News Column

Patent Application Titled "Rotational Ultrasound Imaging Catheter with Extended Catheter Body Telescope" Published Online

July 18, 2014

By a News Reporter-Staff News Editor at Health & Medicine Week -- According to news reporting originating from Washington, D.C., by NewsRx journalists, a patent application by the inventors Meyer, Douglas (Folsom, CA); Van Hoven, Dylan (Oceanside, CA), filed on December 20, 2013, was made available online on July 3, 2014 (see also Volcano Corporation).

The assignee for this patent application is Volcano Corporation.

Reporters obtained the following quote from the background information supplied by the inventors: "Intravascular ultrasound (IVUS) is an important interventional diagnostic procedure for imaging atherosclerosis and other vessel diseases and defects. The procedure involves the threading of an IVUS catheter over a guidewire into a blood vessel and the acquisition of images of the surrounding area using ultrasonic echoes. The three-dimensional images obtained via IVUS are often more informative than images derived from other imaging techniques, such as angiography, which provide only two dimensional images.

"Conventional IVUS catheters come in various designs, including include mechanical or rotational IVUS catheters. In a rotational IVUS catheter, a single transducer having a piezoelectric crystal is rapidly rotated while the transducer is intermittently excited with an electrical pulse. The excitation pulse causes the transducer to vibrate, sending out a series of transmit pulses. The transmit pulses are emitted at a frequency that allows time for receipt of echo signals. The sequence signals interspersed with receipt signals provides the ultrasound data required to reconstruct a complete cross-sectional image of a vessel.

"Conventional rotational IVUS catheters include a drive cable disposed within a catheter body. A transducer is attached to the distal end of the drive cable. A coaxial cable or transmission line is disposed within the drive cable and also couples to the transducer. The coaxial cable delivers the intermittent electrical transmit pulses to the transducer, and delivers the received electrical radio signals from the transducer to the receiver amplifier. The IVUS catheter is removably coupled to an interface module, which controls the rotation of the drive cable and the coaxial cable within the catheter body and contains the transmitter and receiver circuitry for the transducer. Imaging catheters may also include a telescoping element, which is used to advance the transducer towards the distal end of the device.

"Preventing the drive cable from buckling is important during operation of the IVUS catheter. When the drive cable folds over onto itself in the event of significant buckling, the electrical connections of the coaxial cable are severed and the imaging catheter is rendered inoperative. Even in less severe cases, buckling of the drive cable pulls the transducer inward, thereby scanning the incorrect region of the anatomy. This buckling of the drive cable often results from the small but still excessive amount of space between the drive cable and various components of the imaging device that surround the drive cable. Typically, a polyamide tube is used inside the telescope section of the catheter to constrain and support the drive cable, especially when the telescope is fully extended. This helps keep the drive cable from buckling when the telescope is moving forward from the fully extended position. The polyamide tube, however, adds unnecessary complexity (increased part number) to the device and also adds to assembly costs."

In addition to obtaining background information on this patent application, NewsRx editors also obtained the inventors' summary information for this patent application: "The present invention provides a telescoping intraluminal imaging device in which a sheath extends over the telescoping portion of the device in order to provide increased stabilization and accommodation of telescoping drive cables.

"Devices and methods of the invention reduce buckling of drive cables within an intraluminal device by extending a sheath or catheter portion of the imaging device through a telescopic region of the device. The invention provides support and contains the drive cable in the telescoping region. By extending a small-diameter catheter all the way through the telescoping element of an intraluminal device, the excessive space typically associated with drive cable buckling is eliminated.

"Devices of the present invention eliminate drive cable buckling without the need for additional components, such as polyimide tubing. As such, devices of the present invention reduce device complexity and are less expensive to build. Most importantly, however, the present devices achieve greater imaging accuracy than conventional telescopic imaging catheters due to the increased steadiness of the drive cable and its associated transducer.

"An intravascular device of the invention typically has an elongated body configured to fit within the lumen of a vessel, a rotatable shaft positioned inside the elongated body, and a telescoping element. As encompassed by the invention, a portion of the elongated body extends through the telescoping element and the elongated body is configured to contain the rotatable shaft inside the telescoping element. The catheter body extends through the telescope and contains the drive cable even when the telescope is fully extended.

"In preferred aspects of the invention, the elongated body is a catheter and a rotatable drive cable is positioned inside the catheter. The interior dimensions of the catheter are small enough to prevent buckling of the drive cable when the drive cable extends through the telescoping element. For imaging the inside of a vessel, the drive cable may include a working element positioned, in certain aspects, at the distal region of the drive cable, which facilitates imaging the vessel interior. In certain aspects of the invention, the working element is a transducer, such as an ultrasonic transducer for use in IVUS. In other aspects of the invention, the working element comprises an optical element for use in OCT.

"In certain conventional telescoping image catheters, the outer body of the catheter, distal of the telescope, contains the drive cable and keeps it from buckling. As contemplated by the present invention, however, the catheter body is also used to support the drive cable in the telescope. Accordingly, the need for a separate supporting structure, such as the polyamide tube is eliminated and the part number and complexity of the overall device is advantageously reduced.


"FIG. 1 is a sectional side view of a prior art intravascular catheter.

"FIG. 2 is another sectional side view of the prior art intravascular catheter of FIG. 1.

"FIG. 3 is a graphical depiction of a device when in a non-extended position in accordance with the invention.

"FIG. 4 is a graphical depiction of a device when in a extended position in accordance with the invention.

"FIG. 5 is a side view of a device in accordance with the invention.

"FIG. 6 is a detail of distal region of the device.

"FIG. 7 is a sectional side view of the exemplary device of FIG. 5.

"FIG. 8 is a detail of an anchor housing component of the exemplary device of FIG. 5.

"FIG. 9 is a detail of a catheter coupling component of the exemplar device of FIG. 5."

For more information, see this patent application: Meyer, Douglas; Van Hoven, Dylan. Rotational Ultrasound Imaging Catheter with Extended Catheter Body Telescope. Filed December 20, 2013 and posted July 3, 2014. Patent URL:

Keywords for this news article include: Angiology, Electronics, Intravascular, Volcano Corporation.

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Source: Health & Medicine Week

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