An aneurysm is an abnormal widening or ballooning of a portion of an artery, related to weakness in the wall of the artery or blood vessel. Some common locations for aneurysms include: the aorta; the brain (cerebral); the legs (popliteal artery aneurysm); the intestine (mesenteric artery); and the spleen. Aneurysms are either congenital (present before birth) or acquired. It is thought that defects in some component(s) of the artery wall may be responsible for aneurysms. Although in some instances, high blood pressure is thought to be a contributing factor. Atherosclerotic disease (cholesterol buildup in arteries) may also contribute to the formation of certain types of aneurysms. As a result of a defect in the artery wall, the aneurysm can rupture, which can result in profuse bleeding.
Early investigators from the 18th century began experimenting with procedures that involved inserting needles into an aneurysm to induce thrombosis. As a result of a lack of the imaging modalities available today, small or intracranial aneurysms could not be detected and only large lesions of the thoracic or abdominal aorta (as well as proximal extracranial carotid artery and limb aneurysms) could be identified. At the time, unpredictable results were observed and the practice of inducing thrombosis was abandoned.
Following the early failures of attempts to induce aneurysm thrombosis with percutaneous needle insertion led to a renewed interest in medical interventions. One of the earliest medical interventions was the use of potassium iodide for syphilitic aneurysms and aneurysm-related pain. The mechanism of action of potassium chloride was thought to be related to the reduction in the pulse and blood pressure, which in turn led to thrombosis. Other medications included ablation with vinegar, iron perchloride, alcohol, zinc chloride, gelatin, sodium chloride, or ergot salts. These remedies failed to find widespread application due to lack of sound scientific evidence and were soon abandoned because of inconsistent effects.
A clinical observation of a fibrin-coated bullet recovered from an autopsy case, resulted in the postulation that inserting a wire into an aneurysm would provide a much more ideal environment for clot formation, as opposed to the insertion of a simple needle. Upon autopsy it was observed that the coils of wire were filled with fibrinous material and was adherent. As this procedure found widespread application, some of the possible short- and long-term complications became evident, including an increased risk of hemorrhage from subtotal packing and distal embolization of wire or thrombus.
Over the years, advances in surgical procedures allowed for a combined approach by which an aneurysm was exposed surgically and a wire was inserted through a trocar. This approach continued in use as late as 1951. A combined approach of using a laparotomy with a trocar in a position to visualize targets was used. The aneurysm was packed through multiple sites with up to 965 feet of wire that had an abrasive surface. Failures were attributed to underpacking of the aneurysm. The early attempts and advancements made by these clinicians became the fundamentals on which current endovascular treatment of intracranial aneurysms is based. Although the initial attempts made by these pioneers yielded limited success because tools that could be used to navigate the complex intracranial vasculature and execute the treatment modality were lacking, technological advances and improvements facilitated a shift from the extravascular approach to the more physiological endovascular approach. Over time, the shift to catheterization became possible. Initially, a glass chamber was surgically connected to the patient's external carotid artery and then tubing was introduced into the internal carotid artery to access the intracranial vasculature.
Further improvements in the endovascular area led to the use of balloon-tipped microcatheters. This new direction followed the introduction of the Fogarty catheter. This device was developed for the extraction of arterial emboli and thrombi, and led to advancements in the feasibility of balloon catheters. Soon after the development of endovascular detachable balloon embolization therapy, a number of publications describing the outcome of this method in treating various cerebrovascular lesions, including intracranial aneurysms. Due to the growing experience with the detachable balloon embolization approach, a number of problems with this method also became evident.
During initial development, access to the aneurysm was challenging because a guidewire could not be used during catheterization. Second, once the lesion was finally reached, the balloon did not achieve full occlusion of the aneurysm because the device was round or oval and aneurysms take a variety of configurations. Additionally, balloons that do not fully conform to the irregular dimensions of the aneurysm sac are ineffective due in part to the pulsating arterial blood. Over time, the balloon occlusion devices may slowly deflate if they are not filled with nonsolidifying substances. Although parent artery occlusion can still be performed despite this disadvantage, balloon occlusion of the aneurysm sac has been largely abandoned in favor of more novel techniques.
