Patent Application
20170049453
The invention generally relates to the occlusion of hollow structures such as blood vessels, and more specifically to percutaneous delivery of occluders.
Varicoceles, varicose veins, and ducts such as the cystic duct, or the left atrial appendage, are all examples of hollow structures that under certain circumstances benefit from being securely occluded with minimally invasive procedures. Varicocele is one of the leading causes of male infertility. It is characterized by an enlargement of the pampiniform venous plexus, which is a group of veins that drains blood from the testicles. Defective valves or compression of the veins can lead to the formation of a varicocele.
One known method of treatment involves inserting a catheter through a vein in the thigh, guiding it through the vasculature to the affected area, and closing off the malfunctioning veins. Closing off of veins may involve injecting a fluid or inserting a coil or other apparatus to block the blood flow through the veins. But those methods suffer from certain complications. The catheterization procedure may last one or two hours, and there is risk of hematoma, hydrocele, or other injury to the scrotum or other tissues. The artery that supplies blood to the testicle may be injured by these procedures as well.
The present invention provides a device for delivering multiple occluders laparoscopically, thoracoscopically, percutaneously, and for open surgical procedures. Occluders can be delivered in a minimally invasive procedure to a hollow structure such as a blood vessel. The device allows occlusion of such structures without requiring catheterization. An occluder delivery device similar to a syringe is provided that injects occluders directly to the region of interest. The device can hold several occluders at a time, so that multiple occluders can be delivered to a desired location or to multiple nearby locations with only a single injection of the delivery needle or a single insertion of the laparoscopic device. The multiple occluders can also be used in some applications to attach, or fix multiple tissue and/or material layers together, or can be used as a marker or indicator for follow on surgical procedures.
The multiple-occluder delivery device is useful for treatment of varicocele, among other conditions, where the region to be mechanically occluded is larger than the closure region of any single occluder element. It is useful for any procedure where a hollow structure, cavity, duct, or tubular structure is to be occluded. It is also useful for connecting two structures together. To treat varicocele, for example, the delivery device is inserted and the tube containing the occluders is pushed through the target blood vessel. The distal-most occluder is pushed out of the needle, where it expands on the far side of the vessel. The device is pulled back through the vessel, leaving the distal occluder transfixing the vessel. A proximal occluder is pushed out of the needle, and the two occluder elements are pushed towards each other until they lock together. Additional occluders that are lined up in the delivery needle can be deployed in a similar manner without having to withdraw the delivery device from the patient. The multiple-occluder delivery device thus allows several occluders to be implanted with only a single insertion of the needle.
In certain aspects, the invention provides a device for percutaneously or laparoscopically delivering at least one, but typically multiple occluders to a hollow structure. The device includes a hollow tube having a proximal end and a distal end. Several occluders are disposed serially within the tube, each occluder comprising a distal occluder element and a proximal occluder element. The device further comprises a pushing member configured to push an occluder out of the distal end of the tube.
In embodiments, the distal occluder element and the proximal occluder element are separate from but connectable to each other. The distal occluder element may comprise a connecting rod comprising a first connection element. The proximal occluder element may comprise a second connection element. When the distal and proximal occluder elements are pushed together, the connection elements lock together.
In certain embodiments, the distal occluder element is configured to assume a diametrically-reduced configuration when disposed within the tube and a diametrically-expanded configuration when pushed out of the tube. The proximal occluder element may be configured to assume a diametrically-reduced configuration when disposed within the tube and a diametrically-expanded configuration when pushed out of the tube.
The device may further include a locking mechanism configured to hold the distal occluder element to the delivery device after the distal occluder element has been pushed out of the tube. The locking mechanism may comprise a locking sheath with an expandable region and a locking rod extending through the locking sheath. The locking rod may include a locking tip, wherein when the locking tip is pulled back with respect to the locking sheath, it causes the expandable region to expand.
In some embodiments the tube is a needle configured to deliver the occluders percutaneously. In other embodiments, the tube is part of a laparoscopic device, e.g., cannula, and may contain multiple needles or occluder elements. In other embodiments, the tube is present in addition to a needle, and the tube fits within the needle. Each occluder element may comprise a plurality of fingers configured to assume a generally linear shape when in the diametrically-reduced configuration and configured to expand away from each other when in the diametrically-expanded configuration.
