Abstract:
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. The shock waves propagate through the liquid and impinge upon the valve to decalcify and open the valve.

Description:
CLAIM OF PRIORITY 
     The present application is a Divisional of copending U.S. patent application Ser. No. 12/611,997, filed Nov. 4, 2009, which application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/111,600, filed Nov. 5, 2008, now expired; all of the foregoing applications are incorporated herein by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     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&#39;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&#39;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. 
     The present invention provides an alternative treatment system for stenotic or calcified aortic valves. As will be seen subsequently, the embodiments described herein provide a more tolerable treatment for aortic stenosis and calcified aortic valves than the currently performed aortic valve replacement. The invention also provides a more effective treatment than current valvuloplasty therapy. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a valvuloplasty system comprises a balloon adapted to be placed adjacent leaflets of a valve, the balloon being inflatable with a liquid, and a shock wave generator within the balloon that produces shock waves that propagate through the liquid for impinging upon the valve. The balloon may be adapted to be placed on opposite sides of the valve leaflets or within the valve annulus. 
     The system may further comprise an elongated tube. The balloon may be at the distal end of the elongated tube. 
     The balloon may include a first balloon chamber and a second balloon chamber. The first and second balloon chambers may be longitudinally spaced from each other. 
     The elongated tube may include a lumen. The first and second balloon chambers are in fluid communication with the elongated tube lumen. 
     The shock wave generator may comprise a first shock wave source within the first balloon chamber and a second shock wave source within the second balloon chamber. The first and second shock wave sources may comprise a first electrical arc generator and a second electrical arc generator. The electrical arc generators may comprise at least one electrode adapted for connection to a voltage pulse generator. Each of the electrical arc generators may comprise an electrode pair adapted for connection to a voltage pulse generator. Each of the electrode pairs may comprise a pair of coaxially arranged electrodes. 
     They may further comprise a high voltage catheter including the first and second electrical arc generators. The first and second electrical arc generators may be longitudinally spaced from each other for being received within the first and second balloon chambers, respectively. 
     As mentioned above, the balloon may be adapted to be placed within the valve annulus. To that end, the balloon may have a reduced diameter portion adapted to be received within the valve annulus. 
     The balloon may be formed of a compliant material. 
     Alternatively, the balloon may be formed of a non-compliant material. 
     According to another embodiment, a catheter system comprises an elongated carrier and a balloon carried by the elongated carrier. The balloon is arranged to receive a fluid therein that inflates the balloon. The system further includes at least one arc generator including at least one pair of coaxially arranged electrodes within the balloon that forms a mechanical shock wave within the balloon. 
     The system may further include a cable comprising a center conductor and an outer conductive shield insulated from the inner conductor. A first one of the coaxially arranged electrodes may be at least in part formed by the center conductor of the cable, and a second one of the coaxially arranged electrodes may be at least in part formed by the outer conductive shield of the cable. 
     According to a further embodiment, a valvuloplasty method for treating a valve having leaflets and an annulus comprises placing a balloon adjacent to the leaflets of the valve, inflating the balloon with a liquid, and producing shock waves within the balloon that propagate through the liquid for impinging upon the valve leaflets and the valve annulus. 
     The placing steps may be performed by placing the balloon on opposite sides of the valve leaflets. Alternatively the placing step may be performed by placing the balloon within the valve annulus. 
    
    
     
