Sympathetic Nervous System Modulation in Hypertension

This is a study of patients with high blood pressure who are already treated with an angiotensin converting enzyme inhibitor or receptor blocker and have achieved good or fair blood pressure control. The hypothesis is that addition of the beta-adrenergic receptor blocker, sustained-release metoprolol, will provide additional blockade of the sympathetic nervous system, thereby further improving left ventricular filling and blood pressure control.