DE102010051684A1 - Device for controlling movements of catheter-like tool within blood vessel of patient for treatment of e.g. cerebral stroke, has electromagnet and catheter whose spatial orientations are controlled using synchronizing control - Google Patents

Abstract

The device has an electromagnet (2) i.e. traction magnet, moved in spatial directions by a motorized mechanism and exerting pulling force on a magnetic catheter such that a catheter is simultaneously introduced and spatially oriented with respect to a blood vessel structure by the force. Spatial orientations of the magnet and the catheter are controlled using synchronizing control constructed based on a computer or nuclear spin tomographic three-dimensional reconstruction of the structure and a current position of an intraluminal catheter tip detected by an electromagnetic detection.

Description

III. Requirement profile and state of the art in intravascular catheterization

• (see literature, p.

Essential requirements for a method for intravascular catheterization are particularly evident under the demanding anatomical conditions of the brain-supplying arterial vessels: one encounters vessels whose lumen has narrowed towards the distal already to 2-3 mm (A. cerebri media) with correspondingly easily vulnerable vessel walls. Additional disease-related (or age-degenerative) stenoses of the lumen are possible at all levels of the "cerebral vascular tree" and sometimes connected in series as so-called "tandem stenoses". The distally adjacent vessels (Aa. Perforantes, branches of the cerebral artery) are presently difficult or impossible to reach due to their anatomy, disease-related constriction, and an often steep angle of their branching. Already one of the vessel stems (A. carotis interna) shows a curvy course, which must be reconstructed within a short distance in all 3 spatial directions.

This results in requirement 1, a sufficiently precise change of direction of the catheter tip within the smallest possible radius (if possible "on the spot") to make tight curves while preserving the vessel walls can.

Essential mechanical requirements for a high degree of mobility of the catheter tip consist in a tip as small as possible, in the greatest possible flexibility of a catheter tube as thin as possible, in the type of effect on the catheter tip (thrust, tensile force, rotational forces), in the place of the force ( Tube, catheter tip) and, in the case of magnetic methods, also in the strength and shape of the magnetic field (for example the greatest possible concentration of the magnetic field lines around the longitudinal polar axis) in conjunction with a permanent magnet in the catheter tip that is as small as possible in order to ensure prompt coupling to reach with exact spatial orientation of the tip. In magnetic-assisted methods, moreover, the degree of precision achieved depends not insignificantly on whether a sufficiently fine alignment of the magnetic field can be achieved by mechanical means and whether the alignment exactly reproduces the actual vascular anatomy, what the "congruence" of the reference systems (imaging and navigation ) or an effective error control in the process-necessary positioning and horizontal displacement of the patient requires - a sufficiently high "resolution" of today's imaging and the use of a sufficiently sensitive and accurate detection system provided.

The passability of a vessel or a stenosis, as well as the width of the distalization ("supraselective catheterization") depend essentially on the interaction of precision, dimensions of the catheter tip and the strength of the applied magnetic field strength.

Unlike conditions in a body cavity (such as a ventricle), a vessel limits the range of motion of the intraluminal catheter according to a "channel", depending on the lumen width. A lateral deviation of the catheter tip from the ideal path is "anatomically" limited, the more, the thinner the vessel is.

For the magnetic navigation results from the fact that a stable stable " embedding" of the catheter tip in a consuming controlled (homogeneous) magnetic field, combined with a stable "holding" the catheter tip in their respective achieved position and orientation, not a mandatory requirement for the intravascular catheterization , Rather, it can be expected that a small amount of deviation of the catheter tip from the "ideal path" (in the context of a change of position of the magnets or even a temporary loss of magnetic force) is tolerable without endangering the result of the navigation or significantly delay - in difference for navigation within a ventricle or within the brain tissue (stereotaxy).

Brain tissue has by far the greatest vulnerability to ischemia over other body tissues, which in many cases occurs acutely (thromboembolic) and only a short time corridor for causal therapy, i. H. for a recanalization of the sealed vessel. Although the current discussion is about 4-hour time lapse ("systemic lysis") and up to 8 hours ("arterial lysis" with prior catheterization), within which the statistical benefit of the treatment outweighs the risks, the ideal time for treatment is immediate The onset of the first symptoms, in order to expect a complete recanalization and the avoidance of permanent neurological deficits.

The resulting requirement 2 to the intravascular catheterization is thus the highest possible speed of the process or the shortest possible duration to the final position of the catheter.

The navigation within vessels, chambers of the heart and parenchyma to perform different diagnostic and therapeutic interventions at the circumscribed place continues to be predominantly manual in today's inpatient focus: "intervention lists" of neuroradiology and cardiology currently use a wire-assisted navigation with stainless steel guide wires with caliber sizes of 0.008 'to 0.014''(0.36 mm) before insertion of the flexible microcatheter at a relatively high rate of time - averaging between 45 and 60 minutes in the cerebral vessels - and significantly dependent on the experimenter's experience along the vessel are positioning. The corresponding inside diameters of the used microcatheters, which are pushed to the desired position following navigation over the guidewire, are typically 0.010 "and 0.018" (0.46 mm). The feed is made both manually and by machine (so-called "advancer").

• – Die Möglichkeit der Gerinselbildung an der Oberfläche des Katheters mit zunehmender Dauer des Verfahrens.
• – Die Möglichkeit, die Ischämie durch den eingeführten Katheter selbst zu verschlimmern, abhängig von dessen Durchmesser.
• – Sprunghafte, schwer kontrollierbare Bewegungen des Führungsdrahtes (Vorschnellen, „coning” usw.) bei der manuellen Kraftübertragung vom proximalen zum distalen Ende des Drahtes, insbesondere bei langen Übertragungswegen.
• – Die Möglichkeit der Auslösung sog. Gefäßspasmen mit nachfolgender Ischämie, abhängig vom Ausmaß der Gefäßwandirritation.
• – Das relativ hohe Risiko der Verletzung von Gefäßwänden mit der Folge intrazerebraler Blutungen, Loslösung von Gefäßwand-Plaques, akuter Ischämie oder Dissektionen.
• – Die intolerable Zunahme dieser Komplikationen bei komplexen und/oder pathologisch stark veränderten Gefäßverläufen mit kombinierten steilen Gefäßabgängen, stark gewundenen Abschnitten und ausgeprägten Stenosierungen, die bisher nicht selten eine Anwendungsbeschränkung für die Gefäß-Katheterisierung bedeuten.
• – Der große Zeitbedarf angesichts der therapeutischen Erfordernisse, wie sie sich bei akuten vaskulären Krankheitsbildern (insbesondere beim 'zerebralen stroke') ergeben.
• – Die Abhängigkeit des Resultats (und der Komplikationsrate) vom Erfahrungsstand des Untersuchers und demzufolge die Beschränkung des Einsatzes auf erfahrene Zentren, auch bei der Versorgung durchaus häufiger Krankheitsbilder.