The next endovascular approach designed for the selective occlusion of aneurysms was the coil. Modern metallic coils had been available for endovascular arterial occlusion and embolization since 1975, although the use of coils specifically for the treatment of intracranial aneurysms did not occur until the very late 1980s. Subsequently, the use of an endovascular coil embolization with “pushable” platinum coils was employed. One disadvantage to this method was the inability to retrieve the coil after placement. Further refinements of the coil continued, eventually leading to the development of the detachable coil. Coils have since been combined with electrolysis to achieve electrothrombosis (see, Guglielmi detachable coil, available from Boston Scientific). Although it is relatively straightforward to place the tip of a microcatheter into a cerebral berry aneurysm for detachable coil delivery, as endovascular treatment of that aneurysm progresses, it is common to find the tip of the currently used catheter being pushed out of the aneurysm, sometimes making safe or complete coil delivery into the aneurysm space impossible.
Like other aneurysms, cerebral aneurysms may occur as a congenital defect or may develop later in life. One type of cerebral aneurysm is the berry aneurysm, which can be over 2 cm in size. The berry aneurysm resembles a sack of blood attached to one side of the blood vessel and typically has a narrow neck. Other types of aneurysms involve widening or dilation of the entire circumference of a blood vessel in an area. Still other types appear as a ballooning out of a part of a blood vessel. It is estimated that 5% of the population has some type of aneurysm in the brain, with up to 10% of those affected having more than one aneurysm. The vessel wall of an aneurysm can be as thin as 15-100 microns. Cerebral aneurysms can rupture and cause bleeding or hemorrhaging in the area between the brain and the surrounding membrane (the arachnoid); or can extend into the subarachnoid space. It is generally thought that, most aneurysms under ¼ inch in diameter do not rupture. However, with currently available imaging techniques it is now possible to characterize the walls of the aneurysm and possibly predict their behavior, instead of relying on generalities. However, aneurysms that do rupture can have serious consequences including stroke and death. Approximately 20,000 people in the United States suffer a subarachnoid hemorrhage each year. An estimated 1 to 2 percent (three to six million) of Americans have cerebral aneurysms. Although they can occur at any age, they are slightly more common in adults than children and are slightly more common in women than men.
The first catheter cerebral angiograms were performed with straight, uncurved catheters. Uncurved catheters were time consuming for surgeons to use. Catheter cerebral angiography as a technique did not gain clinical acceptance until angiographers learned to place curves at the tip of the catheter in a single plane, which resulted in faster, safer and more selective studies. The next iteration was the invention and refinement of microcatheters (small catheters introduced through larger guiding catheters). These smaller catheters allowed even more selective angiography and hastened the evolution of interventional techniques.
Other devices and methods for treating aneurysms include: U.S. Pat. Nos. 5,980,514 to Kupiecki et al. for Aneurysm Closure Device Assembly; 6,096,034 to Kupiecki et al. for Aneurysm Closure Device Assembly; 6,183,495 to Lenker et al. for Wire Frame Partial Flow Obstruction Device for Aneurysm Treatment; 6,551,303 to Van Tassel et al. for Barrier Device for Ostium of Left Atrial Appendage; 6,569,190 to Whalen II et al. for Methods for Treating Aneurysms; 6,663,607 to Slaikey et al. for Bioactive Aneurysm Closure Device Assembly and Kit; 5,782,905 to Richter for Endovascular Device for Protection of Aneurysm; 5,951,599 to McCrory for Occlusion System for Endovascular Treatment of An Aneurysm; 6,063,111 to Hieshima et al. for Stent Aneurysm Treatment System and Method; 6,093,199 to Brown et al. for Intra-Luminal Device for Treatment of Body Cavities and Lumens and Method of Use; 6,168,622 to Mazzocchi for Method and Apparatus for Occluding Aneurysms; 6,626,928 to Raymond et al. for Occlusion Device for Treating Aneurysm and Use Therefore; 6,746,468 to Sepetka et al. for Devices and Methods for Treating Vascular Malformations; 6,802,851 to Jones et al. for Stent Aneurysm Embolization Method Using Collapsible Member and Embolic Coils; 6,855,153 to Saadat for Embolic Balloon; 6,860,899 to Rivelli Jr. for Method for Treating Neurovascular Aneurysms; 6,036,720 to Abrams et al. for Sheet Metal Aneurysm Neck Bridge; 6,139,654 to Teoh for Minimally Occlusive Flow Disruptor Stent for Bridging Aneurysm Necks; 5,935,148 to Villar et al. for Detachable, Varying Flexibility, Aneurysm Neck Bridge; 6,379,329 to Naglreiter et al. for Detachable Balloon Embolization Device and Method; 4,638,803 to Rand for Medical Apparatus for Inducing Scar Tissue Formation in a Body; 5,476,472 to Dormandy Jr. et al. for Embolization Device and Apparatus Including an Introducer Cartridge and A Delivery Catheter and Method for Delivering the Embolization Device; 5,746,734 to Dormandy Jr. et al. for Introducer Cartridge for Delivering an