JP6626034B2 - Catheter system - Google Patents

Description

  The present invention relates to a catheter having a pressure sensor.

  For treatment of atrial arrhythmia, etc., a catheter is inserted percutaneously into a target site in the heart, and a high-frequency current is applied to the electrode provided at the tip of the catheter to selectively cauterize the abnormal site. Ablation treatments are known.

  In catheter ablation treatments, the contact force between the electrodes of the catheter and the tissue correlates with the ablation area. In recent years, a contact force ablation catheter has been developed which is capable of performing ablation while monitoring the contact force by providing a pressure sensor at the distal end of the catheter.

JP 2012-96036 A

  With conventional contact force ablation catheters, once the catheter is in contact with the tissue, strain remains in the pressure sensor, and it is difficult to determine whether the catheter is in contact with the tissue because the load value does not become zero. There is a problem of becoming.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a technique capable of appropriately correcting a load value obtained by a pressure sensor provided in a catheter.

  One aspect of the present invention is a catheter system. The catheter system is provided with a catheter provided with a pressure sensor for measuring a load applied to the distal end portion, and a measurement value obtained by the pressure sensor is input, and a current value with respect to a maximum value of the measurement value within a predetermined time in the past is input. A data processing unit that calculates the degree of decrease in the measured value and corrects the current measured value to zero when the degree of decrease is equal to or greater than the correction threshold.

  In the catheter system according to the aspect described above, the data processing unit may allow the current measurement value to be corrected to zero when the maximum value is equal to or greater than a maximum measurement value threshold. The correction threshold may be set as a value unique to each catheter. Further, the data processing unit cancels the correction process of the current measured value when the current measured value is equal to or more than the release threshold within a predetermined time when the current measured value is corrected to zero. You may.

  A combination of the above-described elements as appropriate may be included in the scope of the invention for which protection is sought by the present patent application.

  ADVANTAGE OF THE INVENTION According to this invention, the load value obtained by the pressure sensor provided in the catheter can be corrected appropriately.

It is a schematic diagram of a catheter system according to an embodiment. 9 is a flowchart illustrating a procedure for correcting a measured value of a load obtained by a pressure sensor. It is a flowchart which shows the procedure of the correction cancellation process applied after the measured value of the load obtained by the pressure sensor is corrected to zero. The graph (a) showing the actual transition of the load, the graph (b) showing the transition of the measured value of the load without the correction processing, and the graph (c) showing the transition of the measured value of the load with the correction processing FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and description thereof will not be repeated.

  FIG. 1 is a schematic diagram of a catheter system 10 according to the embodiment. The catheter system 10 includes a catheter 20 and a console 60 as main members.

  The catheter 20 has a catheter tube 30 inserted into a human body and a handle portion 40 for a user to operate the catheter 20. The catheter tube 30 is formed of a hollow member, and an ablation electrode 32 is provided at a distal end portion thereof. Note that a plurality of ring-shaped electrodes may be provided on the proximal side of the electrode 32.

  A pressure sensor 34 is built in the catheter tube 30 near the electrode 32. The pressure sensor 34 is not particularly limited as long as it can measure the load applied to the electrode 32, in other words, the contact force between the electrode 32 of the catheter 20 and the tissue. Is a magnetic sensor that senses the deflection of the spring connected between the magnetic sensor and the spring.

  The handle portion 40 is provided with a deflecting operation knob 42. By operating the deflecting operation knob 42, an operation wire (not shown) inserted through the catheter tube 30 is pulled, so that the catheter tube 30 is The distal portion deflects or bends in the desired direction.

  Further, a small substrate 44 is built in the handle portion 40. The small substrate 44 is mounted with a memory such as a ROM in which a correction threshold A described later is recorded, and the correction threshold A can be read out from the ROM as appropriate.

  Console 60 provides information that can be used by a user to adjust the operation of catheter 20. The console 60 includes a computer 62, a keyboard 64, and a monitor 66. A signal line 50 extending from the proximal end of the catheter 20 is connected to the computer 62, and a signal from the catheter 20 is input to the computer 60. The computer 62 has circuits for amplifying, filtering, and digitizing the signal transmitted from the catheter 20. As one of the signals from the catheter 20, there is a signal related to the load applied to the distal end portion of the catheter tube 30 measured by the pressure sensor 34, and the data processing unit 68 provided in the computer 60 performs a load correction process described later. Be executed. By displaying on the monitor 66 the measured value subjected to the load correction processing as necessary, the user can confirm the load at the distal end of the catheter tube 30.

  The correction processing of the load measurement value performed by the data processing unit 68 will be described with reference to a flowchart.

  FIG. 2 is a flowchart showing a procedure for correcting the measured value of the load obtained by the pressure sensor.

  First, the catheter 20 and the computer 62 are connected by the signal line 50 (S10). Next, the correction threshold value A recorded on the small substrate 44 is read, and the correction threshold value A is set so as to be used by the data processing unit 68 (S20). The correction threshold value A is a value for the degree of decrease of the current load measurement value D with respect to the maximum value Max of the load measurement value within the past predetermined time t1 (second), for example, 1 second. It is preferable to be determined accordingly. For example, when a state where the distal end portion of the catheter tube 30 is in contact with the tissue is changed to a state in which the distal end portion is not in contact with the tissue, and a load of 10% remains as a distortion, the correction threshold A is set to 90%. .

  Next, the measurement of the load applied to the distal end portion of the catheter tube 30 using the pressure sensor 34 is started (S30). The measurement value obtained by the pressure sensor 34 is input to the data processing unit 68.