Significant drawbacks resulting from this established advancement method relate to therapeutic efficiency, applicability and safety of vascular catheterization:

• - The possibility of clot formation on the surface of the catheter with increasing duration of the procedure.
• The ability to aggravate ischemia through the inserted catheter itself, depending on its diameter.
• - Abrupt, difficult to control movements of the guide wire (fasting, "coning", etc.) during manual force transmission from the proximal to the distal end of the wire, especially in long transmission paths.
• - The possibility of triggering so-called vascular spasm with subsequent ischemia, depending on the extent of vascular wall irritation.
• - The relatively high risk of injury to the vessel walls, resulting in intracerebral hemorrhage, detachment of vessel wall plaques, acute ischemia or dissections.
• - The intolerable increase in these complications in complex and / or pathologically altered vascular processes with combined steep vessel outflows, highly tortuous sections and pronounced stenosis, which not infrequently mean an application restriction for vascular catheterization.
• - The large amount of time required in view of the therapeutic requirements, as they arise in acute vascular disease (especially in the 'cerebral stroke').
• - The dependence of the result (and the complication rate) on the level of experience of the examiner and, consequently, the limitation of the use to experienced centers, even in the supply of quite common clinical pictures.

The starting point in the development of magnetically assisted navigation systems has until today been the expectation that by means of precise and possibly accelerated movement of the catheter through the vessel, these significant drawbacks of the manual feed can be eliminated and thereby a significant increase in the therapeutic effectiveness and safety of the intravascular catheterization, as also may extend their application to hitherto very problematic vessel conditions or to the acute treatment of cardiac and cerebral diseases.

Development over the past four decades has been dependent on the availability of sufficiently compact and strong axially symmetric electromagnets, as well as the applicability of sufficiently precise mechanics with degrees of freedom in all spatial directions, on the quality of imaging, on the availability of suitable detection systems (electromagnetic , sonographic, biplanar fluoroscopy, etc.) as well as the development of application-oriented strategies, algorithms and procedures in dealing with these techniques, in which a growing understanding of the requirements profile of intravascular catheterization and the interactions between magnetic forces, catheters and the respective physiological and anatomical Conditions (1, 2, 5, 7).

The development of such systems was initially cardiologically and neurosurgically motivated and therefore also carried out in adaptation to the special physiological and anatomical conditions that prevail in the heart chambers and brain tissue. Here it proved to be advantageous to establish a continuously effective magnetic field which precisely aligns the catheter tip and "holds" in its respective position in order to avoid possible deviations of the catheter tip from the ideal path or from its reached position and the target in the region of the ventricle to focus on the duration of the following therapeutic activities. For magnetic-assisted navigation within the heart chambers, a special requirement profile emerged, in which the rhythmic range of movement of the heart itself, the turbulent flow conditions, but also the consequences of a possible deviation of the catheter tip from the ideal path (by loss of magnetic control) a special Role played. The progressive advancing of the catheter was conventionally left to the manual or apparative applied thrust - after the previous alignment of the catheter tip by the magnetic field (2, 3, 4, 5, 6). It focused on the complex control of superimposed or homogeneous magnetic fields, with the aim of the magnetized tip of a Guidance wire or catheter along the magnetic field lines generated in the body, according to the found anatomical conditions, which were each to be determined before the intervention by imaging (computer or magnetic resonance tomography). These systems today provide for the application of mostly multiple external electromagnets (magnet clusters), either mobilized and equipped with different degrees of freedom mechanical suspension for aligning their magnetic fields or fixedly positioned in certain spatial directions, such as in orthogonal or opposing arrangement, surrounding the particular vasculature (1, 2, 3, 6, 11).

Complex process algorithms were developed for the computer-aided implementation.

That from Knight et. al. (3, 4, 5, 7) developed and meanwhile continuously further developed "magnetic navigation system" (MNS) of Stereotaxis ^R (Niobe II system, Stereotaxis ^R , St. Louis, Mo) is internationally in clinical use in the field of university and focused cardiology care. It works with two oppositely arranged, vertically pivoting, complex electromagnets and produces in the heart a homogeneous magnetic field of 0.1 to 0.3 tesla for aligning the magnetized catheter tip. The resulting rate of application of this complex loop in clinical application is not yet sufficiently evaluated and judged in comparison with other methods. Alignment of the magnets occurs for each new position within 5-10 seconds, plus the time required for the assessment of the current catheter location and the resulting controls by the examiner (which is necessarily included in the loop of the procedure), as well as for the further provided mechanical feed of the catheter is to spend. The elaborate technical equipment ensures the exact and "holding" leadership of the catheter tip, as it is required for navigating within the heart chambers.

Magnetic force induced retraction of the catheter simultaneously to its magnetically induced navigation has been repeatedly stimulated and discussed in the prior art (7), especially in connection with the introduction of embolizing material in the form of magnetized so-called "coils" into an aneurysm to gradient-mediate the material to a suitable wall of the aneurysm.

Shachar et. al. (11) developed a sophisticated magnetic system that, in addition to a "navigating force field" for aligning the catheter tip with the generated field lines (0.15-0.3 tesla), also provides a gradient-mediated, longitudinal force to move the catheter (1, 6-3.0 tesla) uses. The complex modulation of the force field also allows the combination of different power approaches and their synchronous use. However, the system is also very complicated and controls the magnetic field through a cluster with a maximum of 8 electromagnets, each arranged in different symmetries and with a correspondingly complex controlling algorithm. Its speed in clinical use has not been sufficiently evaluated.

Another line of development consists in an "all-in-one" concept with close reference to the technique of magnetic resonance imaging or even an implementation of the navigation in the apparatus arrangement of magnetic resonance imaging (8, 9, 10). With the goal of synchronizing imaging and navigation, thereby increasing both precision and avoiding the potential sources of error that can result from the patient's spatial and temporal separation and horizontal displacement, are currently being used by different workgroups made great efforts. However, this development would make the use of navigation very time-consuming in the long term and restrict it to highly specialized centers of the so-called maximum supply.

The development up to now has led to complex and costly systems whose scope of control goes beyond the requirement profile of exclusively intravascular catheterization and whose focus is on special, elective procedures in cardiology or neurosurgical centers, but their use is not due to the long-term unaffordable financial burden in inpatient care and acute treatment of common vascular disease is provided.

In addition, it remains questionable whether the time required for these complex systems until the final positioning of the catheter meets the requirements of an acute treatment (such as the 'cerebral stroke').

The particular focus in the previous development was not on a magnetically guided insertion of the catheter by the effect of a single aligned magnetic gradient. The limitation to exclusively gradient-mediated navigation with a single directed traction along the longitudinal gradient that 'dock' a magnetized catheter tip and follow its spatial orientation has not heretofore been a fundamental principle in vascular catheterization and methodologically appropriate -apparatus innovations and adjustments to clinical processes realized.

• – eine vergleichbar rasche Katheter-Positionierung,
• – eine vergleichbar größere Sicherheit und geringere Traumatisierung,
• – eine relevante Ausweitung der Indikationsstellung bei seiner Anwendung sowie
• – gleichzeitig eine relevante anwendungsorientierte Verfahrensvereinfachung im Vergleich mit bisherigen magnetischen Navigationsverfahren zu erreichen.

It can be expected that a device method according to the presented is able to solve the problems posed in intravascular catheterization

• A comparably fast catheter positioning,
• - a comparably greater safety and less traumatization,
• - a relevant extension of the indication in its application as well as
• - At the same time to achieve a relevant application-oriented simplification in comparison with previous magnetic navigation methods.

