This patent application is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present invention relates to devices and methods for sizing and positioning of collapsible prosthetic heart valves.
"Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.
"Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two types of stents on which the valve structures are ordinarily mounted: a self-expanding stent or a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve must first be collapsed or crimped to reduce its circumferential size.
"When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and re-expanded to full operating size. For balloon-expandable valves, this generally involves releasing the entire valve, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically expands as the sheath covering the valve is withdrawn.
"Despite the various improvements that have been made to the collapsible prosthetic heart valve delivery process, conventional delivery devices, systems, and methods suffer from some shortcomings. For example, in conventional delivery devices for self-expanding valves, clinical success of the valve is dependent on accurate deployment, anchoring and acceptable valve performance. Inaccurate sizing and positioning increases risks such as valve migration, which may result in severe complications due to obstruction of the left ventricular outflow tract and may even result in patient death. Additionally, calcification of the aortic valve may affect performance. Specifically, the degree of calcification may be important for patient selection criteria for valve implantation. Calcification has also been suggested as playing a role in anchoring transcathether implants. The interaction between the implanted valve and the calcified tissue is believed to be relevant to anchoring the valve in place and preventing valve migration.
"Without being bound to any particular theory, it is believed that improper anchoring of the valve may occur due to a mismatch between the size of the native annulus and the size of the prosthetic valve (e.g., using a small size valve in a large annulus), lower calcification levels in the native tissue than actually predicted, or improper positioning of the valve resulting in insufficient expansion of the valve diameter. Moreover, overestimation of the annulus size may cause an oversized valve to be implanted, leading to local complications in the aortic root, including coronary orifice obstruction, aortic dissection and heart blockage. Additionally, oversized valves may cause extended compression and/or stent deformation that affects valve durability.
"In addition, incorrect sizing of a valve due to anatomical variations between patients may require removal of a fully deployed heart valve from the patient if it appears that the valve is not functioning properly. Removing a fully deployed heart valve increases the length of the procedure and increases the risk of infection and/or damage to heart tissue. Thus, methods and devices are desirable that would reduce the likelihood of removal. Methods and devices are also desirable that would reduce the likelihood of valve migration caused by improper anchoring.
"Current methods for estimating the size of a patient's anatomy include imaging techniques such as transthoracic echocardiograms, trans-esophageal echocardiograms and angiography. These imaging methods are not standardized and may yield inconsistent results due to the elliptical shape of the target anatomy. Additionally, none of these techniques allow for contact forces between the annulus and stent to be measured and, thus they do not account for calcification.
"There therefore is a need for further improvements to the devices, systems, and methods for transcatheter delivery and positioning of collapsible prosthetic heart valves. Specifically, there is a need for further improvements to the devices, systems, and methods for accurately measuring the native annulus dimensions and calcification levels in a patient. Such accurate measurement will help to reduce the risks associated with valve migration and improper valve positioning. Among other advantages, the present invention may address one or more of these needs."
In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "In one embodiment, a sizing device for a collapsible prosthetic heart valve may include a collapsible and expandable balloon and at least one microelectromechanical sensor attached to the balloon, the at least one sensor being capable of measuring a property of tissue.
"In some example, the device may include a conduit in fluid communication with the inside of the balloon for delivering a fluid to inflate the balloon. The balloon may include at least one of PET, Nylon, polyurethane or a thermoplastic elastomer. The at least one sensor may be capable of measuring data relating to native valve annulus diameter. The data may relate to the extent of calcification of tissue and may utilize capacitance to measure the information. The at least one sensor may include a piezoelectric material. The at least one sensor may include a polymer such as polydimethylsiloxane or a polyimide. The at least one sensor may also include a fabric. In some examples, the device may include a plurality of sensors arranged about the periphery of the balloon.
"In another embodiment, a sizing device for a collapsible prosthetic heart valve includes a plurality of microelectromechanical sensors coupled end-to-end to form a collapsible and expandable balloon, the plurality of sensors being capable of measuring a property of tissue. The plurality of sensors may be capable of measuring data relating to native valve annulus diameter. The plurality of sensors may be capable of measuring data relating to the extent of calcification of tissue.
"A method for determining the proper fitment of a heart valve within a native aortic annulus may include the steps of introducing a sizing device to the native annulus, the sizing device including (i) a collapsible and expandable balloon, and (ii) at least one microelectromechanical sensor attached to the balloon, expanding the diameter of the balloon within the native annulus, and acquiring data related to a property of tissue using the at least one microelectromechanical sensor.
"In some example, the data may relate to an annulus diameter. The data may relate to an extent of calcification. In some examples, the method further includes a conduit in fluid communication with the inside of the balloon for inflating the balloon, and wherein expanding the diameter of the sizing device comprises injecting a fluid through the conduit to the inside of the balloon. The method may further include the step of deflating the balloon and removing the sizing device from the native annulus.
BRIEF DESCRIPTION OF THE DRAWINGS
"Various embodiments of the present invention are described herein with reference to the drawings, wherein:
"FIG. 1 is a side elevational view of a conventional prosthetic heart valve;
"FIG. 2A is a highly schematic side elevational view of a prosthetic heart valve having poor fitment in a native valve annulus;
"FIG. 2B is a highly schematic side elevational view of a prosthetic heart valve that has migrated from its implantation position in the native annulus;
"FIG. 3A is a side view of an expandable balloon having a microelectromechanical sensor according to a first embodiment of the present invention;
"FIG. 3B is a side view of the balloon of FIG. 3A after inflation;
"FIG. 4 is a perspective view of a microelectromechanical sensor;
"FIG. 5A is a highly schematic view illustrating the sensing of a microelectromechanical sensor;
"FIGS. 5B and 5C illustrate microelectromechanical sensor formed of a capacitative pair;
"FIG. 6A is a side view of a collapsed balloon having microelectromechanical sensors according to a second embodiment of the present invention;
"FIG. 6B is a side view of the balloon of FIG. 6A after inflation;
"FIG. 7 is a side view of an inflatable balloon having microelectromechanical sensors arranged in rings according to a third embodiment of the present invention; and
"FIG. 8 is a side view of an inflatable balloon formed of microelectromechanical sensors according to a fourth embodiment of the present invention.
"Various embodiments of the present invention will now be described with reference to the appended drawings. It is appreciated that these drawings depict only some embodiments of the invention and are therefore not to be considered limiting of its scope."
URL and more information on this patent application, see: Venkatasubramanian, Ramji T.; Peng, Peng. Balloon Sizing Device and Method of Positioning a Prosthetic Heart Valve. Filed
Keywords for this news article include: Heart Valves, Cardio Device, Medical Devices, St. Jude Medical Cardiology Division Inc.
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