CN109512487B

CN109512487B - Safe surgical instrument for grasping and removing thrombus and use method

Info

Publication number: CN109512487B
Application number: CN201910003134.1A
Authority: CN
Inventors: 罗建军; 孙浩; 师用; 任仲靖; 苏笑宇
Original assignee: Northwestern Polytechnical University
Current assignee: Northwestern Polytechnical University
Priority date: 2019-01-03
Filing date: 2019-01-03
Publication date: 2020-06-16
Anticipated expiration: 2039-01-03
Also published as: CN109512487A

Abstract

The invention relates to a safe surgical instrument for grasping and removing thrombus and a using method thereof, which are characterized by comprising a three-dimensional conical structure and a linking structure; the three-dimensional conical structure is characterized in that a distal end protection head is arranged at the conical end of the three-dimensional conical structure, a linking structure is arranged at the opening end of the three-dimensional conical structure, and the main body of the three-dimensional conical structure adopts a net-shaped three-dimensional conical structure and comprises a hollowed-out net-shaped structure consisting of an axial part and a circumferential part; the net-shaped three-dimensional conical structure is made of a biocompatible shape memory material, and the surface of the shape memory material is simultaneously plated with another biocompatible material in all circumferential directions; the biocompatible shape memory material has a coefficient of thermal expansion that is mismatched with the coefficient of thermal expansion of two different materials of another biocompatible material. Can well solve two problems of operation complication caused by acute cerebral vascular rupture and secondary thrombus blockage caused by thrombus fragments in the operation in the prior interventional mechanical thrombus extraction field.

Description

Safe surgical instrument for grasping and removing thrombus and use method

Technical Field

The invention belongs to a surgical instrument, relates to a safe surgical instrument for grasping and removing thrombus and a use method, and relates to a novel and safe surgical instrument for intervening, grasping and removing thrombus in a blood vessel and a use method.

Background

Stroke is the second leading cause of death worldwide, with 80% of them being focal ischemic stroke caused by arterial embolism. It refers to a stroke caused by a thrombotic embolism that causes an acute obstruction in the vascular system, prevents blood flow and deprives surrounding brain tissue of oxygen. In the absence of oxygen, brain cells in the immediate area begin to die and release a range of toxic chemicals that threaten brain tissue cells in the surrounding area. In patients with ischemic stroke, the mortality rate of embolic cerebral infarction is 53% -92% when the diameter of blood vessels is larger than 1 mm. Acute ischemic stroke, however, can be treated by removing the acute obstruction and restoring blood flow to the affected area. In recent years, medical scientists have proposed a variety of treatments to address the problem of ischemic stroke.

The first stroke treatment approved by the U.S. food and drug safety administration (FDA) is the treatment of patients with lytic drugs such as recombinant tissue plasminogen activator, streptokinase or heparin. However, these drugs do not dissolve the blood clot immediately and usually only attack the stroke symptomsThe latter short time period is useful when administered, which means a very short, limited therapeutic window. As another major treatment for stroke, a technique called neuro-interventional stroke intravascular revascularization therapy (ERT), also known as an interventional mechanical embolectomy, is rapidly developing. Compared with traditional intravenous injection dissolving medicines, the current mechanical thrombus removal device has the advantages that the revascularization rate is remarkably improved, the clinical effect is greatly enhanced, and the stroke care system and the stroke care scheme all over the world are thoroughly changed by the technology. Devices that have currently gained FDA approval include MERCI, sold by centralized Medical, Inc. (mountain View, CA)^TMRETRIEVER Thrombus grasping device, PENNUMBBRA marketed by Penumbra (Alameda, Calif.)^TMThrombus grasping device, and new generation stent-type thrombus grasping device TREVO^TM(Stryker Co.) and SOLITARE^TM(eV3 Endovasular, a subsidiary of Covidien).

