacoublay, FR).

The following quote was obtained by the news editors from the background information supplied by the inventors: "From document U.S. Pat. No. 5,135,539, a heart prosthesis being implantable in the pericardial cavity of a patient is known, said prosthesis being capable of replacing the natural left and right ventricles of said patient after ablation thereof and comprising: a stiff body in which artificial left and right ventricles are arranged, each of these artificial ventricles comprising a soft pulsatile membrane: which is capable of beating under the action of a hydraulic fluid, and which is provided within a cavity sealingly partitioned by said membrane into two chambers, one of which is intended for blood flow and the other of which is intended for said hydraulic fluid, the blood chamber of the artificial left ventricle being intended to be connected to the natural left atrium and to the aorta, whereas the blood chamber of the artificial right ventricle is intended to be connected to the natural right atrium and to the pulmonary artery; two hydraulic actuators connected to the hydraulic fluid chambers of said cavities within said stiff body, for alternately injecting therein and expulsing therefrom hydraulic fluid and providing desired values of diastolic and systolic flow rates; and a soft bag widely and sealingly surrounding at least one portion of said stiff body while enclosing said hydraulic actuators, said soft bag serving both as a hydraulic fluid reservoir for said hydraulic actuators and as a compliance chamber.

"In this known heart prosthesis, each actuator is associated with a ventricle and, in order to comply with physiology, both actuators can operate independently from each other and particularly in a synchronised way, that is both ventricles can be respectively and simultaneously either in diastole or in systole. In this case, the result is that said soft bag undergoes large displacements, since the whole fluid required for animating right and left pulsatile membranes is alternately injected, and then drawn into said soft bag. If the capacity of each ventricle is of about 75 cm.sup.3, the volume variations of the bag may reach 150 cm.sup.3. Such high amplitude beats of the bag, on the one hand, may raise issues of housing said prosthesis within the pericardial cavity and, on the other hand, cause an inflammation of the surrounding tissue, with the risk for a thick fibrous capsule to occur, capable of hindering the beats of the bag and altering the operation of the prosthesis.

"Besides, such a synchronised operation requires that both actuators are capable of the same performance, which is of a high power cost.

"In order to overcome these drawbacks, it could be possible, as suggested by document WO-0,191,828, to remove one of said actuators and operate the ventricles in phase opposition, one of said ventricles being in diastole whereas the other is in systole. Thus, the hydraulic fluid is transferred from a ventricle into the other with much reduced beats of the bag. In addition, such a heart prosthesis is advantageous in terms of space and power consumption, since it only comprises one actuator. However, it has the drawback of controlling the intake duration of one of the ventricles based on the ejection of the other, such that the diastole durations are necessarily equal to the systole durations, which does not enable physiology to be complied with. In addition, such a heart prosthesis with one single actuator has the risk, in operation, of either drawing the atria and failing to fill the ventricles, or performing too slow ejection and not maintaining a proper pressure."

In addition to the background information obtained for this patent, NewsRx journalists also obtained the inventors' summary information for this patent: "This invention aims at overcoming these drawbacks by improving the heart prosthesis with two actuators described above.

"For this purpose, according to the invention, such a heart prosthesis with two actuators is remarkable in that: one of said actuators is a main one and is provided between the hydraulic fluid chambers of both artificial ventricles, one of which is driving and the other is driven; the other of said actuators is a auxiliary one and is provided between the hydraulic fluid chamber of said driven artificial ventricle and said reservoir of hydraulic fluid made up by said soft bag; the main actuator: transmits to said driving artificial ventricle diastolic and systolic flow rates having desired respective values for this driving artificial ventricle, and transmits to said driven artificial ventricle: a systolic flow rate opposite to said diastolic flow rate of a desired value for said driving artificial ventricle, and a diastolic flow rate opposite to said systolic flow rate of a desired value for said driving artificial ventricle; and the auxiliary actuator transmits to said driven artificial ventricle correction systolic and diastolic flow rates for correcting said systolic and diastolic flow rates transmitted by said main actuator to said driven artificial ventricle and for communicating respectively to the corrected systolic and diastolic flow rates desired values for said driven artificial ventricle.

"Thus, with the present invention, the beats of the sealed bag are restricted since, in operation, the hydraulic fluid is transferred from one artificial ventricle to the other. However, with said correction flow rates generated by said auxiliary actuator, the diastole and the systole durations are not necessarily equal.

"Besides, the auxiliary actuator can have a lesser power than said main actuator, such that the power consumption of the prosthesis in accordance with this invention is lower than the power consumption of the known prosthesis with two actuators. In addition, the auxiliary actuator can also have a smaller size than the one of said main actuator.

"Preferably, the driving artificial ventricle corresponds to the right artificial ventricle, whereas the driven artificial ventricle corresponds to the left artificial ventricle. In addition, it is advantageous that said main and auxiliary actuators are of the volumetric motor pump type.

"For the convenience of accommodating the prosthesis inside the pericardial cavity, it is also advantageous that said main actuator and said auxiliary actuator are provided in the vicinity of each other. In this case, in order to benefit from the anatomy, said main and auxiliary actuators are provided in the vicinity of the left artificial ventricle and so they communicate commonly with the hydraulic fluid chamber of this latter ventricle, while said main actuator is connected to the hydraulic fluid chamber of the right artificial ventricle by a duct outside said stiff body."

URL and more information on this patent, see: Grimme, Marc; Gourgues, Jean-Elie; Carpentier, Alain; Wartelle, Claude. Implantable One-Piece Heart Prosthesis. U.S. Patent Number 8702793, filed January 7, 2009, and published online on April 22, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=104&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=5170&f=G&l=50&co1=AND&d=PTXT&s1=20140422.PD.&OS=ISD/20140422&RS=ISD/20140422

Keywords for this news article include: Carmat, Cardiology, Pericardial, Prosthetics, Medical Devices.

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Source: Cardiovascular Week