By producing the described procedural requirements and problem solutions, the stated objectives are to be achieved.

IV. Methodological and technical innovations of the project

• 1. The limitation to a tensile force by effecting a magnetic gradient between the magnetized catheter tip and a single external and high degree of freedom spatially exactly aligned electromagnet ("pull magnet") allows alignment and movement of the intravascular catheter tip in one go ("synchronous navigation") where the force reversal (retraction rather than advancement) equips the catheter with a "front-wheel drive" that supports precise guidance of the catheter tip and minimizes the risk of manual feed.
• 2. The use of a C-arm as an integral part of the supporting and aligning mechanism of the electromagnet, with two separately positioned mechanical units are provided: A so-called. "Internal mechanics" conveys the longitudinal displacement of the magnet along the C-arm and its inclination the plane that encloses the C-arm. The motor unit is housed inside and inside the C-arm and uses a rail inside the C-arm for displacement and a ball joint for tilting. A so-called "outer mechanism" causes the C-arm to pivot about its horizontal axis and rotate about the plane it encloses. The motors are positioned within a C-arm articulation (for rotation) and within the C-arm standing pivot (swing). "Inner" and "outer" mechanics allow for spatial alignment one degree of freedom in all spatial directions except for the movement of the magnet within the plane surrounding the C-arm (the variation of the distance of the pole from the catheter tip is here due to the variation of the Magnetic field strength replaced).
• 3. The continuous action of the magnetic traction and a concomitant, mechanically mediated retention give the catheter tip a dynamic "suspension" between the two opposing forces, which both provides their protection, as well as their magnetic coupling and their precise alignment supported on the longitudinal magnetic gradient ,
• 4. The variable length and variable speed segments of catheter insertion due to appropriate rotation of motorized, catheter tube leading and compressing rollers ("Holder"), the respective catheter segment under the controlling and synchronizing influence of the system control to the effect of continuously "handed over" ("permissive indentation") to the catheter tip.
• 5. The use of a catheter, in addition to its correspondingly magnetized and adapted to the detection used tip a small diameter (0.5-1.5 mm) preserve and correspondingly have favorable mechanical properties - essentially made possible by the omission of the conventional Feed process necessary force transmission - and then has on perforations of his tube, immediately at its tip, to improve its flexibility and to exit diagnostic or therapeutic preparations.
• 7. The procedure for constructing a suitable data base from the data set of a 3-D reconstruction of the vessel section created by computed tomography or nuclear spin tomography takes place before navigation begins and is carried out by a programmed algorithm. The data basis is used by the system controller for synchronizing steering of all elements of the control loop during navigation. It includes the segmentation of the entire intake, the adapted order of variation of the magnetic field strength, the resulting guide path of the traction magnet with corresponding positioning commands to its mechanics as well as a synchronized command structure to the "Holder".

V. Detailed description of the method

• (see VIII Illustrations, pp. 18-30)

The closed loop of the method has "executive" devices (electromagnet and its mechanics, holders and microcatheter), "detecting" components (integrated electromagnetic detection, the tool to be detected in the catheter tip and the length determination through the Holder) and via the "Control Panel". The control circuit also has an interface to the data set of the preceding imaging as well as an implemented algorithm for generating a system-conformable data foundation. The control access is provided by the system controller via a corresponding interface. Also provided are those devices that ensure accurate positioning of the patient, his horizontal displacement including a finely-adjustable error correction.

and give a first overview of the arrangement of the electromagnet (scale 1: 16.6 and 1: 13.6) ( 2 ), its mechanics ( 1 . 3 - 7 ) and the integrated electromagnetic detection ( 15b - 15d ) from different viewing directions. The specified dimensions of the mechanics are approximate values. In addition, the horizontally movable examination table ( 26 ), the gantry ( 13 ) of the tomograph ( 11 . 12 ) connects with the effective range of navigation, as well as the horizontal resistance path ( 9 ), the patient's pad ( 10 ) and the position of the holding device for the head of the patient ( 46 ). The position of the tomograph ( 11 . 12 . 13 ), which is not a system-immanent tool, therefore remains indicated. Front view and supervision ( ) also give the estimated distance between antennas ( 15b ) and head of the patient and the distance between the markers ( 15c ) at.

At the beginning of the procedure and before navigation, the procedure for constructing a suitable data base ( 17 ) from the 3-D reconstruction of the relevant vessel course, computed by computer or MRI, to which the control of the control loop of navigation refers. such as . and show sub-steps and results of this process.

The implemented algorithm ( 18 ) via an interface to the data set of the imaging ( 11 ) access. The illustrated vessel course ( 34 ) is first transformed over its entire length into virtual segments ( 37 ). The distance ( 38 ) of the plane perpendicular to the longitudinal axis of the vessel set planes ( 37a ) is in a reciprocal relationship to the change of direction of the longitudinal axis of the vessel ( 36 ) (corresponding to the flow direction), which determines the angle of the sectional planes to one another: the greater the change of direction of the longitudinal vessel axis (ie the degree of curvature of the vessel), the denser the cutting sequence (FIG. 42 ). The specification of the algorithm thus exists in a certain angular extent, from which a new cut is made by the vessel reconstruction. The consideration of stenosis-related changes of direction ( 35 ) depends on the resolution of the imaging used (which has now reached a sufficient quality).

The cutting planes ( 37a ) through the vascular reconstruction are applied to the virtual coordinate system of imaging ( 20 ) based. Thereafter, for each segment, longitudinal vector guides ( 40 ) through the center of the vessel lumen, whose spatial directions, also with respect to the coordinate system ( 20 ), which depicts the sequence of spatial directions in which the direction of flow of the vessel is "aimed". The vectorial data is then sent to the navigation virtual coordinate system ( 19 ), resulting in a virtual horizontal displacement of the coordinate system ( 25 ), which subsequently has to be reproduced in exact agreement by the body which houses the vascular system ( 21 ). The result is a sequence of spatial alignments that the magnetic field of the tension magnet ( 2 ) in order to bring the effective magnetic gradient always in line with the longitudinal vessel axis and to allow the intravascular catheter tip to be magnetically coupled. These spatial coordinates correspond in their sequence to the "path" ( 28 ) on which the pull magnet ( 2 ) during the following navigation around the relevant vessel course ( 34 ) is guided around, in the sense of a precisely defined range of motion.

Finally, the spatial coordinates are translated into corresponding control commands, which are directed as a sequence during navigation to the motorized mechanics of the magnet ( 29 . 30 ).

The resulting length sequence of the segments ( 42 ) over the entire course of the vessel is transferred to a corresponding command structure to the holder ( 8th ), which is sent to the motors of the holder during the following navigation, synchronized with the orientation of the magnet ( 32 ) to allow the segmented indwelling of the catheter.

Although the variation width of the lengths ( 38 ) can only be determined by experimental evaluation, requires an exact understanding of stenosis-induced change of direction of the vessel ( 35 ) at a short distance (in the range of a few millimeters) as short a sequence of steps as possible to a flow that is as smooth as possible. The examiner can make the decision on the respective lengths of the intake segments at any later time during navigation. By contrast, the algorithm generating at the beginning of the method already anticipates this decision and thereby supports the automated procedure of the navigation method.

