An assembly for determining a desired position on a body organ as well as a positioning device suitable for such an assembly The invention relates to an assembly for determining a desired position on a body organ, such as the heart, for the purpose of delivering an electrical pulse to a body organ by means of an electrode, which assembly comprises at least one electrically conductive wire, which is provided with the electrode, which is accommodated in a housing, at one end thereof.

With such an assembly, which is known from US patent US-A- 4,235, 246, an electrode connected to an electrically conductive wire is placed into contact with the body organ (a heart) at a number of successive positions, and an electrical pulse is delivered to the body organ. The response of the body organ to the electric pulse being delivered is measured at said positions, after which it is determined at which position a desired optimum response was obtained. The electrode is then securely attached to the heart wall at that position. It is also possible to use a test electrode in this connection, and to attach another electrode to the heart at the desired position once that position has been determined,.

Although the response of the electric pulse that is being delivered is measured at a number of positions, it is practically impossible to retrace a previously localised position at which a relatively good response to an electrical pulse was obtained.

Consequently, the known electrode is attached to the heart at the position at which a response exceeding a predetermined value is obtained.

The object of the invention is to provide an assembly by means of which the determination of a desired position can take place in a simpler and more accurate manner.

This object is accomplished with the assembly according to the invention in that the assembly further comprises a positioning device

which is provided with a number of recesses in which the housing can be removably positioned.

The positioning device is placed on the body organ, for example the heart, and removably attached thereto. Subsequently the housing is successively positioned in each of the recesses, with the electrode being placed into contact with the body organ. An electrical pulse is delivered at the various positions defined by the recesses, and the response of the body organ thereto is measured. After the response has been measured at a number of positions in this manner, the position at which the desired, optimum response of the body organ was obtained is determined. Subsequently, the housing of the electrode is repositioned in the recess associated with that position, after which the electrode is attached to the body organ. The electrode that is definitively attached to the body organ may not be the same electrode as the electrode by means of which electrical pulses were delivered at a number of different positions. It is also possible to attach the electrode by means of which the various positions were examined to the body organ at the desired, optimum position. Using the positioning device, it is therefore possible in a relatively simple manner to retrace previously examined positions and to determine a position providing an optimum response.

One embodiment of the assembly according to the invention is characterized in that the positioning device comprises an elongated strip, which is provided with a number of recesses on both longitudinal sides.

In this way it is possible to examine a number of positions of the body organ corresponding to the aforesaid recesses over a relatively great distance corresponding to the length of the strip.

Another embodiment of the assembly according to the invention is characterized in that the recesses are semicircular in shape.

A housing of the electrode, for example of circular shape,

can be positioned in said semicircular recesses in a simple manner. The housing can be positioned in a number of rotated positions with respect to the recesses in that case, with the electrode, which is preferably centrally located in the semicircular housing, taking up the same position with respect to the recesses in each of said rotated positions.

Another embodiment of the assembly according to the invention is characterized in that the positioning device is provided with at least one mouthpiece as well as with a vacuum line connected to said mouthpiece.

Using a vacuum to be generated in the mouthpiece, the positioning device can be securely and removably attached to the body organ in a simple manner without any risk of causing damage to the body organ.

The invention will be explained in more detail hereinafter with reference to the drawings, in which Fig. la is a perspective view from above of a positioning device of the assembly according to the invention, Fig. lb is a perspective bottom view of the positioning device that is shown in Fig. la, Fig. 2 is a perspective view of an electrode connected to an electrically conductive wire, Fig. 3 is a perspective, enlarged view of the electrode that is shown in Fig. 2, Fig. 4 shows the use of the assembly according to the invention with a heart.

Like parts are indicated by the same numerals in the figures.

Figs. la and 1b are a perspective view from above and a perspective bottom view, respectively, of a positioning device 1 of an assembly according to the invention. The positioning device 1 comprises an elongated plastic strip 2, which is connected to a handle 4 at one end

3. The strip 2 is provided with a number of mouthpieces 5, each comprising an opening 6. The openings 6 are connected, via a channel (not shown) in the strip 2, to a vacuum line 7 that is connected to a vacuum pump (not shown) on a side remote from the strip 2. The strip 2 is provided with semicircular recesses 8 on both longitudinal sides, on either side of the mouthpieces 5.

Figs. 2 and 3 show a device 11 of the assembly according to the invention, comprising an electrically conductive, relatively stiff wire 12 with a circular, plastic housing 13 present on one end thereof, in which housing an electrode 14 is centrally located. The wire 12 is provided with a handle 15 on a side remote from the housing 13, in which the stiff, electrically conductive wire 12 is connected to a flexible, electrically conductive wire 16. The electrically conductive wire 16 can be connected to an electrical pulse generator (not shown) on a side remote from the handle 15. The diameter of the housing 13 corresponds to the diameter of the semicircular recesses 8 of the positioning device 1.

Fig. 4 shows the use of the assembly according to the invention in determining a desired position on a wall 31 of a heart 32.

If a heart 32 exhibits defects that interfere with the pump function, it is possible, using one or more so-called epicardial pacemaker leads provided with an electrode at one end thereof, to deliver an electrical pulse to the relevant part of the heart. The response of the heart 32 to the electrical pulse depends to a large extent on the position on the heart wall 31. Consequently, it is important that the correct position on the heart wall 31 be determined in order to obtain an optimum, preferably maximum response of the heart 32 to the electrical pulse that is being delivered. To localise the optimum position, the strip 2 is laid on the heart wall 31 of the heart 32 by means of the handle 4. Subsequently, a vacuum is generated in the vacuum line 7, as a result of which the strip 2 is sucked against the heart wall 31 under the influence of the vacuum created in the mouthpieces 5 via the openings 6. Then the stiff

electrically conductive wire 12 is moved into close proximity with the strip 2 by means of the handle 15, with the circular housing 13 being placed into abutment with a semicircular recess 8. Following that, an electrical pulse is applied to the electrode 13 by means of the pulse generator, which pulse is transferred to the heart wall 31 via the electrode 13. Using means that are known per se, the response of the heart 32 is then measured. The housing 13 is successively positioned in (preferably) all semicircular recesses 8, an electrical pulse is delivered to the heart wall 31 at each position, and the response of the heart 32 to each of said pulses is registered.

After an electrical pulse has been delivered to the heart wall 31 near all the recesses 8, it is determined near which of the recesses 8 an optimum response of the heart 32 has been obtained.

Subsequently, an electrode to be definitively attached to the heart 32, which electrode is present in a housing having the same diameter as the housing 13, is placed into abutment with the recess 8 that is associated with the position at which the optimum response was obtained. The electrode is subsequently attached to the heart wall 31, using means that are known per se. Instead of using the device 11, it is also possible to use the electrode that is to be definitively connected to the heart 32 in localising the most optimum position. It is for example possible to use the electrode as described in the aforesaid US patent for this purpose.

Instead of using semicircular recesses 8, it is also possible to provide the strip 2 with fully circular recesses, in which a fully circular housing 13 can be positioned. It is also possible to use oval, square or rectangular recesses, in which cases the housing will have a corresponding shape.

Once the electrode has been definitively attached to the heart wall 31, the vacuum in the vacuum line is released, after which the strip 2 can be moved away from the heart wall 31 in a simple manner by means of the handle 4.