Heart Failure

The left ventricle (LV) is the heart's major pump. It must be strong enough to continuously pump the majority of the body's blood supply.

Medications that Strengthen Heart Muscle Contractions:
Inotropic and Cardiotonic Drugs

Inotropics and cardiotonics are medications that increase the strength of the muscle contractions that pump blood from the heart. Until recently, the inotropic drug digitalis was the main medical treatment for heart failure.

Digitalis - a drug derived from the foxglove plant that has been used to treat heart disease for more than 300 years - makes the heart's contractions stronger, may reduce heart size, and can lessen the frequency or severity of some heart arrhythmias. Digitalis has not been shown to improve survival of heart patients, but it does relieve symptoms and may reduce hospitalizations. Many experts now prescribe drugs proven to prolong life, such as an ACE inhibitor or beta-blocker before digitalis is tried. Digitalis may be useful, however, especially if used in combination with other agents for patients with:

• Systolic dysfunction characterized by a low ejection fraction, or EF (the percentage, or fraction, of blood pumped out of the heart with each beat)
• Heart failure and atrial fibrillation, a rapid, irregular heartbeat arising in the upper chamber. Digoxin (Lanoxin) is the most commonly prescribed form of digitalis.

A recent study reported that low-dose digoxin may be as effective as higher doses for some patients with mild to moderate heart failure . If side effects exist, but are mild, patients may be able to continue digitalis. In one study, it was found that patients who stopped taking digoxin after using it in combination with ACE inhibitors were at risk for worsening heart failure.

While most medications are generally safe when taken as prescribed, all have potential side effects, and some can be dangerous. Digitalis, for example, can cause abnormal heart rhythms that may be life-threatening. Blood tests may be needed to monitor its levels in the blood. Digitalis, many other medications and some non-prescription substances also can interact with other drugs. It is important that your doctor knows every medication you are taking. You also should not discontinue a medication without consulting with your doctor, and report any worrisome side effects or symptoms immediately.

Common inotropic and cardiotonic drugs include:

• Amrinone (Inocor®)
• Digitoxin (Crystodigin®)
• Digoxin (Lanoxin®, Lanoxicaps®)
• Dobutamine (Dobutrex®)
• Milrinone (Primacor®)

Some drugs may be administered intravenously (IV), which means they are infused continuously through an IV tube, or catheter, into a vein. Dobutamine, for example,may be administered in the home with a device called a portable infusion pump.

Treating heart failure at an early stage offers the best chance for a longer and better quality life. Three classes of medications have been the standard treatments for heart failure: ACE inhibitor; diuretics and digitalis.