However, despite great advances in the field of interventional mechanical embolectomy, these thrombus grasping devices that have been used in clinical procedures still have many challenges, the most serious of which include surgical complications due to acute cerebral vascular rupture and secondary thrombus blockage caused by thrombus fragments during surgery. The former is due to the currently employed interventional mechanical embolectomy procedure (e.g., MERCI)^TM、TREVO^TMAnd SOLITARE^TM) Often, after the thrombus is grabbed by the thrombus taking device, the thrombus is dragged from the focus by directly applying left and right force (including radial force or axial force). However, in areas where thrombi are present, the vascular system is often quite fragile, especially neuro-vascular systems are more fragile than similarly sized vessels in other parts of the body and are located in important soft tissues. In general, the thrombus is firmly wedged in the vessel wall, and if the thrombus is directly dragged after being grabbed, due to the viscosity of the thrombus, excessive pulling force applied to the vessels can cause vessel perforation and intracranial acute bleeding to cause life-threatening complications. As to the second difficulty, it is not difficult to understand, since all these current interventional mechanical embolectomy procedures do not have the potential to be performed during the procedureSo that there is a risk of thrombus fragments being generated that, after they are generated, pass with the blood stream into smaller sized blood vessels that are more difficult to reach and treat, thus creating a secondary obstruction.

Therefore, the safe interventional mechanical thrombus removal surgical instrument has important significance and value for safely stripping, capturing and removing thrombus from blood vessels.

Reference to the literature

Disclosure of Invention

Technical problem to be solved

In order to avoid the defects of the prior art, the invention provides a safe grasping and thrombus removing surgical instrument and a using method thereof, aiming at two main problems of interventional mechanical thrombus removal surgery, including surgical complications caused by acute cerebral vascular rupture and secondary thrombus blockage caused by thrombus fragments in the surgery, and being used for safely stripping, capturing and removing thrombus from blood vessels.

Technical scheme

A safe grasping and thrombus removing surgical medical device is characterized by comprising a three-dimensional conical structure and a linking structure; a distal end protection head 106 is arranged at the tapered end of the three-dimensional tapered structure, a linking structure 104 is arranged at the opening end of the three-dimensional tapered structure, and the main body of the three-dimensional tapered structure adopts a net-shaped three-dimensional tapered structure and comprises a hollow net-shaped 105 structure consisting of an axial part 107 and a circumferential part 108; the net-shaped three-dimensional conical structure is made of a biocompatible shape memory material, and the surface of the shape memory material is simultaneously plated with another biocompatible material in all circumferential directions; the biocompatible shape memory material has a coefficient of thermal expansion that is mismatched with the coefficient of thermal expansion of two different materials of another biocompatible material.

The use method of the medical equipment for safely grasping and removing the thrombus is characterized by comprising the following steps:

step 1: controlling the guide wire and the micro-catheter to advance in the blood vessel, and removing the guide wire in the micro-catheter after the micro-catheter passes through the thrombus;

step 2: taking a distal protection head 106 of the medical equipment for grasping and removing the thrombus as the front end, controlling the medical equipment to advance in the microcatheter until the link structure 104 passes through the thrombus, releasing and unfolding the medical equipment after the whole medical equipment extends out of the microcatheter, and placing the medical equipment at the distal end of the thrombus;

and step 3: controlling the microcatheter to withdraw from the thrombus, and simultaneously controlling the grasping and thrombus removing surgical device to move towards the direction close to the thrombus until the grasping and thrombus removing surgical device contacts the thrombus;

and 4, step 4: applying periodically-changing current to two ends of the link structure 104 to change the temperature above and below the phase transition temperature of the shape memory material, so that the diameter size of the mechanical thrombus taking device is periodically changed, and dynamic shear stress is applied to thrombus to reduce the viscosity of the thrombus and promote the separation of the thrombus and the blood vessel wall;

and 5: after the thrombus is separated from the vessel wall, the mechanical thrombus taking device is controlled to advance towards the near end, so that the thrombus is integrally grabbed;

step 6: and finally, removing the mechanical thrombus taking device for grabbing the thrombus from the blood vessel of the patient through the microcatheter to finish the operation.

