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United States Patent [w]
US005846204A [ii] Patent Number:  Date of Patent:
 ROTATABLE ULTRASOUND IMAGING CATHETER
 Inventor: Rodney J. Solomon, Andover, Mass.
 Assignee: Hewlett-Packard Company, Palo Alto, Calif.
 Appl. No.: 886,880
 Filed: Jul. 2, 1997
 Int. CI.6 A61B 8/12
 U.S. CI 600/463; 600/585
 Field of Search 600/445-446,
 References Cited
U.S. PATENT DOCUMENTS
5,024,234 6/1991 Leary et al 128/663.01
5,085,221 2/1992 Ingebrigtsen et al 600/446
5,176,142 1/1993 Mason 128/662.06
5,201,316 4/1993 Pomeranz et al 128/662.06
5,203,338 4/1993 Jang 128/662.06
5,345,940 9/1994 Seward et al 128/662.06
5,348,017 9/1994 Thornton et al 128/662.06
5,368,035 11/1994 Hamm et al 128/662.06
5,377,682 1/1995 Uevo et al 600/446
5,413,107 5/1995 Oakley et al 128/662.06
5,465,726 11/1995 Dickinson et al 128/663.01
5,522,394 6/1996 Zurbrugg 128/662.06
5,570,693 11/1996 Jang et al 600/463
5,592,942 1/1997 Webler et al 600/446
FOREIGN PATENT DOCUMENTS WO 89/04142 5/1989 WIPO .
Primary Examiner—Francis J. Jaworski  ABSTRACT
An ultrasound catheter including a flexible, torsionally-rigid elongate transducer cable having proximal and distal ends, with a transducer housing fixably connected proximate to the distal end. An ultrasound transducer, having a substantially planar surface and a scan plane substantially perpendicular to the planar surface, is fixably connected to a first side of the transducer housing to provide a predetermined two-dimensional cross-sectional image corresponding to an angular position of the ultrasound transducer. The transducer generates a series of successive two-dimensional crosssectional images. In one embodiment, the ultrasound transducer is a linear array transducer which produces a substantially rectangular scan plane. A guide wire sleeve which is fixably connected to a second side of the housing substantially opposing the first side, causes the transducer to follow a predetermined rotational path around the guide wire when a torque is applied to the proximal end of the transducer cable. The guide wire sleeve is preferably configured to insure that the planar surface of the ultrasound transducer is maintained in substantial parallel relationship with the guide wire positioned within the sleeve. An ultrasound imaging system comprising the ultrasound catheter also includes a positioning system coupled to the proximal end of the transducer cable. The positioning system applies a torque to the proximal end of the cable to rotate the array about an axis defined by the guide wire channel. A controller rotates the array between successive image scans and forms a threedimensional image using the plurality of two-dimensional cross-sectional images generated by the array.
17 Claims, 2 Drawing Sheets
U.S. Patent Dec. 8, 1998 Sheet 1 of 2 5,846,204
U.S. Patent Dec. 8, 1998 Sheet 2 of 2 5,846,204
ROTATABLE ULTRASOUND IMAGING
BACKGROUND OF THE INVENTION
1. Field of The Invention 5 The present invention relates generally to interventional
catheters and, more particularly, to catheters providing ultrasound imaging.
2. Related Art
The use of ultrasound for medical imaging is well-known. Since its introduction, advances in technology and clinical practice have made ultrasound a leading medical diagnostic imaging modality. Ultrasound provides high-resolution realtime imaging without the use of ionizing radiation which is 15 used in other imaging techniques. In addition, modern ultrasound equipment is relatively inexpensive and portable. This cost-effectiveness and portability has resulted in the widespread application of ultrasound imaging. For example, ultrasound is used in such clinical applications as cardiology, 2Q obstetrics and gynecology, general abdominal imaging and vascular imaging. In addition, ultrasound is commonly used in surgical and intravascular applications, as well as in guiding other interventional procedures.
A continuing objective of medical imaging techniques is 25 to convey clinical information effectively. While traditional ultrasound image displays are extremely valuable, there has been an increasing interest in new methods for visualization of ultrasound data. There has been particular interest in visualizing the spacial relationships between successively 30 acquired images, and the added clinical utility that such techniques offer. These include the increased information for diagnosis and treatment and for guiding other interventional procedures.
