Valves of the Right Stuff

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Motivation: Morning rounds with a cardiologist is like going from room to room and trying to be a human echo machines.  Is there a valvular problem? The safe answer is almost always yes.  You may not be able to hear it, but the attending can.  Although human beings have refined their ears to distinguish harsh, blowing, and soft transvalvular flow sounds, the ability to fix valvular disease has lagged behind.  Artifical valves have major problems.  Mechanical valves require life long anti-coagulation, and dead tissue valves have finite lifespan.  A surgeon recently showed me the third way: growing valves out of your own tissue.  Sounds like fiction, but the patient did just fine after the tricuspid valve repair operation.  Here is a case series from Italy that demonstrates the magic.

Paper: Quarti, A. et. al. "Preliminary experience in the use of an extracellular matrix to repair congenital heart diseases." Interactive Cardiovascular and Thoracic Surgery (2011) article in press.

Methods: Between 2009 and 2011, 26 patients with congenital heart defect underwent surgery using an extracellular matrix patch (manufactured by CorMatrix).  The matrix was constructed from porcine small intestinal submucosa with expectation that native heart tissue would grow over the matrix.  The immediate post-operative course was reported.

Results:
Patients: Surgery was performed in 26 patients (mean age 6.4 years, range of 8 days to 32 years):

• 10 for pulmonary patch arterioplasty
• 9 for valve leaflet repair (including tricuspid, pulmonary, aortic, and mitral valves)
• 4 for ascending aortic patch aortoplasty
• 3 for aortic arch reconstruction
• 1 for right ventricular outflow tract obstruction

Results: There were no deaths in the peri-operative period.  At follow-up (mean 13.2 months, range 4-25 months), there was no evidence of thrombosis, disruption, shrinkage, leakage, or patch calcification on echo and CXR. 

For the patients with valve repair, follow-up echo only showed trivial to mild regurgitation.  No valve repair required reoperation.  Intial followup of the valve repair cohort (mean of 12.5 months) did not show evidence of progression of regurgitation. 

For cases in which extracellular matrix was used as vascular patch (18 cases), two had pulmonary artery stenosis distal to the patch.  One required operative repair.

Discussion: This paper may be part of the intial foundations of a marked change in valve repair surgery.  If the results eventually hold up in larger study, many of the long-term complications of valve repair surgery such as anti-coagulation, thrombogenic risk, and risk of endocarditis will be significantly decreased.  At present, however, this paper probably generates more questions than answers.  First of all, the follow-up is short, and questions about long-term viability of the ECM repair remain.  Also, most of the subjects were children, and older adults may repopulate the matrix at a different rate than children making extension of the results to adults problematic.  This paper probably lays the groundwork for larger randomized trials.  Finally, the paper does not mention the funding source.  In subsequent trials, it would be preferable if CorMatrix is not part of the trials.