Embolization Device; 5,571,171 to Barone et al. for Method for Repairing An Artery in a Body; and US Patent Publications 2003/0018294 to Cox for Aneurysm Treatment Device and Method of Use; 2004/0044391 to Porter for Device for Closure of a Vascular Defect and Method of Treating the Same; 2004/0059407 to Escamilla et al. for Expandable Stent and Delivery System; 2004/0078071 to Escamilla et al. for Expandable Stent with Radiopaque Markers and Stent Delivery System; 2004/0111112 to Hoffman for Method and Apparatus for Retaining Embolic Material; 2004/0193206 to Gerberding et al. for Methods and Devices for the Treatment of Aneurysms; 2004/0193246 to Ferrera for Method and Apparatus for Treating Aneurysms and Other Vascular Defects; 2005/0033409 to Burke et al. for Aneurysm Treatment Device and Method of Use; 2002/0143349 to Gifford III et al. for Devices and Methods for Treating Vascular Malformations; 2002/0133190 to Horton et al. for InSitu Formable and Self-Forming Intravascular Flow Modifier (IFM), Catheter and IFM Assembly, and Method for Deployment of Same; 2002/0198592 to Wallace et al. for Intracranial Stent and Method of Use; 2003/0100945 to Yodfat et al. for Implantable Intraluminal Device and Method of Using Same in Treating Aneurysm; 2003/0109917 to Rudin for Stent Vascular Intervention Device and Method; 2003/0139802 to Wulfman et al. for Medical Device; 2003/0204244 to tiger for Aneurysm Exclusion Stent; 2005/0107823 to Leone et al. for Anchored Stent and Occlusive Device for Treatment of Aneurysms; 2005/0119684 to Guterman et al. for Aneurysm Buttress Arrangement; 2005/0133046 to Becker et al. for Compositions and Methods for Improved Occlusion of Vascular Defects; European Patent Application EP 1616585 A1 to Tijsma for Device for the Treatment of Aneurysms.
The invention discloses devices and methods for treating aneurysms in mammals. More particularly, the invention discloses a catheter having a distal end and a proximal end and further comprising a first configuration, e.g., a configuration caused by a wire straightening the catheter into a less complex shape so it can be navigated toward or near an aneurysm, and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a vasculature conformable shape. The devices and methods allow a greater number of detachable coils or other embolic material to be delivered into an aneurysm by a microcatheter with less chance of displacement of the distal tip of the microcatheter from the aneurysm.
An aspect of the invention is directed to a system for accessing a cerebral aneurysm. The system comprises: a catheter having a distal end and a proximal end and further comprising a first configuration and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a vasculature conformable shape; and a guidewire insertable through and removeable from a central lumen of the catheter. The system can be configured to have a second configuration that is determined based on a vasculature image from a patient. The second configuration can be determined based on an average vasculature image from a plurality of patients, such as would be used to create a library of devices. In some instances, the second configuration is determined based on an average vasculature image from a plurality of patients. Furthermore, the second configuration can be achieved through computer modeling of one or more vasculature images. The system can further comprising an aneurysm occlusion device for delivery by the catheter to the cerebral aneurysm. The catheter can have a complex curvature, e.g., a curvature that has multiple planes or three or more curves in a single plane. Additionally, the catheter can be patient-specific. Typically, the second configuration is multi-planar, such that the length between any two curves may or may not occur in the same plane as an adjacent length between an adjacent pair of curves. The catheter shape typically is determined from a plurality of images of a patient's vasculature.
Another aspect is directed to a system for accessing a cerebral aneurysm comprising: a catheter having a distal end and a proximal end and further comprising a first configuration and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a shape in more than one plane; and a guidewire insertable through and removeable from a central lumen of the catheter. The system can be configured to have a second configuration that is determined based on a vasculature image from a patient. The second configuration can be determined based on an average vasculature image from a plurality of patients, such as would be used to create a library of devices. In some instances, the second configuration is determined based on an average vasculature image from a plurality of patients. Furthermore, the second configuration can be achieved through computer modeling of one or more vasculature images. The system can further comprising an aneurysm occlusion device for delivery by the catheter to the cerebral aneurysm. The catheter can have a complex curvature. Additionally, the catheter can be patient-specific. Typically, the second configuration is multi-planar, such that the length between any two curves may or may not occur in the same plane as an adjacent length between an adjacent pair of curves. The catheter shape typically is determined from a plurality of images of a patient's vasculature.