For example, therapeutic catheters are commonly used to 35 perform electrophysiological procedures to diagnose and treat cardiac anatomical or conduction system abnormalities. Ultrasound is often used to provide imaging information of the therapeutic catheter's position. Typically, fluoroscopy is initially used to generally position an ultrasound imaging 40 catheter and a separate therapeutic catheter in the left or right atrium or ventricle of the heart. Then, ultrasound imaging is used to assist in the control of a therapeutic device located near or at the end of the therapy catheter. However, conventional ultrasound catheters provide a narrow field of 45 view, making it difficult to locate the therapeutic device. In addition, it is difficult to perform the diagnostic and therapeutic procedures while keeping the therapeutic device in the narrow field of view provided by the ultrasound catheter since both catheters have to be continually maneuvered 50 throughout the performance of the procedure. The resulting unclear and inconsistent imaging makes it difficult to determine the position of the therapeutic device relative to the walls of the heart, resulting in uncertainty in the success of the procedure. 55
One conventional approach for determining the position of a therapeutic device in the ultrasound imaging window is described in U.S. Pat. No. 5,325,860 to Seward et al. Seward discloses a catheter having an ultrasound transducer and channel or port that runs axially along its length. A thera- 60 peutic device may be inserted through the treatment channel to deliver it to a position proximate to the distal end of the catheter for operation within the field of view provided by the transducer. A drawback to this approach is that it is difficult to maintain the cleanliness of the treatment channel. 65 In addition, for the treatment channel to be sufficiently large to receive therapeutic devices, it must consume a significant
portion of the catheter's internal volume. This requirement limits the space available for all other functional elements of the catheter, such as the ultrasound transducer. Thus, the size of the catheter must be increased to accommodate such other functional elements or conversely, the ultrasound transducer and other functional elements must be limited in size.
Another approach to aligning a therapeutic device within an ultrasound imaging window is described in U.S. Pat. No. 5,325,148 to Lesh et al. The Lesh device includes the use of a catheter with a tissue characterization assembly and an ablation assembly permanently fixed relative to each other in a single structure. A drawback to this approach is that the relative fixed positions of the ablative device and the ultrasound transducer are such that the therapeutic device is not in the field of view provided by the transducer. As a result, the transducer cannot be used to monitor the relative position of the therapeutic device and anatomical structure or tissue to receive the desired therapy. Therefore, this device is of little assistance during the performance of a diagnostic or therapeutic procedure.
In addition, a drawback to the above and other ultrasound catheters is that the therapeutic device is physically attached to the ultrasound catheter, limiting the relative movement of the catheters and restricting the location of the therapeutic device to the same general location that containing the ultrasound catheter. However, it may be necessary to view the therapeutic device from a location remote from the therapeutic catheter. For example, when performing intracardiac imaging and ablation therapy, it is often necessary to place the transducer in the right atrium/ventricle to view the ablation electrode in the left atrium/ventricle to reduce the risk of complications.
The inability of conventional ultrasound imaging techniques to continually provide information regarding the location of the therapeutic catheter has resulted in an attempt to generate 3-dimensional ultrasound images. One conventional approach to visualizing the spacial relationships between successively acquired images to obtain a 3-dimensional image has been to manually control of the transducer position. However, a manual positioning system has numerous limitations, proving to be an imprecise technique for positioning an ultrasound transmitting device. For example, with a manual system, the speed at which the array may be rotated is not readily controllable. In addition, an operator manually controlling the rotation of the array may induce stress on positioning system components as well as catheter components by abruptly changing the rotation speed and/or direction. Furthermore, a sufficiently abrupt change in rotational speed and/or direction could over-torque the aforementioned components leading to potentially serious damage to the catheter. In addition, with a manual positioning system the elasticity of the drive mechanism from the handle to the transducer may provide insufficient tactile feedback to the position control mechanism. As such, an operator may have difficulty correlating the extent of the manipulation of the position mechanism required for precise control of the transducer position.
What is needed, therefore, is a means for providing improved visualization of ultrasound data, including the spacial relationships between successively-acquired images. This will enable an administering sonographer to quickly and accurately obtain clinical information as well as to guide diagnostic and therapeutic procedures. Preferably, such a device should be capable of providing a three-dimensional field of view of the surrounding anatomical features to enable the clinician to perform a desired therapy with improved speed, accuracy and success.