Evaluation of Mitral and Tricuspid Regurgitation: Cardiovascular Magnetic Resonance Imaging Versus Echocardiographic Doppler Color Flow Mapping of the Vena Contracta

BACKGROUND, SIGNIFICANCE, AND RATIONALE (including preliminary studies and any results) The integrity of the two atrioventricular valves (AVV)(i.e., the mitral and tricuspid valve) plays an important role in the evaluation and management of patients with congenital and acquired heart disease. Loss of valve integrity (i.e., valve leakage in the reverse direction of normal blood flow), is known as valve regurgitation. Increasing severity of mitral regurgitation has been associated with increased mortality and morbidity. Tricuspid regurgitation can be a progressive problem that results in right atrial and ventricular dilation and possible right heart failure. Similarly, mitral valve regurgitation can result in left atrial and left ventricular enlargement. Treatment options for valvular regurgitation are based upon the degree of regurgitation in both adults and children. Therefore, assessment of the degree of AV valvular regurgitation has important clinical ramifications. AV valve regurgitation can be assessed in several ways, including both invasive and noninvasive modalities. The invasive assessment is performed by cardiac catheterization which enables qualitative and quantitative measurements of AV valve regurgitation and in the past has been considered the "gold standard". Noninvasive assessment is still the preferred method and consists of echocardiography, electrocardiography, chest x-ray, and CMR. TTE can be used qualitatively to describe the amount of AV valve regurgitation by the degree of color flow Doppler reflux into the left atrium during left ventricular contraction. This approach grades the regurgitation as mild, moderate or severe similar to angiographic grading systems, but is relatively subjective and affected by technical factors. TTE can quantitatively evaluate AV valve regurgitation through calculation of regurgitation orifice area, regurgitation volume and regurgitation fraction. These methods have been shown to have a good correlation when used for mitral valves compared to cardiac catheterization and CMR in adults. However, quantitative techniques are time consuming and require multiple measurements and more complex calculations. A simpler technique of objectively characterizing the regurgitation of the AV valves by TTE is measuring the width of the vena contracta (VC). The VC is the narrowest portion of a regurgitant jet which occurs at the level of or just below the valve leaflets and represents the effective regurgitant orifice. In adult studies, this method has shown that increase in VC width of the mitral valve strongly correlates with qualitative angiographic grades and quantitative measurements of regurgitant volume by cardiac catheterization and is a better assessment of regurgitation than measuring the regurgitant jet by TTE. Changes in VC width also had strong correlation with quantitative measurements of regurgitant volume and regurgitant orifice area using TTE. It is our intent to evaluate the feasibility and correlation of measurements of AV valve regurgitation by TTE with focus on the VC in pediatric patients compared to the non-invasive "gold standard" measurements by CMR.