While often medically necessary, traditional aortic valve replacement options come with limitations, particularly for patients who have not yet reached an advanced age.
On the one hand, a bioprosthetic substitute will likely wear out in a decade or two. On the other, a mechanical replacement means a lifetime of burdensome warfarin use, at least until research identifies an effective anticoagulant alternative.
To sidestep these limitations, comprehensive programs have increasingly turned to valve-sparing procedures when possible. At Penn Medicine, we have worked to expand that feasibility to patients with even more complicated presentations. Since 2005, a specialized group of our cardiac surgeons has repaired appropriate aortic valves featuring two leaflets instead of three at the Center for Bicuspid Aortic Valve Diseases, part of the Penn Aorta Center.
Using sophisticated imaging, an extensive surveillance program and careful patient selection, the team has preserved hundreds of native aortic valves, with comprehensive data demonstrating durability and sustained effectiveness. The surgical team has also recently worked to reinvigorate and improve an alternative replacement for unsalvageable aortic valves.
Helping Younger Patients and Watching for Stenosis and Regurgitation With BAV
Up to 2 percent of the population has a bicuspid aortic valve (BAV), the most common congenital heart condition. Patients needing initial BAV support are generally on the younger side for cardiovascular care — in their 40s, 50s or 60s, with some presenting even younger.
"It's basically a disease of people who are in the prime of their lives regarding families and careers," says Joseph Bavaria, MD, a BAV repair pioneer and the co-director of the Penn Aorta Center. "It's important that we execute excellent treatment options."
While some bicuspid valves function as well as their three-leaflet counterparts, others leak; BAV is a common cause of aortic insufficiency (AI). BAVs may also have leaflets that are stiffer and thicker than normal, making aortic stenosis (AS) more likely. AI can lead to dangerous left ventricular (LV) remodeling, while AS can cause myocardial fibrosis. Some people with a BAV experience both AI and AS.
Although patients can live for years with mild to moderate AI, it must be properly categorized to avoid long-term harm to the heart. Unfortunately, current national guidelines can let patients sustain irreversible heart damage, even with a 2020 update that lowers the LV function threshold.
Recognizing the Connection Between BAV and Aortic Aneurysms
Another major challenge with bicuspid valves comes in the form of aortic disease. Up to 50 percent of BAV patients also have a thoracic aneurysm, likely from a combination of shared embryonic changes and a weakened aorta from unusual blood flow. Some aneurysms need treatment, even if the BAV does not warrant intervention. Others require evaluation and close monitoring.
The location of such aneurysms varies:
- Root, ascending aorta and arch: 45 percent
- Ascending aorta and arch: 28 percent
- Ascending only: 14 percent
- Root only (Marfan-like and most dangerous): 13 percent
Even if patients do not have an aneurysm at the time of BAV diagnosis, their risk for eventually developing one is 80 times greater than the general population. Up to 30 percent will develop an aneurysm within 10 to 20 years.
Using TEE and MR to Evaluate BAV
Given the prevalence of BAV and the potential complications, transesophageal echocardiography (TEE) plays a crucial role. All patients with enlarged aortic sinuses or ascending aortas should have their aortic valves imaged, just as all patients with a BAV need their thoracic aortas examined. Evaluation is best done at a comprehensive aorta center.
Beyond confirming the presence of a BAV and taking aortic measurements, the Penn team uses TEE to assess valves for repairability, by looking at the number of fenestrations, degree of calcification and amount of asymmetry. The team then creates virtual 3D models from CT scans to plan repairs, using software developed at Penn.
Penn specialists also use TEE to screen family members. Among patients, up to 9 percent of first-degree relatives also have a BAV, though not all the genetic variants responsible are known yet. Family members flagged by TEE screening can then get a care plan to protect their health, whether through monitoring or an intervention.
Other appropriate advanced imaging includes cardiac MR with 4D flow to evaluate any eccentric jets, a common feature of BAVs and one that can make classification of AI challenging. Cardiac MR can also track subtle LV changes and look at specific areas of the aortic wall.
"We have the ability to look at aortas moving in real time," says Nimesh Desai, MD, the other co-director of the Penn Aorta Center. "We can actually image the stress that's on the wall of the aorta to try and understand if there are reasons why that person might be at a unique risk or need further evaluation."
Making BAV Repair Possible for More Patients and Improving Ross Procedure
While many Penn patients still need classic aortic valve replacement, a significant portion undergo repair. Techniques include plication of extra leaflet length for the prolapsed segment; triangular resection for calcified, thickened raphe; and/or raphe release. Even if Penn surgeons do not need to replace the aortic root, they tighten or reinforce the annulus, an extra step shown to make aortic valve repairs more durable.
A review of data from 2002 to 2020 shows the team treated 1,556 patients with BAV disease. Of those:
- 984 received standalone aortic valve replacement because of regurgitation, stenosis or a combination
- 333 received a Bentall procedure or proximal aortic reconstruction
- 134 received primary leaflet repair, with some also needing ascending aorta replacement
- 105 received primary leaflet repair and root reimplantation
While stenotic aortic valves cannot be repaired, the Penn team is working to make treatment less burdensome through improved Ross procedures. A patient's pulmonary valve is the next best option to the native aortic valve for function, durability and quality of life. The prosthetic that replaces the harvested pulmonary valve faces lower hemodynamic forces in that part of the heart and can last longer than a prosthetic aortic valve.
"It's an incredible operation for younger patients," Dr. Bavaria says, noting that Penn's innovations avoid root dilation, a previous Ross shortcoming. "It's much improved compared to what we did 20 years ago."
Assessing Success of Penn Center for Bicuspid Aortic Valve Diseases
Each Penn BAV patient is encouraged to follow through with surveillance visits, whether they end up needing an intervention or not. Regular monitoring with imaging is critical for health and safety. The BAV center follows more than 1,000 patients from around the country at individualized intervals.
Among patients who have received BAV repair at Penn, results trend in a positive direction. At two years out, 98 percent of BAV patients undergoing valve repair and root replacement retain freedom from regurgitation. At the 10-year mark, 86 percent of these patients still avoid AR. Data also show low reoperation rates and effective left ventricular remodeling.
For the first time, BAV repair for severe aortic regurgitation was included in joint guidelines from the American College of Cardiology (ACC) and American Heart Association (AHA) with the groups' 2020 update. But the vague wording — "valve repair may be considered in selected patients" — leaves too many patients still facing the prospect of replacement with an artificial valve, the Penn team believes.
"We have the ability to treat these patients very well, with the ability to repair valves rather just replace them," Dr. Bavaria says. "We also have a great understanding of how to treat the aneurysmal component and have a very longitudinal approach that provides the care these patients need for life."