Kits are also provided for to facilitate treating a blood vessel aneurysm. The kits comprise: an aneurysm treatment device adapted to be delivered to a blood vessel aneurysm; and a catheter having a distal end and a proximal end and further comprising a first configuration and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a shape in more than one plane. Additional components of the kit can include one or more of stents, occlusive devices or materials, a storage wire for retaining a storage shape, and sterile packaging.
Another kit provides for treating a blood vessel aneurysm and comprises: an aneurysm treatment device adapted to be delivered to a blood vessel aneurysm; and a catheter having a distal end and a proximal end and further comprising a first configuration and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a vasculature conformable shape. Additional components of the kit can include one or more of stents, occlusive devices or materials, a storage wire for retaining a storage shape, and sterile packaging.
Another aspect is directed to a catheter comprising: a lumen extending therethrough, a distal end and a proximal end wherein the distal end is adapted and configured to be positioned within a lumen of an aneurysm and to deliver aneurysm occlusion devices therein, wherein the catheter further comprises a first configuration and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a shape in more than one plane.
Methods are also included. One method includes the method of treating an aneurysm comprising: advancing a catheter having a distal end and a proximal end and further comprising a first configuration and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a vasculature conformable shape, in its first configuration to a target location; positioning a distal tip of the catheter within the lumen of an aneurysm; removing a guidewire from within the lumen of the catheter; wherein the catheter assumes the vasculature conformable shape after removal of the guidewire. One or more occluding devices can be delivered to the aneurysm. During the process of delivering the occluding devices, the catheter remains securely positioned within the vasculature such that the distal tip is not displaced from within the lumen of the aneurysm during delivery of the occluding devices or material. The method allows for a fill percentage greater than 25%. Furthermore, the method reduces the recurrence of aneurysms.
Another method of treating an aneurysm comprises: advancing a catheter having a distal end and a proximal end and further comprising a first configuration and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a shape in more than one plane, in its first configuration to a target location; positioning a distal tip of the catheter within the lumen of an aneurysm; removing a guidewire from within the lumen of the catheter; wherein the catheter assumes the vasculature conformable shape after removal of the guidewire. One or more occluding devices can be delivered to the aneurysm. During the process of delivering the occluding devices, the catheter remains securely positioned within the vasculature such that the distal tip is not displaced from within the lumen of the aneurysm during delivery of the occluding devices or material. The method allows for a fill percentage greater than 25%. Furthermore, the method reduces the recurrence of aneurysms.
Additionally, a method of making a catheter is provided for. The method of making the catheter comprises: obtaining an image of a vasculature of a patient; identifying the three-dimensional geometry of the vasculature; manufacturing a catheter having a distal end and a proximal end and further comprising a first configuration and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a vasculature conformable shape. The method can use a plurality of vasculature images from a plurality of patients to derive a variety of shapes to create a library of devices. Alternatively, the method can produce a patient specific catheter.
In another aspect, a method of making a catheter is provided for that comprises: obtaining an image of a vasculature of a patient; identifying the three-dimensional geometry of the vasculature; manufacturing a catheter having a distal end and a proximal end and further comprising a first configuration and a second configuration wherein the first configuration is adapted and configured to be delivered through a vasculature and the second configuration is adapted and configured to assume a shape in more than one plane. The method can be achieved using a plurality of vasculature images from a plurality of patients to achieve a library of shapes based on average sizes, curves and shapes. Alternatively, a patient specific catheter can be produced.
A mandrel is also provided for that comprises: a distal end and a proximal end and a configuration configured to impart a vasculature conformable shape to catheter.
All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
The catheter can be braided or non-braided. Heating and cooling of the polymer enables the catheter to retain its shape after processing even if the catheter is not formed from a shape memory material. Typically the shape of the catheter is controlled by the shape of the mandrel, as discussed further below.
As with other catheter designs currently available, this catheter assembly has the ability to: achieve access through the vasculature to the brain (or other vascular site) often, but not necessarily, using a guide wire; can optionally include the inflation of an inflatable member or balloon to close or to restrict an artery or the mouth of an aneurysm prior to or during placement of a vaso-occlusive device, thereby requiring a fluid pathway for inflation of the inflatable member; flexion of a flexible neck in the region of the distal end of the catheter by a wire extending proximally through the catheter; and introduction of a vaso-occlusive device or material for eventual placement in the vasculature, thereby requiring a pathway or storage region for the vaso-occlusive device. These functions may be achieved by features found at the proximal and distal regions of the catheter.
