Inotropic Agents
<p>What are inotropes?</p>
<p>Inotropic agents, or inotropes, are medicines that change the force of your heart's contractions. There are 2 kinds of inotropes: positive inotropes and negative inotropes. Positive inotropes <strong>strengthen</strong> the force of the heartbeat. Negative inotropes <strong>weaken</strong> the force of the heartbeat.</p>
<p>Why do I need inotropes?</p>
<p>Both kinds of inotropes are used in the treatment of many different cardiovascular conditions. The kind of inotrope you are given depends on the condition you have. </p>
<p><strong>Positive inotropes</strong> strengthen the heart's contractions, so it can pump more blood with fewer heartbeats. This medicine is usually given to patients with <a class="CPPAGEID_676" href="http://www.texasheart.org/HIC/Topics/Cond/CHF.cfm">congestive heart failure</a> or <a class="CPPAGEID_672" href="http://www.texasheart.org/HIC/Topics/Cond/Cardiomyopathy.cfm">cardiomyopathy</a>. These medicines may also be given to patients who have had a recent <a class="CP___PAGEID_688" href="http://www.texasheart.org/HIC/Topics/Cond/HeartAttack.cfm">heart attack</a>. In some cases, inotropes are given to patients whose hearts have been weakened after heart surgery (in cases of cardiogenic shock). </p>
<p><strong>Negative inotropes</strong> weaken the heart's contractions and slow the heart rate. These medicines are used to treat <a class="CPPAGEID_681" href="http://www.texasheart.org/HIC/Topics/Cond/hbp.cfm">high blood pressure</a> (hypertension), chronic <a class="CPPAGEID_676" href="http://www.texasheart.org/HIC/Topics/Cond/CHF.cfm">heart failure</a>, abnormal heart rhythms (<a class="CPPAGEID_668" href="http://www.texasheart.org/HIC/Topics/Cond/Arrhythmia.cfm">arrhythmias</a>), and chest pain (<a class="CPPAGEID_667" href="http://www.texasheart.org/HIC/Topics/Cond/Angina.cfm">angina</a>). They are sometimes used in heart attack patients to reduce stress on the heart and prevent future <a class="CP___PAGEID_688" href="http://www.texasheart.org/HIC/Topics/Cond/HeartAttack.cfm">heart attacks</a>.</p>
<p>How do inotropes work?</p>
<p>Positive and negative inotropes work in different ways. </p>
<p><strong>Positive inotropes</strong> help the heart pump more blood with fewer heartbeats. This means that although the heart beats less, it also beats with more force to meet the oxygen demands of your body. </p>
<p>For example, one kind of positive inotrope called <a class="CP___PAGEID_2892" href="http://www.texasheart.org/HIC/Topics/Meds/digimeds.cfm">digoxin</a> strengthens the force of the heartbeat by increasing the amount of calcium in the heart's cells. (Calcium stimulates the heart to contract.) When the medicine reaches the heart muscle, it binds to sodium and potassium receptors. These receptors control the amount of calcium in the heart muscle by stopping the calcium from leaving the cells. As calcium builds up in the cells, it causes a stronger force of contraction. </p>
<p><strong>Negative inotropes</strong> include beta-blockers, calcium channel blockers, and antiarrhythmic medicines and they all work in different ways: </p>
<p><strong>Beta-blockers</strong> "block" the effects of adrenaline on your body's beta receptors. This slows the nerve impulses that travel through the heart. As a result, your heart does not have to work as hard because it needs less blood and oxygen. Beta-blockers also block the impulses that can cause an arrhythmia. </p>
<p><strong>Calcium channel blockers</strong> slow the rate at which calcium passes into the heart muscle and into the vessel walls. This relaxes the vessels. The relaxed vessels let blood flow more easily through them, thereby lowering blood pressure. </p>
<p><strong>Antiarrhythmic medicines</strong> slow the electrical conduction in the heart. </p>