Term
| the 5 Objectives in the tx of cardiovascular dz (from book) |
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Definition
1. Control rhythm disturbances
2. maintain or increase cardiac output
a. increase the strength of contraction
b. decrease the afterload
(1) Arteriolar dilator
c. Decrease the preload
(a) Venodilator
3. Relieve fluid accumulations
a. Diuretics
b. Dietary salt restriction
4. Increase the oxygenation of the blood
a. bronchodilation
5. Ancillary tx
a. Narcotics/sedative
b. Oxygen |
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Term
| the 5 Objectives in the tx of cardiovascular dz (from lecture) |
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Definition
(From lecture)
- control rhythm and rate
- increase/decrease force of myocardial contractions. Dz may affect the ability of the heart to pump
- control fluid accumulation (may be orig used for urinary system)
- increase oxygenation of the blood
- maintain cardiac output (cardiac output = stroke volume x heart rate)
one of the keys to good tissue perfusion |
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Term
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Definition
| the strength of cardiac contractions |
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Term
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Definition
| drugs that improve the strength of cardiac contraction |
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Term
| 4 beneficial effects and one potential toxic effect of the use of cardiac glycosides. |
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Definition
4 beneficial effects
- improved cardiac contractility
- decreased heart rate
- antiarrhythmic effects
- decreased signs of dyspnea
potential toxic effect
- often associated with high or toxic serum levels of drugs
- can include anorexia, vomiting, diarrhea, and various arrhythmias |
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Term
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Definition
| the force of cardiac muscle contraction |
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Term
| • Positive inotropic drugs |
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Definition
| drugs that improve the strength of contraction. . Positive inotropic drugs improve heart function in cases of heart failure (when the heart is not pumping well enough), heart attacks and various types of heart disease. They can be divided into four types based on how they work: Apart from digoxin, other positive inotropic drugs should be used only for acute or end-stage heart failure because their prolonged use has been shown to worsen the disease outcome, and they may even increase the risk of death in some heart failure patients. These drugs can have a short-term benefit for some patients, but they may be harmful with long-term use. In general, calcium levels are increased by positive inotropic drugs. One of the most important factors affecting the strength of the heart's muscular contractions is the level of calcium in the fluid inside the heart's muscle cells. Calcium is one of the most common electrolytes in the human body |
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Term
| • Negative inotropic drugs |
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Definition
| - lessen the heart’s workload by decreasing the rate and strength of the heartbeat. These effects decrease the amt of blood that the heart pumps, the blood pressure in the vessels and the amt of oxygen that the heart uses. Also results in a decrease in the electrical activity of the heart. Although it seems contrary, NIDs are sometimes used to tx heart failure, a condition in which the heart is weakened. NIDS know as beta-blockers significantly improve heart fxn, symptoms, exercise performance and survival in certain types of heart failure. In general, calcium levels are decreased by negative inotropic drugs. One of the most important factors affecting the strength of the heart's muscular contractions is the level of calcium in the fluid inside the heart's muscle cells. Calcium is one of the most common electrolytes in the human body. |
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Term
| • Positive chronotropic drugs |
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Definition
| affects the heart rate by affecting the nerves controlling the heart, or by changing the rhythm produced by the sinoatrial node. Positive chronotropes increase the heart rate |
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Term
| • Negative chronotropic drugs |
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Definition
| affects the heart rate by affecting the nerves controlling the heart, or by changing the rhythm produced by the sinoatrial node. Negative chronotropes decrease the heart rate |
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Term
| • Positive dromotropic drugs |
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Definition
| A dromotropic agent is one which affects the conduction speed in the AV node, and subsequently the rate of electrical impulses in the heart. Positive dromotropic drugs speed conduction. Dromotropic derives from the Greek word "dromos", meaning running, a course, a race |
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Term
| • Negative dromotropic drugs |
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Definition
| A dromotropic agent is one which affects the conduction speed in the AV node, and subsequently the rate of electrical impulses in the heart. Negative dromotropic drugs slow conduction. Dromotropic derives from the Greek word "dromos", meaning running, a course, a race |
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Term
| Catecholamines such as epinephrine are used in veterinary cardiology primarily for __ |
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Definition
| short-term management of severe heart failure due to their short serum half-lives. |
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Term
| List 5 factors that may predispose the heart to arrhythmias |
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Definition
1. conditions that cause hypoxemia
2. electrolyte imbalances
3. increased levels of or increased sensitivity to catecholamines
4. drugs such as digitalis compounds, thiobarbiturates, inhalant anesthetics (halothane), xylazine, and others.
5. cardiac trauma or dz that results in altered cardiac cells |
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Term
| 12. List 6 categories of antiarrhythmic drugs and give an example of each. |
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Definition
(4 basic categories/2 subcategories)
1. Class 1A – includes: quinidine, procainamide
2. Class 1B – includes: lidocaine, tocainide, and mexiletine
3. Class 1C – includes: flecainide and encainide
4. Class II – includes beta-adrenergic blockers (propranolol)
5. Class III – includes bretylium and amiodarone
6. Class IV – includes the calcium channel blockers (verapamil, nifedipine, amlodipine, and diltiazem) |
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Term
| how do vasodilator drugs work? |
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Definition
| Vasodilator drugs act by dilating arteries, veins, or both. Dilatory activity may be brought about by direct action on vessel smooth muscle, through blockage of sympathetic stimulation, or by preventing conversion of angiotension I to angiotension II. Dilation of constricted arteries tends to decrease afterload and improve cardiac output. Preload is also reduced because of pooling of blood in dilated veins |
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Term
| List 4 vasodilator drugs and classify each as arteriodilator, venodilator, or mixed. |
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Definition
1. Hydralazine – primarily arteriolar dilator. Acts directly on smooth muscle in the arterial wall by interfering with calcium movement and inhibiting the contractile state. Net result is that peripheral resistance is reduced and cardiac output is often greatly improved in animals with CHF. Some recommend that hydralazine be used with a diuretic because it may activate the rennin-angiotensin system and cause water retention.
