News Column

Researchers Submit Patent Application, "Shock Wave Valvuloplasty Device with Moveable Shock Wave Generator", for Approval

February 27, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors ADAMS, John M. (Snohomish, WA); GOFF, Thomas G. (Mountain View, CA), filed on October 4, 2013, was made available online on February 13, 2014.

The patent's assignee is Shockwave Medical, Inc.

News editors obtained the following quote from the background information supplied by the inventors: "Aortic calcification, also called aortic sclerosis, is a buildup of calcium deposits on the aortic valve in the heart. This often results in a heart murmur, which can easily be heard with a stethoscope over the heart. However, aortic calcification usually doesn't significantly affect the function of the aortic valve.

"In some cases, though, the calcium deposits thicken and cause narrowing at the opening of the aortic valve. This impairs blood flow through the valve, causing chest pain or a heart attack. Doctors refer to such narrowing as aortic stenosis.

"Aortic calcification typically affects older adults. But when it occurs in younger adults, it's often associated with an aortic valve defect that is present at birth (congenital) or with other illnesses such as kidney failure. An ultrasound of the heart (echocardiogram) can determine the severity of aortic calcification and also check for other possible causes of a heart murmur.

"At present there is no specific treatment for aortic calcification. General treatment includes the monitoring for further developments of heart disease. Cholesterol levels are also checked to determine the need for medications to lower cholesterol in the hope to prevent progression of aortic calcification. If the valve becomes severely narrowed, aortic valve replacement surgery may be necessary.

"The aortic valve area can be opened or enlarged with a balloon catheter (balloon valvuloplasty) which is introduced in much the same way as in cardiac catheterization. With balloon valvuloplasty, the aortic valve area typically increases slightly. Patients with critical aortic stenosis can therefore experience temporary improvement with this procedure. Unfortunately, most of these valves narrow over a six to 18 month period. Therefore, balloon valvuloplasty is useful as a short-term measure to temporarily relieve symptoms in patients who are not candidates for aortic valve replacement.

"Patients who require urgent noncardiac surgery, such as a hip replacement, may benefit from aortic valvuloplasty prior to surgery. Valvuloplasty improves heart function and the chances of surviving non-cardiac surgery. Aortic valvuloplasty can also be useful as a bridge to aortic valve replacement in the elderly patient with poorly functioning ventricular muscle. Balloon valvuloplasty may temporarily improve ventricular muscle function, and thus improve surgical survival. Those who respond to valvuloplasty with improvement in ventricular function can be expected to benefit even more from aortic valve replacement. Aortic valvuloplasty in these high risk elderly patients has a similar mortality (5%) and serious complication rate (5%) as aortic valve replacement in surgical candidates.

"Transarterial aortic valve replacement is a new procedure where the aortic valve is replaced with a self-expanding nitinol valve structure. Such procedures benefit from a smooth non-calcified circumference to attach the new valve. Large calcium deposits may induce leaks around the valve preventing a firm consistent attachment of the valve to the aorta. Thus there is a need for a calcium free valve bed to attach such self-expanding valves.

"An alternative method and system for treating stenotic or calcified aortic valves is disclosed and claimed in co-pending U.S. application Ser. No. 12/611,997, filed Nov. 11, 2009 for SHOCKWAVE VALVULOPLASTY SYSTEM. As described therein, a balloon is placed adjacent leaflets of a valve to be treated and is inflatable with a liquid. Within the balloon is a shock wave generator that produces shock waves that propagate through the liquid and impinge upon the valve. The impinging shock waves soften, break and/or loosen the calcified regions for removal or displacement to open the valve or enlarge the valve opening.

"The approach mentioned above provides a more tolerable treatment for aortic stenosis and calcified aortic valves than the previously performed aortic valve replacement. It is also a more effective treatment than current valvuloplasty therapy. For patients undergoing transaortic or catheter based aortic valve replacement, this new method can soften, smooth, and open the aortic valve annulus more effectively than current valvuloplasty and prepare the area for a catheter delivered valve.

