Objective: The purpose of this study was to analyze the behavior of the mitral valve ring and the left ventricle in dilated cardiomyopathy.
Methods: We analyzed 68 fixed adult human hearts, divided into 48 hearts with dilated cardiomyopathy of ischemic or idiopathic origin and 20 hearts free of pathologic heart conditions. Digital images of the mitral ring perimeter, attachment of the anterior and posterior leaflets, and fibrous and muscular portions were collected. We also measured the internal perimeter of the left ventricle, the distance from the septum to the anterior and posterior papillary muscles, the distance between the papillary muscles, and the extension of interventricular septum.
Results: The analysis of the results showed proportional distribution of the ring's fibrous portion (r2 = 0.98) and muscular portion (r2 = 0.99) according to the degree of mitral valve dilation. Linear regression revealed that the perimeters of anterior and posterior leaflet attachments (r2 = 0.96 and r2 = 0.98, respectively) also had a proportional relation. We did not observe proportionality between the degree of dilation of the mitral ring and the left ventricle. It was observed that dilation of the left ventricle takes place globally in its segments.
Conclusion: Differently from what was thought, in ischemic or idiopathic dilated cardiomyopathy, dilation of mitral ring is proportional and does not exclusively affect the posterior portion. The degree of left ventricular dilation does not determine the degree of dilation of the mitral ring because they are independent processes. These observations shed new light on the techniques used to correct mitral valve insufficiency in dilated cardiomyopathy.