In related aspects, the invention provides a method for occluding a hollow structure, or clamping multiple tissue or material layers together. The method involves: (i) providing a multiple-occluder delivery device comprising a hollow tube containing a plurality of occlusion elements; (ii) positioning the tube adjacent to a first position on a hollow structure to be occluded; (iii) advancing the tube through a proximal wall and a distal wall of the hollow structure; (iv) deploying a distal occlusion element from the tube; (v) withdrawing the tube back through the hollow structure; (vi) deploying a proximal occlusion element from the tube; (vii) pushing the distal and proximal occlusion elements together to clamp the hollow structure, thereby occluding the first position; (viii) positioning the tube adjacent to a second position on the hollow structure; and (ix) repeating steps (iii) through (vii) to occlude the second position. In certain embodiments, the method involves inserting the tube percutaneously. In other embodiments the tube can be positioned using laparoscopic imaging or visualization. The imaging modality may be integrated with the occluder delivery tube, or cannula or separate from it.
The method may involve using a multiple-occluder delivery device that includes a hollow tube having a proximal end and a distal end; a plurality of occluders disposed serially within the tube, each occluder comprising a distal occluder element and a proximal occluder element, wherein the distal occluder element is configured to assume a diametrically-reduced configuration when disposed within the tube and a diametrically-expanded configuration when pushed out of the tube and wherein the proximal occluder element is configured to assume a diametrically-reduced configuration when disposed within the tube and a diametrically-expanded configuration when pushed or deployed out of the tube; and a pushing member configured to push an occluder out of the distal end of the tube. The method may further involve using the pushing member to push a distal occluder element out of the tube, such that the distal occluder element expands to its diametrically-expanded configuration; and using the pushing member to push a proximal occluder element out of the hollow tube, such that the proximal occluder element expands to its diametrically-expanded configuration. In other embodiments, the distal occluder may be pushed or pulled out of the tube using the locking rod.
In some embodiments the distal occluder element and the proximal occluder element are separate from but connectable to each other. In other embodiments the distal occluder element and the proximal occluder element are part of a single occluder device. The distal occluder element may comprise a connecting rod comprising a first connection element and the proximal occluder element may comprise a second connection element. When the distal and proximal occluder elements are pushed together, the connection elements lock together.
Some embodiments of the method involve using a device that further comprises a locking mechanism configured to hold the distal occluder element to the delivery device after the distal occluder element has been pushed out of the tube. When the tube is retracted through the distal wall and proximal wall of the hollow structure, the locking member remains coupled to the distal occluder element. The locking mechanism may include a locking sheath comprising an expandable region and a locking rod extending through the locking sheath, the locking rod comprising a locking tip. When the locking tip is pulled back with respect to the locking sheath, it causes the expandable region to expand.
In some embodiments, each occluder element comprises a plurality of fingers configured to assume a generally linear shape when in the diametrically-reduced configuration and configured to expand away from each other when in the diametrically-expanded configuration.
In a related aspect, the invention provides a device for delivering multiple occluders. The device includes a chamber containing a first occluder and a second occluder and a pushing member configured to extend axially through the chamber to deploy the occluders through a distal end of the chamber.
In certain aspects, each occluder comprises a distal occlusion element and a proximal occlusion element. The chamber can be an elongated tube. The occluders can be disposed within the chamber in series. In other embodiments, the device includes a second chamber, substantially similar to the first chamber, situated parallel to the first chamber, and the occluders are therefore disposed in parallel. In some embodiments, the first and second chambers are disposed within a barrel.
The present invention relates to a delivery device capable of delivery and deployment of multiple occluders for partial or complete occlusion of hollow structures including cavities, ducts, tubular structures, or regions or portions of ducts, cavities and tubular structures. The present invention may for example be used to treat a varicocele by occluding the pampiniform venous plexus. Alternatively, it can be used to occlude a part of the stomach to create a sleeve or pouch that minimally invasively and selectively bypasses sensing regions or guides towards sensing regions in the stomach for weight reduction and weight control purposes. A film can be applied on top surface of the stomach and the occluders deployed through this film, such the film is attached to the outer surface of the stomach, clamped by the proximal occluder fingers, while the distal fingers also clamp the two walls of the stomach together. The film, which may be a polymer, or mesh material, can act to support the occlusion elements and extend the closure forces applied between the occluder elements to the tubular structure, i.e., in this case the stomach. Methods and devices of the invention are also useful for cholecystectomies for closing the main artery and duct and other blood vessels when removing a gallbladder, in laparoscopic, percutaneous, or open surgical procedures. The invention is ideal for any procedure where a hollow structure, cavity, duct, or tubular structure is to be occluded. Devices of the present invention are low cost and so they are ideal as single-use devices for a patient. In some embodiments, however, the device can be reused.
