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Publication numberWO2003077759 A1
Publication typeApplication
Application numberPCT/NL2003/000210
Publication date25 Sep 2003
Filing date20 Mar 2003
Priority date20 Mar 2002
Publication numberPCT/2003/210, PCT/NL/2003/000210, PCT/NL/2003/00210, PCT/NL/3/000210, PCT/NL/3/00210, PCT/NL2003/000210, PCT/NL2003/00210, PCT/NL2003000210, PCT/NL200300210, PCT/NL3/000210, PCT/NL3/00210, PCT/NL3000210, PCT/NL300210, WO 03077759 A1, WO 03077759A1, WO 2003/077759 A1, WO 2003077759 A1, WO 2003077759A1, WO-A1-03077759, WO-A1-2003077759, WO03077759 A1, WO03077759A1, WO2003/077759A1, WO2003077759 A1, WO2003077759A1
InventorsGheorghe Aurel Marie Pop, Filho Carlos Alberto Dos Reis
ApplicantMartil Instruments B.V.
Export CitationBiBTeX, EndNote, RefMan
External Links: Patentscope, Espacenet
Catheter with integrated signal-processing device
WO 2003077759 A1
Abstract
The invention relates to a catheter comprising a tube-like body with a distal and a proximal end, wherein on the distal end is placed at least one measuring element which is connected via a connecting line to a signal-processing device, wherein the signal-processing device is connected integrally to the tube-like body and comprises a connection for a detecting device. The invention also relates to an assembly of a catheter, comprising a radio-frequency source on the distal end of the catheter and a localizing device which comprises a plurality of receiving members and a connection for a detecting device, which receiving members are placed in a plane with a known relative position to each other and are suitable for receiving the signal from the radio-frequency source.
Claims  (OCR text may contain errors)
1. Catheter comprising a tube-like body (1) with a distal (2) and a proximal (3) end, wherein on the distal (3) end is placed at least one measuring element which is connected via a connecting line to a signal-processing device, characterized in that the signal -processing device is connected integrally to the tube-like body and comprises a connection for a detecting device.
2. Catheter as claimed in claim 1, characterized in that the signal -processing device comprises an integrated circuit .
3. Catheter as claimed in either of the foregoing claims, characterized in that two measuring electrodes are arranged on the distal end and the signal-processing device is embodied such that an electrocardiogram (ECG) can be shown on the detecting device if the measuring electrodes receive electrical signals from a pumping heart.
4. Catheter as claimed in any of the foregoing claims, characterized in that it comprises features for performing impedance measurements, and the signal -processing device is embodied such that impedance measurements can be performed therewith.
5. Catheter as claimed in claim 4, characterized in that the features for performing an impedance measurement comprise two measuring electrodes arranged on the distal end and two field electrodes, these field electrodes being placed on the distal end such that the two measuring electrodes fall within these field electrodes.
6. Catheter as claimed in any of the foregoing claims, characterized in that the catheter comprises measuring elements for measuring physiological parameters such as temperature, pressure and pH.
7. Catheter as claimed in any of the foregoing claims, characterized in that the signal -processing device is connected integrally to the proximal end of the tube-like body.
8. Catheter as claimed in any of the foregoing claims, characterized in that the connection for the detecting device comprises a radio- frequency channel.
9. Catheter as claimed in any of the foregoing claims, characterized in that the tube-like body comprises at least one cavity.
10. Catheter as claimed in any of the foregoing claims, characterized in that the catheter comprises markings on the outside which are suitable for determining how far the catheter has penetrated into a body.
11. Assembly of a catheter as claimed in any of the foregoing claims, comprising a radio-frequency source on the distal end of the catheter and a localizing device which comprises a plurality of receiving members and a connection for a detecting device, which receiving members are placed in a plane with a known relative position to each other and are suitable for receiving the signal from the radio-frequency source.
12. Assembly as claimed in claim 11, characterized in that the connection for the detecting device comprises a radio-frequency channel.
13. Assembly as claimed in claim 11, characterized in that the detecting device is integrated with the localizing device .
Description  (OCR text may contain errors)

CATHETER WITH INTEGRATED SIGNAL-PROCESSING DEVICE

Catheter comprising a tube-like body with a distal (2) and proximal end, wherein on the distal end is placed at least one measuring element which is connected via a connecting line to a signal-processing device. This device is preferably embodied as an integrated circuit or chip.