The constructed data base ( 17 ) also contains the required variation of the magnetic field strength in adaptation to the variation of the distance ( 39 ) between magnet pole and catheter tip as well as possible (stenosis-related) resistances during the passage. A corresponding command sequence to the voltage generation ( 31 ) of the electromagnet is provided for the following navigation. For this purpose, for each longitudinal vector guide through the vessel segments, the intersections ( 19a ) with the levels of the surrounding coordinate system ( 19 ) of the navigation (on which the electromagnet ( 2 ) and thus also the respective distance between vessel and magnetic pole ( 39 ), certainly. To the penetration of air, skin, calf, meninges, cerebrospinal fluid and brain tissue ( 41 ) and additionally allow the catheter to be inserted, the field strength is adjusted accordingly. In this case, the priority for the algorithm to achieve the indentation in each case with the minimum effective field strength (The controlling variation of the distance of the magnetic pole to the vessel by the motorized mechanism is not provided in the process and can at best in the context of an error control by shifting the patient table take place (see below)).

Although the "range" of the field strength to be applied will be the result of experimental and pre-clinical evaluation, a variation of the magnetic field strength between 0.5 and 3.0 tesla can be assumed in advance. In particular, the passage of stenosis-related resistances requires restrictive preclinical examinations.

In addition, the variation of the magnetic field strength at any point in the navigation can also be performed by the examiner via a corresponding interface (FIG. 43 ), for example in the passage of a stenosis-related resistance - one of the possible problem situations.

The presented method is based on the spatial and temporal separation between acquisition of the data basis (imaging and its preparation) and the execution of the navigation, which makes an intermediate horizontal displacement of the body or the vascular system from the sphere of action of the imaging into the area of action of the navigation necessary , ( 21 ).

As already described, in the construction of the data base, a transmission of the coordinate system of imaging ( 20 ) to the coordinate system of navigation ( 19 ), which was equivalent to a "virtual horizontal shift". Before the start of navigation, the corresponding horizontal displacement of the body now takes place ( 21 ), in which the vascular system is located, with the aim of restoring the "congruence" of constructed data base and real vascular system.

Systematic errors can result both from the process of horizontal displacement, as well as from intermediate positional changes of the body. They can result in the deviation of the catheter tip in all spatial directions, with shifts in the range of a fraction of a millimeter up to several millimeters are to be expected. Insufficient congruence sooner or later will result in resistance to further catheter insertion that the vessel wall offers. Already deviations in the millimeter range would therefore be intolerable, whereby they would prove to be problematic, especially in the passage of narrow vessel turns, steep vascular discharges or narrow stenoses, less in stretched sections of a vessel.

• 1. die konstante Lagebeziehung (22) zwischen Tomograph (11–13) und Navigationssystem (1–5, 7), wobei der Abstand zwischen beiden Geräten möglichst gering sein sollte,
• 2. eine längenkontrollierte Horizontal-Verschiebung des Körpers, die hier durch Anwendung einer über Spannungspegel gesteuerten Widerstandsbahn (9), die den Untersuchungstisch trägt, sichergestellt wird sowie
• 3. die fixierende Lagerung des Körpers (46 und 47), ggf. auch eine vorausgehende Sedierung und Muskelrelaxation.

The avoidance of such systematic errors includes (s. )

• 1. the constant positional relationship ( 22 ) between tomograph ( 11 - 13 ) and navigation system ( 1 - 5 . 7 ), whereby the distance between both devices should be as small as possible,
• 2. a length-controlled horizontal displacement of the body, here by applying a voltage level controlled resistance path ( 9 ), which carries the examination table, is ensured as well as
• 3. the fixing bearing of the body ( 46 and 47 ), possibly also a previous sedation and muscle relaxation.

The error detection essentially results from the interaction of the selected detection method ( 15 ) (here an electromagnetic procedure) and the system control ( 16 ) (both are described in detail below). The system controller receives position data on the catheter tip in real-time and in electronically processed form from the continuous detection ( 15 ) and first compares these spatial data with the expected values of the generated data basis, s. , A current catheter position "outside" the expected vessel wall indicates insufficient "congruence".
(The detection of a deviation from the "congruence" depends crucially on the sensitivity and precision of the selected detection method - previous application-oriented studies have shown that the electromagnetic detection with sufficient precision and sensitivity and small deviations or changes in the position of an intravascular Markers (probe, ring, etc.) can make recognizable).

Nevertheless, it makes sense in this section of the procedure, that is before the start of navigation In addition, another imaging technique should be performed with good precision and sensitivity, such as biplanar fluoroscopy, to sharpen the detection of a lack of congruence with the vascular history and position of the catheter tip.

In addition, it is provided that the method of error detection continuously or at close intervals also later during navigation done, although the horizontal displacement is completed and active and passive movements of the body is counteracted.

Furthermore, for an orienting control over the actual lengths of the intake segments, a continuous length control, s. ( 33 ) by the holder during the collection. The system controller compares this data with the intended lengths of the collection segments of the generated data base and identifies deviations that may indicate a misfeed (effective resistance over a longer section, "snagging" of the catheter tip).

The correction for lack of "coincidence" occurs as shown in , by a fine adjustment of the body position in the millimeter range and in all three spatial directions ( 23 . 24 ), which is available at the examination table and which is possible at any point in the procedure, with the system control specifying the direction and mail of the correction.

The correction is thus initially made by the change in position of the body and not by a recalculation of the data basis. The design of the algorithm used is designed to allow the corrective procedures to be done automatically, but the examiner has the option of making the corrections himself, either via interface or manually at the table.

In addition, a recalculation of the data base, based on the current data on the position of the catheter tip, at any time.

As in and is shown as an executive element of the control loop is a single solenoid ( 2 ) provided ("single-coil system"). When adapting to the needs of this navigation system, it makes use of already available technical possibilities: it becomes a superconducting electromagnet to be cooled ( 2 ) in the form of a cylindrical, axially symmetrical ring of a compressed under air close copper coil ( 2 B ) with an exposed ferromagnetic core cylinder ( 2a ), which generates a sufficient magnetic force field (up to 3 tesla) and the field lines of its poles magnetic field as strong as possible along the longitudinal axis ( 36 . 39 ), followed by sufficient magnetic coupling of the catheter tip ( 14b ). The distance of the pole during navigation, s. ( 39 ), from the facing pole of the catheter tip ( 14b ) depends on the position of the magnet and the position of the vessel and is estimated at 10-40 cm. The media to be penetrated ( 41 ) exist in addition to the air between pole and skull roof on the one hand in the skin, skull bones, meninges, cerebrospinal fluid and vessel wall on the other in the brain tissue of different thickness to the target vessel ( 34 respectively. 37 ), and represent an overindividually small fluctuating portion of this distance. A magnetic field strength of 0.5-2 tesla could be sufficient. The expansion of the core cylinder is likely to reach a pole face diameter of 12-15 cm and a length of 45-50 cm.