Advantageous effects

According to the safe thrombus grasping and removing surgical instrument and the using method, the interventional mechanical thrombus grasping device can apply dynamic shear stress to the surface of thrombus by periodically changing the diameter size of the thrombus grasping device. Because the special mechanical property of the thrombus is utilized, namely when dynamic shear stress is applied to the surface of the thrombus, the viscosity of the thrombus is gradually reduced. Therefore, the novel interventional mechanical thrombus extraction operation method using the thrombus grasping device can ensure that the thrombus is safely stripped from the blood vessel wall so as to avoid blood vessel perforation and intracranial acute bleeding complications. Meanwhile, the interventional mechanical thrombus taking device provided by the invention is of a net-shaped three-dimensional conical structure, the net-shaped design can ensure that blood can still normally circulate in the operation process, and meanwhile, the interventional mechanical thrombus taking device has the function of grabbing thrombus fragments generated in the operation process, so that the thrombus fragments are prevented from flowing to a far-end blood vessel to form secondary obstruction. In summary, the invention provides a novel safe interventional mechanical embolectomy surgical method, which can well solve two problems of surgical complications caused by acute cerebral vascular rupture and secondary thrombus blockage caused by thrombus fragments in the operation in the current interventional mechanical embolectomy field.

Drawings

FIG. 1 shows the change of the thrombus viscosity after the dynamic shear stress is applied at different frequencies, and it can be seen that the thrombus viscosity is greatly reduced when the frequency of the applied dynamic shear stress reaches a certain value.

FIG. 2 is a schematic view of a safe grasping and thrombus removing surgical instrument;

FIG. 3 is a diagram of a structural simulation of an interventional mechanical embolectomy device in finite element analysis software when the temperature exceeds the transformation temperature of the shape memory alloy;

FIG. 4 is a simulation diagram of the structure of an interventional mechanical embolectomy device in finite element analysis software at a temperature below the transformation temperature of the shape memory alloy, and it can be seen that the diameter of the mechanical embolectomy device is reduced in size due to deformation in the circumferential direction as the temperature is reduced.

Fig. 5 to 15 are schematic views illustrating the process of using the safe surgical instrument for grasping and removing thrombus provided by the invention.

Detailed Description

The invention will now be further described with reference to the following examples and drawings:

in the process of safely and efficiently stripping thrombus from blood vessel, we first studied the mechanical properties of thrombus in blood. Most thrombi are firmly wedged in the vessel wall after being formed due to the viscosity of the thrombi, and if the thrombi are directly dragged after being grabbed by the thrombi grabbing device, the overlarge pulling force exerted on the blood vessels can cause perforation of the blood vessels and intracranial acute bleeding complications, and the life safety of a patient is damaged. However, thrombus is a protein fibrous tissue, which has a special mechanical property. We have found that when dynamic shear stress is applied to the surface of thrombus, the viscosity of thrombus is gradually reduced, and the degree of reduction is related to the frequency of applying dynamic shear stress, as shown in FIG. 1, when the dynamic frequency reaches a certain value, the viscosity of thrombus is greatly reduced (the principle is similar to that of sinking into marsh, when an object continuously struggles in the marsh, the viscosity of marsh is reduced due to the application of dynamic shear stress, and the object sinks deeper).

Therefore, by utilizing the special mechanical property of thrombus, we propose a novel safe interventional mechanical thrombus extraction operation method for safely stripping, capturing and removing thrombus from blood vessel, and simultaneously provide a novel mechanical thrombus extraction device design concept equipped by the operation method. The interventional mechanical thrombus taking device is of a net-shaped three-dimensional conical structure, the net-shaped design can ensure that blood can still normally circulate in the operation process, and meanwhile, the interventional mechanical thrombus taking device has the function of grabbing thrombus fragments generated in the operation process, so that the thrombus fragments are prevented from flowing to a far-end blood vessel to form secondary obstruction. Meanwhile, the novel mechanical thrombus taking device provided by the invention can be placed in various common miniature medical interventional catheters and is controlled and operated to a focus by a doctor in the operation process. But is different from the traditional basket net hollow mechanical embolectomy device appearing in the current literature or patent,

the mechanical thrombus taking device provided by the invention has the function of generating dynamic shear stress on thrombus. Referring to fig. 2, reference numeral 104 is a link structure for linking the grasping apparatus with an external connecting rod, and simultaneously, current can be conducted to form a closed-loop current path with the grasping apparatus; 105 is a hole of the hollowed-out mesh-shaped gripping device, and the hollowed-out design can ensure that the gripping device can not block the circulation of blood flow in the whole process; 106 is a far-end protection head of the gripping device, and the rigidity is low, the structure flexibility is large, so that the head of the gripping device can not hurt the vessel wall due to the overlarge rigidity in the gripping process, and the effect of buffering protection is achieved; 107 is an axial portion of the conical gripping device, which portion consists only of shape memory material; 108 is a circumferential portion of the conical gripping device having both a shape memory material and a stress layer material (aluminum material in the particular example of embodiment), and by changing the temperature, the stress deforms the circumferential portion, thereby changing the size of the opening of the conical gripping device.

