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37 Cards in this Set
- Front
- Back
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Arrhythmias can be due to...
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abnormal impulse conduction or abnormal impulse formation
These abnormalities may be caused by trauma, hypoxemia, myocardial disease, inflammation ,acidosis, or any cause of myocardial injury |
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When do arrhythmias need to be treated?
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when they cause hemodynamic dysfunction (low blood pressure/flow) or may result in future complications such as worsening arrhythmias or heart failure due to increased myocardial oxygen consumption and to high or low of a heart rate
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How do class I, II, III, and IV antiarrhythmics work?
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I- sodium channel blocker
2- beta blocker 3. potassium channel blocker 4- calcium channel blocker |
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What is the difference in action potential duration between a Class Ia and Class Ib and Class I c antiarrhythmic?
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class Ia = prolonged action potential
class Ib = shortened action potential Class Ic= no effect on action potential -alterations in action potential can break arrhythmias due to mechanisms such as reentry |
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Class Ia antiarrhythmics include?
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Quinidine
Procanamide Disopyramide |
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Class Ib antiarrythmics include?
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Lidocaine
Phenytoin Tocanide Mexiletine |
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Class Ic antiarrhthymics include?
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flecanide
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Class II antiarrhythmics include
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propranolol
timolol pindolol atenolol esmolol metoprolol caredolol |
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Class III antiarrhythmics include
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brtylium
aminodarone sotolol |
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class IV antiarrhythmics include
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verapamil
diltiazem |
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What is a non classified antiarrhythmic?
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digitalis glycosides
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what drugs can be used for superventricular arrhythmias in dogs like (atrial premature contractions, atrila tachycardia, atrial flutter and atrial fibriliation)
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digoxin, beta blockers, calcium channel blockers, quinidine and procanamide
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For what arrhythmia is quinidine the drug of choice for in horses?
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atrial fibrillation
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what is the goal of theraphy with antiarrhythmics in atrial fibrillation in dogs?
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often the fibrilliation is associated with underlying disease so conversion is difficult or only last a short period. Therefore rate control is often the main goal
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why might digitalis glycosides be better than Ca2+ blockers and Beta Blockers in dogs with atrial fibrillation?
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since many of these dogs have underlying heart disease digitalis glycosides may be better b/c they do not decrease contractilitylike Ca channel blockers and beta blockers
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What drugs are useful for ventricular arrhythmias in dogs?
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lidocaine, mixiletiene , procanamide, beta blockers, sotolol, amidarone
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What is the drug of choice for tachyarrhythmias (superventricular or ventricular) in cats?
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beta-blockers
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what are some adverse effects of procanamide?
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hypotension with rapid injection, can be proarrhythmic, GI distrubance also reported.
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What are the adverse effects of lidocaine?
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CNS abnormalities at high dosese, GI side effects, can be proarrhythmic, hypotenision if given rapidly, cats very senstive, some feel lidocaine should not be used in cats
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Phenotoin can be used to treat arrythmias caused by?
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digitalis
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Which beta blockers are selective Betal 1
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atenolol, esmolol and metopolol
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which beta blockers are selective for beta 1 and beta 2 (not alpha)
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propanolol, timolol, pindolol
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which beta blockers act on beta 1, beta2 and alpha
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carvedilol
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which beta blockers are better at decreasing peripheral vascular resistance (selective or nonselecitve)
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nonselective due to no beta 2 blocakgde
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how do beta blockers decrease RAAS
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via BETA 1 blockade
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What are the pharmacological effects of beta blockers on the heart?
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decreased contractility and decreased heart rate via beta 1 effect.
if block beta 2 can cause increased resistance less vasodilation also can cause bronchospasm |
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why are selective beta blockers better in asthma patients/
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no beta 2 blockage so they do not cause bronchoconstriction
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adverse effects of nonselective beta blockers include
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sudden withdawal can cause tachycardia due to upregulation of beta receptors when on drug
sinus bradycardia and decreased contractility (via Beta1) hypoglycemia (due to beta 2 blocade) bronchospasm via beta 2 hyperkalemia GI side effects sedation |
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what antiarrhythmic has potassium channel blcoking and beta blcoking properites?
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sotolol
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what Ca channel blocker acts more on blood vessel Ca channels and which act more on myocardial Ca channels?
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verapamil, diltiazem work more on heart to slow heart rate and decrease contractility
amlodopine and nicardipine work more on blood vessles causing vessel dilation |
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What are the hemodynamic effects of calcium channel blockers/
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if dilate vessels can decrease afterload
if act on heart can decrease heart rate and contractility |
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how do calcium channel blockers decrease heart rate, contractility or cause vessel dilation?
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they decrease intracellular Ca2+ levels
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How do digitalis glycosides control superventricular arrhythmias?
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they sensitize the baroreceptors so that sympathetic drive is inihibited at a lower pressure
Increased contractility may alos reflexly decrease heart rate. |
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Drugs used in emergency management of hypertension Include:
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nitroprusside, nicardipine, fenolodampam, beta blockers
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drugs used in management of stable hypertenison
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ACE inhibitors, amlodopine, beta blockers, diuretics, hydralazine, angiotensin II antagonists
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why are diuretics less often used for hypertension in animals/
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mechanism of hypertension is often secondary to other disease (eg. renal disease or hyper tension) unlike people which often have primary hypertension. Therefore other drugs appear to be better first line agents
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when is emergency management of hypertension necessary?
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when pressure are very high and resulting in organ injury (stroke, retinal hemorrhage, etc)
drugs used in emergency allow quick titratable control which is necessary in cases of emergency in which organs are starting to be damaged by hypertension. |
