RecruitingDrug trialUse of Phenylephrine for Assessment of Mitral Regurgitation SeverityThe study proposes to develop a phenylephrine protocol to be used during transesophageal echocardiography, whereby intravenous phenylephrine would be used to increase afterload with the intent to mimic the awake hemodynamic profile and variation that occurs with normal physical activity. The expectation is to see changes in severity of Mitral Regurgitation (MR) grade with increasing afterload, which in turn can provide more accurate quantification of MR severity to assist in clinical decision making.