JP6604709B2 - Measuring device - Google Patents

Description

  The present invention relates to a measurement device that performs measurement by inserting a first end of a long member into a lumen of a living body.

  One index for determining the treatment policy for stenotic lesions in the coronary artery is the coronary flow reserve ratio (FFR). The coronary flow reserve ratio is the ratio of the internal pressure (Pa) upstream to the internal pressure (Pd) downstream of the stenotic lesion (FFR = Pd ÷ Pa). The coronary flow reserve ratio indicates the blood flow that is inhibited by a stenotic lesion. For example, if the coronary flow reserve ratio is 0.6, only 60% of the maximum blood flow is obtained by the stenotic lesion. It is judged that there is no flow. Generally, percutaneous coronary intervention (PCI) is indicated if the coronary flow reserve ratio is 0.75 or less, and pharmacotherapy is indicated if it is 0.8 or more.

  As a device for measuring internal pressure in a coronary artery, a device in which a pressure sensor is provided on a guide wire is known (Patent Documents 1 and 2). Two pressure sensors are arranged at a distance from the distal end of the guide wire, the guide wire is inserted into the coronary artery, and the two pressure sensors are respectively provided at the proximal portion and the distal portion of the stenotic lesion. The internal pressure can be measured by positioning. Moreover, the thing provided with the blood-flow sensor and the temperature sensor other than a pressure sensor is well-known (patent documents 3-5).

JP-T-2001-517993 Japanese National Patent Publication No. 10-525269 JP-T-2001-504249 JP 2001-25461 A Special table 2008-514308

  The guide wire having the pressure sensor as described above is required to be downsized or meridized so that it can be inserted into a small coronary artery. However, a sensor having a diaphragm such as a pressure sensor has a limit in size and size reduction due to its structure. In order to reduce the size, a structure using a semiconductor is required, which is expensive.

  In addition, in order to perform PCI, it is necessary to know the inner diameter of the coronary artery in which stenosis has occurred. At present, the inner diameter of the coronary artery is measured by image analysis using X-rays irradiated from the outside. However, since the inner diameter of the obtained image changes depending on the X-ray irradiation direction, it is difficult to measure the inner diameter quickly and accurately. .

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a small and meridian device capable of measuring the internal pressure of a fluid flowing through a lumen in a living body lumen.

  Another object of the present invention is to provide an apparatus that can quickly and accurately measure the inner diameter of a coronary artery.

  The measuring device according to the present invention has a first end and a second end, and the first end side is provided on the first end side of the long member that can be inserted into the lumen and the long member. A hot-wire anemometer.

  The long member is inserted into the lumen from the first end side. At any position in the lumen, the flow rate of the fluid flowing through the lumen is measured by a hot wire anemometer.

  In this measuring apparatus, a plurality of wires that can move in a direction away from the long member are arranged on the first end side of the long member at intervals around the axis of the long member. May be.

  The wire moved in the direction away from the long member contacts the inner wall of the lumen. Since a plurality of wires are arranged at intervals around the axis of the long member, the first end side of the long member is fixed near the center of the lumen. Thereby, a hot-wire anemometer can be arranged near the center of the lumen.

  The wire rod is a cantilever, and the measuring device includes a measuring unit that measures the displacement amount of the cantilever, and a contact sensor that is provided at the tip of the cantilever and detects contact with the inner wall of the lumen. Furthermore, you may comprise.

  Based on the displacement amount of the cantilever, the inner diameter of the lumen can be calculated.

  The measuring apparatus further includes an outer cylinder into which the elongate member and the cantilever are inserted, and the cantilever is covered with the outer cylinder so that the tip is held at a position close to the elongate member, The tip may move in a direction away from the elongated member by being exposed from the outer cylinder.

  By operating the outer cylinder with respect to the cantilever, the amount of movement of the tip of the cantilever is displaced.

  The elongate member may be a guide wire.

  The elongate member may be a microcatheter.

  According to the present invention, it is possible to realize a small and thin measuring device that measures the flow velocity of the fluid flowing through the lumen. Based on the obtained flow velocity, the inner pressure of the lumen can be calculated. Further, the inner diameter of the lumen can be measured based on the displacement amount of the cantilever. Thereby, the inner diameter of the lumen can be measured simultaneously with the measurement of the inner pressure of the lumen.