The proximal catheter end 90 may be provided with a fitting 102 (e.g., a “LuerLok”) through which fluid may be supplied to the catheter's inflation lumen through a side port 104. The proximal end 90 of the catheter 100 is provided with a second port 106 and a fitting 108 through which a push/pull wire may be used to manipulate the flexible neck region 120 in the distal catheter tip 130. The proximal end fitting 102 includes an axially extending port 114 which communicates with the catheter's delivery/guide wire lumen. The optional guide wire 140 may have any suitable construction or configuration for guiding the flexible catheter shaft 110 to its target location within the body. The proximal end 90 of the guidewire 140 may be equipped with a handle or control mechanism 142 adapted to apply torque to the guidewire 140 during catheter operation. The guidewire 140 may have a variable stiffness or stepped diameter along its length to aid in steerability of the guidewire. Typically increased steerability is achieved by, for example, a configuration that uses a larger-diameter, stiffer proximal region and one or more smaller-diameter, more flexible distal regions, as will be appreciated by those skilled in the art. Other configurations can be employed without departing from the scope of the invention.
The distal portion 92 of the catheter 100 may include an articulating neck region 120, and an opening or aperture 116 for delivery of the vaso-occlusive device or material. This opening 116 may also be used for delivery of drugs and the vaso-occlusive device to the selected vascular site.
The inflatable section can be formed from a thin sleeve of polymeric material and attached at its opposite sleeve ends to a relatively more rigid tube section. Flexion of the articulating neck region 120 is achieved through remote manipulation of the push/pull wire 122 by the user.
Some of the various configurations of the catheter's lumina (inflation, push/pull, and delivery) are displayed in
A storage wire may also be provided which is maintained in a lumen of the catheter during delivery and storage in order to maintain the catheter in substantially a single plane, similar to the depiction shown in
The tube constructions, hinge region construction, and other tubing forming the various lumina discussed herein may be created through extrusion, sequential production (in which the parts are manufactured separately and later assembled together), or some other method.
A. Shaping
Shaping can be achieved by a variety of mechanism apparent to those skilled in the art. In one method, three dimensional rotational catheter angiography are used to develop a three-dimensional model of the vasculature. The three dimensional model is then used as a basis to create a three-dimensional design for the catheter wherein the catheter has two or more curves in two or more planes at its distal end. The two or more curves can correspond to vascular curves adjacent to the aneurysm, or can be major curves adjacent the aneurysm (e.g., not necessarily curves appearing in sequence). Typically a suitable imaging technique for determining the shape of the device enables the user to make a three-dimensional volumetric evaluation of the blood vessels.
The catheter itself can then be shaped by, for example, inserting a mandrel into the catheter tip and then shaping the catheter to a desired curvature. The mandrel itself can also be formed from suitable shape memory materials. The curves of the mandrel can then be exaggerated to compensate for any loss of shape that might occur, for example, when the device is deployed. Once the desired curvature is achieved, the catheter is heated using steam or some other suitable heating mechanism. The process of heating results in the catheter retaining that shape. Thereafter the mandrel is removed and the shaped catheter is ready for deployment or packaging.
Alternatively, one or more images may be taken of a patient on whom the aneurysm procedure is to be performed. In obtaining an image of the vasculature in a mammal, a number of internal imaging techniques known in the art are useful for electronically generating a vascular image. These include magnetic resonance imaging (MRI), computed tomography scanning (CT, also known as computerized axial tomography or CAT, as well as CT angiogram or CTA), magnetic resonance angiography (MRA), 3-dimensional rotational angiogram (3DRA), angiogram, and ultrasound imaging techniques. Other techniques may be apparent to one of skill in the art. As will be appreciated by those skilled in the art, different imaging techniques may require different levels of manipulation to achieve the methods descried here. A variety of imaging techniques can be used to achieve the shaping, including:
CT/CTA
A computed tomography (CT) or computer axial tomography (CAT) scan uses X-rays to make detailed pictures of structures inside of the body. The CT uses multiple images, each in a single plane, or slice, of to obtain a tomogram. Following injection of contrast intravenously the vasculature will they come denser. The images can then be compiled to generate a three-dimensional representation of vasculature architecture for a patient. Alternatively this can be performed in two steps one prior to injection of the contrast and one after and subtracted from each other. The Computer is then able to make three-dimensional images of the blood vessels which can be rotated in any direction.