The present invention provides advantages over traditional varicocele treatments. A known varicocele treatment procedure is shown in
The present invention combines three key characteristics: the ability of the occluder to clamp, enabling easy and controlled occlusion of hollow structures such as blood vessels; transfixion, which provides anchoring similar to a surgically applied transfixion suture, thereby securing the implant in place and eliminating slippage; and grasping with interweaving between occluding arms, which allows occlusion of both arteries and veins of different size and wall thickness, and ensures an area of hemostasis around the needle entry point.
The occluder and delivery device used in this procedure is of a prototype design that can easily be modified to optimize its performance depending on the circumstance. Although, in an embodiment of the occluder, the combined length from tip-to-tip of two occluder fingers is 5.5 mm, vessels up to 9.5 mm have been occluded with a single occluder. That is due to projection of closure due to the rippling of the tissue produced by the interdigitation of the occluder fingers. In other vessels, placement of two occluder clips successfully occluded these vessels of 1 cm diameter or greater. However, the size and length of the occluder used can be easily modified to match the vessel size, such that single clip vessel occlusion can easily be achieved.
Deployment of the occluders involves minimal patient discomfort and recovery, with only a local injection of anesthetic at the site of the needle injection and or occlusion to minimize patient discomfort. The entire procedural time can be less than 30 seconds per occlusion. This makes such an occlusion method a very cost-effective.
Visualization can also be aided by ultrasound. Delivery tubes of the invention, including needles and laparoscopic cannulas, may be coated with an echogenic or reflective material to enhance ultrasound visualization. Occluder elements can be made echogenic by laser scribing or surface roughening or by coating with echogenic or reflective materials such as polymers.
As seen most clearly in
As shown in
Once the tube 113 is deployed through the distal wall of the hollow structure 77, the distal occlusion element 22 can be pushed out through the distal end of the tube 113. When the distal occlusion element 22 is outside of the tube 113, the fingers 29 expand to the diametrically-expanded configuration, as shown in
An advantage of the occluder elements configured so that they are aligned in the same orientation with the expandable portion of each of the occluder elements oriented toward the hollow structure to be occluded is that it allows easy removal or retraction of a distal occlusion element if deployed unintentionally in an undesirable location, and to be re-deployed at a desired site, even after full deployment. The delivery device is capable of retracting the distal occluder element back into the delivery tube or by passing the tube over the deployed distal occluder element, thereby re-sheathing the distal occluder element, and compressing the expandable fingers back into the diametrically-reduced configuration.
This can be achieved by pulling up on the locking mechanism, which pulls the distal occluder into the occluder delivery tube. The occluder delivery tube may also be pushed down over the distal occluder element to collapse the distal occluder and re-sheath.
Returning to
The expansion of the sheath expansion region 85 prevents the distal occluder 22 from falling off the locking mechanism 81. The expansion of the locking sheath can also be done when the sheath expansion region 85 is inside the distal occluder 22, thus fixing the position of the distal occluder 22 on the locking mechanism 81.
In an embodiment of the invention, an occluder pusher 55 is used to push the distal occluder 22 out of the needle, as shown in
The locking mechanism 81 is activated by moving the locking sheath 83 forward away from the delivery device handle (not shown) and moving the locking rod 86 backwards towards the delivery device handle. By moving the sheath 83 and rod 86 in opposite directions relative to each other, locking or release of the distal occlusion element 22 can be achieved. The locking sheath expansion region 85 expands, thereby acting as a lock to prevent the distal occluder 22 from moving beyond the end of the locking rod 86. In another embodiment, the distal occlusion element 22 can be locked onto the locking mechanism 81 by the force the expanded locking expansion region 85 exerts on the distal occluder element 22. In another embodiment, the distal occluder 22 locks onto the locking rod 86, and is released from the locking rod 86 when a proximal occluder 24 locks with the distal occluder 22, thereby unlocking the distal occluder 22 from the locking rod 86 by pushing on the locking element region between the distal occluder 22 and locking rod 86.
Other possible embodiments and constructions are also envisioned. Another embodiment of the invention does not require the locking mechanism to have a sheath. In one embodiment, the locking mechanism simply consists of a rod with a fixed enlarged region, e.g., bulbous, or sphere, at the distal end. In an embodiment of the invention, the force that the occluder pusher exerts on the occluder elements, allows the occluder elements to be pushed and expand over the bulbous region and be deployed.