For water cooling, a flow of about 0.4-0.5 gpm. be sufficient (in not shown).

A hydraulically effected advancement and retraction of the iron core inside the magnet to expand the magnetic pole variably and to change the concentration of the field lines is not initially provided here (a possible requirement will result from the preclinical application of the method).

A parabolic, the magnet surrounding, appropriately coated shield, which could also lead to an amplification of the force field is also not initially provided (in not shown).

The motorized mechanism is designed to support the weight of the pull magnet while allowing for its sufficiently precise spatial orientation. As in . and shown is a C-arm ( 1 ) made of steel (or made of another sufficiently strong material), which guides the magnet inside. The C-arm surrounds the body part in question at a distance that leaves enough space for the magnet, but also allows the greatest possible proximity of the pole face to the body surface.

The construction includes an "inner" ( and ) and "outer" mechanics ( ). Their combination allows the magnet a degree of flexibility in all spatial directions - by moving along the arc ( 3e ), pulled by an engine block ( 3a ) moving within a rail of the C-arm ( 3c ), by pivoting the bow ( 1a ) mediated by another engine block ( 6 ) as well as by the inclination ( 3d ) of the magnetic axis with respect to the plane of the C-arm, mediated by a ball joint ( 3b ).

The range of motion of the magnet is further extended by the rotation of the C-arm ( 1b ) around the plane which it encompasses, mediated by a motorized joint articulating with another slide rail of the arch ( 4 ) standing on the stationary element of the supporting fixture ( 5 ) is attached. This rotation allows for further lateralization of the magnet to both ends of the C-arm. However, it is not always possible in all levels (horizontal, vertical or inclined planes) or can only be executed to a limited extent, due to the space requirement of the relevant body part (FIG. 27 , so-called "exclusive zone").

The sequence of the magnetic movement and the corresponding chain of position commands to the motors of the mechanics were already generated at the beginning of the method in the context of the constructed data base and are used during navigation by the system control ( 16 ) to the "inner" and "outer" mechanics ( 29 . 30 ). Since in addition to the longitudinal concentration of the magnetic field lines and the step intervals in the change of direction of the magnet affect the exact alignment of the force and the magnetic coupling of the catheter tip, as small as possible motion segments (in the millimeter range or as a nearly continuous movement) - in accordance with the smallest possible possible segmentation of the vessel course.

The examiner retains the ability to control the movement and orientation of the magnet itself at any point in the procedure ( 43 ) by specifying the length and number of individual steps and influencing the spatial direction by means of suitable equipment.

Another executive element, shown in , consists in a motorized mechanical apparatus (Holder) ( 8th ), which is located outside the body, the catheter tube to the point of entry into the body (so-called "lock") leads ( 8i ) and by means of an array of 5 transverse to the longitudinal axis of the catheter guide rollers ( 8a ) exerts a continuous, compressive pressure on the catheter tube which opposes the pulling force of the magnet continuously acting on the catheter tip and prevents the insertion during the collection interval.

The feeder takes place with the controlled rotation of the 5 guide rollers ( 8a ), thus "releasing" a segment of the variable length variable speed catheter tubing and "permitting" its entry through the continuous effective magnetic pull force (permissive indentation). Numbers and lengths of all indentation segments were already included in the construction of the data base ( 17 ) certainly. However, they can also be defined by the examiner at any later time ( 43 ).

The Holder has a glass surround ( 8j ) for better observability of its functions and is provided with an elongate guide rail ( 8h ) which connects the catheter tube ( 14d ) within a securing channel before entry into the holder ( 8g ) and after leaving ( 8i ) leads to the so-called "lock" (entry into the body). The engine block comprises 5 separate electric motors ( 8b ), the drive shafts in the respective rotary rods ( 8k ) pass over the rollers. While the 3 rollers positioned under the catheter tube and the associated 3 motors have fixed roller bearings ( 8d ) or suspensions, the 2 rollers positioned above the catheter tube, with their respective motors, have a "spring-loaded" suspension in the form of a front rail (FIG. 8c ) with 2 roller bearings for the rotating rods of the two rollers and a corresponding resilient suspension for the engines.

The two upper rollers and their engines are powered by 2 compressors ( 8f flanking a variable pressure on both the transverse to them front rail ( 8c ), as well as on a rear, transverse to them rail ( 8th ), the two upper electric motors ( 8b ) exercise. This results in the lowering of the two upper roller motor units, thus for compression and retention of the catheter tube. The two compressors work synchronously and lower the front and rear rails by the same amount necessary for sufficient compression of the hose, which at the same time allows rotation of the rollers.

The electric motors are subject to the system control ( 32 ) from which they receive appropriate signals during navigation, such as in the case of an intermediate retraction of the catheter. They also work synchronously and allow the rollers to rotate in both directions of rotation and at variable speed. With continued compression of the catheter tubing (and continued effective traction on the catheter tip), retraction is accomplished with the speed and duration of controlled synchronous rotation of the rollers. During controlled collection, the retention thus remains effective, preventing uncontrolled rashing of the catheter (and corresponding trauma to the vessel walls). The feeder stops when the rotation stops.

The rotation in a different direction of rotation allows a controlled retraction of the catheter, as well as its removal from the vessel. In the case of a longitudinally no longer movable Catheter tip, indicating substantial deviation, entrapment, or stenotic resistance, the counter-rotating of the guide rollers and a measured retraction of the catheter can be used to reset it (and also the system control) to the previous position, respectively Remobilize the catheter tip.

The rotation of the guide rollers is controlled by a continuous length control ( 33 ) of the intake segments whose results are routed continuously to the system control and for comparison with the previously calculated values of the data base and thus also for the detection of errors or disturbances of the collection.

Both during the collection, as well as during the collection intervals, the catheter tip, which in each case in the corresponding indentation segment ( 37 ) of the vessel ( 34 ) is in a special position ("suspension") between 2 opposing forces, shown in FIG namely, the traction force of the aligned electromagnet continuously acting on the catheter tip ( 2 ) and the simultaneous via the catheter tube mediated, mechanical support by the holder ( 8th ). This opposite force approach causes on the one hand a permanent longitudinal tension of the catheter tube ( 14d ), but at the same time supports the magnetic coupling of the catheter tip ( 14a ) and their exact alignment at the longitudinal tensile gradient ( 36 ) or counteracts a lateral deviation of the catheter tip.

On the other hand, it is to be expected that the longitudinal tension of the catheter tube could lead to vascular wall damage and detachment of plaques, conceivable by the pressure exerted and the "grinding" of the catheter tube on the inner vessel wall (FIG. 34a ), especially in the area of vascular turns and outlets (the occurrence and extent of this undoubtedly damaging effect will have to be clarified by preclinical evaluation). The system algorithm provides for the control of this potential risk factor to adjust the applied field strength of the pull magnet within a range (0.5-2 tesla) with orientation at the minimum required field strength.

Although it can be expected that both catheter, as well as guide wires of different diameter and magnetized material for various clinical tasks can be navigated intravascularly by the presented method, here is the use of a correspondingly thin-lumen microcatheter ( 14 ) (0.5-1.5 mm diameter), shown in FIG whose clinical benefit is essentially due to the recanalization of acute vascular occlusions by lysis. The method presented here allows the abandonment of the use of guidewires and thereby also leads to a considerable time savings.