MRA
MRA enables imaging of blood vessels. Typically pictures of arteries are generated in order to evaluate the arteries for stenosis (abnormal narrowing) or aneurysms (vessel wall dilations). MRA is most often used in evaluating the arteries of the neck and brain. A variety of techniques can be used to generate pictures. For example, paramagnetic contrast agents such as gadolinium can be used. Additionally, flow related enhancement techniques can be used where most of a signal on an image is due to blood which has recently moved into the plane.
Angiogram/3-D Rotational Angiogram
The angiogram is an x-ray picture taken to visualize the inner opening of a blood filled structure, such as an artery or vein. Angiograms are achieved with the use of a catheter. The images may be taken as still images, e.g. x-ray, or displayed on fluoroscopic film. The images can also be obtained volumetrically prior and after contrast injection once subtracted from each other and or alternatively only after contrast injection and manipulated based on the density. With this data to three-dimensional images of the blood vessels are made and can be rotated in any directions
MRI
MRI can be used to understand the direction of the blood vessels. As techniques change, it may also become suitable for making a volumetric evaluation of blood vessels. One advantage of MRI is good contrast between various types of tissue, including cartilage, bone, joint fluid, ligaments, muscle, blood and moving material such as blood and blood vessels which facilitates a delineation and segmentation of data sets. Another advantage is the coverage of the entire region of interest in a single scan within acceptable acquisition times. See, MRI Basic Principles and Applications, Second Edition, Mark A. Brown and Richard C. Semelka, Wiley-Liss, Inc. (1999).
MRI employs pulse sequences that allow for better contrast of different parts of the area being imaged. Different pulse sequences are better fitted for visualization of different anatomic areas, for example, hyaline cartilage or joint fluid. More than one pulse sequence can be employed at the same time. A brief discussion of different types of pulse sequences is provided below.
High Resolution 3D MRI Pulse Sequences
Routine MRI pulse sequences available for imaging tissue include conventional T1 and T2-weighted spin-echo imaging, gradient recalled echo (GRE) imaging, magnetization transfer contrast (MTC) imaging, fast spin-echo (FSE) imaging, contrast enhanced imaging, rapid acquisition relaxation enhancement, (RARE) imaging, gradient echo acquisition in the steady state, (GRASS), and driven equilibrium Fourier transform (DEFT) imaging. As these imaging techniques are well known to one of skill in the art, e.g. someone having an advanced degree in imaging technology, each is discussed only generally hereinafter. While each technique is useful for obtaining a cartilage degeneration pattern, some are better than others.
Conventional T1 and T2-Weighted Spin-Echo Imaging
Conventional T1 and T2-weighted MRI depicts vasculature, and can demonstrate defects and gross morphologic changes.
Gradient-Recalled Echo Imaging
Gradient-recalled echo imaging has 3D capability and ability to provide high resolution images with relatively short scan times.
Fast Spin-Echo Imaging
Fast spin-echo imaging may be another useful pulse sequence to evaluate vasculature. Incidental magnetization transfer contrast contributes to the signal characteristics of vasculature on fast spin-echo images and can enhance the contrast between the vasculature and surrounding tissue.
B. Sizing
The microcatheter can be formed or selected so that it will achieve a near anatomic fit with all or part of the vasculature through which it travels to correspond to the twists and turns of the surrounding or adjacent vessel walls. The shape of the catheter can be based on the analysis of an electronic image (e.g. MRI, CT, angiography, digital tomosynthesis, optical coherence tomography or the like) for a particular patient and therefore be patient specific, or can be based on an analysis of a plurality of patients, or a plurality of patients within a specific criteria, to achieve an average three-dimensional shape that is directed to the identified vasculature architecture. A near anatomic shape tracking can be achieved using a method that provides a virtual reconstruction of the shape of the vasculature in one or more electronic images.
In one embodiment of the invention, a vascular architecture can be reconstructed by interpolating the images. Alternatively, the vasculature can be reconstructed using morphological image processing technique. In a first step, the vascular image can be extracted from the electronic image using manual, semi-automated and/or automated segmentation techniques (e.g., manual tracing, region growing, live wire, model-based segmentation), resulting in a binary image. Vascular sizing can be performed in 2-D or 3-D with an appropriately selected structuring element.
As described above, the catheter can be formed or selected from a library or database of systems of various sizes and curvatures so that it will achieve a near anatomic fit or match with the surrounding or adjacent vasculature. These systems can be pre-made or made to order for an individual patient. In order to control the fit or match of the catheter system with the surrounding or adjacent vasculature, a software program can be used that projects the vascular system over the vascular system where it will be used. Suitable software is commercially available and/or readily modified or designed by a skilled programmer.
