DE20107567U1 - Instrument for percutaneous extraction of pulmonary emboli - Google Patents

Description

Prof. Dr. med. Dipl.-Ing. Thomas Schmitz-Rode
Kupferstrasse 5, 52070 Aachen

Professor Dr. med. RoIfW. Günther
Brussels Ring 73c, 52074 Aachen

UTILITY MODEL REGISTRATION Instrument for percutaneous extraction of pulmonary emboli

Even in the age of prophylactic anticoagulation, acute pulmonary embolism is a common and often life-threatening event. The standard treatment for massive pulmonary embolism is drug thrombolysis with streptokinase, urokinase or tissue plasminogen activator. Imaging tests (echocardiography, angiography, computer tomography) often show only minimal recanalization after thrombolysis. Therefore, some patients die of right heart failure despite high-dose thrombolysis.

Alternatively, if thrombolysis is contraindicated (e.g. intracranial injury, after surgery) or if thrombolysis fails, the embolus material can be surgically removed. The procedure using the heart-lung machine is very stressful and has a high mortality rate.

This gap in therapeutic needs was recognized as early as 1964 and a mechanical instrument with endoscope-like control was developed that was designed to extract pulmonary emboli non-surgically via a venous puncture site. This suction catheter by Greenfield was not successful due to its cumbersome handling. The attempt to fragment pulmonary emboli using a high-speed catheter system (Günther/Schmitz-Rode 1991) failed due to the technical complexity and insufficient pulmonary controllability.

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of the catheter. A modified pigtail catheter (Schmitz-Rode/Günther, 1995), which is rotated in the embolic occlusion and thus causes a rough fragmentation of the embolus material, has proven effective in initial clinical studies (Schmitz-Rode et al., Chest 1998, JACC 2000). However, the system only fragments the soft, fresh embolus part. It fails with firmer, organized emboli. Even if the pulmonary arteries are filled with embolus masses from central to peripheral, the fragmentation has little chance of successful recanalization, since the fragments cannot float away to the periphery.

Thus, there remains a need for an instrument that allows non-surgical removal of emboli from the pulmonary circulation.

The invention described here is based on the object of providing an easy-to-handle and pulmonarily controllable instrument that captures emboli in the pulmonary arteries and encases them in such a way that they can be safely removed from the circulation through the right heart and via the percutaneous venous access.

To solve this problem, a device is proposed with the features specified in the characterizing part of claim 1. Although the device is primarily designed for the pulmonary arteries, its use in other vascular regions is conceivable, e.g. in miniaturized form for thrombectomy in hemodialysis shunts.

The structure of the extraction instrument according to the invention is shown in the drawings Fig. 1-4.

The designation of the components by numbers corresponds to the numbers given in brackets in the following description.

Fig. 1 shows the schematic structure of the extraction instrument in a lateral view (Fig. la) and an axial view (Fig. lb).

Fig. 2 illustrates the axial displaceability of the open half-basket compared to the sheathed half-basket in a side view of the extended and the maximally shortened open half-basket.

Fig. 3 shows the procedure for retrieving pulmonary emboli and the different configurations that the extraction instrument takes.

Fig. 4 shows a simplified version in which the open half-basket remote from the catheter has been replaced by a simple guide wire (“single-braced basket”).

In the embodiment shown in Fig. 1, the extraction instrument consists of two concentrically connected components: a coated half-basket (3) near the catheter and a non-coated full basket (1), which is made up of three wire struts (la-c), and which encloses the half-basket (3) in such a way that an uncoated "open" half-basket (4) far from the catheter results. The coating of the half-basket (3) can consist of a metal net or a textile net. Both components (1,3) have an axis or struts that lead into the catheter (2) and are made of elastic, self-expanding material. By advancing the catheter (2), both components are radially compressed and completely coated by the catheter; by retracting the catheter (2), the instrument expands to its maximum unfolding diameter due to its elasticity. The basket struts (la-c) and those of the half-basket (3) are preferably made of metal wire, with Nitinol is a particularly suitable material due to its shape memory. In order to make the tip of the basket (1) atraumatic, it can be closed with a ball (Id). The open half-basket (4) can be shortened compared to the coated half-basket (3) in order to draw embolic material trapped therein into the coated half-basket (3) (Fig. 2a). Conversely, the half-basket (3) can also be lengthened (= pushed forward) compared to the half-basket (4) in order to capture embolic material (Fig. 2b). The construction of the open half-basket from a few wire struts (three or four) represents an optimal configuration. On the one hand, the wire struts serve as guide rails for the advancement of the coated half-basket (3) in the unfolded state, and on the other hand, a few struts do not hinder the capture of embolic material in the interior of the non-coated half-basket (4).