"In the shock wave valvuloplasty described above, the impingement intensity of the shockwaves diminishes as a function of the distance from the shock wave origination point to the valve. More specifically, the impingement intensity of the shock waves is inversely proportional to the square of the distance from the shock wave origination point to the valve. Hence, when applying the shock waves, it would be desirable to maximize their effectiveness by being able to minimize the distance between the shock wave source and the valve location being treated at that moment. The present invention address this and other matters of importance in providing the most efficient and effective treatment possible."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "According to one embodiment, a valvuloplasty system comprises a balloon adapted to be placed adjacent leaflets of a valve. The balloon is inflatable with a liquid. The system further includes a shock wave generator within the balloon that produces shock waves that propagate through the liquid for impinging upon the valve. The shock wave generator is moveable within the balloon to vary shock wave impingement on the valve.

"The shock wave generator may be moveable within the balloon to subscribe a circular area. The shock wave generator may further be moveable within the balloon to subscribe a cylindrical space.

"The shock wave generator includes at least one electrode.

"The system may further comprise an elongated element that carries the at least one electrode to extend into the balloon and an elongated sheath through which the elongated element extends. The at least one electrode may be moveable within the balloon by displacement of the elongated element and/or the sheath. The at least one electrode may be moveable within the balloon to subscribe a circular area and may be further moveable within the balloon to subscribe a cylindrical space.

"The system may further comprise an elongated carrier with the balloon being at one end of the carrier in sealed relation thereto. The system may further comprise an elongated element that carries the at least one electrode to extend through the carrier into the balloon. The at least one electrode may be moveable within the balloon to subscribe a circular area by rotational displacement of the elongated element and may be further moveable within the balloon to subscribe a cylindrical space by rotational and axial displacement of the elongated element.

"The carrier has a distal end and a proximal end and the elongated element has a distal end and a proximal end. The balloon may be at the distal end of the carrier and the at least one electrode may be at the distal end of the elongated element so that the elongated element may extend through the carrier from the balloon to the proximal end of the carrier and the elongated element may be displaceable at the proximal end of the carrier.

"The system may further include an elongated sheath through which the elongated element and the at least one electrode extend. The size of the circular area subscribed by the at least one electrode within the balloon may be adjustable by axial displacement of the elongated element with respect to the sheath. To that end, the at least one electrode may extend from the elongated element at an angle. The at least one electrode and the elongated element are formed from a common conductor.

"The system may further comprise a cage enclosing the at least one electrode that prevents the at least one electrode from contacting the balloon. The cage may be formed of electrically insulative material. Alternatively, the cage may be formed of conductive material and include an insulation covering at least a portion of the cage. The shock wave generator may further include a second electrode within the balloon. The cage may form the second electrode.

"The shock wave generator may further include a reflector that directs the shockwaves generated by the at least one electrode in a desired direction. The reflector may be arranged to move with the at least one electrode.

"The at least one electrode may comprise an electrode pair.

"The electrode pair are formed by coaxially disposed electrodes including a center electrode and an outer electrode circumscribing the center electrode. The shock wave generator may further include a reflector carried by the electrode pair that directs the shockwaves in a desired direction. The reflector may be coupled to the outer electrode.

"The shock wave generator may further include a pulsating voltage source. The pulsating voltage source may be arranged to provide the at least one electrode with a negative polarity.

"The balloon may comprise first and second chambers and the shock wave generator may comprise the at least one electrode within the first chamber and a second electrode within the second chamber. The at least one electrode may be moveable within the first chamber and the second electrode may be moveable within the second chamber. Each of the at least one electrode and the second electrode may be arranged for movement to subscribe a cylindrical space.

"Each of the at least one electrode and the second electrode may comprise a first electrode pair and a second electrode pair, respectively. The first and second electrode pair may each be formed by coaxially disposed electrodes including a center electrode and an outer electrode circumscribing the center electrode.

"One of the at least one electrode and the second electrode may be a distal electrode with respect to the other one of the at least one electrode and second electrode. The distal electrode may be moveable axially so as to be proximal to the other one of the at least one electrode and second electrode.

"One of the at least one electrode and the second electrode may be a distal electrode with respect to the other one of the at least one electrode and second electrode. The distal electrode may be reflexed in a proximal direction.

"According to another embodiment, a valvuloplasty system for treating a calcified valve comprises an elongated carrier, a balloon at one end of the carrier in sealed relation thereto, the balloon being inflatable with a liquid and including a first chamber and a second chamber, and a shock wave generator including a first electrode within the balloon first chamber and a second electrode within the balloon second chamber. The electrodes are arranged to produce shock waves within their respective balloon chambers that propagate through the liquid and impinge upon the valve being treated adjacent the balloon chambers. The first electrode is moveable within the first balloon chamber and the second electrode is moveable within the second balloon chamber.

