Calcification of the aortic valve is common, especially amongst the elderly. In this progressively degenerative disease, calcium deposits accumulate on the leaflets of the aortic valve reducing their mobility and restricting blood flow from the heart to the body. In the initial stages, this condition is well tolerated. However, when the restriction (i.e. stenosis) becomes severe, patients develop shortness of breath, fatigue, chest pain and a prognosis of 50% mortality within the subsequent two years. Surgical aortic valve replacement is generally recommended at this point. Unfortunately, aortic valve replacement surgery is highly invasive carrying substantial perioperative morbidity, including prolonged recovery and increased mortality limiting its application in the elderly and other high risk patient groups. An estimated 50% of patients with aortic stenosis are therefore denied or choose not to have this valve replacement surgery.
Balloon Aortic Valvuloplasty
In the mid-1980s with the advent of catheter based cardiovascular procedures, valvuloplasty techniques were developed to dilate the stenotic valve leaflets using balloons. The force exerted by the inflated balloon across the valve creates fissures within the calcified and rigid leaflets making them more flexible. The improved leaflet flexibility provided by balloon aortic valvuloplasty (BAV) permits greater valve opening, and reduces the transvalvular pressure gradient and associated symptoms. However, the primary limitation of this procedure remains the limited improvement in valve opening as well as near uniform restenosis one year following the procedure. The recently developed transcatheter aortic valve replacement (TAVR) procedure is proving to be an effective solution for both of these problems.
BAV is mandatory just prior to transfemoral or transapical valve implantation. Balloons currently being used are based on the same design as those first developed for the procedure in the 1980s. These aortic balloons pose major limitations for both the safety and efficacy of this procedure.
Conventional Balloon Catheter Limitations
Aortic valvuloplasty procedures can be compromised by balloon slippage during inflation which can result in extended procedure and ischemic time. The V8™ catheter features a "figure-8" shape balloon that enables the bulbs at either end of the balloon to "lock" into either side of the aortic annulus.
In addition, a physician operator is unable to determine precisely the amount of dilation force exerted on the aortic valve annulus during balloon aortic valvuloplasty (BAV). Given this limitation, the treatment tendency is to undersize the dilation balloon in an attempt to limit complications. However, by doing so, the operator potentially accepts some procedural compromises such as sub-optimal valve area gain, and a higher rate of balloon slippage.
Despite these precautions, catastrophic aortic root dissection during stand-alone BAV is believed to occur in 1% to 3% of cases. This generally leads to a precipitous death without means of resuscitation.
Based on these limitations, InterValve, Inc. believes there is an opportunity through catheter design to obtain acceptable aortic valve area improvements without increasing the risk of annular rupture. With the InterValve V8™ Aortic Valvuloplasty Balloon Catheter, the figure-8 shape is maintained throughout inflation allowing for the operator to choose a balloon size that enhances leaflet extension at the point of balloon bulb contact while minimizing the risk of annular rupture with a reduced diameter at the waist of the balloon which is aligned with the annulus when placed properly.