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Fundamentals of Pharmacology for Veterinary Technicians . Chapter 8 Cardiovascular Drugs. Basic Anatomy and Physiology. The functions of the cardiovascular system include delivery of oxygen, nutrients, and hormones to the various parts of the body
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Fundamentals of Pharmacology for Veterinary Technicians Chapter 8 Cardiovascular Drugs © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Basic Anatomy and Physiology • The functions of the cardiovascular system include delivery of oxygen, nutrients, and hormones to the various parts of the body • The cardiovascular system also transports waste products to the appropriate waste removal system © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Basic Anatomy and Physiology © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Basic Anatomy and Physiology • The electrical impulses of the heartbeat originate in the sinoatrial node (SA node) • Heart rate is controlled primarily by the autonomic nervous system: • Stimulation of the parasympathetic nervous system slows heart rate • Stimulation of the sympathetic nervous system increases heart rate © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Basic Anatomy and Physiology • Workload of the heart is divided into preload and afterload • Preload: volume of blood entering the right side of the heart • Afterload: force needed to push blood out of the ventricles • If the heart is not working properly, it can compensate by a few mechanisms: • Increase heart rate • Increase stroke volume • Increase efficiency • Enlarge itself © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Cardiovascular Drugs • Types of cardiovascular drugs • Positive inotropic drugs: increase the force of myocardial contraction • Negative inotropic drugs: decrease the force of myocardial contraction • Positive chronotropic drugs: increase heart rate by altering the rate of impulse formation at the SA node • Negative chronotropic drugs: decrease heart rate by altering the rate of impulse formation at the SA node • Positive dromotropic drugs: increase the conduction of electrical impulses • Negative dromotropic drugs: decrease the conduction of electrical impulses © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Cardiovascular Drugs • Positive inotropes • Cardiac glycosides: • Increase the strength of cardiac contractions, decrease heart rate, have an antiarrhythmic effect, and decrease signs of dyspnea • Side effects include anorexia, vomiting, diarrhea, and cardiac arrhythmias • Examples include digoxin and digitoxin • Catecholamines: • Increase the force and rate of myocardial contraction, constrict peripheral blood vessels, and increase blood glucose levels • Examples include epinephrine, dopamine, dobutamine, and isoproterenol © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Cardiovascular Drugs • Antiarrhythmic drugs • Used to correct variation in the normal beating of the heart (which can lead to reduced cardiac output) • Types of antiarrhythmic drugs include local anesthetics, membrane stabilizers, beta-adrenergic blockers, action potential prolongation drugs, and calcium-channel blockers • Examples of antiarrhythmic drugs are listed in Table 8-3 © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Cardiovascular Drugs • Vasodilators • Drugs used to dilate arteries and/or veins, which alleviates vessel constriction and improves cardiac output • Examples include angiotensin-converting enzyme inhibitors, arteriole dilators, venodilators, and combined vasodilators © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Cardiovascular Drugs • Diuretics • Drugs that increase the volume of urine excreted by the kidneys and thus promote the release of water from the tissues (lowers the fluid volume in tissue) • Used in the treatment of hypertension • Categories of diuretics include thiazides, loop diuretics, potassium-sparing diuretics, osmotics, and carbonic anhydrase inhibitors • Examples are listed in Table 8-4 © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Cardiovascular Drugs • Anticoagulants • Inhibit clot formation by inactivating one or more clotting factors • Used to inhibit clotting in catheters, to prevent blood samples from clotting, to preserve blood transfusions, and to treat emboli • Examples include heparin, EDTA, coumarin derivatives, aspirin, and blood transfusion anticoagulants © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Cardiovascular Drugs • Hemostatic drugs • Help promote the clotting of blood • May be parenteral or topical • Parenteral • Vitamin K1 • Protamine sulfate • Topical • Silver nitrate, hemostat powder, gelfoam gelatin sponges, thrombogen topical thrombin solution © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.
Cardiovascular Drugs • Blood-enhancing drugs • Affect RBCs • Affect the production or quality of RBCs • Examples: • Iron • Erythropoietin © 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.