How nitrates treat systolic heart failure
Nitrates are medicines that act as vasodilators because they mimic the effect of one of the body's own natural chemicals called nitric oxide, which causes arteries and veins to widen (dilate).
Nitrates can improve heart failure symptoms by:
- Dilating the coronary arteries. These are the arteries that carry blood to the heart itself. If your heart failure is caused by coronary artery disease, increasing the width of these arteries may help deliver more blood to your heart and may help it pump more efficiently.
- Dilating the veins. The large veins of the body, particularly in the legs, have the ability to hold a lot of blood. By dilating these veins, nitrates reduce the amount of blood returning to the heart, thereby reducing the buildup of fluid in your lungs.
- Dilating the systemic arteries. Systemic arteries are blood vessels that carry blood to the rest of the body (excluding the heart and lungs). The blood pressure in these arteries determines how hard your heart needs to pump. By dilating these arteries, nitrates may relieve some of the work your heart needs to do.
- Dilating the pulmonary arteries. Dilating the arteries of the lungs (pulmonary arteries) also reduces the amount of work your heart needs to do. This effect is particularly helpful for the right side of your heart, which is often weakened along with the left side of the heart in some forms of heart failure.
How well do nitrates work? Organic nitrates are usually prescribed with other drugs such as hydralazine, angiotensin-converting enzyme (ACE) inhibitors, digoxin, and diuretics. Nitrates typically improve symptoms when they are used in combination with these other drugs, but they do not increase the survival rate for people with heart failure. Nitrates have been proven to reduce the rate of death from heart failure only when they are prescribed together with the vasodilator hydralazine. The combination of hydralazine and a long-acting nitrate compound is particularly useful for people who cannot tolerate taking ACE inhibitors. Nitrates are also a good choice for people with heart failure who also have coronary artery disease, because these agents can dilate the coronary arteries.
How common are nitrates in treating systolic heart failure? Nitrates are considered a second choice in medicine for heart failure. Your doctor probably will prescribe a nitrate in addition to first-choice drugs like diuretics, ACE inhibitors, and beta-blockers.
A more convenient way of taking a nitrate is by using a patch (for example, Nitro-Dur) that you wear on the skin for about 12 hours per day. One problem with all nitrates is that your body can become "tolerant" and no longer respond if exposed to the nitrates for too long. For this reason, the patch should be taken off at night, and pills should be taken only during the day.
| Author: | Robin Parks, MS | Last Updated: September 1, 2006 |
| Medical Review: | Caroline S. Rhoads, MD - Internal Medicine Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology | |
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