The primary function of this device is the detection of the intracavitary electrocardiogram (ECG) and transmission thereof to a remotely situated detecting device, which can be a dedicated device or a commercially available notebook, palmtop, mobile phone or the like. The connection between the chip and the detecting device consists of a wire connection or a type of radio-frequency channel, for instance based on WAP or 'blue tooth' technology. The chip is also able to measure the impedance of blood by means of a repetition mechanism of stimulation-and-measurement signals on the electrodes of the catheter. The measurement interval varies for instance from 8-20 mS synchronised with the intracavitary electrocardiogram (ECG) .

In the context of this patent application a "signal- processing device" is understood to mean any device that receives a signal as input and generates as output a signal derived from the input signal. The signal -processing device can for instance be a sampling device or a transmitting device . Normally speaking a central venous catheter is arranged in the case of different indications in a broad spectrum of medical disciplines; particularly in the intensive and medium level care wards in cardiology, internal medicine, gynaecology and surgery. The catheter is frequently introduced by means of puncture with the Seldinger technique in the vena jugularis or in the vena subclava, although the vena antecubita in the left or right arm may also be used (figure 2) . The arranging of a central venous line is not normally done with flouroscopic monitoring, although after arrangement a radiological check must be performed to find out whether the catheter is located in the ideal position, in or close to the right- hand atrium. Radiology after the introduction will reveal whether the catheter has erroneously gone in the wrong direction, for instance in the direction of the head of the patient. It is also possible that the catheter has been inserted too far and comes to be situated in the right-hand ventricle, which may cause arrhythmia. Re-positioning may be necessary following a radiological check. With the catheter according to the present invention the electrode on the distal end will detect the intracavitary ECG signal in the right-hand atrium as soon as it arrives there. Coming from the vena antecubita in the left or right arm, or coming from the left or right vena subclava or vena jugularis, it is apparent that the distance to the right-hand atrium can be estimated subject to the height of the patient and the exact entry position of the catheter; the catheter itself has markings every 10mm (figure 1) . Where no intracavitary ECG signal appears when the catheter has been introduced over the estimated distance to the right-hand atrium, this means that the catheter has gone in the wrong direction. The intracavitary ECG will be transmitted, as described above, by the telemetry function implemented in the chip at the proximal end and will be received by a remotely located detecting device, which can be a commercially available portable computer (such as a notebook or a palmtop) or a portable telephone with WAP technology. The amplitude of the normal intracavitary ECG signal in the right-hand atrium varies between 0.1 and 1 mV and will be measured between two electrodes on the distal end. In the case where four electrodes are arranged on the distal end for impedance measurements, the two inner measuring electrodes will be used for detection.

As soon as the catheter is inserted further, the P- curve morphology of the atrium will change and a larger QRS-complex will appear, which means that the catheter is entering the right ventricle, which must be prevented. The appearance of the intracavitary ECG of the atrium is therefore useful in finding out whether the catheter has reached the ideal position in or close to the right-hand atrium, and insertion too far toward the right ventricle is also prevented.