In order to provide the mechanical embolectomy device with the capability of periodically changing the size, the specific embodiment uses two different biocompatible materials in the circumferential direction of the device, but not limited to the design, and can also use a shape memory material with a two-way memory function on the circumferential part, and the method can also provide the mechanical embolectomy device with the capability of periodically changing the size.

The main body of the mechanical embolectomy device is made of shape memory alloy with biocompatibility, and the surface of the shape memory alloy is simultaneously plated with another biocompatible material in all circumferential directions. Therefore, in the operation process, after the overall temperature of the mechanical embolectomy device changes, if the temperature is lower than the phase transition temperature of the shape memory alloy, the shape memory alloy forming the main body structure changes from austenite to martensite, and the Young modulus of the material is reduced, so that the structure in the axial direction generates stress due to the mismatch of the thermal expansion coefficients of the two different materials, so that the mechanical embolectomy device deforms in all circumferential directions, and the diameter size of the mechanical embolectomy device changes macroscopically; conversely, when the bulk temperature returns to the transformation temperature of the shape memory alloy, the shape memory alloy comprising the host structure changes from martensite to austenite, while the Young's modulus increases, and the diameter dimension of the mechanical embolectomy device returns to its original dimension due to the shape memory function. Therefore, when the overall temperature of the mechanical thrombus removal device is periodically changed artificially in the interventional mechanical thrombus removal operation process (the overall temperature of the mechanical thrombus removal device can be periodically changed by applying periodically changed current and utilizing the principle of Joule heating), the diameter size of the mechanical thrombus removal device provided by the invention can be periodically changed, when the change is applied to the surface of the thrombus, a dynamic shear stress is equivalently applied to the thrombus, and the mechanical property of the thrombus can be seen to be greatly reduced, so that the thrombus is promoted to be safely peeled off from the blood vessel wall, and the blood vessel perforation and intracranial acute hemorrhage complications are avoided. In conclusion, the interventional mechanical thrombus removal device provided by the invention can well solve two problems of operation complications caused by acute cerebral vascular rupture and secondary thrombus blockage caused by thrombus fragments in the operation in the field of interventional mechanical thrombus removal at present.

According to the mechanical property analysis of the thrombus and the application method of the novel mechanical thrombus taking device, the thrombus can be safely stripped, captured and removed from the blood vessel, and the specific steps are as follows:

1. tracking a guide wire placed in the microcatheter and guiding the guide wire to the proximal end of the blood vessel where the thrombus is located;

2. controlling the guide wire to advance in the blood vessel and pass through the thrombus;

3. controlling the micro-catheter to advance in the blood vessel through the guide wire, and enabling the tail end of the micro-catheter to pass through the thrombus;

4. removing the guide wire in the microcatheter;

5. the novel mechanical thrombus taking device provided by the invention is placed in a micro-catheter, and the advance of the mechanical thrombus taking device in the micro-catheter is controlled until the mechanical thrombus taking device passes through the thrombus;

6. releasing and unfolding the mechanical thrombus taking device from the micro catheter, and placing the mechanical thrombus taking device at the far end of thrombus;

7. controlling the micro-catheter to advance towards the proximal end and withdraw from the thrombus, and simultaneously controlling the mechanical thrombus taking device to advance towards the proximal end until the mechanical thrombus is contacted;

8. the whole temperature of the mechanical thrombus taking device is periodically changed, so that the temperature is changed at the phase change temperature of the shape memory alloy, the diameter size of the mechanical thrombus taking device is periodically changed, dynamic shear stress is applied to thrombus, the viscosity of the thrombus is reduced, and the thrombus is separated from the vessel wall;

9. after the thrombus is separated from the vessel wall, the mechanical thrombus taking device is controlled to advance towards the near end, so that the thrombus is integrally grabbed;

10. and finally, removing the mechanical thrombus taking device for grabbing the thrombus from the blood vessel of the patient through the microcatheter to finish the operation.