2. Nitroglycerin – primarily a venodilator that reduces preload as a result of pooling of blood in peripheral vessels and decreased venous return to the heart. Some arteriolar dilation may occur at higher doses. Applied topically to the hairless areas of small animal pts. . Used to improve cardiac output and reduce associated pulmonary edema. In equine med, nitro is used as a leg sweat to reduce swelling and to tx laminitis.
3. Prazosin – combined vasodilator. Reduces blood pressure and peripheral vasoconstriction by blocking alpha-1 adrenergic receptor sites. Apparently does not activate the renin-angiotension system. Used for adjunctive tx of CHF, dilated cardiomyopathy in dogs, systemic hypertension, and pulmonary hypertension
4. Angiotensin-Converting Enzyme Inhibitors – ACE Inhibitors – Captopril and enalapril are combined vasodilators that exert their effects of blood vessels by preventing formation of the potent vasoconstrictor angiotension II. They prevent the conversion of angiotension I to angiotension II by inhibiting ACE. Both products may be administered with cardiac glycosides and furosemide. |
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Term
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Definition
| primarily arteriolar dilator. Acts directly on smooth muscle in the arterial wall by interfering with calcium movement and inhibiting the contractile state. Net result is that peripheral resistance is reduced and cardiac output is often greatly improved in animals with CHF. Some recommend that hydralazine be used with a diuretic because it may activate the rennin-angiotensin system and cause water retention. |
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Term
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Definition
| primarily a venodilator that reduces preload as a result of pooling of blood in peripheral vessels and decreased venous return to the heart. Some arteriolar dilation may occur at higher doses. Applied topically to the hairless areas of small animal pts. . Used to improve cardiac output and reduce associated pulmonary edema. In equine med, nitro is used as a leg sweat to reduce swelling and to tx laminitis. |
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Term
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Definition
| combined vasodilator. Reduces blood pressure and peripheral vasoconstriction by blocking alpha-1 adrenergic receptor sites. Apparently does not activate the renin-angiotension system. Used for adjunctive tx of CHF, dilated cardiomyopathy in dogs, systemic hypertension, and pulmonary hypertension |
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Term
| Angiotensin-Converting Enzyme Inhibitors |
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Definition
| ACE Inhibitors – Captopril and enalapril are combined vasodilators that exert their effects of blood vessels by preventing formation of the potent vasoconstrictor angiotension II. They prevent the conversion of angiotension I to angiotension II by inhibiting ACE. Both products may be administered with cardiac glycosides and furosemide. |
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Term
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Definition
3. Furosamide
Generic name: Furosamide
Trade name: Lasix
Specific properties:
Used for diuretic therapy for pulmonary edema and other signs and symptoms of chronic heart failure. Furosamide works by causing diuresis. It reduces the reabsorption of sodium and other electrolytes in the loop of Henle, which is why it is sometimes referred to as a loop diuretic. As sodium ions remain in the kidney tubules (the loop of Henle or the distal tubules) the increased osmotic pull on water molecules caused by the sodium ions causes more water to be retained by the tubules and voided as urine. The diuresis causes decreased preload due to reduced plasma volume.
Adverse Reactions/Precautions:
Hypokalemia (low blood potassium). Potassium supplementation may be needed.
Weakness and shock (must be used ith caution in dehydrated or shocky animals)
Dehydration
Hyponatremia (low blood sodium) |
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Term
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Definition
7. Epinephrine
Generic name: Epinepherine
Trade name: Adrenalin Chloride
Specific properties:
Used for short-term treatment of severe heart failure, increases cardiac contractions through beta-1 receptor stimulation. Aids the circulatory systems after heart failure. It is also used to treat anaphylaxis.
Adverse Reactions/Precautions:
Used only for short-term treatment, it may increase the potential for arrhythmias and makes the heart work much harder. Other side effects include hypertension (high blood pressure), anxiety and excitability |
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Term
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Definition
6. Lidocaine
Generic name: Lidocaine
Trade name: N/A
Specific Properties
Antiarrhythmic that is given intravenously. May be used to control Premature Ventricular Contractions (PVCs). Also used to treat ventricular tachycardia/off-label use for ventricular arrhythmias. Lidocaine prevents depolarization and decreases cell automaticity through blocking sodium ions from entering the cell, thus stabilizing myocardial cell membranes,
Adverse reactions/Precautions
Major precaution – care must be taken to ensure that lidocaine given for an arrhythmia does not contain epinephrine, as that catecholamine increases heart workload and increases the potential for arrhythmias.
Rare side effects include drowsiness, depression, ataxia, muscle tremors. Cats must be monitored closely for potential nervous system effects. |
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Term
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Definition
5. Pimobendan
Generic name: Pimobendan
Trade name: Vetmedin
Specific Properties:
Used to treat canine atrioventricular insufficiency and dilated cardiomyopathy. Available in chewable form. It is a positive inotropic drug increases the strength of cardiac contractions by affecting the level of calcium in the heart muscle while block the enzyme phosphodiesterase.
Adverse Reactions/Precautions
A few side effects – lethargy, anorexia, diarrhea
Contraindications – hypertrophic cardiomyopathy, arotic stenosis, and other physical issues with the heart not related to biochemical disorders. |
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