In another embodiment of the invention, the locking rod contains an expandable bulb. There are various ways the tip of locking rod can be made to expand. It may be an inflatable and deflatable structure (e.g., a balloon) with defined dimensions. The inflation may be done by gas (e.g., nitrogen or air) or liquid (e.g., saline). In another embodiment it may be an expandable construction of various designs consisting of expandable elements whose release is controlled at the proximal end of the rod by the operator, for example a bulb with tines that expands by rotation, or bumps, or the like. The bulb can also be inflated to multiple sizes, and in one embodiment, it is inflated initially significantly, so that it acts to separate the hollow structure from tissue beneath the vessel, stretching and making space for the deployment of the distal occlusion device so that it does not penetrate or impact the tissue beneath. The bulb can then be deflated to a smaller size to act as a stop.
In the configuration of
As shown in
In the embodiments of the current invention where the fingers 29 are aligned in the same orientation for both the proximal 24 and distal 22 occluder, such as the embodiment shown in
It should be noted that in some embodiments, the distal occlusion element is purposely embedded in tissue surrounding the structure to be occluded, so that the fingers of the distal occlusion element are not directly touching the structure to be occluded, avoiding any possible damage from the distal occlusion element, while the surrounding tissue compresses the structure to be occluded. Similarly, the proximal occlusion element can be deployed in tissue surrounding the structure to be occluded, so that its fingers are not in direct contact with the structure to be occluded. The two occlusion elements are then locked together and the structure is occluded. This concept can be applied to all embodiments disclosed herein.
Thus far, the occluder has been defined as a two-part device having separate proximal and distal occlusion elements configured to connect together to transfix a hollow structure. However, the invention also provides a one-part occluder that can be deployed in much the same way as the two-part device. Like the two-part occluder, a one-part occluder still has a proximal and distal end (which can be described as a proximal occlusion element and a distal occlusion element). A one-part occluder can be made of various materials, such as nitinol, shape memory material, super elastic material, or the like. It may be made of stainless steel. It can be made of superelastic or plastic material. It may be primarily metallic, or polymeric, or ceramic.
A two part occluder has an advantage that positioning of the two parts is highly precise, and the clamping is accurate, whereas a single part occluder provides for less control of deployment of proximal and distal fingers.
In some embodiments, the single piece occluder can be made out of two pieces that are welded, soldered, glued, or epoxied together at their intersection to form a one-part occluder. The proximal 24 and distal 22 portions of the single occluder can expand to be C-shaped and curve onto themselves, as shown in
Occlusion elements may be made using Stereo-lithography, additive printing methods where the fingers and post are deposited in their relaxed state, and then cooled so that the fingers collapse so they can be loaded into the delivery needle. They can also be made by injection molding, and may consist of polymers, metals, composites and the like.
In another embodiment of the invention, either the single piece occluder or the two piece occluder may have supporting tissue or polymer or material, pre-attached to the fingers to form a webbing, to assist in further distributing the closing force, constraining the tissue of the hollow structure to be occluded, delivering particular chemicals or drugs in a time-release manner, or to hold the tissue down, and to provide better sealing to prevent blood bile or lymph material leakage.
The webbing material may be coated on top of the fingers, or below the fingers as shown in
Similar embodiments are also envisioned for the two-part occluder. The two-part occluder proximal and or distal fingers may be coated with a webbing material similar to the single occluder element. The webbing can be collapsed along with the fingers similar to an umbrella folding, to fit within the delivery needle.
The webbed occluder devices are also usefule for sandwiching tissue or closing an opening such as a Patent Foramen Ovale (PFO).
Turning now to
Using any of the multiple-occluder delivery devices described herein, a hollow structure can be occluded by deploying occluders into tissue surrounding the hollow structure, without penetrating the hollow structure itself.
In certain embodiments, the multiple-occluder delivery device can be used for bariatric surgery. Occluders can be deployed to a patient's stomach 565 to create a gastric sleeve to reduce the size of the stomach. As shown in
In certain embodiments of the method of delivery, the needle is inserted at an angle to the element to be occluded, or tissue to be clamped, to minimize the footprint of the occluder transverse to the tubular structure to be occluded or tissue to be clamped. Deployment of the occluder element occurs at an angle smaller than 90 degrees to the tubular structure, or tissues to be occluded or clamped. The occluder may be a one- or a two-part occluder. By deploying the occluder at an angle relative to the vessel, in some instances where the vertical connection point of the occluder is parallel to the vessel, the effective perpendicular protrusion of the occluder relative to the vessel is minimized.