Fig. 5 shows a blood vessel with an occlusive thrombus 201. The blood vessel has a proximal end 202 and a distal end 203. In accordance with the method of the present invention for treating a thrombus, the microcatheter 130 is first controlled to access the vascular system. This is done by conventional means. The microcatheter is placed in a large blood vessel proximal to the thrombus (not shown, often a leg vessel). A micro-guidewire 204 is advanced through the micro-catheter and through the occluded thrombus 201 as shown in fig. 6. With the guidewire 204 in place, the microcatheter 130 is advanced over the guidewire 204 until the tip of the microcatheter 130 passes through the occluded thrombus 201 (fig. 7). As shown in fig. 8, the guidewire 204 is removed, leaving the microcatheter 130 in place, with its tip passing through the occlusive thrombus 201 and ready for placement of the thrombus grasping device 110. Referring to fig. 9, the thrombus extraction device 110 is advanced through the lumen of the microcatheter 130 until it is deployed at the distal end of the microcatheter 130. Upon deployment, the thrombus capture device 110 automatically changes to a designed tapered mesh structure due to shape memory function.

As shown in fig. 10, when the thrombus capture device 110 is deployed, the microcatheter 130 is withdrawn proximal 202 of the occlusive thrombus 201. The thrombus capture device 110 is manipulated to ensure it is fully engaged with the thrombus 201 (fig. 11). At this time, the entire temperature of the thrombus extraction device 110 is finely adjusted by joule heating. After the periodic weak variable current is applied, the overall temperature of the mechanical thrombus taking device is periodically changed (the processes of fig. 11 and fig. 12 are continuously repeated), and is changed at the phase transition temperature of the shape memory alloy, so that the diameter size of the mechanical thrombus taking device is also periodically changed, dynamic shear stress is applied to thrombus, the purpose of reducing the viscosity of the thrombus is achieved, and the thrombus is separated from the vessel wall (fig. 13), so that the method can take out the thrombus 201 while minimizing the risk of arterial injury. The thrombus removal device 110 is then withdrawn to force the thrombus mass 201 into the mesh structure (fig. 14). Finally, the mechanical thrombus taking device for grabbing the thrombus is removed from the blood vessel of the patient through the microcatheter, and the operation is completed (fig. 15). It can be seen that the thrombus grasping device 110 is able to coat the clot well during removal and prevent debris from flowing to the distal vessel causing a secondary occlusion.

Finally, the inventor further carries out finite element analysis simulation verification on the structure of the interventional mechanical embolectomy device.

FIG. 3 shows a structural simulation of an interventional mechanical embolectomy device in finite element analysis software when the temperature exceeds the transformation temperature of the shape memory alloy. And fig. 4 is a structural simulation diagram of the interventional mechanical embolectomy device in finite element analysis software when the temperature is lower than the phase transition temperature of the shape memory alloy, and it can be seen that when the temperature is reduced, the shape memory alloy forming the main body structure is changed from austenite to martensite, and the elastic modulus of the material is reduced, so that the mechanical embolectomy device can deform in all circumferential directions due to the mismatch of the thermal expansion coefficients of the two different materials, thereby changing the diameter size of the mechanical embolectomy device macroscopically and meeting the deformation requirement of the safety interventional mechanical embolectomy surgical method on the embolectomy device provided by the invention.

Claims

1. A safe grasping and thrombus removal surgical medical device, characterized by comprising a three-dimensional conical structure and a linking structure (104); a far-end protection head (106) is arranged at the tapered end of the three-dimensional tapered structure, a linking structure (104) is arranged at the opening end of the three-dimensional tapered structure, and the main body of the three-dimensional tapered structure adopts a net-shaped three-dimensional tapered structure and comprises a hollow net-shaped (105) structure consisting of an axial part (107) and a circumferential part (108); the net-shaped three-dimensional conical structure is made of a biocompatible shape memory material, and the surface of the shape memory material is simultaneously plated with another biocompatible material in all circumferential directions; the biocompatible shape memory material and the other biocompatible material have mismatched thermal expansion coefficients of two different materials;

the current with periodic change is applied to the two ends of the link structure (104), so that the whole temperature of the three-dimensional conical structure is changed above and below the phase change temperature of the shape memory material, the diameter size of the mechanical thrombus taking device is changed periodically, dynamic shear stress is applied to thrombus, the viscosity of the thrombus is reduced, and the thrombus is separated from the blood vessel wall.