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41 Cards in this Set
- Front
- Back
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What do Positive inotropic drugs do? |
Increase the force of myocardial contraction |
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What do Positive chronotropic drugs do? |
Increase heart rate by altering the rate of impulse formation at the SA node |
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Cardiac glycosides |
•⬆the strength of heart contraction •⬇heart rate •antiarrhythmic effect •⬇signs of dyspnea
Ex: Digotox and Digitoxin *Digotox no longer commercially available b/c of better products w/ fewer side effects |
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Catecholamines |
•⬆force & rate of myocardial contraction •constrict peripheral blood vessels •⬆blood glucose levels Ex: Epinephrine, Dopamine, Dobutamine |
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Epinephrine |
CATECHOLAMINE Receptors: Alpha & Beta
•Bronchodilation •⬆blood glucose levels •⬆heart rate •⬆contractility
Side effects: possible arrhythmias, hypertension |
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Dopamine |
CATECHOLAMINE Receptors: a1 & B1
•precursor to norepinephrine •⬆heart contractility, rate, and BP •used to treat acute heart failure, severe shock, & oliguric renal failure
Side effects: tachycardia, dyspnea, vomiting |
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Catecholamine receptors |
a1: •constriction of peripheral blood vessels ⬇ •constricts blood vessels w/i the area & prevents rapid diffusion of drug away from injection site a2: •affects CNS by causing drowsiness & sedation B1: •⬆HR & force of heart contractions ⬇ •⬆blood glucose levels •treats animals w/ decreased cardiac function B2: •causes Bronchodilation |
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Dobutamine |
CATECHOLAMINE Receptors: beta, slight B2 & alpha •⬆HR & force of contraction •widely used as CRI |
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Inodilators |
•⬆force of heart contraction •⬆vasodilation of peripheral vessels (positive inotrope) •DOES NOT increase oxygen demand of heart •used to treat CHF due to AV valve failure or DCM Side effects: anorexia, lethargy, diarrhea, dyspnea Ex: Pimobendan (Vetmedin (R)) |
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Antiarrhythmic drugs |
•used to correct variation in the normal beating of the heart (which can lead to reduced cardiac output) MEDS EFFECT IN THE HEART •decreased automacity •Alter the rate of electrical impulse conduction •Alter rate of refractory period Ex: Lidocaine, Mexilentine, propanolol, atenolol, amiodarone, sotalol, diltiazom |
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Types of antiarrhythmic drugs |
LOCAL ANESTHETICS •prolongs action potential by working as a local anesthetic to the nerves and myocardial membrane MEMBRANE STABILIZATION •work by blocking the influx of sodium into the cell, thus stabilizing the myocardium & preventing depolarization (shortens action potential) BETA-ADRENERGIC BLOCKERS •work by blocking beta-adrenergic receptors or by preventing release of norepinephrine from the adrenergic (depresses the depolarization phase) POTASSIUM CHANNEL BLOCKERS •works by lengthening the time between action potentials, which decreases the sinus rate (prolongs repolarization) CALCIUM CHANNEL BLOCKERS •works by blocking channels that allow calcium to enter the myocardial cell. (Depresses depolarization and lengthens repolarization) |
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Workload is divided into... |
Preload: volume of blood entering the right side of the heart (usually associated with right-side heart diz) Afterload: force needed to push blood out of the ventricles (usually associated with left-sided heart disease) |
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What is stroke volume? |
Amount of blood ejected from LV with each heart beat |
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What is cardiac output? |
Stroke volume x heart rate (amount of blood pumped from the heart in one minute) |
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How does the heart compensate if it's not functioning properly? |
•⬆heart rate •⬆stroke volume •⬆efficiency of the heart muscle (reducing afterload) •enlarge itself by dilating the chambers or by thickening the myocardium |
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Hypertention results in |
Prolonged force put on the vessels of the vascular system Leads to left ventricle thickening (heart has to work harder to pump out the blood to the body) |
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Hypotention results in |
The tissues of the body not receiving sufficient amount of oxygenated blood Allows wasted products to accumulate and cells to die from lack of oxygen |
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Example of a local anesthetic antiarrhythmic drug |
