CN201033076Y

CN201033076Y - Heart pipe three-dimensional marking and measuring system

Info

Publication number: CN201033076Y
Application number: CNU2007200785731U
Authority: CN
Inventors: 程煜; 薛奋; 周继勇; 李楚雅
Original assignee: Individual
Current assignee: Sichuan Jinjiang Electronic Science and Technology Co Ltd
Priority date: 2007-02-14
Filing date: 2007-02-14
Publication date: 2008-03-12
Anticipated expiration: 2017-02-14

Abstract

The utility model discloses a three-dimension marking and mapping system for cardiac catheter, which is characterized in that: the system comprises a supply oscillator being able to produce sinusoidal signals of three different frequencies with mutual independence; the three signals pass through a first bandpass filtering and a constant flow source to form an actuating signal of three different frequencies which then can be sent to three pairs of electrodes on the surface. The signal input from the keeper electrode and reference electrode of the cardiac catheter passes a second bandpass filtering, difference amplifier and anti-aliasing filter, and then the digital signal transformed by A/D can be sent to a digital signal processor. The marking and mapping system of the utility model has the advantages of good real time, high veracity, safe use and simple circuit organization.

Description

Three-dimensional mapping system of cardiac catheter

Technical Field

The utility model relates to a three-dimensional mapping system of cardiac catheter for confirm the accurate position of cardiac catheter in the human body.

Background

The three-dimensional mapping system is used for electrocardio medical instruments. Aims to establish a three-dimensional model of the inner wall of a heart cavity when performing heart operations such as atrial fibrillation. The existing mapping system uses a special catheter, and the operation cost is high.

Disclosure of Invention

The utility model aims to provide a: the cardiac catheter three-dimensional mapping system has the advantages of low operation cost, high accuracy, good real-time performance and safe use.

The technical scheme of the utility model is that:

a cardiac catheter three-dimensional mapping system comprises a signal source P1, wherein the signal source generates three sinusoidal signals with different frequencies and independent of each other, and the three signals 17, 18 and 19 form three excitation signals with different frequencies through first band-pass filtering and a constant current source and are output to three pairs of body

surface electrode plates

7, 8,9, 13, 11 and 10; also included are cardiac catheter 15 for localization (electrodes 20, 21 are referred to as localization electrodes) and cardiac catheter 14 for reference (electrode 22 is referred to as reference electrode). The differential signals input from the electrodes 20 and 22, and the electrodes 21 and 22 are subjected to second band-pass filtering, differential amplification and anti-aliasing filters, and are subjected to A/D conversion, and converted digital signals are sent to a digital signal processor.

And the digital signal processor outputs the three-dimensional coordinates of the positioning electrode after filtering.

The utility model has the advantages that: the three excitation signals can be simultaneously applied to the patient, so that the real-time performance is good, and the accuracy is high. Because the voltage difference acquired at the same moment contains the voltage difference of three frequency components, namely the three-dimensional coordinates of the same point are generated at the same moment, the limitation of the switching speed of three excitation signals in time-sharing measurement on the response time of a circuit is avoided, the real-time performance is not good, and the accuracy is not high. Digital demodulation is realized in a Digital Signal Processor (DSP), an acquisition circuit is simplified, the reliability of the circuit is improved, and the interference of cardiac contraction and respiration can be better eliminated by adopting digital filtering. The position of the reference electrode 22 is monitored by one body surface electrode 12, and when the position of the reference electrode changes, a doctor can be reminded to rebuild the model in time, so that the safety of the operation is improved.

Drawings

Fig. 1 is a schematic block diagram of the present invention.

Fig. 2 is a schematic view of a catheter inserted into a human body.

Fig. 3 is a schematic view of the body surface electrode sheet on the human body.

Fig. 4 is a schematic diagram of a signal source applied to an electrode sheet.

Fig. 5 is a schematic diagram of a cardiac catheter electrode.

Detailed Description

The present invention will be further explained with reference to the drawings and examples.

The utility model discloses a concrete embodiment 1, as shown in fig. 1, 2, 3, 4, 5, signal source P1 can be realized with direct digital frequency synthesizer (DDS), the sinusoidal wave that the production frequency is 30KHz, 36KHz, 40KHz respectively, first band-pass filtering P2 can be realized with second order active filter, constant current source P3 realizes with voltage-controlled current source, form sine wave excitation signal 17, 18, 19, paste three pairs of

output electrode slice

1A, 1B, 2A, 2B, 3A, 3B and

electrode line

10, 11,7, 8, 13, 9 on the patient, the position is forebreast-back respectively, right axilla-left axilla, the neck is back-left thigh inboard. Three excitation signals are respectively connected to three pairs of electrode plates and are simultaneously applied to the patient P4, and the three currents form a three-dimensional electric field at the heart of the patient. This process, we call the establishment of a three-dimensional electric field (from P1 to P4).

During surgery, a catheter (electrode 22) is placed in the coronary sinus of the patient and is kept in place throughout the three-dimensional mapping process to determine the origin of the measurement, which is referred to as the reference electrode. A catheter is also placed within the heart chamber to map the spatial location of the electrodes 20.