Fig. 2 also uses a simple example to illustrate how the axial displacement of the open half-basket (4) relative to the coated half-basket (3) can be technically achieved. The basket struts (la-c) run continuously along the outer surface of the half-basket (3), then run in the catheter (2) and exit at the outer end of the catheter next to a shaft (5) that is firmly connected to the end of the half-basket (3) closest to the catheter. The outer end of the basket struts (6) can now be moved relative to the shaft (5) that carries the coated half-basket (3). This shortens or lengthens the half-basket (4). Stabilizing the coaxial sliding mechanism of basket (1) and half-basket (3) is a guide (7a-c) of the basket struts (Iac) on the circumference of the front opening of half-basket (3) (e.g. by means of eyelets), which allows axial but not radial or circumferential mobility.

Fig. 3 shows a possible chronological sequence of different configurations that the instrument assumes during use. First, the catheter (2) with an inner stylet is placed over a guide wire in the pulmonary artery flow path. After removing the inner stylet and guide wire, the basket (1) is collapsed and pushed forward in the catheter until the ball tip (4) just emerges from the catheter tip (Fig. 3a). After retracting the catheter by about half the length of the basket (1), the open half-basket (4) is released. The basket struts expand (Fig. 3b). When positioned in the embolic occlusion, embolic material (shown hatched) enters the interior of the half-basket (4) in this configuration, which can be supported by a rotational movement of the basket (1) that has been released so far. By retracting the catheter further, the coated half-basket (3) is also released (Fig. 3c). Now the half-basket (4) is shortened and the embolus material is drawn into the coated half-basket (3) (Fig. 3d). In a further step, the catheter (2) is advanced in front of the basket (1) and the basket is completely compressed in the catheter (Fig. 3e). During this process, the liquid part of the embolus is pressed out through the mesh of the coating of the half-basket (3). Inside the basket is the cellular and tissue matrix of the embolus, which is removed by pulling the entire instrument through the catheter (2) that remains in position.

externally extracted. After cleaning the basket (1) and the half-basket (3) and reinserting it via the catheter (2) still in the pulmonary artery, the described procedure can be repeated until the pulmonary artery is recanalized.

In a further embodiment, not shown, the coated half-basket (3) near the catheter encloses the basket (1), i.e. the basket struts run within the surface of the half-basket (3) and are not guided through eyelets (8a-c). This arrangement allows a correspondingly large-caliber half-basket (3) to be anchored all around to the vessel wall by its radial expansion force, so that the vessel cross-section is completely filled by the expanded half-basket (3). With the instrument stabilized in the vessel in this way, the basket (1) can then be extended with a rotational movement, i.e. the half-basket (4) can be extended to capture clots. All further steps then take place as shown from Fig. 3c.

Fig. 4 shows the minimal version of the open half-basket (4), which here consists of only a single longitudinal strut (1) which is connected to the circumference of the coated half-basket (3) via an eyelet (7) in an axially movable manner. This single strut can also take on the function of a guide wire.

Claims (8)

1. Extraction device for clots in the vascular system, consisting of an elastically radially expandable basket at the tip of a catheter, wherein the basket is compressed by advancing an enveloping catheter and is unfolded by withdrawing the catheter, characterized in that the basket consists of a sheathed portion near the catheter and an uncovered portion remote from the catheter. 2. Extraction device for clots in the vascular system, consisting of an elastically radially expandable instrument at the tip of a catheter, the instrument being compressed by advancing an enveloping catheter and being unfolded by retracting the catheter, characterized in that the instrument is composed of an uncovered basket and an enclosed half-basket, both of which are connected to the catheter in such a way that the enclosed half-basket is located coaxially inside or outside the section of the basket near the catheter, thus resulting in an uncovered section of the basket remote from the catheter, and this uncovered section of the basket remote from the catheter can be shortened or lengthened by axial displacement relative to the half-basket near the catheter. 3. Device according to claim 2, characterized in that the axial displaceability of the non-sheathed section of the basket remote from the catheter is provided by the fact that the longitudinal struts forming the open basket section remote from the catheter continue along the sheath of the sheathed half-basket into the catheter axis and thus enclose the sheathed half-basket, while at the same time being axially movable relative to it. 4. Device according to claims 1-3, characterized in that the open half-basket is composed of three or four longitudinal struts. 5. Device according to claims 1-4, characterized in that the basket struts consist of Nitinol. 6. Device according to claims 1-5, characterized in that the sheath of the sheathed half-basket is a mesh made of metal or textile braid, with Nitinol being a preferred metal alloy. 7. Device according to claims 1-3, characterized in that the open half-basket in the extreme case consists only of a longitudinal strut which corresponds to a guide wire which is axially displaceably connected to the sheath of the sheathed half-basket near the catheter. 8. Device according to claims 1-6, characterized in that the open half-basket remote from the catheter has an umbrella-shaped sheath in the region of its tip remote from the catheter.