The invention relates to a device for connecting a cardiac biventricular assist means including a dual-chamber pumping device, the chambers of which each comprise an inlet and an outlet including cardiac valve prostheses, the outlet of the one chamber being connected to the aorta and the outlet of the other chamber being connected to the pulmonary artery, and featuring an electrically powered compressor means provided between the two chambers.
Cardiovascular diseases have since become the number one fatality in western industrial nations with ishemic heart disease and heart failure being the most frequent causes of death in Germany. Of a total of 2.7 million in in-patient treatment for cardiovascular diseases, roughly 15% die.
Implantable mechanical ventricular assist devices (VAD) have been in use now clinically for some 15 years. This form of therapy mainly serves as a bridge to transplant when no donor organ is available or the patient is already in such a critical health condition that he would in all probability fail to survive the acute stress of a heart transplantation and the initial high-dosis immune suppressive therapy involved. Then, following stabilization over several months by a VAD with an improvement in the organ functions detrimented previously by acute or chronic diminished circulation, the patients can be admitted to heart transplantation with a higher anticipated success.
More recent results have shown that the functioning of the heart may be improved by this therapy to such an extent that there is a possibility of system explantation without a subsequent heart transplantation (bridge to recovery). A future aim with assist systems of enhanced reliability is to allow them to remain in the body as an alternative to transplant (ATT).
Due to the lack of donors and organ allocation in accordance with a waiting list early or, in some cases, premature application for transplantation is experienced which results in suboptimal organ allocation. By making use of suitable heart assist systems on a full-scale basis available donor organs could be optimally allocated by eliminating a waiting time calculation and the result of the heart transplantation could be improved on recovery of the organ functioning following mechanical ventricular assistance.
Since no fully implantable, biventricular assist system is hitherto available, only extracorporal systems for assisting biventricular failure could hitherto find application. Left ventricular assist systems are built as a rule with a pump chamber.
Currently, the only way of assisting both ventricles is with a total artificial heart (TAH) which, however, is too big to be additionally implanted as an assist system. Instead, the native heart in this case would have to be totally removed, resulting in no back-up being available should the artificial system fail. This therapy also eliminates the bridge to recovery (BTR) option since the heart has been removed. Experience has furthermore shown that it is easier to make the transplantation when the patient had the supply of an assist system than when a total artificial heart (TAH) was implanted.
Problematic in a biventricular assist is making the connection to the right ventricle because of its thin muscle tissue. Hitherto this connection was made via anastomosis to the right atrium. Since the tissue here too is relatively thin, haemorrhage complications may arise should the suture rupture. On top of this, there is the danger of the atrium collapsing on blood intake due to an assist system.
The objective of the invention is to apply a device for connecting a cardiac biventricular assist means to both ventricles safely and durably.
In accordance with the invention this objective is achieved for a cardiac biventricular assist means as set forth in the preamble of claim 1 by the features of the characterizing clause. Advantageous aspects read from the sub-claims.
Since the right ventricle is not required to produce such a high pressure as the left ventricle which needs to pump the blood via the aorta throughout all of the body, the muscle tissue of the right ventricle is weaker than that of the left ventricle.
This is why, in accordance with a first embodiment of the invention a one-part or multi-part adapter flexible at least in part is provided with two through-passageways each separate from the other, the adapter being securely held, on the one hand, in a port in the apical portion of the septum and, on the other in a port in/at the apex of the left ventricle so that the through-passageway extending into the left ventricle is connected directly or by means of a first flexible tube to the inlet (12a) of the one chamber of a dual-chamber pumping device and the other through-passageway extending into the right ventricle is connected directly or by means of a second flexible tube to the inlet of the other chamber.
In this arrangement any suitable dual-chamber assist system can be used in conjunction the invention, also suitable being the compact system to assist the left ventricle adapter as it reads from DE 102 17 635 A1. How this system is modified to permit its application as a biventricular assist system in accordance with the invention will now be described in detail.
In accordance with one advantageous aspect of the invention the one-part adapter (20) comprises a flexible, funnel-shaped portion contacting the septum on the right following application of the adapter into the port thereof, a circumferential bead in full contact with the septum on the right following application of the adapter, and a receiving portion with the two through-passageways porting into the two ventricles. In addition, a displaceable, sleeve-shaped locking ring is provided outside of the left ventricle on the receiving portion.
Each of the two through-passageways in the receiving portion of the adapter may have an approximately semi-circular cross-section. Furthermore, in accordance with the invention, the outer sides of the one-part adapter, especially the funnel-shaped portion, the circumferential bead and part of the receiving portion may be covered with tissue material at least in part.