  The data processing unit 68 records the current measurement value D (g), and obtains the maximum measurement value Max (g) which is the largest among the measurement values D (g) recorded during the past t1 (second). Holds the maximum measured value Max (g) and the current measured value D (g) (S40).

Subsequently, it is determined whether or not the maximum measured value Max (g) is equal to or larger than the maximum measured value threshold B (S50).
If the maximum measured value Max (g) is less than the maximum measured value threshold B (No in S50), the process returns to S30, and the load is measured again.

  On the other hand, when the maximum measured value Max (g) is equal to or larger than the maximum measured value threshold B (Yes in S50), the degree of decrease of the current measured value D (g) from the maximum measured value Max is equal to or larger than the correction threshold A. For example, the ratio W = (Max−D) / Max × 100 of the difference (Max−D) between the maximum measured value Max and the current measured value D (g) with respect to the maximum measured value Max (g) is It is determined whether it is equal to or more than the correction threshold A (%) (S60).

  If the ratio W is less than the correction threshold value A (%) (No in S60), the current measurement value D (g) is used, the process returns to S30, and the load is measured again. On the other hand, when the ratio W is equal to or more than the correction threshold A (%) (Yes in S60), the current measurement value D (g) is corrected to zero (S70).

  When the current measured value D (g) has been corrected to zero, a correction release process (S80) described later is executed.

(Correction cancellation processing)
FIG. 3 is a flowchart illustrating a procedure of a correction cancellation process applied after the measured value of the load obtained by the pressure sensor is corrected to zero.

First, a countdown of a predetermined time t2 (second), for example, one second is started (S100).
The load is measured simultaneously with the start of the countdown (S110). Next, it is determined whether or not the current measured value D (g) obtained by the measurement is equal to or greater than the release threshold C (g) (S120).

  If the current measured value D (g) is equal to or greater than the release threshold C (g) (Yes in S120), the correction process for the current measured value D (g) is terminated (S150). In other words, after the current measured value D (g) becomes equal to or greater than the release threshold C (g) within the predetermined time t2, the correction process for the current measured value D (g) is not performed.

  On the other hand, if the current measured value D (g) is less than the release threshold C (g) (No in S120), it is determined whether or not t2 (second) has elapsed from the start of the countdown (S130). If t2 (second) has not elapsed since the start of the countdown (No in S130), the process returns to the determination in S110.

  On the other hand, when t2 (second) has elapsed from the start of the countdown (Yes in S130), the current measurement value D (g) is corrected to zero (S140), the countdown is reset, and the process returns to S100.

  FIG. 4 is a graph (a) showing the actual transition of the load, a graph (b) showing the transition of the measured value of the load without correction processing, and the transition of the measured value of the load with the correction processing. It is the figure which compared graph (c).

  As shown in FIG. 4, when the tip of the catheter does not come into contact with the tissue and the actual load becomes zero, if no correction processing is performed, it is assumed that the load is generated due to the strain generated in the pressure sensor. A measurement result is obtained (see FIG. 4B). On the other hand, when the correction process is performed, when the degree of decrease of the current measurement value with respect to the maximum value of the measurement value within the past predetermined time t1 (second) becomes equal to or greater than the correction threshold A, the current measurement is performed. The value is corrected to zero (see FIG. 4C).

  In addition, after the point where the tip of the catheter does not actually come into contact with the tissue, until the tip of the catheter comes into contact with the tissue again, if there is no correction processing, the measured value gradually decreases due to the elimination of distortion. (See FIG. 4B). On the other hand, when performing the correction process (the correction release process at this timing), the measured value is corrected to zero at every cycle t2 (second) (see FIG. 4C).

  When the distal end of the catheter comes into contact with the tissue again, the correction processing is canceled, and a measurement value corresponding to the actual load is obtained (see FIG. 4C).

  According to the catheter system 10 described above, when the load is detected by the pressure sensor 34 even though the distal end portion of the catheter tube 30 is not actually in contact with the tissue, the measurement value by the pressure sensor 34 is appropriately adjusted. Can be corrected.

  Further, by setting the correction threshold value A for each catheter, the load can be corrected more appropriately in accordance with the characteristics of each catheter.

  Further, after the measured value of the load is once corrected to zero, when the load actually occurs again, it is possible to appropriately set the necessity of the correction of the measured value of the load.

  The present invention is not limited to the above embodiments, and various modifications such as design changes can be made based on the knowledge of those skilled in the art. Embodiments can also be included in the scope of the present invention.

Reference Signs List 10 catheter system, 20 catheter, 30 catheter tube, 32 electrodes, 34 pressure sensor, 40 handle part, 42 knob for deflection operation, 44 small board, 50 signal line, 60 console, 62 computer, 64 keyboard, 66 monitor, 68 data Processing unit

Claims (4)

A catheter provided with a pressure sensor for measuring a load applied to the tip portion,
The measured value obtained by the pressure sensor is input, and the degree of decrease of the current measured value with respect to the maximum value of the measured values within a predetermined time in the past is calculated. A data processing unit for correcting the value to zero,
A catheter system comprising:   The catheter system according to claim 1, wherein the data processing unit allows the current measured value to be corrected to zero when the maximum value is equal to or greater than a maximum measured value threshold.   The catheter system according to claim 1, wherein the correction threshold is set as a value unique to each catheter.   The data processing unit, when the current measurement value is corrected to zero, cancels the correction process of the current measurement value when the current measurement value is equal to or more than the release threshold within a predetermined time. The catheter system according to any one of claims 1 to 3.

Images