The second band-pass filtering P5 connected with the first band-pass filtering and the second band-pass filtering can be realized by a second-order active filter, and the amplifying filtering P6 can be realized by a differential operational amplifier firstly and then by a second-order active low-pass filter to realize anti-aliasing filtering. P7 should choose high-speed A/D device, and the sampling rate should be greater than 2 times of the highest frequency of the excitation signal. P8 can be realized by using a DSP chip.

When the positioning catheter is positioned in the heart chamber, a voltage difference is generated between the positioning electrode and the reference electrode, and the voltage difference is a composite of three frequency components. The voltage difference component of each frequency component is proportional to the distance between the positioning electrode and the reference electrode in the corresponding electric field direction. From the three voltage difference components, the distances between the positioning electrode and the reference electrode in the three electric field directions, i.e., the three-dimensional coordinates of the positioning electrode with respect to the reference electrode, can be calculated. When the positioning electrode contacts the inner wall of the heart chamber, the three-dimensional coordinates of the contact point of the inner wall of the heart chamber relative to the reference electrode can be determined. When there are enough points, a three-dimensional model of the inner wall of the heart chamber can be built.

The three-dimensional coordinate generation process of the positioning electrode relative to the reference electrode is described from P5 to P8. Signals input from the positioning electrode and the reference electrode are subjected to band-pass filtering P5, differential amplification and anti-aliasing filtering P6, converted into digital signals through A/D conversion P7 and sent to DSP processing P8. And performing band-pass digital filtering in the DSP, and performing digital demodulation to obtain the three-dimensional coordinates of the positioning electrode relative to the reference electrode. The three-dimensional coordinates obtained at the moment contain the interference of the cardiac contraction and the respiration, and the three-dimensional coordinates with the interference of the cardiac contraction and the respiration eliminated can be obtained by performing low-pass digital filtering once again. Digital demodulation and digital filtering are realized in the DSP, so that an acquisition circuit is simplified, and the reliability of the circuit is improved. The data accuracy obtained by the digital demodulation method is higher than that obtained by the analog demodulation method.

The above digital demodulation is an orthogonal sequence demodulation method, and the principle is as follows:

suppose that the excitation signal contains n frequency components and has an angular frequency K _i ω, the measured voltage signal is sampled uniformly (N > 2max (K) at N points per cycle ₀ ，K ₁ ，…，K _n-1 ) The sequence obtained after):

in the formula of U _i Mode of voltage at ith frequency component, phi _i J is an integer from 0 to N-1 corresponding to the phase angle at that frequency.

Respectively constructing sine sequences by considering the orthogonal characteristic of trigonometric function

S ₁ ：Sin(2K _i π j/N) and S ₂ ：Cos(2K _i π j/N), then Sn and S1

And the inner products of S2 are respectively:

since N is a known quantity, S _n (j) Measured voltage signal, therefore A _i1 And A _i2 Respectively correspond to

The real and imaginary parts of the voltage at the respective frequencies.

From tg (phi) _i )＝A _i2 /A _i1 Can find phi _i Substituting the formula (1) to obtain U _i I.e. the modulus of the voltage at the corresponding frequency.

The specific embodiment of the utility model 2, the reference electrode in the above scheme need keep the position unchanged at the operation in-process, just can accomplish the three-dimensional model modeling of heart intracavity wall. It is therefore necessary to monitor the position of the reference electrode. In the scheme, a body surface electrode is added as a second reference electrode to monitor the position of the reference electrode 22, and the body surface electrode consists of an electrode plate 16 and an electrode connecting wire 12. I.e. obtaining the three-dimensional coordinates of the reference electrode relative to a second reference electrode of the body surface, in exactly the same way as described above. If the position of the reference electrode changes, the physician is alerted that re-modeling is required.

The utility model discloses a concrete embodiment 3, on embodiment 1's basis, increases electrode 21 as supplementary measuring electrode, and the measuring method is the same with electrode 20's measuring method for confirm the relative position between electrode 20 and the electrode 21, with the direction of confirming the pipe.

Claims

1. A cardiac catheter three-dimensional mapping system, comprising: the system comprises a signal source, wherein the signal source generates three sinusoidal signals with different frequencies and mutually independent, and the three signals form three excitation signals with different frequencies through first band-pass filtering and a constant current source and are output to three pairs of body surface electrode plates; the device also comprises a cardiac catheter (15) used for positioning, an electrode (20) used as a positioning electrode, an electrode (21) installed on the cardiac catheter (15), a cardiac catheter (14) used for reference and an electrode (22) used as a reference electrode; differential signals input from the electrode (20) and the electrode (22) and the electrode (21) and the electrode (22) are subjected to second band-pass filtering, then subjected to differential amplification and anti-aliasing filters, subjected to A/D conversion, and converted into digital signals, and sent to a digital signal processor.

2. The cardiac catheter three-dimensional mapping system according to claim 1, wherein pairs of the reference electrode and the positioning electrode are connected to a second band-pass filter.

3. The cardiac catheter three-dimensional mapping system according to claim 1, wherein a second reference electrode is connected to the second band-pass filter.

4. The system according to claim 1, wherein the digital signal processor outputs the filtered and demodulated three-dimensional coordinates of the positioning electrode.