In accordance with a further preferred embodiment a multi-part adapter comprises an insertion part, a funnel-shaped portion, a receiving part having a bead at the one end and two through-passageways extending into the left and right ventricle respectively to which the corresponding inlet of the chambers is connected directly or by means of flexible tubes. Furthermore, a beadlike tissue band is provided for sliding on the receiving part. In addition, the funnel-shaped insertion part in accordance with the invention may also feature a circumferential collar.
For locating the funnel-shaped insertion part in the receiving part of the multi-part adapter a sawtooth profile may be configured on both parts, preferably on the outer side of the insertion part. Furthermore in accordance with the invention both the insertion part and the receiving part may be covered outwardly at least in part by tissue material.
When a flexible tube is stapled by a conventional suture stapler to the atriums, for example to the right atrium, to one or both of the ventricles, arteries and other suitable locations, and blood needs to be removed, an adapter version in accordance with the invention is applied in a flexible tube to optimise the flow whilst the adapter stabilizes the vessel port. In this arrangement, depending on the version of the suture stapler involved, the flexible tube is stapled to the corresponding vessel and the necessary port incised, for example, through the wall of the vessel in the apex of the left ventricle or right atrium. However, the remaining projection protruding inwardly (into the lumen) constitutes a major thrombosis risk. This is because the blood taken from the corresponding vessel recirculates behind the bead-like projection or becomes totally stationary in thus constituting an added thrombosis risk.
In addition, it is to be noted that the flexible tubes provided for such connections are generally incapable of maintaining a port open in strong muscle tissue, such as for example in the tissue of the left ventricle. To prevent such a closure or at least a restriction in the port provided in the vessel, a correspondingly rigid or at least partly rigid adapter in accordance with the invention is inserted by means of which, for one thing, the port is maintained open to the desired degree and thus stabilized and, for another, an optimal flow is assured.
Such a rigid or at least partly rigid adapter inserted into the flexible tube comprises in accordance with an advantageous aspect of the invention a portion featuring a funnel-shaped port translating into a circular cylindrical hollow portion. Furthermore, the adapter in accordance with the invention is configured outwardly as a stepped circular cylinder so that on application of this adapter to a tube stapled to a vessel a step of the stepped circular cylinder protruding inwardly comes into full contact with the projection. To improve a connection between the projection and the step of the stepped circular cylinder both can be adhesively bonded together.
To secure the adapter in place axially a sleeve can be press-mounted outwardly on to the flexible tube and on the adapter inserted therein. However, this sleeve may also be held in place by other means mechanically on the inserted adapter or connected to the latter.
The invention will now be detailed with reference to the drawings in which:
a and 8b are views of an insertion aid for applying an insertion part;
b are section views of an insertion aid for applying an insertion part including a funnel-shaped portion in the septum;
a and 14b are diagrammatic simplified illustrations of applying an adapter by means of an insertion aid;
c is a section view of an inserted adapter and
a and 15b are illustrations showing application of one variant of an adapter into a vessel port by means of an insertion aid.
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Provided between the two atriums 18 and 19 and the corresponding ventricles 3 and 2 are valves in the form of the tricuspid valve 5 and mitral valve 10 respectively. Illustrated furthermore diagrammatically between the left ventricle 2 and aorta 8 is the aortic valve 7 as well as between the right ventricle 3 and the pulmonary artery 9 leading to the lung is the pulmonary valve 6.
Illustrated below the heart 1 diagrammatically is a dual-chamber pumping device as detailed in DE 102 17 635 A1 of which only the two chambers are indicated in the drawing greatly simplified and diagrammatically, namely a chamber 12 and a chamber 15 arranged there behind in the drawing. The two chambers 12 and 15 each comprise inlets 12a and 15a as well as outlets 12b and 15b respectively.
Accommodated in the region of the inlets and outlets are the cardiac valve prosthetics 17 indicated shaded in the drawing. Secured to the outlets 12b and 15b of the two chambers 12 and 15 are the ends 13a and 16a of the two flexible tubes 13 and 16 respectively. The other ends 13b and 16b of the flexible tubes 13 and 16 are fixedly connected to the aorta 8 and pulmonary artery 9 respectively.
Secured to the inlet ports 12a and 15a of the chambers 12 and 15 are the ends 11a and 14a of a first flexible tube 11 and second flexible tube 14 respectively. The other ends (not shown) of the two flexible tubes 11 and 14 are secured to the corresponding ends of an adapter 20 indicated in
Provided between the two chambers 12 and 15 of the dual-chamber pumping device is a compressor device shown and detailed in DE 102 17 635 A1 (not shown in the diagrammatic illustration of the drawing). As already indicated above the left ventricular assist system known from DE 102 17 635 A1 can be modified into a dual-chamber pumping device for cardiac biventricular assistant, substantially involving eliminating the Y-adapter through which in the left ventricular assistant system the inlets and outlets of the two pump chambers are ported together.