Throughout the disclosure, delivery devices are described that include arrangements of occluder elements disposed within a tube. In a typical arrangement of a serial delivery device, several proximal and distal occluder elements are lined up within the tube in an alternating fashion. In that way, a distal occluder element can be deployed out of the tube, followed by a proximal occluder element, which locks together with the distal occluder element to occlude a structure. The delivery device can then occlude another location or the same location by deploying the next distal occluder element, followed by the next proximal occluder element, and so on. The device is thus configured to make several occlusions without needing to be withdrawn from the patient and without needing to reload the device.
In some embodiments, each occluder is designed to push the occluder in front of it (and to be pushed by the occluder behind it). There are several ways to achieve that pushing action, as described herein. In a preferred embodiment, an occlusion element made of a shape-memory material such as Nitinol is shape set to achieve a particular geometry that allows the distal end of one occlusion element to firmly contact the proximal end of the element in front of it in the delivery device.
Likewise, the distal occlusion element 722 is configured with widened finger tips 723, which allow the distal occlusion element 722 to make contact with the proximal occlusion element in front of it (not shown).
Following laser cutting, as shown in
The proximal and distal occluder elements (also known as proximal and distal clips) are configured to lock together with a locking mechanism. The locking mechanism may include sets of windows and tangs that fit together. For example, the distal clip can be laser cut with one or more windows around the circumference of the hollow tubular section of the clip. The clip can include one window or several windows. The corresponding proximal occlusion element can be cut to include one or more tangs, each tang configured to snag into a window, thereby locking the two occlusion elements together.
One concern with a tang-and-window mechanism is that the two occlusion elements must align so that the tang enters the window. The tangs and windows of the present invention are designed in such a way that they snag together regardless of the angular orientation of the occlusion elements. That design feature is known as “angular relation indifference,” and is illustrated in greater detail in
In some embodiments, the tangs and windows are configured to connect together to orient the fingers of one occlusion element with the fingers of the other occlusion element. For example, the windows may be configured to receive the tangs and shift them into the desired position, thereby orienting the two occlusion elements in a certain way. It may be desirable, for example, for the fingers of a distal occluder to be offset with respect to the proximal occluder to achieve an interdigitating configuration. The benefits of interdigitation have been explained in detail above. In other embodiments, it may be desirable for the fingers to align so as to compress the structure between aligned fingers. Other alignments may be preferable as well, including partially offset fingers.
As explained above, devices of the invention include a locking mechanism for holding the distal occlusion element in place after it has been deployed from the delivery tube. Additional details of one embodiment of the locking mechanism are shown in
In
In
References and citations to other documents, such as patents, patent applications, patent publications, journals, books, papers, web contents, have been made throughout this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes.
Various modifications of the invention and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including references to the scientific and patent literature cited herein. The subject matter herein contains important information, exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof.
Background
Secure, permanent occlusion of the great and small saphenous veins, their tributaries, and perforators, is critical for the successful treatment of varicose veins. Current minimally invasive methods replacing surgery are all endoluminal, and involve heat (radio-frequency or laser), chemicals (sclerosants and glues) or a combination mechanical and chemical (MOCA). The objective of this study was to evaluate in a porcine model, the performance of a percutaneous delivery of the Amsel™ Vessel Occluder (AVO) utilizing ultrasound guidance. The AVO has previously received FDA pre-market 510(k) clearance for use in open surgical procedures for tubular structures ranging in diameter from 2-7 mm.
Methods:
The AVO, a novel mechanical occlusion clip similar to a transfixion suture, is delivered through an 18G hypodermic needle, which transfixes the targeted vessel. The AVO is subsequently expanded on either side of the vessel wall, collapsed and locked together to effect secure vascular occlusion. Under general anesthesia, the targeted vessels in five swine, weighing >60 kilograms, were identified and vessel size measured. Patency of the targeted vessels was confirmed on duplex ultrasound (DUS). Each animal provided multiple vessels for percutaneous AVO occlusion. Occlusion was confirmed by DUS and by direct examination of the occluded vessel after open surgical exploration.
Results:
30 vessel occlusions were performed percutaneously including the common and superficial femoral arteries and veins (n=25), the carotid artery (n=3) and the external jugular veins (n=2). Measured vessel sizes ranged from 1.8-12.7 mm. Following vessel transfixion, occlusion was achieved in less than 30 seconds. A second AVO, if necessary, was employed to completely occlude the targeted vessel where the vessel was larger than 7 mm diameter (n=2; external jugular vein 12.7 mm and carotid artery 7 mm), or where the initial AVO did not occlude the vessel due to non-transfixion (n=1). Post-occlusion surgical exposure confirmed that all targeted vessels were successfully occluded and demonstrated no evidence of injury to any of the adjacent structures.
