Device for dosed narrowing of the pulmonary artery and cuff fixation

Abstract

The invention relates to medical equipment, specifically to a device for the graduated narrowing of the pulmonary artery. The device for the graduated narrowing of the pulmonary artery comprises a cuff made of a non-absorbable material for encircling the artery to form a loop, a hollow tubular fixing fragment made of an elastomeric material, and a metal vascular clip whose legs are no wider than the length of the hollow tubular fixing fragment. The ends of the cuff extend through the hollow tubular fixing fragment. The vascular clip is positioned transversely over the hollow tubular fixing fragment and is capable of plastic deformation for transverse compression of the hollow tubular fixing fragment along with the ends of the cuff passing within it. The hollow tubular fixing fragment made of an elastomeric material is capable of being compressed by the metal vascular clip, with the space between the threads of the cuff filled with elastomer.The utility model improves the reliability of cuff fixation on the pulmonary artery by creating a uniform compression force, preventing thread slippage and eliminating their damage under prolonged cyclic loading. 3 clauses, 1 fig.

Description

[0001] The utility model relates to the field of medicine, namely to cardiovascular surgery, and can be used in the surgical palliative treatment of congenital heart defects accompanied by increased pulmonary blood flow and pulmonary hypertension (in particular, with defects of the interventricular septum, atrioventricular communication, transposition of the great arteries), in cases where precise intraoperative dosed narrowing of the pulmonary artery is required.

[0002] Surgical techniques for pulmonary artery constriction (banding) are known, based on encircling the vessel trunk with tape or thread, followed by tying knots or suturing the tape with suture material to secure the achieved degree of constriction. This method is characterized by the difficulty of intraoperatively dosing the degree of constriction, as tying a knot or placing a suture results in discrete and not always controllable changes in the cuff circumference, which complicates the selection of an optimal hemodynamic gradient.

[0003] Devices for pulmonary artery constriction are known that allow for varying the degree of constriction using hydraulic control elements. In particular, a device (patent US 20080097497 A1, A61B 17 / 12, published April 24, 2008) is known, comprising a silicone cuff whose interior is connected via a microcapillary tube to a subcutaneous inflation reservoir. The degree of constriction is varied by percutaneous injection of fluid into the reservoir. We used this device as a prototype.

[0004] Also known is a device for minimally invasive pulmonary artery bandaging (patent US 20140236211 A1, A61B 17 / 00, published 08 / 21 / 2014), consisting of a hexagonal frame with inflatable balloon elements connected to an external pressure source via a tube approximately 200 mm long with an internal diameter of 0.200 mm.

[0005] Common disadvantages of known hydraulic devices include high design complexity, the risk of depressurization of the closed fluid circuit during prolonged cyclic pulse loads on the vessel, the risk of occlusion of microcapillaries by protein deposits, and the risk of infection of the subcutaneous port. Furthermore, polymer balloon elements are prone to becoming coated with coarse fibrous tissue, making subsequent bandage removal during radical correction of heart defects extremely traumatic. Therefore, the prior art lacks a simple mechanical device devoid of closed pneumohydraulic circuits that ensures reliable cuff fixation.

[0006] In this regard, there remains a need to create a mechanical device that is extremely simple in design, devoid of closed pneumatic-hydraulic circuits, but allows the surgeon to perform precise, smooth, dosed narrowing of the pulmonary artery in situ, ensuring absolutely reliable and irreversible fixation of the cuff after selecting the required degree of narrowing.

[0007] The technical problem, which the claimed utility model is aimed at solving, is the development of a mechanical device for intraoperative dosed narrowing of the pulmonary artery with an optimized system for retaining the narrowing element.

[0008] The technical result consists in increasing the reliability of fixation of the cuff on the pulmonary artery by creating a uniform compression force, preventing slippage of the threads and eliminating their damage during long-term cyclic loading.

[0009] The stated technical result is achieved by a device for dosed pulmonary artery constriction and cuff fixation comprising a cuff formed as a thread or tape made of a non-absorbable material and designed to encircle the pulmonary artery to form a loop. The device is equipped with a tubular fixation fragment and a metal vascular clip. The tubular fixation fragment is designed as a hollow tube made of an elastomeric polymer material, through the internal lumen of which the free ends of the cuff are passed. The metal vascular clip is positioned over the tubular fixation fragment and is capable of plastic deformation to transversely compress said fragment along with the ends of the cuff passing within it.