"The shock wave generator further includes a pulsating voltage source. The pulsating voltage source is arranged to provide the first and second electrodes with a negative polarity. Each of the first and second electrodes is moveable within its respective balloon chamber to subscribe a cylindrical space.

"The system may further comprise a first drive element coupled to the first electrode and a second drive element coupled to the second electrode. The first and second electrodes may each be arranged to subscribe a cylindrical space by rotational and longitudinal displacement of their respective drive element.

"Each of the first electrode and the second electrode may comprise a first electrode pair and a second electrode pair, respectively. The first and second electrode pair may each be formed by coaxially disposed electrodes including a center electrode and an outer electrode circumscribing the center electrode.

"One of the at least one electrode and the second electrode may be a distal electrode with respect to the other one of the at least one electrode and second electrode. The distal electrode may be moveable axially so as to be proximal to the other one of the at least one electrode and second electrode.

"The distal electrode may be reflexed in a proximal direction.

"According to another embodiment, a valvuloplasty method for treating a cardiac valve comprises the steps of placing a balloon adjacent to the valve, inflating the balloon with a liquid, and introducing a shock wave generator into the balloon arranged to produce shock waves within the balloon to propagate through the liquid for impinging upon the valve. The method further includes the steps of producing shock waves within the balloon with the shock wave generator and changing the position of the shock wave generator within the balloon to vary the shock wave impingement upon the valve.

"The shock wave generator may include at least one electrode and the producing step may include applying pulsating electrical energy to the at least one electrode. The step of changing the position of the shock wave generator within the balloon may include moving the at least one electrode along an arcuate path.

"The arcuate path has a radius of curvature and the step of changing the position of the shock wave generator within the balloon may further include varying the radius of curvature.

"The step of changing the position of the shock wave generator within the balloon may include moving the at least one electrode longitudinally within the balloon. The step of changing the position of the shock wave generator within the balloon may include moving the at least one electrode within a subscribed cylindrical space. The method may include the further steps of introducing a second shock wave generator into the balloon arranged to produce shock waves within the balloon to propagate through the liquid for impinging upon the valve, producing shock waves within the balloon with the second shock wave generator, and changing the position of the second shock wave generator within the balloon to vary the shock wave impingement upon the valve.

BRIEF DESCRIPTION OF THE DRAWINGS

"The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The various described embodiments of the invention, together with representative features and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify identical elements, and wherein:

"FIG. 1 is a cut away view of an aortic valve of a heart with a treatment balloon placed on both sides of the aortic valve leaflets, according aspects of the present invention;

"FIG. 2 is a partial perspective view of an electrode pair which may be employed as a shock wave generator within the treatment balloon of FIG. 2 according to aspects of the invention;

"FIG. 3 is a simplified schematic diagram of a valvuloplasty system according to aspects of the invention;

"FIG. 4 is a partial perspective view of another electrode pair which may be employed as a shock wave generator within the treatment balloon of FIG. 2 according to further aspects of the invention;

"FIG. 5 is a sectional view taken along lines 5-5 of FIG. 4;

"FIG. 6 is a partial perspective view of an electrode pair which may be employed as a shock wave generator within the treatment balloon of FIG. 2 that includes a reflector that reflects and focuses the shock waves in a desired direction according to further aspects of the invention;

"FIG. 7 is simplified side view illustrating the operation of the reflector of FIG. 6;

"FIG. 8 is a cut away view of an aortic valve of a heart with another treatment balloon placed on both sides of the aortic valve leaflets at the distal end of a valvuloplasty system, according to further aspects of the present invention; and

"FIG. 9 is a plan view of the proximal end of the valvuloplasty system of FIG. 8."

For additional information on this patent application, see: ADAMS, John M.; GOFF, Thomas G. Shock Wave Valvuloplasty Device with Moveable Shock Wave Generator. Filed October 4, 2013 and posted February 13, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1577&p=32&f=G&l=50&d=PG01&S1=20140206.PD.&OS=PD/20140206&RS=PD/20140206

Keywords for this news article include: Surgery, Angiology, Treatment, Cardiology, Aortic Stenosis, Medical Devices, Aortic Valve Stenosis, Shockwave Medical Inc..

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Source: Politics & Government Week


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