Transvenous Annuloplasty for Ischemic Mitral Regurgitation
What is transvenous annuloplasty?
Transvenous annuloplasty, conceptually, is an alternative to conventional surgical annuloplasty. Currently, it is only an early development stage activity at multiple companies and centers; no products of this type have been permanently implanted in human subjects. Various approaches are being explored by Viacor and other investigators and companies. The objective is to substitute a percutaneous procedure for a surgical, bypass procedure in appropriate patients. The primary target for our device is ischemic mitral regurgitation.
Our device, the Viacor Percutaneous Transvenous Mitral Annuloplasty (PTMA) device, is placed in the venous continuity from the coronary sinus, great cardiac vein and into the anterior interventricular vein. The device is catheter-based and is intended to provide for both a diagnostic procedure, and as appropriate, a permanent implant. During the diagnostic step, the interventionist will evaluate the impact on mitral regurgitation and the sizing and placement issues for the implant. If various imaging and hemodynamic criteria are met, the device facilitates detachment of a permanent implant.
We are currently conducting individual center pilot studies in humans with a device that we can place temporarily while assessing the reduction in mitral regurgitation.
What advantages does the Viacor Percutaneous Transvenous Mitral Annuloplasty (PTMA) device have over others on the market?
The surgical procedure is well-established with excellent acute and chronic results. Unfortunately the associated procedure morbidity and mortality are rather high in key patient cohorts and the surgical insult to the patient is considerable. Our objective is to develop a procedure that for selected patients provides the benefits of surgical annuloplasty without the associated risk and trauma of open heart surgery.
It is too early to say how our product might compare to the other proposed methods in the field as none of the methods have reached definitive human cases.
What patients would benefit most from using this device?
We suspect that the best patients will turn out to be those with greater than 2+ mitral regurgitation with ischemic origin who are at risk of congestive heart failure, but would ordinarily not be referred for surgery due to the associated morbidity or mortality.
What are the challenges with visualization of the surgical site when using this device versus conventional annuloplasty, and how are they being addressed?
Surgical annuloplasty has the advantage of direct, suture attachment of the ring to the mitral annulus. Visualization is direct. Unfortunately, the patient is on bypass, so skilled interpretation of the correct degree of correction is required. By comparison, venous implantation is structurally adjacent to the mitral annulus. Complex anatomical interaction, particularly with the circumflex artery, must be accounted for. A considerable advantage of the percutaneous approach is that we are able to simultaneously observe the device angiographically and valve competence via echocardiography and hemodynamic monitors. The device can be tuned in real time.
What does this procedure cost compared to conventional annuloplasty?
While it is still rather early to say, we expect the cost profile for the device procedure to be similar to other structural implants such as AAA devices.
How much of a reduction in hospital stay and postoperative complications do you foresee when using this device?
Hospital stay for the percutaneous device could quite reasonably be reduced to a day or two, assuming the need for careful observation, and ultimately to an outpatient procedure.
What studies have been conducted thus far (any human)? How long has data been collected on an inserted device?
We have done a small number of human patients with an early, temporary device. These procedures were conducted for less than one hour. We have extensive experience with long-term implants (60 days) in various animal models.
What patients are being enrolled in the current clinical pilot trial?
Same as above, 2+ MR with ischemic origins. We are excluding patients with MR from other causes, such as prolapse or congenital malformations.
How long before larger clinical trials begin?
We expect to continue to expand the scope and complexity of our temporary studies for the rest of this year. We have not yet announced our implant study plans publicly.
Who do you foresee performing these procedures when the device is approved (i.e., interventional cardiologists, electrophysiologists, or cardiothoracic surgeons)?
So far our team is a mix of surgeons, interventionalists, echocardiographers, and radiologists. We are confronting a very challenging disease state, involving multiple, complex interactions. For the foreseeable future, I expect there to be continued intensive involvement of these and other disciplines.
Another interesting technology in development is magnetic guidance for interventional procedures. Is this a technology that could potentially utilized to guide and implant the PTMA device?
We have not yet taken advantage of magnetic guidance. We have been focused on echo and angio.
Can you describe Viacor as a company and how work on this device first began?
Viacor was co-founded by Dr. Marc Gillinov of the Cleveland Clinic and Dr. John Liddicoat of Beth Israel Deaconess in Boston. It is a development-stage company founded in 1999. The company was founded by the doctors mentioned above to pursue improved approaches to the treatment of valvular diseases. We have fifteen full-time employees.
Jonathan Rourke discloses an employment affiliation with Viacor, Inc.