No vet labeled products available; not commonly used |
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Example of a membrane stabilization antiarrhythmic drugs |
Lidocaine: depresses myocardial excitement Mexiletine: action similar to Lidocaine |
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Example of beta-adrenergic blocker antiarrhythmic drugs |
Propanolol: depression of SA node and slows AV node conduction Atenolol |
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What drug is useful for chocolate toxicity when HR >200 BPM? |
Propanolol |
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Example of potassium channel blocking antiarrhythmic drugs |
Amiodarone and Sotalol •both drugs increase the duration of the action potential. •used for emergency tx of ventricular tachycardia & fibrillation ****used in animals that are resistant to other drugs |
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Example of a calcium channel blocker antiarrhythmic drug |
Diltiazem: blocks calcium passage, dilating coronary and peripheral blood vessels with results in reduction of cardiac workload |
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Vasodilators |
Dilate arteries and/ or veins, which alleviates vessel constriction and improves cardiac output (reduces afterload) THINK GARDEN HOSE WITH THUMB OVER THE END |
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Examples of vasodilators (categories) |
Angiotensin-converting enzyme (ACE) inhibitors, Angiotensin receptor blockers, arteriole dilators, venodilators, and combined vasodilators |
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ACE inhibitors |
•the prils •venous and arterial vasodilators Ex: Enalapril, Benazepril, Captopril Side effects: hypotention, 'pril' cough, v/d/a, and can elevate renal enzymes so need to monitor! |
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Angiotensin receptor blockers |
Telmisartan •oral solution for cats •helps reduce proteinuria in cats w/ chronic kidney diz Side effects: hypotention, mild GI upset, mild reduced RBC, mild hepatic enzyme increase (reversible) |
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Arteriole dilators |
Hydralazine: used to reduce afterload associated w/ CHF Side effects: hypotention & GI signs |
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Venodilators |
Nitroglycerin: ointment is used to improve cardiac output and reduce pulmonary edema •wear gloves! Also available as a transdermal patch Side effects: rashes and irritation at the site |
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Combined vasodilators |
Prazosin & nitroprusside Side effects: hypotension & GI signs (restlessness with nitroprusside) |
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Calcium channel blockers |
•inhibit the movement of calcium through the myocardial cell membranes and vascular smooth muscle •decreases the force of cardiac contractions Side effects: hypotention & anorexia Ex: Diltiazem •used to treat CHF and hypertension |
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Diuretics |
Increase the volume of urine excreted by the kidneys and thus promote the release of water from the tissues (diuresis) •used in the treatment of hypertention ND pulmonary edema |
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Categories of diuretics |
Loop diuretics, potassium-sparing diuretics, and osmotic diuretics |
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Loop diuretics |
Cl, K, Ca, H, Mg, HCO3 leave... affects loop of Henle Ex: Furosemide (Lasix (R)) Side effects: hypokalemia |
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Potassium-sparing diuretics |
Inhibits aldosterone➡Na leaves➡K stays Ex: Spironolactone Side effects: hyperkalemia |
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Osmotic diuretics |
Osmosis: large molecules that can be filtered by glomerulus but cannot be reabsorbed back into the blood Ex: Mannitol Side effects: vomiting, electrolyte imbalance |
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Name the positive inotropes |
CARDIAC GLYCOSIDES •Digotox •Digitoxin CATECHOLAMINES •Epinephrine •Dopamine •Dobutamine |
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Name the inodilators |
Pimobendan |
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Name the antiarrhythmic drugs |
MEMBRANE STABILIZATION •Lidocaine •Mexiletine BETA-ADRENERGIC BLOCKERS •Propanolol •Atenolol POTASSIUM CHANNEL BLOCKERS •Amiodarone •Sotalol CALCIUM CHANNEL BLOCKERS •Diltiazem |
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Name the vasodilators |
ACE INHIBITORS •Enalapril •Benazepril •Captopril ANGIOTENSIN RECEPTOR BLOCKERS •Telmisartan ARTERIOLE DILATORS •Hydralazine VENODILATORS •Prazosin •Nitroprusside CALCIUM CHANNEL BLOCKERS •Diltiazem |
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Name the diuretics |
LOOP DIURETICS •Furosemide POTASSIUM-SPARING DIURETICS •Spironolactone OSMOTIC DIURETICS •Mannitol |
