Structural Heart Disease Repair: A New Frontier for Interventionalists
- Posted on: 6/19/08
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To be fair, pediatric interventional cardiologists began paving the way in the 1990s with endovascular repair of congenital heart defects, but the field is expanding to include adult patients. Interestingly, some adults who have had surgical repair of their congenital heart defects as infants or children repair that often can now be done percutaneously are now in need of revision, which in some cases can be done endovascularly.
Structural heart disease itself is a bit of an ambiguous umbrella term for any condition related to the heart and major arteries, rather than the smaller blood vessels. Conditions that fall within this category range from congenital defects that may of immediate concern (coarctation of the aorta and atrial septal defects) to those that can become a problem later in life (patent foramen ovale, left atrial appendage). Structural heart disease also can be acquired, due to aging, injury or infection, for instance, valve disease. Some can be congenital or a result of a disease process, for instance, ventricular septal defects can be congenital or become a problem post-myocardial infarction.
Within a few short years, interventional repair of structural heart defects has boomed and is expanding at a incredible rate, including new and varied approaches to percutaneous treatment as well as new indications for treatment. Many if not most of these therapies are in the experimental phase, numerous trials are ongoing and the excitement is palpable.
Within a few short years, interventional repair of structural heart defects has boomed and is expanding at a incredible rate, including new and varied approaches to percutaneous treatment as well as new indications for treatment. Many, if not most, of these therapies are in the experimental phase, numerous trials are ongoing and the excitement is palpable.
One of the most exciting aspects of this expanding arena of treatment is the positive effect it will have on the multidisciplinary approach to care. For years, many of us in the field have been trumpeting the multidisciplinary approach, but in reality, adoption has been slow. Setting up a structural heart disease program creates a great opportunity to foster cooperation among the various disciplines. At Baptist Cardiac and Vascular Institute, we have seen first-hand that the only way to make this work is if we all work together toward the common goal. It's a great opportunity and there should be no animosity.
There are also many opportunities to work together through a combination approach. For instance, rather than doing a sternotomy to surgically replace a diseased aortic valve, the surgeon can make a small incision, and we can replace the valve using catheters, with no need for heart-lung bypass.
As with endovascular repair of aortic abdominal aneurysms (AAA), percutaneous repair of many structural heart defects is gaining a toehold in the care arena by offering treatment for patients who are not appropriate surgical candidates.
Some of these minimally invasive technologies eventually may become the standard of care, while others will remain an option for high-risk surgical patients.
Among these developing technologies, percutaneous closure of PFO has jumped out to an early lead in part because of the great need. PFO is an incomplete closure in the septum between the left and right atria of the heart, allowing right to left shunting and setting up potential for small or large blood clots to travel to the brain. Standard treatment for a PFO includes antiplatelet and anticoagulation therapy and surgery, although the latter is rarely employed as its risks are typically thought to outweigh the benefits. The less-invasive repair offered by non-surgical closure fills a void in care.
Approximately 20 percent of all people have a PFO, and in most cases, will go about their lives without ever knowing it. But studies have shown that of those 55 and younger who suffer embolic stroke, as many as 60 percent have a PFO.
Within the last 10 years, several percutaneously placed occlusion devices have become available, most of them various versions of tiny umbrella-shaped devices that can be advanced through a catheter and deployed at the site of the PFO to close the shunt. Recently, a new bioresorbable collagen-based occlusion device is in testing and other percutaneous PFO closure approaches have been developed, including radiofrequency ablation and suturing.
As patients began undergoing PFO closure, many noted that that their migraines had abated. Research suggests that about 40 percent of people who have migraine with aura also have PFOs, and several studies now underway are exploring the possibility of PFO closure for the treatment of migraines. The PFO-migraine connection is not yet clear.
Thousands of people with symptomatic PFOs have been receiving closure devices under an investigational device exemption, but there now is a call for more rigorous data to support PFO closure. The FDA is now requiring the device companies to set up registries, which will help in tracking outcomes, and has encouraged randomized trials. Many centers claim the latter is problematic, because few patients want to take the risk of being randomized. We may get our answer, however, through several trials that are underway to study PFO closure to treat migraine with aura.
At Baptist Cardiac and Vascular Institute, we are now studying the varied anatomy of the PFO defect to determine which patients are more likely to suffer transient ischemic attacks (TIAs) versus embolic stroke, and early evidence points to microembolization or thrombus fragmentation due to the hypermobile septum.
At Baptist, we have corrected more than 150 PFOs with very good results. These are people who have had neurological symptoms, including a major stroke or transient ischemic attacks (TIAs) of unknown origin. Patients are only considered for closure if they have experienced at least two neurological incidents that can be documented.
We have seen patient after patient whose quality of life was compromised by repeated TIAs or a major stroke due to a PFO. One patient, a vibrant man in his 50s, came to us paralyzed from the nose down. We determined he'd had a stroke due to a total occlusion of the basilar artery. We removed the thrombus by direct intra-arterial cerebral lytic therapy and determined that the patient had a large PFO, which had led to paradoxical embolization. We closed the PFO and he has now reclaimed his life and is back to his previous activities, including water skiing.
Closure devices for atrial septal defects and ventricular septal defects work similarly to PFO closure and also have had encouraging results. Also growing as a treatment is percutaneous repair of the left atrial appendage. Chronic atrial fibrilllation affects more than 2.2 million adults and increases the risk of stroke: 90 percent of all clots come from the left atrial appendage. The standard of care is medical management with warfarin, an extremely difficult drug to manage. The device used to correct this condition works similarly to the PFO device by sealing off the left atrial appendage. We have had good success using this approach and are currently participating in a randomized trial.
Percutaneous treatment of heart valves is another expanding area, including replacement of aortic and pulmonic valves, and repair of mitral valves.
At the upcoming International Symposium on Endovascular Therapy (ISET) meeting, Dr. Eberhard Grube will discuss the CoreValve Trial, which focuses on an exciting new technology that offers a percutaneous approach to replacing aortic heart valves that have become diseased due to stenosis. Patients in the current trial are not surgical candidates for valve repair. This is an approach that only a few years ago seemed impossible and yet which one day may replace surgical repair of diseased valves. The valve is built into a self-expanding stent and delivered via catheter.
Endovascular methods of repair of mitral valves being tested include suturing or via use of a clip-like device.
These are truly exciting times, both because we are faced with an expanding care arena, but also because it provides a great opportunity for all disciplines interventional cardiologists, interventional radiologists, vascular surgeons and cardiac surgeons to work together.
Interventionalists and allied health professionals hungry for more information are encouraged to attend the International Symposium on Endovascular Therapy (ISET) meeting January 28 “ February 1, in Hollywood, Florida. A pre-ISET nurse/technologist symposium will be held January 27th. For the first time, the meeting will feature an entire session on structural heart disease. Presentations include an update on percutaneous aortic valve therapy, mitral valve repair, patent foramen ovale (PFO) closure for stroke and migraine prevention, left atrial appendage closure and left ventricle aneurysm repair.
ISET also will feature several live cases of endovascular therapy of structural heart cases, including PFO closure and left atrial appendage closure. Visit www.iset.org for more information.