The design of the microcatheter can be based on a variety of models already in clinical use:
With the aim to achieve a point-like approach of the tensile force at the catheter tip, forms a cylindrical permanent magnet ( 14b ) smallest possible pole surface (0.5-1.5 mm diameter) the front area of the catheter tip ( 14a ). Its magnetic axis is aligned in the longitudinal axis of the catheter and tapered its pole face forward to improve the magnetic coupling. Suitable magnetically responsive materials are available, such as NbFe35, NdFeB (Neodymium-Iron-Barium), or SMCo5 (Samarium-Cobalt). The magnet is followed by the detection-related device ( 14c ), in the present method a encompassing (0.5-1.0 mm diameter), as narrow as possible (0.5 mm) ring of polymerized plastic whose intraluminar position is to be determined by the electromagnetic (RADAR) system used. The catheter tip should not exceed a total length of 2.5 mm in order to allow close directional change even within vessels with diameters of 2-3 mm.

The used hose material ( 14d ), which also encloses the catheter tip, has certain mechanical properties in addition to a very smooth surface: When using very thin catheter tubes (0.5 mm diameter) a great flexibility is maintained, which improves the mobility of the catheter tip and close changes of direction with as small as possible Radius allowed. However, in the presented method, the continuous "suspension" of the catheter between traction and retention can be expected to cause longitudinal tension on the tube, which in turn may limit its flexibility and thus the maneuverability of the catheter tip. Also in this regard, the control algorithm of the system always provides for the application of the lowest possible field strength of the pull magnet to limit this effect.

At the same time, the special positioning of the catheter between tensile force and retention requires the least possible elasticity in the longitudinal direction in order to avoid a transient expansion of the tube with deviation of the catheter tip.

Flexibility of the tubing, length of the catheter tip and the type of force application (tensile force) have a significant influence on the position of the fulcrum when changing the direction of the catheter. Flexibility of the tube and shortness of the catheter tip are to be optimized so far that there is a pivot point mounted as far forward as possible. To further optimize the flexibility of the tube as close as possible to the catheter tip, there are 4 perforations ("slots") ( 14e ) in the longitudinal direction of the catheter, each offset by 45 ° provided immediately behind the catheter tip, in particular to predispose this section as a fulcrum.

In addition, the leakage of the lysis preparation and the contrast agent through these perforations.

The control loop of the navigation system is closed by its detecting limb, which makes use of electromagnetic detection, which already has data and clinical experience. It is used for sufficiently accurate position determination of the catheter tip in real time.

When selecting the detection method (currently there are capacitive, inductive, optical and electromagnetic methods in this highly specialized field of application or evaluation), priority has been given to a low cost procedure that works in the presence of strong magnetic fields and dense structures (bone penetrating, which has a high resolution and sensitive detection and which provide the position data on the position of the catheter tip in real time and in electronic form to the system controller and thus can also provide an important prerequisite for an automated procedure of the navigation method (visual methods, such as biplanar fluoroscopy, by contrast, entail that the examiner necessarily remains involved in the control loop of the procedure by judging the visual material / visualization of the event and making appropriate decisions).

For the application of electromagnetic detection, it is also advantageous that it allows different configurations and thus allows adjustments to practical requirements that may arise only when implementing and applying the navigation method (UW-RADAR, Continuous Wave (CW) Radar, Frequency Modulated (FM-CW) Radar or Pulse Doppler Radar).

Their coordinate-oriented data structure, which can be related to the coordinate system of navigation, represents a further advantage over other detection methods.

The selected electromagnetic detection achieves the goal of its task by detecting the energetic differences of the materials in the catheter tip against the background of the environment ("RADAR signature") and referring to an integrated spatial coordinate system, which in turn is based on the coordinate system of navigation in Cover can be brought.

represents the implemented detection: sequential UWB signals from 4-6 antennas ( 15b ) as close as possible to the patient on the floor and above the C-arm ( 1 ) are positioned. The distance to the head of the patient should be estimated at about 80 cm (s. ).

From the catheter tip ( 14c ) reflected signals become a radio frequency module ( 15 ), so changed to a "signature" that they can be optimally distinguished from the signals of the environment, reinforced and related to an integrated coordinate system, its 8 "marker" also close to the patient in the C-arm and in another C-arm with Orthogonal position to the main C-arm are arranged so that they describe the corner points of a cube (with synchronous pivoting of both C-arms) and their echo signals to build the coordinate system ( 15a ) can be used. The distance between two markers is estimated at about 80 cm.

Thereafter, the conversion into electronic pulses by an analog-to-digital converter for further processing by the system controller ( 15e and 16 ). The position data are finally referred to the coordinate system of the navigation and compared with the already generated data base. The detection appears to be sufficiently sensitive and precise in order to detect even slight systematic errors in the horizontal displacement of the patient and in establishing the spatial "congruence" of the generated data basis and the actual position of the catheter tip (the course of the vessel). Possible deviations would already be recognizable immediately at the beginning of the navigation and a correction accessible. Possibly, there are still possibilities, precision and sensitivity during the development, eg. Eg by changing antenna positions, to optimize.

The recognition and imaging of the current spatial orientation of the intravascular catheter tip (possibilities that may result from a very high resolution of the detection system as well as the use of 2 detection coils in the catheter tip) have for the presented navigation method and for exclusively intravascular catheterization not essential : Lesser lateral deviations of the tip from the ideal path appear tolerable, while the larger, the progress Disturbing deviations are counteracted on the one hand by the continuous alignment of the tip on the tensile gradient and on the other hand - at least in thin-lumen vessels - are set by the canalizing vessel walls limits.

The controlled and synchronized interaction of the executive and detecting components of the control loop, presented in , is controlled by the software-based control panel ( 16 ) based on the generated data base and its continuous alignment with the detected position of the catheter tip realized.

It receives continuous data of the detection ( 15 ) to the current position of the catheter tip, it relates to the data of the generated data base ( 17 ) of the system and continuously takes in accordance with the course of the vessel (ie its "congruent" reproduction) the exact orientation of the magnetic field ( 29 . 30 ) by sending appropriate control commands to the motors of the mechanics of the electromagnet.

A corresponding command sequence is sent synchronously to the mechanics of the holder ( 32 ) to release a specific intake segment of defined length at a defined speed to the tensile force ( 31 ) of the magnet, which is also adapted synchronously to the respective distance between magnetic pole and catheter tip via appropriate instructions to the voltage generation of the magnet.

Upon completion of the catheter segment retraction, the system controller receives "feedback" information about the actual capture length (Holder) and the new actual position of the catheter tip (detection).

Already before the start of the navigation, as well as in close temporal distances during the navigation, the system control analyzes the obtained data with regard to a sufficient "congruence" and corrects the deviation either automatically or gives instructions to the examiner, who first over a Correction of patient position done.

However, a correction by regenerating a customized data foundation is also provided in the algorithm. A decision is made by the investigator.

Implemented algorithms ensure the mastery of possible problem situations as well as the correction of possible errors during the navigation and thus provide an essential basis for the security, the speed and for an automated procedure of the procedure.

