An ACE inhibitor (or angiotensin-converting-enzyme inhibitor) is a pharmaceutical drug used primarily for the treatment of hypertension (elevated blood pressure) and congestive heart failure. This group of drugs causes dilation of blood vessels, which results in lower blood pressure. In treating heart disease ACE inhibitors are usually used with other medications. A typical treatment plan will often include an ACE inhibitor, beta blocker, a long-acting nitrate and a calcium channel blockerin combinations that are adjusted to the individual patient's needs.