Surgical placement of a cardiac prosthetic valve improves cardiovascular symptoms and, in many patients, is a lifesaving procedure. In 3 to 6 percent of patients, however, paravalvular prosthetic regurgitation occurs and may lead to heart failure or hemolytic anemia.
Traditionally, the treatment of symptomatic paravalvular prosthetic regurgitation has been open heart surgery. Operative repair may be challenging owing to anatomic or technical factors that led to the development of the prosthetic regurgitation, in addition to the associated surgical morbidity and mortality.
As a less invasive alternative, percutaneous approaches to the treatment of paravalvular prosthetic regurgitation have been developed. These percutaneous approaches use a variety of complex catheter techniques to deliver occluder devices to the site of paravalvular prosthetic regurgitation.
"Among experienced operators, defects involving mechanical or biological prosthetic valves can be treated with procedural success rates of about 90 percent and a low risk (<5 percent) of complications," according to Charanjit S. Rihal, M.D., an interventional cardiologist and chair of the Division of Cardiovascular Diseases at Mayo Clinic in Rochester, Minn.
In a patient with paravalvular regurgitation involving an aortic prosthesis, the defect typically is engaged using a retrograde approach from the femoral artery.
For patients with mitral defects, transseptal access to the left atrium is obtained from the femoral vein, followed by placement of a steerable sheath. The deflective tip of this sheath allows antegrade engagement of the mitral defect.
Once a prosthetic defect is crossed with a guide wire, a telescoped coronary guide catheter or a long delivery sheath is advanced, followed by placement of an appropriately sized occluder device in the defect. Echocardiography, which is essential, guides the procedure and allows its completion without the need for contrast. The occluder is released at the site of the paravalvular defect after demonstration of considerable reduction in the regurgitation, stability of the device and no interference with the prosthetic valve.
"Due to the serpiginous, calcific nature of some paravalvular defects, special techniques may be needed to pass delivery catheters," says Paul Sorajja, M.D., an interventional cardiologist at Mayo Clinic in Rochester. In these instances, an arteriovenous rail can be created, in which a guide wire is snared in a distal chamber and exteriorized.
For patients with two left-sided mechanical prostheses, this wire rail also can be created by exteriorizing the wire through the left ventricular apex via direct left ventricular puncture. The operator then uses both ends of the rail to provide support for passage of a delivery catheter across the paravalvular defect.
Paravalvular prosthetic defects also may be highly eccentric or crescent shaped. As a result, coverage of these types of lesions with a single large occluder may result in prosthetic interference from device overhang. "In these cases, multiple devices with smaller diameters can be placed simultaneously using two delivery catheters or sequentially with an anchor-wire technique," according to Allison Cabalka, M.D., a pediatric interventional cardiologist at Mayo Clinic in Rochester. Imaging with 3-D transesophageal echocardiography is helpful for examining the configuration of the defects to determine the potential need for these advanced catheterization techniques.
The Cardiac Catheterization Laboratory at Mayo Clinic in Rochester has been a leader in percutaneous repair of paravalvular prosthetic regurgitation. More than 140 patients have undergone the procedure to date. Patients with paravalvular prosthetic regurgitation are routinely evaluated by expert echocardiologists and interventionists in dedicated specialty clinics. Candidates for percutaneous repair are patients with one or more of the following:
Informed consent is obtained following a detailed discussion about the risks of the procedure and the option of reoperation, which frequently includes consultation with cardiovascular surgery colleagues.
Given the potential for a less invasive alternative to open surgical correction, there has been great enthusiasm for percutaneous repair of paravalvular prosthetic regurgitation. Emerging techniques allow the routine use of this procedure in patient candidates and will continue to evolve to address this increasingly recognized complication of prosthetic valves.