As an example of a problem to be expected may strong resistance against the further insertion of the catheter serve: The algorithm then has to first distinguish whether there is only a lack of "congruence" of navigation and real vessel course, whether alone a stenosis (with possible deviation of the catheter tip ) the resistance or whether it is a combination of both. Based on the result of this analysis, an automatic or investigator-determined error or problem correction may be made, such as horizontally readjusting the patient's position on the examination table, retracting the catheter to remobilize the catheter tip or increasing the magnetic field temporarily.

Under defined conditions (to be determined before the procedure), the system controller stops the automatic procedure with a corresponding error or problem message and transmits it to the controller through a corresponding interface (mode change). The system controller already provides a customized action plan for the subsequent "problem management". This mode change can also be brought about by the examiner himself at any time during the procedure.

The system controller presents the examiner with a continuous synoptic visualization of the processes in real time on the monitor ( 44 ). It contains the reconstruction of the course of the vessel on a generated data basis and the current position of the catheter tip, visualizes the degree of "congruence" and indicates in the case of an intolerable deviation while the spatial direction in which a position correction would have to be done (usually a horizontal correction to is expected).

In addition, the system control ensures the criteria and standard documentation of the process flow on data carrier.

The presented navigation system has possibilities on different elements of the controlling loop to optimize the performance of the system (in particular the speed of the procedure and the precision with which the positioning of the catheter takes place), which only makes the further development clear. Certainly, the system would benefit from changes that bring about an improvement in the magnetic coupling, alignment and mobility of the catheter tip. In particular, there is likely to be potential for further optimization.

VI. Expected benefits

• 1. bisher schwierig zu passierende anatomische Gegebenheiten – physiologisch- oder krankheitsbedingt – wie etwa Tandem-Stenosen, hochgradige Stenosen, starke Krümmungen oder steile Gefäßabgänge ausreichend exakt nachvollzogen werden können, daher passierbar werden, und dass ebenso dünnlumige distale Gefäßzweige besser erreicht werden können (im Vergleich mit dem gängigen Vorschub-Verfahren) – entsprechend der Anforderung 1 an die Gefäß-Katheterisierung (s. S. 3),
• 2. eine Zeitersparnis im Verfahrensablauf in Aussicht steht, die im Wesentlichen aus der Art der Kraft (Zugkraft) und ihres Ansatz-Punktes (Katheterspitze), dem ermöglichten Verzicht auf die Anwendung eines Führungsdrahtes, aus der Verfahrensvereinfachung sowie aus dem erreichten Grad der Automatisierung resultiert und was dem besonderen zeitlichen Erfordernis bei der Akutbehandlung zerebraler Gefäßverschlüsse entgegen kommen würde (im Vergleich mit dem gängigen Vorschub-Verfahren, wie auch mit den bisher entwickelten magnetgestützten Systemen) – entsprechend der Anforderung 2 an die Gefäß-Katheterisierung (s. S. 3),
• 3. ein erheblich günstigeres Risiko- bzw. Komplikations-Profil für die Gefäß-Katheterisierung erreicht werden könnte, was neben den patientenbezogenen Vorteilen unter anderem eine wesentliche Voraussetzung für anwendende Kliniken darstellt, fortan auf die bisher erforderlichen aufwendigen Anpassungen, wie etwa das Vorhalten einer Neurochirurgie in Bereitschaft, verzichten zu können (im Vergleich mit dem gängigen Vorschub-Verfahren),
• 4. die Indikationsbreite für die Gefäß-Katheterisierung (im Bereich der Akutbehandlung vaskulärer Verschlüsse nach Ausprägungsgrad und Lokalisation der Läsion, nach Alter des Patienten, nach Komorbidität des Patienten) nachhaltig erweitert und einer deutlich größeren Anzahl von Patienten als bisher zugänglich gemacht werden könnte,
• 5. das System eine Verfahrensvereinfachung mit sich bringen würde (Reduzierung der technisch-apparativen Aufwands und der sofware-basierten Ausstattung), im Wesentlichen resultierend aus der Beschränkung auf einen einzelnen Elektromagneten zum Erreichen einer synchronen Navigation (gegenüber den bereits entwickelten magnetgestützten Systemen),
• 6. das Navigations-Ergebnis in geringerem Maße von klinischen Erfahrungen und manuellen Fertigkeiten des Untersuchers abhinge, als es beim herkömmlichen Verfahren der Fall ist, was sich im Wesentlichen aus dem erreichten Grad an Automatisierung ergeben würde (im Vergleich mit dem gängigen Vorschub-Verfahren),
• 7. sich unter Berücksichtigung der Aspekte 1. bis 6. der Weg in die stationäre Regelversorgung für die Gefäß-Katheterisierung eröffnen könnte, wobei ihr Hauptnutzen dann im Wesentlichen in der Akutbehandlung häufiger vaskulärer Verschlüsse, insbesondere der hirnzuführenden Gefäße, zur Abwendung oder Abmilderung bleibender neurologischer Defizite und lebenslanger Behinderungen bestehen könnte.

The favorable influence of essential mechanical parameters (degree of mobility of the catheter tip, precision of their steering, cross section of the catheter) through the interaction of all components of the illustrated control circuit can be expected for the clinical application of the method

• 1. anatomical conditions hitherto difficult to pass - physiological or disease-related - such as tandem stenoses, high-grade stenoses, severe bends or steep vessel drains can be sufficiently accurately understood, therefore passable, and that also thin-lumen distal branches of the vessel can be better achieved (im Comparison with the usual feed method) - in accordance with requirement 1 for vascular catheterization (see page 3),
• 2. There is a prospect of saving time in the process, which essentially results from the type of force (tensile force) and its point of application (catheter tip), the possible omission of the use of a guide wire, the simplification of the procedure and the degree of automation achieved and what would be the special time requirement for the acute treatment of cerebral vascular occlusions would meet (compared with the common feed method, as well as with the previously developed magnetic-based systems) - according to the requirement 2 to the vascular catheterization (see page 3) .
• 3. a significantly more favorable risk or complication profile for the vascular catheterization could be achieved, which represents, among other things, the patient-related benefits, inter alia, an essential prerequisite for clinics, henceforth on the previously required costly adjustments, such as the provision of neurosurgery in readiness to be able to do without (in comparison with the usual feed process),
• 4. The range of indication for vascular catheterization (in the area of acute treatment of vascular occlusions according to degree of expression and localization of the lesion, according to age of the patient, after comorbidity of the patient) could be sustainably extended and made accessible to a significantly larger number of patients than before,
• 5. The system would bring about a simplification of the procedure (reduction of the technical and equipment-related expenses and the software-based equipment), essentially as a result of the restriction to a single electromagnet for achieving a synchronous navigation (in comparison to the already developed magnetically supported systems),
• 6. The navigation result would depend to a lesser extent on clinical experience and manual skills of the examiner than would be the case in the conventional method, which would essentially result from the degree of automation achieved (as compared to the conventional advancing method). .
• 7. Considering the aspects 1 to 6, the way into the stationary standard care for vascular catheterization could open, with its main benefit then essentially in the acute treatment of common vascular occlusions, especially the brain-feeding vessels, to avert or mitigate permanent neurological Deficits and lifelong disabilities could exist.