[0010] The tubular elastomer fixation element, when compressed by a metal clip, ensures uniform radial compression on the cuff threads, preventing slippage. The elastomer tube also serves as a damping pad, preventing direct contact between the metal edges of the clip and the cuff material, thereby maintaining the structural integrity of the threads under cyclic pulse loads.

[0011] In a specific embodiment, the tubular fixation fragment is made of medical-grade silicone or polyurethane. Elastomeric polymers were chosen due to their elastic deformation properties: when the fragment is compressed by a rigid metal clip, the elastomer tightly fills the space between the cuff threads, generating a uniform radial compressive force. This maximizes static friction, preventing thread slippage, and also serves as a damping protective pad, preventing contact between the metal edges of the clip and the cuff.

[0012] In the preferred embodiment, the metal vascular clip is made of titanium or a titanium-based alloy. These materials are characterized by an optimal yield strength and the absence of elastic return after plastic deformation, ensuring a constant compressive force applied to the tubular fragment.

[0013] For ease of intraoperative cuff tightening, a removable tourniquet tube, not part of the device, can be used. The ends of the cuff, after passing through the tubular fixation fragment, are passed through the lumen of this tube, which provides countertraction and is removed after the clip is secured. Polytetrafluoroethylene (ePTFE) tape is optimal for the cuff material. This material minimizes surrounding tissue reaction and the formation of fibrous adhesions, allowing for atraumatic loop removal during subsequent cardiac reconstructive surgeries.

[0014] The utility model is explained by a drawing, where figure 1 schematically depicts a device for the dosed narrowing of the pulmonary artery during surgical intervention until the moment of final fixation.

[0015] The following positions are indicated in Figure 1:

[0016] 1 - cuff made of non-absorbable material (eg ePTFE);

[0017] 2 - tourniquet tube (removable surgical instrument, not included in the design of the device);

[0018] 3 - tubular fixing fragment (elastomer tube);

[0019] 4 - cuff loop covering the pulmonary artery;

[0020] 5 - clamp (surgical hemostatic clamp for temporary fixation of the ends of the cuff, auxiliary tool, not included in the device).

[0021] The device is structurally a system of interacting elements, some of which are implanted into the patient’s body for a long period of time, while others are used exclusively intraoperatively as auxiliary instruments.

[0022] The main working element is cuff 1, which forms a loop 4 around the pulmonary artery trunk. Cuff 1 is made of a flat tape 2 to 6 mm wide or a braided surgical suture (e.g., USP 2 or 3) made of a non-absorbable, highly biocompatible material. Expanded polytetrafluoroethylene (ePTFE) is the preferred material. The use of ePTFE prevents trauma to the vessel intima, minimizes the formation of a dense fibrous ring, and facilitates debanding during subsequent stages of defect correction.

[0023] Both free ends of cuff 1 are passed through tubular fixing fragment 3. This fragment is a hollow cylinder 3-10 mm long, made of an elastomer, such as medical silicone or polyurethane, with a Shore A hardness in the range of 40-70. The internal diameter of tubular fixing fragment 3 in its initial (undeformed) state is slightly larger than the total transverse dimension of the ends of cuff 1 passed through it, allowing them to slide freely longitudinally.

[0024] Proximal to tubular fixation fragment 3, tourniquet tube 2 is installed in the system. The ends of cuff 1, extending from element 3, pass through the entire longitudinal lumen of tourniquet tube 2. Tube 2 is made of a rigid polymer (e.g., polycarbonate or polyvinyl chloride) and is 10-20 cm long, allowing its proximal end to extend beyond the surgical incision (thoracotomy or sternotomy). At the exit of tourniquet tube 2, the free ends of cuff 1 can be temporarily fixed with surgical clamp 5.

[0025] The metal vascular clip (not shown in the figure, as it is applied externally with a surgical clipper) is made of chemically pure titanium (Ti) or titanium alloy. Titanium was chosen due to its high ductility when the yield point is exceeded and the absence of elastic recoil. The clip is initially V- or U-shaped, and the width of its legs does not exceed the length of the tubular fixation fragment 3.

[0026] The device is manufactured using known materials and technologies. The cuff is made of stretched polytetrafluoroethylene (ePTFE) tape 4 mm wide and 0.4 mm thick. The tubular fixation fragment is a section of medical silicone tubing with an inner diameter of 2.0 mm, an outer diameter of 3.5 mm, and a length of 8 mm. The metal vascular clip, made of titanium alloy (Ti-6Al-4V), is U-shaped with legs 5 mm long, 1.5 mm wide, and 0.8 mm thick. The device is assembled intraoperatively by sequentially threading the free ends of the cuff through the tubular fragment and, if necessary, through the removable tourniquet tube. After tightening the loop, the clip is applied with a standard clipping tool, plastically deforming and compressing the elastomer insert.