FIG. 1 is a diagram illustrating a measurement apparatus 10 according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing the II-II cross section of the measuring apparatus 10 in a state where the contact sensor 31 is in contact with or close to the outer peripheral surface of the guide wire 11. FIG. 3 is a partial cross-sectional view showing a II-II cross section of the measuring apparatus 10 in a state where the contact sensor 31 is separated from the outer peripheral surface of the guide wire 11. FIG. 4 is a diagram illustrating the operating principle of the hot-wire anemometer 23.

  Hereinafter, preferred embodiments of the present invention will be described. In addition, this embodiment is only one embodiment of this invention, and it cannot be overemphasized that an embodiment can be changed in the range which does not change the summary of this invention.

  As shown in FIG. 1, the measuring device 10 includes a guide wire 11 and an arithmetic device 12. The guide wire 11 has an outer diameter and a length that can be inserted into a human coronary artery, for example. The distal end of the guide wire 11 is formed by winding another stainless steel rope in a spiral shape around the core wire of the stainless steel, and can be bent according to the curvature of the blood vessel. In addition, a harness 13 for transmitting a detection signal of each sensor to be described later can be inserted into the internal space of the guide wire 11. The distal end (right end in FIG. 1) of the guide wire 11 corresponds to the first end, and the proximal end (left end in FIG. 1) corresponds to the second end.

  The arithmetic unit 12 receives detection signals of respective sensors, which will be described later, and calculates blood flow velocity, pressure, and blood vessel inner diameter, and includes hardware such as a CPU, ROM, and RAM, for example. A program for realizing the calculation is stored.

  A hot wire anemometer 23 is provided at the tip of the guide wire 11. The principle of the hot-wire anemometer 23 is as follows. When a thin metal wire (heat wire) heated by flowing an electric current is placed in the fluid, the temperature of the heat wire decreases and the electric resistance value also changes due to the cooling action of the flow. This cooling effect increases as the flow rate increases. The hot-wire anemometer 23 measures the flow velocity using this property.

  As FIG. 4 shows, the hot wire 24 which comprises the hot wire anemometer 23 comprises one of the resistance in a Wheatstone bridge. Reference numeral 25 is a compensation amplifier, and reference numeral 26 is a voltmeter.

The relationship between the current I flowing through the hot wire 24 and the flow velocity U of the fluid perpendicular to the hot wire 24 is expressed by the following equation.
I ² R / (R−R ₀ ) = A + BU ⁿ
Here, R ₀ is the resistance when the hot wire 24 is at the same temperature as the fluid, and A and B are constants when the hot wire 24 is in a fluid at a constant temperature, and can be determined by measurement with the flow velocity U changed. n is generally 0.5.

  The non-equilibrium voltage generated between the BDs due to the temperature / resistance change of the heat wire 24 accompanying the change in the flow velocity is returned to the power supply terminal of the bridge through the compensation amplifier 25, and the temperature / resistance of the heat wire 24 becomes constant. The bridge voltage V is measured by the voltmeter 26, and the arithmetic unit 12 calculates the flow velocity based on the measured value.

The computing device 12 computes FFR based on the flow velocity. An example of the FFR operation is an operation based on Bernoulli's theorem. Here, the flow velocity upstream of the stenosis of the coronary artery is U ₁ and the pressure is P ₁ . The flow rate at the stenosis of the coronary artery is U ₂ and the pressure is P ₂ . The flow velocity downstream of the stenosis of the coronary artery is U ₃ and the pressure is P ₃ . The following equations hold for these.
1/2 · U ₁ ² + P ₁ / ρ = 1/2 · U ₂ ² + P ₂ / ρ = 1/2 · U ₃ ² + P ₃ / ρ = C (constant)
Where ρ is the density of the fluid.

From the above formula, the following three formulas are obtained.
P ₁ = ρ (C−1 / 2 · U ₁ ² )
P ₂ = ρ (C−1 / 2 · U ₂ ² )
P ₃ = ρ (C−1 / 2 · U ₃ ² )

Then, FFR, that is, P ₁ / P ₃ is expressed by the following equation.
P ₁ / P ₃ = (C−1 / 2 · U ₁ ² ) / (C−1 / 2 · U ₃ ² )

Since Bernoulli's theorem relates to non-viscous fluids, it is necessary to consider viscosity in blood vessels having an inner diameter of 160 mm or less, but Hagen-Poiseuille's law holds for laminar flow. Therefore, when blood passes through the arteriole of the flow resistance Rf and the pressure changes by ΔP, the following equation holds.
ΔP = RfQ (where Q is volume)
Therefore, a blood vessel having an inner diameter of 160 mm or less can be handled by storing the conversion table in the arithmetic device 12 in advance.

