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ISCHEMIC HEART DISEASE

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Ischemic heart disease is simply when the oxygen supply to the heart does not match the demand. Often this means that the coronary blood vessels have a reduced diameter limiting the blood flow to the heart.

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Pharmacologically, the treatment of coronary artery disease focuses on the reduction of myocardial oxygen demand.

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To reduce myocardial oxygen demand, β-blockers (Chapters 10 and 11) can be used to decrease heart rate and contractility. Calcium channel blockers (Chapter 11) reduce systemic vascular resistance and decrease myocardial contractility. Nitrates (Chapter 11) will produce venous dilation, which will decrease preload and decrease oxygen demand by the heart. Finally, antiplatelet drugs (Chapter 14), such as aspirin, will prevent thrombus formation in the coronary arteries. Lipid-lowering drugs (Chapter 15) have been shown to reduce the risk of heart attacks in patients with coronary artery disease.

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Unstable angina is treated with nitroglycerin, antiplatelet, and anticoagulant drugs. Finally, acute myocardial infarction is treated with thrombolytic agents (Chapter 14).

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CONGESTIVE HEART FAILURE

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Heart failure occurs when the heart can no longer pump enough blood to meet the demands of the body. After removal or correction of the precipitating cause, further treatment of heart failure involves management of the symptoms. Standard treatment for hospitalized patients has been a loop diuretic (Chapter 11) with a vasodilator that is rapidly acting. Sometimes a drug that increases contractility is also added or used in place of the vasodilator.

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Treatment of heart failure is targeted toward decreasing cardiac workload, controlling excess fluid, and enhancing myocardial contractility.

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REDUCTION OF CARDIAC WORKLOAD

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Angiotensin-converting enzyme (ACE) inhibitors lessen the symptoms of heart failure by reducing cardiac workload.

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Achieving a reduction in cardiac workload can be as simple as reducing physical activity or keeping heart rate low pharmacologically with a β-blocker or by inhibiting the cardiac pacemaker (ivabradine). Alternatively, vasodilator therapy can be used. ACE inhibitors (Chapter 11) are usually used in this instance. ACE inhibitors have been shown to improve symptoms, slow the progression of the heart failure, and prolong survival. The angiotensin II receptor antagonists are also used.

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Other vasodilators can also be used to reduce the cardiac workload. Studies have shown that the combination of hydralazine and isosorbide dinitrate can produce improvement in patients with heart failure.

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Nitroprusside is used in the treatment of acute heart failure because it reduces both preload and afterload without affecting contractility.

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Nesiritide is a recombinant form of human B-type natriuretic peptide, a naturally occurring hormone produced by the ventricle. It produces natriuresis, diuresis, and vasodilation by increasing intracellular cyclic guanosine monophosphate (cGMP) levels. It is used for relief of the dyspnea in patients with heart failure. Neprilysin ...

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