[0027] The device operates as follows:

[0028] During the operation, the surgeon isolates the pulmonary artery trunk and creates a bypass tunnel behind it. Cuff 1 is wrapped around the vessel, forming a loop 4. The free ends of cuff 1 are then passed into the chest through tubular fixation fragment 3 and tourniquet tube 2. The ends of cuff 1 are brought out and grasped with clamp 5 (a clamp is a conventional surgical instrument and is not considered a utility model).

[0029] During the hemodynamic adjustment phase, the surgeon monitors pressure in the right ventricle, pulmonary artery, and systemic circulation using invasive sensors and transesophageal echocardiography. For graduated arterial constriction, the classic principle of the Rumel tourniquet is used: the surgeon pulls clamp 5 with the ends of cuff 1 toward themselves, simultaneously advancing rigid tourniquet tube 2 distally into the wound. The distal end of tube 2 rests against elastomeric tubular fixation fragment 3. This countertraction causes the ends of cuff 1 to slide through fragment 3, resulting in loop 4 smoothly tightening around the artery. If excessive constriction is observed (drop in oxygen saturation or excess pressure in the right ventricle), the surgeon releases the traction, and under the action of pulsatile blood pressure, the pulmonary artery expands loop 4, returning part of the length of cuff 1 back. This process is completely reversible and allows for the optimal vessel diameter to be selected with high precision (down to a millimetre).

[0030] After ensuring the desired hemodynamic profile has been achieved, the surgeon performs final fixation. A surgical clipper loaded with a titanium vascular clip is inserted into the wound. The clip is placed transversely over the elastomeric tubular fixation fragment 3. When the clipper handles are squeezed, the legs of the titanium clip are plastically deformed, brought together, and firmly compressed against fragment 3.

[0031] A complex physical and mechanical fixation process occurs. A rigid titanium clip forms a non-expandable external corset. Under its influence, the silicone wall of tubular fixation fragment 3 experiences elastic deformation. The silicone strives to regain its shape, generating intense, all-round radial pressure on the internal ends of cuff 1. This elastomeric compression embeds the polymer into the microscopic irregularities of the ePTFE cuff. According to the laws of physics, a multiple increase in normal force (compression force) leads to a proportional, sudden increase in static friction. As a result, the ends of cuff 1 are securely locked within fragment 3. At the same time, the soft silicone dampens the constant hydraulic shocks transmitted from the pulmonary artery wall, preventing contact between the metal edges of the clip and the delicate ePTFE fibers. This completely prevents fatigue failure or the effect of “rubbing” of the tape at the point of fixation.

[0032] After final clamping of the clip, the surgeon removes clamp 5. Using surgical scissors, the excess ends of cuff 1 are trimmed directly above the level of the applied vascular clip. The trimmed sutures, along with the rigid tourniquet tube 2, are removed from the chest.

[0033] All that remains in the patient's body are the closed loop 4 of cuff 1, the tubular fixing fragment 3, and the titanium clip that compresses it. Due to the absence of bulky hydraulic cylinders, reservoirs, and long connecting microtubes (typical of similar devices), the design boasts phenomenal spatial compactness and absolute mechanical reliability, eliminating any risk of depressurization.

Claims

1. A device for the dosed narrowing of the pulmonary artery, comprising a cuff made of a non-absorbable material for enclosing the artery to form a loop, characterized in that it comprises a hollow tubular fixing fragment made of an elastomeric material and a metal vascular clip, the width of the legs of which does not exceed the length of the hollow tubular fixing fragment, wherein the ends of the cuff are passed through the hollow tubular fixing fragment, and the vascular clip is installed over the hollow tubular fixing fragment in the transverse direction and is designed with the possibility of plastic deformation for transverse compression of the hollow tubular fixing fragment together with the ends of the cuff passing inside it, wherein the hollow tubular fixing fragment made of an elastomeric material is designed with the possibility of its compression by the metal vascular clip with filling the space between the threads of the cuff with elastomer.

2. The device according to paragraph 1, characterized in that the cuff is made of polytetrafluoroethylene.

3. The device according to paragraph 1, characterized in that the clip is V-shaped.

4. The device according to paragraph 1, characterized in that the clip is U-shaped.

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