Conclusions:
This study confirms that the AVO can be effectively delivered percutaneously in the porcine model to occlude blood vessels under ultrasound guidance. The AVO provides a mechanical means of permanent, secure vessel occlusion, similar to a transfixion suture, thus eliminating the problem of recanalization which may occur following thermal or chemical vessel occlusion methods. This method of permanent, percutaneous occlusion may be a useful, time-saving and cost-effective adjunct to current primary methods of treating reflux in the saphenous veins, their tributaries or perforators, for the treatment of symptomatic varicose veins. In addition, in the event of other treatment method failures (thermal or chemical) the AVO provides a simple alternative.
Introduction
Varicose veins and its late manifestations are common in the adult population, increasing in prevalence with increasing age. It is estimated that 23% of US adults, suffer from varicose veins and 6% from chronic venous disease. It is generally more common in women than men between the ages of 40-80 yrs, although this difference decreases with age. Untreated, varicose veins may eventually progress to severe chronic venous insufficiency with symptoms and other manifestations including lower extremity venous ulceration. The related health care costs associated with chronic venous disease approaches one billion dollars annually in the US.
Although the pathophysiology of chronic venous disease, with lower extremity venous valvular dysfunction has been known since Trendelenburg described his tests for VV, most of the care is still directed at treating varicose veins only when symptoms or complications occur. The standard of care in the US for the treatment of varicose veins until the turn of the 21st century was surgery with high ligation and stripping of the saphenous vein with phlebectomy of the presenting varicosities. More recently, alternative treatments for varicose veins including endothermal ablation, with laser or radiofrequency, together with chemical treatments, sclerosants and chemical adhesives or a combination (MOCA), have replaced surgery as the standard of care. These procedures have brought the treatment of varicose veins out of the hospital surgical operating rooms and into the outpatient surgical clinics, reducing hospital costs for patient management and minimizing patient morbidity. This migration to an office-based procedure has also altered who performs the procedure
The underlying pathophysiological approach to the treatment of these patients has not changed and is aimed at preventing reflux in the lower extremity veins by occluding a long segment of the saphenous vein from the sapheno-femoral junction (SFJ) to just below the kneeand phlebectomy of the superficial varicosities.
In the early 1990's Claude Franceschi, described an alternative saphenous “sparing” approach to treat the venous reflux associated with varicose veins. This approach, CHIVA (Cure conservatrice et Hemodynamique de L′Issufsance veineuse en Ambulatoire or conservative hemodynamic cure for varicose veins) unlike the surgical and endovascular approaches does not eliminate all reflux saphenous vein, but directs the flow of the “refluxing” blood into the deep veins of the lower extremity. In theory this relieves the venous pressure the superficial veins of the extremity and eliminates the clinical consequences of varicose veins. Because of the combination of demanding ultrasonic expertise, and the necessary surgical skills required to execute this approach, CHIVA has not been widely adopted, particularly in the United States.
For both pathophysiological approaches secure, permanent occlusion of the targeted veins, which include the saphenous veins, their tributaries, and perforating veins, is critical for the successful treatment of varicose veins and venous insufficiency. One of the concerns with the chemical and adhesive techniques is “leakage” of the chemical into the deep system, especially at the sapheno-femoral junction (SFJ). Indeed, the VenaSeal protocol encourages compression of the great saphenous vein just below the SFJ. Permanent and percutaneous of the GSV at this location would be advantageous.
The objective of this study was to evaluate the safety and efficacy of a novel mechanical occlusion clip, the Amsel™ Vessel Occluder (AVO), delivered percutaneously with ultrasound guidance in the porcine model.
Materials and Methods:
Device Description:
The Amsel Occluder Clip, is preloaded in the 18G needle of the AVO delivery device (
The AVO clip and delivery device has received FDA 510 (k) clearance, similar to other metal non-transfixing clips (hemoclips) for the occlusion of blood vessels 2 mm-7 mm in diameter, as well as for other tubular structures such as the cystic duct or fallopian tube.
