Invited Commentary

Abstract

For nearly half a century the mitral valve has been replaced or reconstructed with rigid, inflexible metallic rings or frames. It was not known for many years that this may affect both the mitral annular (MA) and left ventricular outflow tract (LVOT) dynamics. Dynamic imaging was not available then, and surgeons were more concerned with patient survival. Since the demonstration in 1996 that fixing the MA with a rigid ring can cause LVOT obstruction, many elegant studies have been designed to quantify the dynamic changes in both aspects. Komoda and colleagues [1Komoda T. Hetzer R. Oellinger J. et al.The relationship between the mitral annulus and left ventricular outflow tract.ASAIO J. 1997; 43: 932-936Crossref PubMed Scopus (10) Google Scholar] from Berlin have clearly demonstrated these changes using three-dimensional magnetic resonance imaging. Their observation suggests that fixing the MA with a complete rigid ring for repair or replacement both (1) reduced dynamic expansion of the LVOT by 25% to 40% [1Komoda T. Hetzer R. Oellinger J. et al.The relationship between the mitral annulus and left ventricular outflow tract.ASAIO J. 1997; 43: 932-936Crossref PubMed Scopus (10) Google Scholar] as compared with normal subjects during the systolic phase and (2) reduced the share of the LVOT in its ratio with left ventricular base areas by its inflexibility with a rigid ring in the mitral position [2Komoda T. Hetzer R. Hofmeister J. et al.Dynamic change in the left ventricular base with or without a rigid mitral valve prosthesis.ASAIO J. 1997; 43: M392-M395Crossref PubMed Scopus (75) Google Scholar]. The study by Caimmi and colleagues [3Caimmi P.P. Diterlizzi M. Grossini E. et al.Impact of prosthetic mitral rings on aortomitral apparatus function: a cardiac magnetic resonance imaging study.Ann Thorac Surg. 2009; 88: 740-745Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar] is timely, and it elegantly demonstrates that the gradients across the LVOT may progress with time when the MA is circumferentially fixed with a rigid ring or prosthesis. They have also demonstrated that these changes can be minimized, although not abolished, by using a partial ring that permits MA flexion in the inter-trigonal area, which affects LVOT dynamics. It is necessary to understand how well nature provides for smooth and unobstructed blood flow in the normal heart with perfect functional adjustments between related parts (ie, the MA and LVOT). The present study and previous studies have made these observations easy to understand and apply in clinical practice. There is however two, albeit small, limitations in the study by Caimmi and colleagues [3Caimmi P.P. Diterlizzi M. Grossini E. et al.Impact of prosthetic mitral rings on aortomitral apparatus function: a cardiac magnetic resonance imaging study.Ann Thorac Surg. 2009; 88: 740-745Abstract Full Text Full Text PDF PubMed Scopus (19) Google Scholar]. These patients underwent coronary bypass surgery, which may have influenced ventricular function adversely. Perhaps a similar study in patients without ischemic heart disease would contribute to a better demonstration of these dynamic changes. The second limitation is the length of follow-up. Whether these gradients worsen as time passes and predispose to aortic valve disease or ventricular dysfunction needs evaluation. Impact of Prosthetic Mitral Rings on Aortomitral Apparatus Function: A Cardiac Magnetic Resonance Imaging StudyThe Annals of Thoracic SurgeryVol. 88Issue 3PreviewThe circumference of the aortic annulus adjusts proportionally with changes in left ventricular volume. These dimensional changes in the aortic annulus improve the left ventricular outflow tract (LVOT) hemodynamics and enhance the anterior mitral valve leaflet (AML) movement. In this study, we investigated the impact of circumferential and partial circumference prosthetic mitral rings on aortomitral apparatus function. Full-Text PDF