Heart Failure Medication


Medications can help alleviate the symptoms of heart failure, but they can't cure it.
Medications can help alleviate the symptoms of heart failure, but they can't cure it.
© istockphoto/erichood

Heart failure is a chronic, progressive condition in which a damaged heart fails to beat as well as a normal heart. As a result, the body's cells are not able to get the blood and oxygen they need to function properly. Among people over 65 years of age who are admitted to the hospital, heart failure is the most common diagnosis. And because the American population is aging, the number of heart failure diagnoses is increasing every year.

Symptoms associated with heart failure include:

  • Rapid heartbeat
  • Unusual fatigue during exertion
  • Shortness of breath during mild exercise
  • Buildup of fluid in various parts of the body
  • Inability to withstand cold
  • Attacks of shortness of breath and coughing when lying in bed that are relieved only by sitting or standing

As the heart becomes unable to effectively pump out the blood that enters its chambers, fluids tend to build up in the body, a condition called fluid overload that's responsible for many of these symptoms. Improving heart function along with reducing fluid overload can dramatically improve these symptoms. Let's take a look at the kinds of drugs that are most commonly used to treat heart failure, and then see how they're used.

Types of Heart Failure Medication

Diuretic Drugs

Diuretic drugs help the kidneys excrete more sodium in the urine. The sodium, because it associates with water, takes excess water with it. The reduction in the amount of fluid flowing through the blood vessels reduces pressure on the blood vessel walls. Doctors will probably suggest that a patient taking diuretics should make some changes in his or her lifestyle, such as eating a low-sodium diet.

There are three main classes of diuretic medicines, each of which works a little differently.

  • Thiazide diuretics moderately increase urine output and also act to widen blood vessels, helping to lower blood pressure in two ways. This is the most prescribed type of diuretic.
  • Loop diuretics are stronger than thiazides. They produce more effective elimination of sodium and a greater increase in urine flow.
  • Potassium-sparing diuretics are often prescribed in combination with thiazide and loop diuretics. As their name suggests, they help prevent the loss of too much potassium, which can be a problem with other types of diuretics.

Diuretic drugs sometimes become less effective over time, resulting in a condition called diuretic resistance. In some instances, diuretic resistance is treated with a non-drug therapy called ultrafiltration in which the excess fluid is filtered out of the blood.

Vasodilator Drugs

Vasodilator drugs relax the smooth muscles that line blood vessel walls, causing the blood vessels to dilate and allow an increased amount of blood to flow through them. This has two beneficial effects -- it's easier for the heart to pump blood, and the blood pressure goes down. So, vasodilator drugs relieve symptoms associated with heart failure and treat high blood pressure. Uncontrolled high blood pressure puts a burden on the heart and the blood vessels that can lead to permanent damage over time, so controlling it is important.

Inotropic Drugs

There are two basic types of inotropic drugs: Positive inotropic drugs increase the force of the heart's muscular contractions, and negative inotropid drugs decrease it. By decreasing stress on the heart, negative inotropic drugs decrease blood pressure, the volume of blood that the heart pumps and electrical activity in the heart.

On the next page we'll learn about how and when doctors usually prescribe these drugs.

The Course of Treatment for Heart Failure

Treatment of mild heart failure usually starts with an ACE inhibitor, the most common vasodilator drug for heart failure patients. Studies have shown that ACE inhibitors are beneficial for treating heart failure symptoms and prolonging the life of patients with chronic heart failure. They also help increase the excretion of sodium and water, helping to reduce fluid overload.

One of the next steps is often the use of a type of negative inotropic drug called a beta-blocker. Studies have shown that beta-blockers can benefit heart failure patients by improving their symptoms and heart function, and, in some cases, the chance of survival.

In more severe heart failure, a diuretic is added. Even if diuretics alone controls a patient's symptoms, they should be used in combination with an ACE inhibitor and often a beta-blocker. A thiazide diuretic may be sufficient -- if not, a loop diuretic is used.

Diuretic drugs are used in most heart failure patients because heart failure leads to retention of sodium and water by the kidneys, which can lead to fluid overload. Congestion in the lungs can interfere with their ability to exchange oxygen from the air and can be life-threatening. Doctors prescribe diuretic drugs for all patients with heart failure who have evidence of fluid overload, such as lung congestion, raised jugular venous pressure or peripheral edema, and most heart failure patients are eventually placed on a diuretic drug.

Doctors usually start patients on a low dose of a diuretic and increase the dose until the effective range is reached. When the diuretic is working effectively, the patient will lose weight because of fluid loss. If a patient doesn't respond even to high doses of a diuretic, a doctor will often prescribe intravenous administration or more than one diuretic. Sometimes diuretics work better in combination. Patients are usually maintained on a diuretic, once it is working, to prevent episodes of fluid overload. Periodic adjustments may be needed in the dose, and care must be taken to prevent side effects like:

  • Imbalances in electrolytes (small molecules in the fluids in our bodies, like sodium)
  • Inappropriate activation of some hormonal systems
  • Low blood pressure
  • Increase in level of serum creatinine (a chemical in the blood that's used to measure kidney function)
  • Symptoms of kidney failure
  • Interactions with other drugs

If heart failure is so severe that a combination of an ACE inhibitor and a diuretic fails to relieve symptoms, digoxin, the most commonly prescribed positive inotropic drug, may be added. Studies have shown that digoxin can reduce the symptoms of patients who are already receiving diuretics and ACE inhibitors. The prolonged use of other positive inotropic drugs has been shown to increase the risk of death in some heart failure patients -- so they should only be used for acute or end-stage heart failure.

For more information about heart failure treatments and medications, take a look at the links on the next page.

Related HowStuffWorks Articles

More Great Links

Sources

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