In yet another embodiment, the catheter system can be projected over the vascular system where the catheter will use used using one or more 3-D images. The vasculature and other anatomic structures that might be of interest are extracted from a 3-D electronic image such as an MRA, 3-D rotational angiogram or a CTA using manual, semi-automated and/or automated segmentation techniques. A 3-D representation of the vasculature and other anatomic structures as well as the catheter system is generated, for example using an angiogram machine, such as the Philips Allura Xper FD20/10 available from Philips Medical Systems. For a description of various parametric surface representations see, for example Foley, J. D. et al., Computer Graphics: Principles and Practice in C; Addison-Wesley, 2.sup.nd edition, 1995).
The 3-D representations of the vasculature and other anatomic structures and the catheter system can be merged into a common coordinate system. The catheter system can then be placed at the desired treatment site. The representations of the anatomic structures and the catheter system are rendered into a 3-D image, for example application programming interfaces (APIs) OpenGL®. (standard library of advanced 3-D graphics functions developed by SGI, Inc.; available as part of the drivers for PC-based video cards, for example from www.nvidia.com for NVIDIA video cards or www.3dlabs.com for 3Dlabs products, or as part of the system software for Unix workstations) or DirectX® (multimedia API for Microsoft Windows® based PC systems; available from www.microsoft.com). The 3-D image can be rendered showing the vasculature or other anatomic objects, and the catheter system from varying angles, e.g. by rotating or moving them interactively or non-interactively, in real-time or non-real-time.
The software can be designed so that the catheter system with the best fit relative to the vasculature is automatically selected, for example using some of the techniques described above. Alternatively, the operator can select a catheter system, and project it or drag it onto the target vascular site using suitable computer tools and techniques. The operator can move and rotate the catheter systems in three dimensions relative to the target vascular site and can perform a visual inspection of the fit between the catheter system and the target vascular site. The visual inspection can be computer assisted. The procedure can be repeated until a satisfactory fit has been achieved. The procedure can be performed manually by the operator; or it can be computer-assisted in whole or part. For example, the software can select a first trial catheter that the operator can test. The operator can evaluate the fit. The software can be designed and used to highlight areas of poor alignment between the catheter and the surrounding target vasculature. Based on this information, the software or the operator can then select another catheter and test its alignment. One of skill in the art will readily be able to select, modify and/or create suitable computer programs for the purposes described herein.
In another embodiment, the target vascular site can be visualized using one or more cross-sectional 2-D images. Typically, a series of 2-D cross-sectional images will be used. The 2-D images can be generated with imaging tests such as angiogram, CTA, MRA, CT, MRI, digital tomosynthesis, ultrasound, or optical coherence tomography using methods and tools known to those of skill in the art. The catheter system can then be superimposed onto one or more of these 2-D images. The 2-D cross-sectional images can be reconstructed in other planes, e.g. from sagittal to coronal, etc. Isotropic data sets (e.g., data sets where the slice thickness is the same or nearly the same as the in-plane resolution) or near isotropic data sets can also be used. Multiple planes can be displayed simultaneously, for example using a split screen display. The operator can also scroll through the 2-D images in any desired orientation in real time or near real time; the operator can rotate the imaged tissue volume while doing this. The catheter system can be displayed in cross-section utilizing different display planes, e.g. sagittal, coronal or axial, typically matching those of the 2-D images demonstrating the cartilage, subchondral bone, menisci or other tissue. Alternatively, a three-dimensional display can be used for the catheter system. The 2-D electronic image and the 2-D or 3-D representation of the catheter system can be merged into a common coordinate system. The catheter system can then be placed at the desired target vascular site. The series of 2-D cross-sections of the anatomic structures, the target vascular site and the catheter system can be displayed interactively (e.g. the operator can scroll through a series of slices) or non-interactively (e.g. as an animation that moves through the series of slices), in real-time or non-real-time.
Prior to performing the procedure on a patient, the surgeon can preoperatively analyze the vasculature of the patient, for example, using CTA and MRA images. Using standard surgical techniques, the patient is anesthetized and an incision is made in order to provide access to the vasculature. Once an appropriate sized incision has been made (typically at the common femoral artery), a guiding catheter is advanced into, for example, the cervical carotid artery in the usual fashion (with or without a wire or even exchanged over a wire after a diagnostic catheter first made access into the carotid artery). A microcatheter over a micro wire is then advanced through the guiding catheter. Alternatively the guiding catheter can be advanced further if it is flexible enough and similar techniques described above can be used to shape the guiding catheter is well to provide more stability. The microcatheter is advanced over the wire to get it close to the aneurysm and also provide stiffness. The wire is then pulled back and they've microcatheter is advanced into the aneurysm with or without wire assist.