  As shown in FIGS. 1 to 3, an outer cylinder member 33 is provided outside the guide wire 11. The outer cylinder member 33 has an inner diameter slightly larger than the outer diameter of the guide wire 11, and can be bent along the blood vessel in the same manner as the guide wire 11. The outer cylinder member 33 extends to the proximal end of the guide wire 11 in a state where the hot-wire anemometer 23 at the distal end of the guide wire 11 is exposed to the outside. The outer cylinder member 33 can slide relative to the guide wire 11 in the axial direction 51.

  The moving mechanism 34 is connected to the base end side of the outer cylinder member 33, and moves the outer cylinder member 33 in the axial direction 51 using a rack and pinion mechanism, a ball screw, or the like. The driving amount of the moving mechanism 34 can be grasped by, for example, an encoder. Based on the output of the encoder, driving of the moving mechanism 34 is controlled. The moving mechanism 34 is not essential. For example, the practitioner may directly operate the outer cylinder member 33.

  A cantilever 32 extending along the axial direction 51 is provided on the distal end side of the guide wire 11 and in the gap with the outer cylinder member 33. The cantilever 32 has a base end that is fixed to the outer peripheral surface of the guide wire 11 and a distal end that extends toward the distal end of the guide wire 11 and is curved so as to open outward. Although not shown in each figure, three cantilevers 32 and contact sensors 31 are arranged around the axis of the guide wire 11 at equal intervals, that is, at 120 ° intervals. The cantilever 32 corresponds to a wire.

  As shown in FIG. 2, the cantilever 32 is covered with the outer cylinder member 33, so that the curved shape is elastically deformed and abuts or approaches the outer peripheral surface of the guide wire 11. As shown in FIG. 3, when the outer cylinder member 33 is slid to the proximal end side and the distal end side of the cantilever 32 is exposed to the outside, the cantilever 32 is elastically restored to a curved shape, and the distal end side of the guide wire 11 is Move away from the outer surface.

  A piezo element 37 is provided along the axial direction 51 on the inner surface side of the cantilever 32, that is, on the guide wire 11 side. When the cantilever 32 is bent, the piezo element is also bent, and a voltage corresponding to the bent shape is applied to the harness. 13 to output to the arithmetic unit 12. The output of the piezo element 37 is proportional to the distance at which the tip of the cantilever 32 is separated from the outer peripheral surface of the guide wire 11. Therefore, based on the output of the piezo element 37, the calculation device 12 calculates the distance at which the tip of the cantilever 32 is separated from the outer peripheral surface of the guide wire 11. The piezo element 37 corresponds to a measuring unit.

  A contact sensor 31 is provided at the tip of the cantilever 32. As the cantilever 32 is elastically deformed, the contact sensor 31 moves toward and away from the outer peripheral surface of the guide wire 11. Similar to the cantilever 32, the contact sensor 31 outputs a detection signal to the arithmetic device 12 through the harness 13.

  The computing device 12 computes the displacement amount of the cantilever 32 when the contact sensor 31 outputs a detection signal indicating that it has contacted the inner wall of the blood vessel based on the output of the piezo element 37. The displacement amount of the cantilever 32 is proportional to the distance from the outer peripheral surface of the guide wire 11 to the inner wall of the blood vessel. Since the outer diameter of the guide wire is known, the arithmetic unit 12 outputs a detection signal indicating that the contact sensor 31 provided at the tip of each of the three cantilevers 32 has contacted the inner wall of the blood vessel. The displacement amount of the three cantilevers 32, that is, the distance from the outer peripheral surface of the guide wire 11 to the inner wall of the blood vessel is calculated, and the inner diameter of the blood vessel is calculated from the obtained three points by, for example, a three-point measurement method.

  Further, the tips of the three cantilevers 32 are separated from the outer peripheral surface of the guide wire 11 and come into contact with the inner wall of the blood vessel, whereby the hot-wire anemometer 23 is supported near the center of the blood vessel.