The advantages of the catheter according to the invention are that radiological checking is no longer necessary after the correct configuration of the intracavitary arterial ECG has been observed on the screen of the detecting device. Radiological checking costs time and X-radiation has negative effects; an assistant has to come with a mobile radiology device or the patient has to be transported with his bed to the radiology department. After adequate placing of the distal end of the catheter in the right-hand atrium, a permanent telemetric monitoring of the heart rhythm can furthermore be obtained via the chip and external electrodes on the skin or the chest are no longer necessary. The wires to these external electrodes often hinder the patient in his/her movement. The distal electrodes on the catheter together with the chip moreover enable impedance measurements which sufficiently indicate the haemocrit value and the blood viscosity (see patent application: PCT/NLOO/00378 and PCT/NL01/00281) . If only low frequency is used, in this case 20 kHz, a complicated internal shielding between the conductive wires is not necessary to prevent the influence of stray radiation. If higher frequencies are used for impedance measurements, which is a necessary requirement for measuring the capacity in the blood, special shielding will be necessary, as described in patent application PCT/NL01/00281.

In the simplest model of the catheter according to the invention, processing of the intracavitary ECG is not carried out by the chip. All signal processing can in this case be performed by the computer used as detecting device.

In the more refined model of the catheter, signal processing on the chip can be used for time control of the repetitive impedance measurements for short time intervals (8-20 msec) , initiated on the intracavitary ECG.

In a further embodiment of the catheter according to the present invention additional functions can be implemented in the chip to allow permanent monitoring of the blood temperature and other functions.

The signal processing device can be disposable and be already arranged on the proximal end of the catheter during manufacture, or can be used a number of times and arranged as a knob on the proximal end of the catheter. The proximal end of the catheter will always be outside the patient, so that such a device does not have to be sterilized.

In another embodiment of the catheter according to the invention a microchip of small dimensions with a radio frequency source can be arranged during manufacture on the tip of the catheter. After unpacking of the catheter and prior to use, the transmitter is activated. A board (figure 3), which contains a row of receiving members ('sniffers') such as receiver coils that is placed above the chest of the patient, can be used to determine the position of the transmitter chip (tip of the catheter) by determining which receiving member in the matrix receives the transmitted signal with the maximum amplitude. The co-ordinates of the corresponding receiving member will then be transmitted to the remotely located detecting device and converted into visual information about the location of the catheter. Any movement of the tip of the catheter can thus be easily followed during insertion of the catheter. With such a function it will be much easier to reach the ideal position in the upper region of the right-hand atrium, where an intracavitary ECG signal will appear.

The "catheter location board" preferably consists of a matrix of receiving members which are placed in a regular grid of 10mm x 10mm. One end of each receiving member is connected to the same wire, the common wire. The other end of each receiving member is connected to a multiplex circuit, which makes it possible to individually detect the signal induced in each coil by means of a full detection cycle. In view of the fact that the amplitude of the signal induced in a coil varies in inverse proportion to the distance to the radio-frequency source, the position of the catheter will be detected by identifying which coil receives the signal with maximum amplitude. The co-ordinates of the maximum signal coil are transmitted to the remotely located detecting device, which will translate this information into a visual indication of the catheter position.

The radio- frequency source is temporarily activated by the chip which is connected to the proximal end of the catheter. The energy source for the entire system is located at the proximal end. The invention will be described further on the basis of the following figures.

Figure 1 shows a schematic overview of the catheter according to the invention. Figure 2 shows a detail of the distal end of the catheter of figure 1.

Figure 3 shows an overview of the positions where the catheter according to the invention can be introduced into the human body. Figure 4 shows an overview of a catheter detection board according to the invention.

Figure 5 shows an overview of the use of an assembly according to the invention.

Figure 6 shows a further overview of the use of an assembly according to the invention.

The catheter shown in Figure 1 comprises a tube-like body (1) with a distal (2) and proximal (3) end. Tube-like body (1) comprises two lumina which are connected to lines (12, 13) . At the distal end, a detailed view of which is shown in figure 2, there are situated two measuring electrodes (5, 6) with which the signal of the intracavitary ECG can be detected. In addition, the impedance of the blood can be measured with these electrodes (5, 6) on the basis of the current flowing through the field electrodes (7, 8) . The mutual distance between the electrodes is 1 mm. The electrodes on the distal end are connected by means of connecting lines (20,21,22,23) to the signal processing device (9) on the proximal (3) end. This signal processing device is embodied as an integrated circuit on a chip that is integrated onto the proximal end of the tube-like body of the catheter.