       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 the left ventricle, the aorta, and the aortic valve of a heart showing a reduced aortic valve open area and thickened valve leaflets due to calcium and fibrotic tissue; 
         FIG. 2  is a cut away view of the aortic valve of a heart with a treatment balloon placed on both sides of the aortic valve leaflets, according to an embodiment of the present invention; 
         FIG. 3  is a schematic view of a dual shockwave balloon embodying the invention attached to a high voltage power supply; and 
         FIG. 4  is a cut away view of a heart showing an alternate valvuloplasty shock wave balloon according to a further embodiment and aspects of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIG. 1 , it is a cut away view of the left ventricle  12 , the aorta  14 , and the aortic valve  16  of a heart  10  with a stenotic and calcified aortic valve  16 . Here more particularly, it may be seen that the opening  17  of the stenotic and calcified aortic valve  16  is restricted in size and that the valve leaflets  18  are thickened with calcium deposits and fibrotic tissue. The thickened leaflets  18  and smaller valve opening  17  restrict blood flow from the heart creating excess work for the heart  10  and poor cardiac output. As previously mentioned, current treatment includes replacement of the valve or attempts too stretch the valve annulus with a balloon. 
       FIG. 2  is a cut away view of the aortic valve  16  with a treatment balloon  22  placed on both sides of the aortic valve leaflets  18 . The balloon  22  may be formed from a compliant or a non-compliant material. The balloon, as seen in  FIG. 2 , is at the distal end of an elongated tube  23 . The treatment balloon  22  has two longitudinally spaced chambers  24  and  26  that share a common inflation lumen  25  of the tube  23 . Alternatively the balloon chambers  24  and  26  may not share the same inflation fluid path. The chambers  24  and  26  are longitudinally spaced such that chamber  24  is positioned on one side of the aortic valve leaflets  18  and chamber  26  is positioned on the other side of the aortic valve leaflets  18 . The chambers  24  and  26  are inflated with saline/contrast mixture, for example. Each chamber  24  and  26  may contain an electrode (as shall be seen subsequently) that can produce electrical arcs to deliver timed shock waves. The shock waves can be synchronized to concurrently impinge upon both sides of the leaflets  18  to maximize the effectiveness of breaking calcium deposits. Such shock waves may be generated and also synchronized to the R wave of the heart  10  in a manner as described for example in co-pending application No. 61/061,170 filed on Jun. 13, 2008, which application is incorporated herein in its entirety. 
       FIG. 3  is a schematic view of a valvuloplasty system  11  embodying the present invention. The system  11  includes the dual shockwave balloon  22 . The balloon  22  has received a high voltage catheter  32  that is connected to a high voltage power supply  30 . The schematic representation shows the positioning of the balloon chambers  24  and  26  above and below the leaflets  18  of the aortic valve  16 . As previously described, shock waves will impinge upon opposite sides of the leaflets  18  to more effectively break calcium deposits in the valve leaflets  18 . The annulus will also be treated in this arrangement. To that end, the high voltage catheter  32  includes electrode pairs  34  and  36  that are coaxially arranged electrodes placed in chambers  24  and  26  respectively of the balloon  22 . More specifically, electrode pair  34  is at the distal end of a first cable and comprises a center conductor  33  and an outer conductive shield  35 . Similarly, electrode pair  34  is at the distal end of a second cable and comprises a center conductor  37  and an outer conductive shield  39 . High voltage pulses from power supply  30  are applied to the electrode pairs  34  and  36  in a manner as described in the aforementioned application Ser. No. 61/061,170 to create shockwaves within the fluid within the chambers  24  and  26  of the balloon  22 . The shock waves impinge upon the valve leaflets  18  and the valve annulus to cause the break up of calcium deposits and fibrotic tissue on the valve leaflets  18  and annulus to open the aortic valve  16 . 
       FIG. 4  shows an alternate valvuloplasty shock wave balloon  42  at the distal end of an elongated tube  43 . The balloon  42  is placed in the annulus of the aortic valve  16 . To that end, the balloon  42  has a reduced diameter portion  45  for being received within the valve annulus. The balloon  42  has a high voltage catheter  44  therein that terminates in an electrode pair  46 . As in the previous embodiment, the electrode pair  46  may comprise a pair of coaxially arranged electrodes where a center conductor may form at least a part of one electrode and at an outer conductive shield may form at least a part of the other electrode. The catheter  44  and its electrode pair  46  provide shock waves as previously described. Such an arrangement will decalcify the leaflets  18 . This not only will decalcify the leaflets  18 , but will also soften the aortic valve annulus and expand its diameter. Hence, the balloon  42  provides the added advantage of exerting expansion pressure directly to the annulus of the valve to remodel the annulus diameter. 
     While particular embodiments of the present invention have been shown and described, modifications may be made, and it is therefore intended to cover all such changes and modifications which fall within the true spirit and scope of the invention.