JPH06151B2 - Electrodes for cardiac pacemakers - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrode for a cardiac pacemaker.

(Prior Art and Problems Thereof) A cardiac pacemaker is composed of a main body including a control unit, electric wires and electrodes. The performance required for electrodes, especially for implantable cardiac pacemakers, is that the electrodes easily adhere to the heart, the polarizability of the pulse generated by the pacemaker is low, and the signal from the heart is detected. The impedance (input impedance) may be small, and the impedance (output impedance) when a signal is emitted to the heart may be large. Therefore, conventionally, Pt or a Pt alloy that is harmless to the living body and has a high electric conductivity is used. Alternatively, the surface of Pt alloy is mechanically roughened by sandblasting or glass beads to increase the substantial surface area to improve the polarizability and the input impedance. There was no effect, and improvements in these aspects were desired.

(Object of the Invention) The present invention has been made in view of the above-mentioned needs, and an object thereof is to minimize the physical size of the electrode in order to increase the output impedance, and to reduce the polarizability and the input impedance. To do. In particular, reducing the polarizability leads to prevention of malfunction of the pacemaker, extension of battery life, and increased responsiveness to the heart.

(Structure of the Invention) The present invention provides P on an electrode made of Pt or a Pt alloy.
It is characterized by being coated with a mixture of t and a Pt group oxide.

As a result of diligent studies to reduce the polarizability and the input impedance, the present inventors have found that in order to reduce these, the affinity for hydrogen ions and chloride ions in body fluid is smaller than the actual surface area, and , It was discovered that the polarizability and input impedance can be reduced very effectively by using a material having excellent catalytic ability to discharge these ions for the electrode. That is, in order to reduce the polarizability, hydrogen ions and chlorine ions at the interface between the electrode and the body fluid are made into atoms or molecules in the shortest possible time, so that the polarizability becomes extremely small, and as a result, the input impedance also becomes small. The present inventors have conducted experiments to find a material having excellent catalytic ability for these hydrogen ions and chlorine ions, and have concluded that the Pt group oxide is most suitable.

In the present invention, the electrode material is limited to Pt or Pt alloy,
This is because these materials are harmless to the living body and have excellent electrical conductivity. Further, the reason why the coating layer is limited to the mixture of Pt and the Pt group oxide is that Pt enhances the adhesion strength between the coating layer and the base, and the pt group oxide has an excellent catalytic ability for hydrogen ions and chlorine ions. Is.

The coating method applied to the present invention includes a physical vapor deposition method, a chemical vapor deposition method, a baking method, a thermal spraying method, a plating method and the like, but is not limited to these methods, and if Pt and a Pt group oxide are coated, Any method may be used. Further, the coating does not have to be applied to the entire surface, and only the portion that comes into contact with the body fluid is sufficient. Furthermore, the coating thickness is 0.5
It was confirmed that the catalytic ability was sufficiently exhibited when the value was μ or more.

(Example) An example of an electrode for a cardiac pacemaker according to the present invention will be described together with a conventional example.

First, a conventional example will be described. An electrode 1 for a cardiac pacemaker having a size and shape shown in FIG.
Glass beads of μ were blasted to increase the effective surface area.

Explaining Example 1 next, an electrode 1 for a cardiac pacemaker having a size and shape shown in FIG. 1 is made of Pt, and Pt—Pd 30 wt% is sprayed on the head 2 by plasma spraying to form a coating film 3. Then, an electrode for a cardiac pacemaker was obtained as shown in FIG. At this time, the film thickness was 2.5μ.
This electrode was subjected to oxidation treatment at 700 ° C. for 2 hours in the air to obtain a Pt-PdO mixture.

Next, Example 2 will be described. An electrode 1 for a cardiac pacemaker having the dimensions and shape shown in FIG. 1 was made of a Pt-Ir 33 wt% alloy, and Pt-I was baked on this head 2 by a baking method.
A coating film 3 containing 75 wt% of rO ₂ was obtained, and the electrode for a cardiac pacemaker shown in FIG. 2 was obtained. At this time, the film thickness was 0.8 μ.

The electrodes for cardiac pacemakers of the conventional example and Examples 1 and 2 thus obtained were measured for the polarizability from the pulse waveform in the test circuit shown in FIG. 3, and the input impedance in the test circuit shown in FIG. Upon measurement, the results shown in Table 1 below were obtained.

In FIG. 3, 10 is an electrolytic cell, solution 11 is NaCl 9 g, water 1
, Ethanol 1, the cathode 12 in the solution is a cardiac pacemaker electrode, the anode 13 is a 12 cm ² Ti plate, and the distance between the electrodes is 50 mm. 14 is a constant current power supply of 10 mA, and 15 is an oscilloscope for measuring waveforms.

In FIG. 4, 10 to 13 are the same as those in FIG. 3, and therefore their explanations are omitted. 16 is a 100 mV, 50Hz power supply, 17 is a 10Ω shunt resistor, and the input impedance is measured.

Calculation of polarizability of the is to derive from the V _max and V _p of the P pulse waveform of FIG. 5 as follows.

Polarizability (%) = (V _p / V _max ) × 100 Further, the calculation method of the sensing impedance is as follows.

As is clear from Table 1 above, the electrodes for cardiac pacemakers of Examples 1 and 2 have remarkably low polarizability and the input impedance is orders of magnitude smaller than the electrodes for cardiac pacemakers of the conventional examples.

(Effects of the Invention) As described in detail above, according to the method for manufacturing an electrode for a cardiac pacemaker of the present invention, the physical size is made as small as possible and then the Pt group oxide is coated.
The polarizability is extremely low, the responsiveness from the heart is high, the power consumption is low, the sensing impedance is extremely low, and it is possible to obtain an extremely reliable electrode for a cardiac pacemaker. .

[Brief description of drawings]

FIG. 1 is a diagram showing the shape and dimensions of a conventional cardiac pacemaker electrode, FIG. 2 is a diagram showing an electrode having a coating film of Pt and a Pt group oxide obtained by the example, and FIG. 3 is a polarizability. FIG. 4 is a diagram showing a test circuit for measurement, FIG. 4 is a diagram showing a test circuit for measuring sensing impedance, and FIG. 5 is a diagram showing a pulse waveform as an element for calculating polarizability.

Claims (1)

[Claims] 1. A cardiac pacemaker electrode comprising a cardiac pacemaker electrode made of Pt or a Pt alloy coated with a mixture of Pt and an oxide of a Pt group metal.