Without wishing to anticipate the results of a later clinical evaluation of this procedure (for example, in comparison with the established systemic lysis), it can be expected that its clinical application would bring significant advantages for the range of indications, the therapeutic efficacy, the risk profile and, if necessary, They may also provide cost-benefit benefits (in clinics of different categories) for vascular catheterization, which are likely to positively correlate positively.

VII. Literature

• 1. Jenkins A, Parker H "Electromagnetic support arrangement with threedimensional control" J Appl Phys 1959; 30: 238-239
• Second Montgomery DB et. al. "A new magnet system for intravascular navigation" Med Biol Engl 1968; 6: 143-147
• 3. Howard MA, Mayberg M, Grady MS, Knights RC, Gillies GT U.S. Patent No. 5,125,888 (1992)
• 4th Grady MS, Howard MA, Dacey RG et. al. "Experimental study of the magnetic stereotaxis system for catheter manipulation within the brain" J Neurosurg 2000; 93: 282-288
• 5th Mc. Neill RG, Knight RC "Characteristics of an improved magnetic-implant guidance system" Biomechanical Engineering 1995; Vol. 42
• 6. Creighton IV "Magnetic navigation system and magnet system therefor" U.S. Patent No. 7,305,263 (2007)
• 7th knight et. al. "Control method for magnetic stereotaxis system" U.S. Patent No. 5,654,864 (1997)
• 8. Gillie's GT "Catheter navigation within MR imaging device" US Pat. No. 6,834,201 (2004)
• 9. Kucharczyk J "Combined magnetic resonance imaging and magnetic stereotaxy surgical apparatus and processes" US Pat. No. 6,298,259 (2001)
• 10th Zhung K, Krafft AJ "Real-time MR navigation and localization of an intravascular catheter with ferromagnetic components "Magn Reson Mater Phy 2010; 23: 153-163
• 11. Shachar Y "Apparatus for Shaped Magnetic Field Control for Catheter, Guidance, Control and Imaging" EP 2080488 A2 (2009).

VIII. Illustrations

(P. 18) for an overview of the navigation loop. The executives are red, the detecting parts blue, the controlling parts black.

(P. 19) for the construction of the "coordinate system of navigation" and its "virtual horizontal displacement".

. and (P. 20) for the construction of the data basis.

(P.21) shows the horizontal displacement of the patient.

(P. 22) represents the electromagnet and its "internal mechanics".

(P. 23) shows the range of motion of the "inner mechanics".

(P. 24) shows the range of motion of the "outer mechanics".

(P. 25) shows the holder in side view and top view.

(P.26) shows the microcatheter in cross section, side and front view.

(Page 27) illustrates the opposite force at the catheter tip.

(P. 28) represents integrated electromagnetic detection.

(P. 29) shows the side view of the navigation system

(P. 30) shows the front view and top view of the navigation system.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5125888 [0093]
• US 7305263 [0093]
• US 5654864 [0093]
• US 6834201 [0093]
• US 6298259 [0093]
• EP 2080488 A2 [0093]

Cited non-patent literature

• Knight et. al. [0015]
• Shachar et. al. [0017]
• Jenkins A, Parker H "Electromagnetic support arrangement with threedimensional control" J Appl Phys 1959; 30: 238-239 [0093]
• Montgomery DB et. al. "A new magnet system for intravascular navigation" Med Biol Engl 1968; 6: 143-147 [0093]
• Grady MS, Howard MA, Dacey RG et. al. "Experimental study of the magnetic stereotaxis system for catheter manipulation within the brain" J Neurosurg 2000; 93: 282-288 [0093]
• Mc. Neill RG, Knight RC "Characteristics of an improved magnetic-implant guidance system" Biomechanical Engineering 1995; Vol. 42 [0093]
• Zhung K, Krafft AJ "Real-time MR navigation and localization of an intravascular catheter with ferromagnetic components" Magn Reson Mater Phy 2010; 23: 153-163 [0093]

Claims (5)

Device for controlling the movements of a catheter-like tool within a blood vessel by aligning a magnetic field acting from outside the body, characterized in that via a single magnetic gradient between the poles of a magnetized catheter tip and a single electromagnet movable in all spatial directions by a motorized mechanism, a traction is exerted on the catheter tip which simultaneously effects the indentation and the spatial orientation of the catheter in accordance with the course of the vessel, a synchronizing control based on a data structure constructed from a computerized or MRI 3-D reconstruction of the vessel profile, and depending on the current position of the intraluminal catheter tip, continuously determined by electromagnetic detection, the spatial orientation of the electromagnet and the motorized guidance de s catheter outside the body, which exerts an intermittent mechanical retention of the catheter controls. Device for carrying out the method according to claim 1, characterized in that the tip of a microcatheter has in its front portion a cylindrical, permanent magnet whose polar axis lies in the longitudinal axis of the catheter and in its rear portion has the detection-determined device, and in that the catheter tube has longitudinal perforations immediately behind the catheter tip for exiting the therapeutically or diagnostically active substances and for improving its flexibility. Apparatus for carrying out the method according to claim 1, characterized in that a motorized mechanism for guiding the catheter portion is provided outside the body, which opposes the continuous acting on the catheter tip tensile force of the magnet, a mechanical retention of the catheter by an arrangement of transverse to the catheter longitudinal axis positioned rollers causes compression of the catheter tube, the catheter tube by rotation of the rollers with variable speed and duration releases to its insertion through the magnetic field, characterized in continuous action of the tensile force on the catheter tip allows a segmented to almost flowing indentation of the catheter, by the opposing guide The catheter tube retracts the catheter in a controlled manner and, after completion of the procedure, extracts it again from the vessel and carries out a continuous length determination of the intake segments, the results of which are continuous to the control panel for further control of the feeder. Device for carrying out the method according to claim 1, characterized in that a motorized mechanism carries the electromagnet on the inside of a pivotable about its horizontal axis C-arm and longitudinally displaceable, in addition, the inclination of the electromagnet and its polar axis relative to the plane of the C Bends, allows the rotation of the C-arm around the plane, which it encloses, provides and receives from a system controller continuously synchronized, electronic instructions to the motors, for positioning the electromagnet with freedom of movement in all directions around the body portion around harbors the relevant vessel course. Device for carrying out the method according to claims 1 to 5, characterized in that before the start of the navigation, the construction of a data base for controlling the entire method of navigation by a computer-aided procedure is provided, the algorithm of such a record on a computer or MRI 3-d reconstruction of the vessel course can be accessed over the entire length of the relevant vessel segmentation depending on the respective degree of curvature and made for each segment a longitudinal vector guide through the center of the vessel lumen and related to a virtual coordinate system - with the Results of a design of the guide path of the magnet, the polar axis of which is always brought into line with the longitudinal axis of the flow direction of the vessel and the flow direction always points to the magnet, a sequence corresponding Position commands to the mechanics of the magnet, a variation sequence of the magnetic field strength to be applied and a control sequence for the mechanism for guiding the catheter outside the body.

Images