At the distal end the catheter further comprises a radio-frequency source that is integrated onto a chip. This radio-frequency source can be used to directly localize the distal end of the catheter, as will be further described in figures 4-6.

The length of tube-like body (1) is roughly 700 mm and the diameter is roughly 6 French. Markings are arranged on tube-like body (1) at a mutual distance of 10 mm. By means of these markings it is possible to estimate how far the tip of the catheter at the distal end has been inserted into the body of a patient. Tube-like body (1) comprises two curves in the direction of the distal end, whereby the distal end with the electrodes remains clear of the walls of the atrium. Present at the proximal end of the tube-like body are conduits which are connected to the lumina of tube-like body (1) . Medication or an infusion liquid can be carried in these conduits. The lumina are connected to the side opening (18) or the end opening (17) . The flow of the liquid medication or infusion liquid can be influenced by means of taps (13, 14) . Figure 3 shows a schematic view of the position of different arteries into which the catheter according to the invention can be introduced. The catheter according to the invention can be arranged by puncture in the vena jugularis (25) or the vena subclava (26) using the Seldinger technique or by doing this in the vena antecubita (27) in the left or right arm (not shown) . From here the catheter is moved toward the right-hand atrium (28) . Having arrived in the right-hand atrium, electrical signals from the heart will be received by measuring electrodes (5, 6) which are converted into an ECG signal by the signal processing device (9) . On the basis of the markings on tube-like body (1) it is possible to determine whether the distal end of the tube-like body must have arrived in the right-hand atrium, by estimating the distance the tip must have covered from the position of entering the body to the right-hand atrium.

Figure 4 shows a catheter detection board (29) with which the position of the tip of the catheter at the distal end can be determined. For this purpose the tube-like body (1) comprises a radio-frequency source (16) at the distal end (2) . The radio- frequency source transmits a signal that can be received by receiver coils (30) which are placed in a matrix inside a catheter detection board (31) . The receiving members are placed inside a matrix in a regular grid of 10 mm x 10 mm. One end of every receiver coil (30) is connected to a central wire (33), the other end (32) of every receiving member (30) is connected to a multiplex circuit (40) . This makes it possible to individually detect the signal, which is indexed in each coil, in a detection cycle. The position of the radio-frequency source (16) relative to the catheter detection board can be determined by identifying which coil (30) receives the signal of the radio- frequency source with a maximum amplitude.

The position of the distal end (2) of the catheter can be determined with such a catheter detection board.

Figure 5 shows an overview of the use of the catheter detection board. Catheter detection board (29) is coupled to a detecting device. The detecting device can be a computer (35) or a mobile telephone (36) , and the connection between catheter detection board (31) and the detecting device can be a wire connection (37) or a radio frequency (38) . By reading the position of radio-frequency source (16) relative to catheter detection board (29) on the detecting device, the doctor (39) introducing the catheter into the body of the patient (34) can determine the position of the distal end of the catheter in the body of the patient.

The catheter detection board (31) shown in figure 6 has a display screen (41) which consists of an LCD screen or a LED matrix of the desired resolution, whereby the position of the radio-frequency source (16) at the distal end (2) of the catheter can be directly monitored. The signal processing device at the proximal (3) end of the catheter is connected via a connecting line (42) to a computer (35) from which the ECG signal can be directly read. Detecting device (35) can be a computer such as a laptop or any other digital agenda or palm computer.

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Classifications
International ClassificationA61B5/06
Cooperative ClassificationA61B5/06, A61B5/062
European ClassificationA61B5/06
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