In addition, the section view provided in the Y-adapter at the outlet end is replaced by two conventional cardiac valve prosthetics 17, directly located in the outlet portions of the two chambers 12 and 15 of the dual-chamber pumping device. The compressor device provided in DE 102 17 635 A1 can be taken over substantially unchanged together with the drive unit assigned thereto as well as the further units provided for the drive unit.
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For example, by means of the relatively rigid wire 27′ movingly attached to the bottom of the cap reinforced by ribs 27″, the cap 27 is shifted down from the deformed insertion portion 23, resulting in the flexible funnel-shaped insertion portion 23 flaring to press against the septum 4 on the left by its own tension, as indicated in
The outer sides of the adapter 20, particularly of the funnel-shaped insertion portion 23, the circumferential bead 24 as well as part of the outer surface area of the receiving portion 25 may be expediently covered with tissue material. The ends of the one-part adapter 20 protruding outwardly from the left ventricle 2 should be chamfered to create a neat transition between the adapter 20 and the applied flexible tubes 11 and 14 or inlets 12a and 15a respectively. This prevents deposits materializing in the interface between the adapter 20 and flexible tubes 11, 14 or inlets 12a, 15a respectively. The one-part adapter 20 as well as more particularly the flexible, funnel-shaped portion may be made of a plastics material or of metal, for example nitinol, a material which expands in response to warmth.
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To locate the receiving part 32 in the funnel-shaped insertion part 30 a sawtooth profile is configured on both parts, preferably on the outer side of the receiving part 32. The receiving part 32 features in turn two through-passageways 34 and 35 respectively. The through-passageways 34 and 35 are in turn connectable either by means of flexible tubes 11 and 14 or by correspondingly dimensioning the receiving part 32 also directly to the inlets 12a and 15a of the chambers 14 and 15 respectively of the dual-chamber pumping system. The two arrows as shown in
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The adapter 40 is made of a rigid material, e.g. metal and is thus more or less unchangeable in shape; it is either inserted into the flexible tube 11 or is already accommodated therein. Prior to applying the adapter 40 an end-to-side anastomosis is implemented by means of a suture stapler (not shown) the staples of which are to be adapted to the thickness of the heart tissue. In this arrangement, the flexible tube 11′ is stapled to the tissue in the apex of the left ventricle 2 as is indicated in
Depending on the suture stapler employed, the flexible tube 11 is stapled to the tissue before the port 2a is incised in the tissue of the left ventricle 2 by the ring scalpel of the suture stapler. A remaining projection 42 protruding inwardly into the lumen constitutes a major thrombosis risk. Fluid flowing in the direction of the arrow in
Where strong muscle tissue such as that of the left ventricle 2 is involved, it is to be noted that the stapled flexible tube is unable directly to maintain the applied port 2a open. To prevent this happening, the adapter 40 inserted in the flexible tube 11 is engineered rigid so as to stabilize the port 2a, for one thing, and, for another, to optimise the flow through the adapter.
This is why a one-part adapter 40 engineered fully or partly rigid is inserted which features in its interior a portion 45 having a funnel-shaped port translating into a hollow circular cylindrical portion 46. Outwardly the adapter 40 is configured as a stepped circular cylinder 41. If such an adapter 40 is not already integrated in the flexible tube 11′ it is inserted into the corresponding tube and pushed towards the projection 42 of the already stapled tube until a step 44 of the stepped circular cylinder 41 of the adapter 40 comes into contact fully with the projection 42. To enhance the connection of the adapter 40 inserted in the tissue port, the step 44 of the adapter 40 can be adhesively bonded to the projection 42.
To create a satisfactory flow transition to advantage the ends of the funnel-shaped portion 45 or circular cylindrical portion 46 can be chamfered or rounded. To prevent the adapter from slipping out of place, a sleeve or a sleeve/ring 47 can be mounted outwardly over the flexible tube 11 stapled to the tissue and, where necessary, also adhesively bonded to the tissue of the left ventricle 2. However, any other suitable means of making the connection between sleeve/ring 47 and the adapter 40 and the flexible tube 11 surrounding the latter is just as possible. Likewise, the adapter 40 can be adhesively bonded to the flexible tube 11 which in turn may be adhesively bonded to the tissue via its projection 42, as already described.
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In this arrangement, each of the two arrows in
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Number | Date | Country | Kind |
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10 2004 014 337.4 | Mar 2004 | DE | national |