Methods and Technique
Five female domestic pigs (Sus scrofa domestica), each weighing more than 60 kg at time of implantation, underwent percutaneous occlusion of selected veins and arteries (N=30). The study was performed at the Lahav Institute of Animal Research, Israel, under the supervision of the veterinary surgeon, the scientific manager at this institute. The studies were approved by the Institute of National Animal Care and Use Committee, Israel. Each animal was allowed to acclimate for at least 3 days prior to surgery. On the day of surgery food was withdrawn and only water was allowed.
Prior to occlusion, the selected arteries and veins in the groins and neck were examined with Duplex ultrasound. Vessels were selected, measured for size, and patency confirmed with Doppler Ultrasound. Similar to that for any minimally invasive access device a small incision was made in the skin at the site of needle entry. The ultrasound transducer was held in one hand and the AVO in the other hand. Under ultrasound guidance the needle of the device is inserted into the targeted vessel. A small hole in the needle approximately 6 cms from the needle tip allows blood to escape confirming entry into the vessel lumen (Figurela). The pulsatility and color of the bloods helps to distinguish between artery and vein. The needle is passed through the vessel, transfixing the vessel. Once the vessel is transfixed, ultrasound guidance is not essential. The AVO clip is delivered with 4 consecutive simple manoeuvres on the delivery device: the distal occluding element is delivered, assumes its predetermined configuration and is gently pulled back onto the vessel confirmed by a slight resistance; the proximal occluding element is then delivered and the two elements locked together. Finally, the locked occluding elements are released, allowing the needle and delivery device to be withdrawn (
Study Design
Selected vessels (Table 1) were examined with Duplex ultrasound, measured and patency confirmed with Doppler flow. Three board certified interventional radiologists participated in this study. Following each percutaneous occlusion, Duplex examination of the occluded vessel was performed to confirm occlusion (
The integrity of the AVO clip occlusion with holding pressure measurements, as well as the tissue response and healing of the implanted occluding AVO by both inspection and histo-pathological examination has been previously documented and reported following surgical vessel occlusion with the AVO.
Results
30 vessel occlusions with the AVO were performed percutaneously in 5 different pigs by 3 different interventional radiologists (IR1, IR2, IR3) (Table 1). The size of the vessel occluded, the number of clips required for occlusion and the success of the occlusion confirmed with Duplex ultrasound and surgical exposure, are shown in Table 1.
There were 10 proximal femoral artery and 8 proximal femoral vein occlusions (vessel size range: 3.6-7 mms), and 5 distal femoral arteries (superficial femoral arteries) and 1 distal superficial femoral vein (vessel size range: 2-3.5 mms) occlusions; 4 carotid artery occlusions (n=3: vessel size range 3.6-7 mms, n=1: vessel size 8.3 mms), one external jugular vein (vessel size:12.7 mms) and one tributary of the external jugular vein (vessel size: 9.5 mms) occlusions. It should be noted that all occlusions were achieved with a single AVO, except for the external jugular vein (vessel size 12.7 mms) in which 2 clips were required for complete occlusion.
The targeted vessel was not occluded on two occasions, one due to the clip being placed on the edge of the femoral vein and not centrally transfixing the vein) and the other, where one AVO was delivered outside the vessel into the underlying muscle. The IR recognizing the misplacement placed a second AVO to occlude the vessel. All other vessels were occluded with a single AVO clip.
In two femoral vein occlusions, where the AVO was not centrally placed, however, the veins were found to be completely occluded, with no Doppler flow. On surgical exposure, complete vessel occlusion was confirmed. However, the expanded occlusion elements of the AVO clip although not centrally placed had included some surrounding connective tissues to achieve complete occlusion of the vessel.
Despite the close proximity of the femoral vein, artery and nerve, in their tight neurovascular bundle covered by the muscle in the groin of the pig, each targeted vessel was occluded without impinging on the other vessel and or the accompanying nerve, and without injury to any of these adjacent structures. These occlusions in the pig are considerably more demanding than in the targeted veins for the treatment of varicose veins.
Discussion
This study confirms that the AVO can be effectively and safely delivered percutaneously under ultrasound guidance to accurately and securely occlude blood vessels in the porcine model. This represents a first in the ability to occlude blood vessels ranging from 2-12.7 mms directly through the skin via a fine hypodermic needle. The Amsel Occluder's novel design combines three key characteristics, bi-planar clamping that enables easy and controlled occlusion of blood vessels, transfixion, that provides anchoring similar to a surgically applied transfixion suture that secures the implant in place and eliminates slippage, and grasping with interweaving between occluding “arms”, which allows occlusion of both arteries and veins of different sizes and wall thickness, and ensures an area of hemostasis around the needle entry point (
The Amsel Occluder and delivery device used in this procedure is of a prototype design that can easily be modified to optimize its performance depending on the circumstance. Although the AVO occluder is only cleared for patient use for vessels between 2-7 mms, we have successfully occluded vessels up to 9.5 mm with a single AVO clip (see Table 1). In larger vessels, placement of a second AVO clip has successfully occluded larger vessels. However, the size and length of the occluder used in this study can be easily be modified to match the vessel size, such that single clip vessel occlusion can easily be achieved.