Using information on curvature of the vasculature, a physical model of the surfaces of the vasculature can be created. This physical model can be representative of a limited section of the vasculature encompassing or adjacent to the aneurysm, or can be a model of substantially the entire vasculature. This model can also take into consideration the presence or absence of brain, muscle, bone or other tissue. The location of the aneurysm can be included in the model, for example using a 3D coordinate system or a 3D Euclidian distance. Typically, the model includes the region encompassing all or part of the aneurysm along with a section of vasculature having two or more bends prior to the aneurysm. In this way, an optical curvature of the catheter can be determined.
The various curves shown in the embodiments of
As illustrated in
The devices herein can be made as patient-specific devices based on an analysis of a specific patient's vasculature, or can be selected from a library of devices. Kits include a pre-formed mandrel, a catheter, such as a catheter having a pre-determined shape which includes curves in more than one plane. A storage wire is provided to keep the catheter in a flat plane during shipment and storage. The catheters are typically stored under sterile conditions, as would be appreciated by those skilled in the art. Removal of the storage wire allows the catheter to regain its three dimensional, multi-planar shape. One or more guidewires can be provided to facilitate steering the catheter to a target location. Furthermore, a plurality of vaso-occlusive devices can be provided for delivery into an aneurysm by the catheter. The catheters of the kits can be pre-shaped based on patient specific data and then shipped to a recipient. Alternatively, the catheters of the kits are selected from a library of devices.
Fifteen consecutive patients with known cerebral vascular pathology were examined by catheter rotational angiography. These patients then underwent treatment with endovascular coils. On the workstation, the arterial segments beginning at the aneurysm and extending proximally for the next three major curves were measured from greatest curvature to greatest curvature. The microcatheter forming wire was then bend in 3-dimensions to reflect those measurements. The resulting curve was then exaggerated to allow for the expected straightening when the microcatheter would be introduced into the bloodstream.
The forming ware was then placed in the microcatheter, and these curves were set in the tip of the microcatheter with a steam generator. The finished microcatheter had a plurality of complex curves in multiple planes.
The time needed to reconstruct arteries on current workstations takes only minutes. Measurements were achieved in less than one minute and on average in less than 5 minutes. All 15 patients had satisfactory endovascular treatment of their aneurysm. No catheter backed-out of the aneurysm and no patient suffered a complication. The time needed to perform an endovascular procedure using conventionally available microcatheters can range from about 2 to about 7 minutes. The amount of time required to perform these 15 procedures with the complex curves ranged from 1 to 4 minutes. The amount of time was reduced 40% or more, which, among other things, decreases the amount of radiation a patient is subjected to during a procedures.
Using a complex shape microcatheter not only can be easier to access an aneurysm but also will help better filling of the aneurysm. The catheter or hugs the greater curvatures of the artery therefore it is more stable in the aneurysm this allows that are packing density. For example if the back of the first curve of the aneurysm is not against the opposite wall of the artery from the aneurysm as the coils are pushed forward the catheter is pushed backward. A similar concept applies for remainder of the curvatures.
A group of patients with pre-determined characteristics would be chosen. The characteristics can be selected from genetic markers, sex, race, ethnicity, BMI, age, etc. Each patient is then examined by catheter rotational angiography to assess vascular anatomy. On the workstation, similar arterial segments for the patients are compared for three or more major curves. The results are analyzed and compared to identify similar structures and to put together a library of catheters having three or more curves in two or more planes. The microcatheter forming wire having shape memory properties is then bend in 3-dimensions to reflect those measurements but would allow for storage in two dimensions. The resulting curve is then exaggerated to allow for the expected straightening when the microcatheter is introduced into the bloodstream.
The forming ware was then placed in the microcatheter, and these curves would be set in the tip of the microcatheter with a steam generator. The finished microcatheter would have a plurality of complex curves in multiple planes.
A physician could then analyze the vasculature of a patient having an aneurysm and select an aneurysm access device from a library of devices.
While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.
This application also claims the benefit of U.S. Provisional Application No. 60/864,013, filed Nov. 2, 2006 by R. Sean Pakbaz et al. entitled Complex Curve Microcatheters for Berry Aneurysm Endovascular Therapy, which is incorporated herein by reference in its entirety.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US07/83505 | 11/2/2007 | WO | 00 | 12/4/2009 |
Number | Date | Country | |
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60864013 | Nov 2006 | US |