Use of Phenylephrine for Assessment of Mitral Regurgitation Severity

Inclusion Criteria: * Patients 18 years or older with MR on baseline echocardiographic evaluation who are scheduled to undergo TEE for further evaluation of mitral regurgitation. Exclusion Criteria: * The following patients will be excluded from the study: 1. Patients who are not clinically eligible for TEE. 2. Patients with contraindications to esophageal intubation. 3. Patients with hemodynamic instability. 4. Patients with acute decompensated heart failure (HF). 5. Patients with un-revascularized severe coronary artery disease (triple vessel or left main disease). 6. Patients with ongoing unstable angina or ongoing myocardial infarction (MI) 7. Patients with significant arrhythmias including atrial fibrillation. 8. Patients with uncontrolled hypertension (BP ≥ 150/90 mmHg). 9. Patients with preexisting bradycardia (HR \< 50) and heart blocks. 10. Patients with severe symptomatic peripheral vascular disease. 11. Patients with severe pulmonary hypertension (estimated systolic pulmonary arterial pressure sPAP ≥ 60mm Hg). 12. Patients who are at high risk for intracranial bleeding such as patients with previous strokes, transient ischemic attack (TIA) and vascular malformations. 13. Additionally, patients with mean arterial blood pressure MAP \> 100 mmHg during TEE and those with severe MR, effective regurgitant orifice area (ERO \> 39cm2) on baseline TEE evaluation will not be given phenylephrine and excluded from the study.