The technique is simple, and is similar to other standard percutaneous interventional procedures. Our device involves minimal patient discomfort and recovery, with only a local injection of anesthetic at the site of percutaneous insertion. The entire procedural time is minimal, less than 30 seconds per occlusion, making such an occlusion method a very cost-effective adjunct to current primary methods of treating reflux in the saphenous veins, their tributaries or perforators. All three interventional radiologists participating in this study achieved great success and facility with minimal time spent in familiarizing themselves with the delivery device.
The possible clinical applications for the AVO in varicose veins are summarized in Table 2. Of the many advantages and opportunities in the application of such a mechanical, secure and permanent vessel closure device (Table 2), the elimination of the occurrence of post-occlusion recanalization and recurrent reflux following the current thermal or chemical venous ablation. This remains one of the commonest causes of recurrent reflux and varicosities following such treatments. Mechanical occlusion with the AVO, similar to a surgical suture ligation, may also eliminate the need for the extensive length of vessel occlusion necessary to prevent the occurrence of recanalization and recurrence of the reflux in the treated vessels. In those cases where the SFA is too large to provide safe laser or RF endo-ablation partial or complete occlusion of the SFJ with the AVO may be an alternative to open surgery (R).
Using the Amsel Vessel Occluder for targeted vessel occlusion may facilitate the CHIVA method of treating venous reflux with saphenous vein preservation, to be more minimally invasive. With the increasing popularity in the use of chemical agents for vein ablation, prior occlusion of the SFJ and the large tributaries or perforators, to the intravenous injection of foam sclerosants and glues, may be a simple and secure way to prevent or minimize leakage into the deep venous system, avoiding open surgical ligation and minimizing the potential harmful local and systemic effects of these chemicals.
Finally, with such a simple, minimally invasive and reliable interventional method to treat venous reflux, the Amsel Vessel Occluder may allow patients diagnosed with clinically significant reflux and venous insufficiency, prior to the onset of the clinical manifestations of varicose veins, to undergo early intervention to minimize the cosmetic and debilitating consequences of varicose vein and venous insufficiency and their associated health care costs.
The following references are incorporated herein by reference in their entirety:
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This application claims the benefit of and priority to U.S. Provisional Application Ser. No. 62/203,655, filed Aug. 11, 2015, and U.S. Provisional Application Ser. No. 62/298,724, filed Feb. 23, 2016, and is a continuation-in-part of U.S. application Ser. No. 14/639,814, filed Mar. 5, 2015 (which claims the benefit of and priority to U.S. Provisional Application Ser. No. 62/084,989, filed Nov. 26, 2014), which is a continuation-in-part of U.S. application Ser. No. 14/272,304, filed May 7, 2014 (which claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/948,241, filed Mar. 5, 2014, and U.S. Provisional Application Ser. No. 61/820,589, filed May 7, 2013), which is a continuation-in-part of U.S. application Ser. No. 13/857,424, filed Apr. 5, 2013 (which claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/620,787, filed Apr. 5, 2012), which is a continuation-in-part of U.S. application Ser. No. 13/348,416, filed Jan. 11, 2012 (which claims the benefit of and priority to U.S. Provisional Application Ser. No. 61/431,609, filed Jan. 11, 2011), the entire contents of each of which are incorporated by reference herein in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62203655 | Aug 2015 | US | |
| 62298724 | Feb 2016 | US | |
| 62084989 | Nov 2014 | US | |
| 61948241 | Mar 2014 | US | |
| 61820589 | May 2013 | US | |
| 61620787 | Apr 2012 | US | |
| 61431609 | Jan 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14639814 | Mar 2015 | US |
| Child | 15226577 | US | |
| Parent | 14272304 | May 2014 | US |
| Child | 14639814 | US | |
| Parent | 13857424 | Apr 2013 | US |
| Child | 14272304 | US | |
| Parent | 13348416 | Jan 2012 | US |
| Child | 13857424 | US |