[Operational effects of this embodiment]
According to the measurement apparatus 10 according to the present embodiment, for a stenotic lesion in which the distal end side of the guide wire 11 is inserted into the coronary artery and the position is confirmed in advance, the stenosis site and the flow velocity upstream and downstream of the stenosis site are It can be measured by the hot-wire anemometer 23. The calculation device 12 can calculate FFR based on the obtained flow velocity.

  Further, the arithmetic device 12 measures the inner diameter of the blood vessel based on the displacement amount of the cantilever 32. Thereby, in the lumen of a living body such as a coronary artery, the flow velocity and the internal pressure of the fluid flowing through the lumen and the inner diameter of the blood vessel can be measured.

[Modification]
In the embodiment described above, the elongated member is realized by the guide wire 11, but a microcatheter may be used instead of the guide wire 11. By using the microcatheter, the microcatheter can be inserted and withdrawn while the guidewire is placed in the blood vessel, and a balloon catheter or the like can be inserted into the blood vessel using the guidewire.

  In the embodiment described above, the three cantilevers 32 and the contact sensors 31 are provided on the distal end side of the guide wire 11. However, if the number of the cantilevers 32 and the contact sensors 31 is three or more, four cantilevers 32 and the contact sensors 31 are provided. There may be five. For example, the four cantilevers 32 and the contact sensor 31 may be arranged around the axis of the guide wire 11 at equal intervals, that is, at 90 ° intervals.

  In the above-described embodiment, the amount of displacement of the tip of the cantilever 32 is measured based on the output of the piezo element 37. Instead of the piezo element 37, the cantilever 32 is irradiated with light, and the cantilever 32 is The guide wire 11 may be provided with light detection means for detecting the position of reflected light, that is, the bending angle, and the displacement amount of the cantilever 32 may be measured by the light detection means.

  In the embodiment described above, the guide wire 11 is provided with the cantilever 32. However, when it is not necessary to measure the inner diameter of the blood vessel, the guide wire 11 is curved and bulges outside the guide wire 11 instead of the cantilever 32. A wire or the like that can be formed may be provided as a wire.

10 Measuring device 11 Guide wire (long member)
DESCRIPTION OF SYMBOLS 12 Computation device 23 Heat ray anemometer 31 Contact sensor 32 Cantilever 33 Outer cylinder member 37 Piezo element (measuring means)

Claims (7)

A long member having a first end and a second end, the first end side being insertable into a blood vessel of a human body ;
A metal wire provided on the first end side of the elongate member;
An arithmetic unit electrically connected to the metal wire by a connection line extending from the second end of the elongate member,
The metal wire is a resistor that generates heat when power is supplied, and is exposed so as to be in contact with blood in the blood vessel .
The arithmetic unit is
The other three resistors in the Wheatstone bridge with the metal wire as one resistor,
At the connection point of the four resistors of the Wheatstone bridge, the first connection point and the second connection point opposite to the first connection point are connected to the input terminal, and the output terminal is grounded. A compensation amplifier connected to a third connection point opposite to the connection point of 4 ;
A voltmeter for measuring the output voltage of the compensation amplifier;
And a measuring device that calculates the flow velocity of blood flowing through the blood vessel using the voltage measured by the voltmeter. The above arithmetic unit calculates the flow velocity U using Equation 1.
I is the current value of the current supplied to the metal wire and is a value corresponding to the voltage value measured by the voltmeter,
R is the resistance of the metal wire ,
R0 is the resistance of the metal wire when the metal line is the same temperature as the fluid,
The measuring apparatus according to claim 1, wherein A and B are constants.

3. A plurality of wire rods that are movable in a direction away from the long member on the first end side of the long member with a space around the axis of the long member. The measuring device described in 1. The wire is a cantilever,
Measuring means for measuring the displacement of the cantilever;
The measuring apparatus according to claim 3 , further comprising a contact sensor provided at a tip of the cantilever and detecting contact with the inner wall of the blood vessel . An outer cylinder into which the elongate member and the cantilever are inserted;
The cantilever is covered with the outer cylinder, the tip is held at a position close to the long member, and the tip is moved away from the long member when exposed from the outer cylinder. Item 5. The measuring device according to Item 4 . The elongate member, the measurement device according to any of claims 1 a guide wire 5. The elongate member, the measurement device according to any of claims 1 a microcatheter 5.

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