Cardiovascular Drugs Flashcards
What are cardiac stimulants used to treat?
Cardiogenic shock
Beta 1 agonists are cardiac stimulants - list them in order of most potent to least.
Isoproterenol
Epinephrine
NE
Dopamine - safest
What is an example of a phosphodiesterase inhibitor that is a cardiac stimulant?
Aminophylline
T/F. Cardiac stimulants are positive chronotropes and positive inotropes.
True
What are the 4 big effects of CHF?
1) increased SNS (catecholamine release stimulated, increased heart rate, arrhythmias, vasoconstriction)
2) increase RAAS (angiotensin II - retain sodium and water - edema.)
3) increase ADH (more edema)
4) myocardial hypertrophy (heart is working really hard to pump blood)
T/F. In CHF, there is too much blood in the body.
False. The volume is adequate but it is not being distributed properly.
What are some ways to treat CHF without drugs?
- decrease sodium intake
- decrease exercise
What is an example of a positive inotrope used to treat CHF? Route of administration?
Digitalis/Digoxin
per os, IV
How does Digitalis work?
increases calcium concentration in the myocardiocytes by inhibiting NaK ATPase and increasing sodium to exchange for Ca –> this gives heart more energy to contract
What is Digitalis used to treat? Why isn’t it used much anymore?
- CHF and atrial arrhythmias in dogs
- narrow safety margin
What would you use in a case of Digoxin toxicity?
Digibind
fluorescent AB that binds to Digoxin in the blood so that it cannot be absorbed
As positive inotropes, when are Dopamine and Dobutamine used?
in emergencies –> 1 dose!
injection
What are 2 examples of injectable inodilators?
Inamrinone
Milrinone
Which is the most commonly used inodilator? Route of administration?
Pimobendan
oral
What is Pimobendan used for?
Treat CHF in DOGS (due to dilated cardiomyopathy of chronic degenerative valvular disease)
How does Pimobendan work?
sensitizes the heart to Ca by enhancing the interaction between Ca and troponin C
When should you NOT use Pimobendan?
- if you can’t increase the CO (i.e., d/t physical abnormalities)
- hypertrophic cardiomyopathy
T/F. ACE inhibitors are vasodilators.
True!
When would you use an ACE inhibitor?
-treat CHF in dogs
What are some examples of ACE inhibitors? Which is used in the US?
Enalapril, Benazapril, Captopril
US: Enalapril
Which diuretics are best to use to treat CHF? Why?
- Potassium sparing diuretics
- because you don’t want to add a K imbalance (like with loops and thiazides) since the heart is already having problems
- also these drugs antagonize Aldosterone and stop the potential issue with RAAS d/t CHF
Which diuretics should you NOT use with CHF?
osmotics (used for LOCALIZED edema)
Which beta blocker is best to use for CHF?
Carvedilol (nonselective Beta and alpha 1 blocker) - inhibits renin in RAAS
- prolongs lifespan of heart failure patients
- used in early CHF to block harmful SNS effects on heart
T/F. Oxygen and nebulizer can be considered drug treatments for CHF.
True
What is an arrhythmia?
An abnormality in the heart rate and rhythm
What are some causes of arrhythmia?
- innervation imbalance (psns vs sns)
- electrolyte imbalance (K, Ca, Mg)
- hypoxemia
Sodium channel blockers are class ___ antitachyarrhythmics.
I
What do antitachyarrhythmic class IA do and which drugs does the class include? IB? IC?
IA - prolongs AP - Quinidine
IB - shortens AP - Lidocaine
IC - not important
T/F. Class I antitachyarrhythmics can affect both atria and ventricles, but MOSTLY does atria.
FALSE. Mostly does ventricle
What is Quinidine used to treat? What antitachyarrhythmic drug class does it belong to?
-ventricular arrhythmias
ATRIAL FIBRILLATION IN HORSES
Class IA
What is Lidocaine used for? What antitachyarrhythmic drug class does it belong to?
- drug of choice for ventricular arrhythmias d/t anesthesia/surgery
- Class IB
What is Phenytoin used for? What antitachyarrhythmic drug class does it belong to?
- treat digitalis-induced arrhythmias in dogs
- Class IB
Which Class II antitachyarrthmic drug is used to treat sudden onset supra ventricular tachycardia?
Propanolol
Which type of tachyarrhythmias do Beta Blockers treat?
supra ventricular and ventricular
What is Bretylium used for? What antitachyarrhythmic drug class does it belong to?
- treat recurrent tachyarrhythmias that do not respond to other drugs –> usually used just by cardiologists
- Class III
What are Verapamil and Diltiazem used for? What antitachyarrhythmic drug class does it belong to?
- treat supra ventricular tachyarrhythmias, myocardial hypertrophy in cats
- Class IV
Which Antitachyarrhythmic drugs only treat atrial arrhythmias?
Class IV
What are the MOA of the 4 classes of antitachyarrhythmic drugs? An examlple of each? What type of arrhythmias they are used for?
Class I: Na channel blockers (IA: prolong AP, Quinidine, supra ventricular and ventricular; IB: shortens AP, Lidocaine/Phenytoin, ventricular)
Class II: Beta blockers, Propanolol, supraventricular and ventricular
Class III: K-channel blockers, Bretylium, ventricular (mainly)
Class IV: Ca-channel blockers, Verapamil/Diltiazem, supraventricular
What are the main drugs you would use to treat atrial tachyarrhythmias?
Digoxin, Ca-channel blockers
What is the main drug you would use to treat ventricular tachyarrhythmia?
Lidocaine
What is the drug of choice to treat supra ventricular and ventricular tachyarrhythmias in CATS?
beta blockers
Which drugs are used to treat bradyarrhythmias? Which degrees of bradyarrhythmia?
1) Incomplete AV block: Atropine or Isoproterenol
2) Sinus bradycardia: Atropine or Isoproterenol
3) Complete AV block: epinephrine
Your patient has an incomplete AV block causing bradyarrhythmia and also has low blood pressure, which drug should you treat them with?
Atropine
NOT Isoproterenol because of the low BP (has strong B2 effects)
What are the #1, #2, and #3 vasoconstrictors?
1- phenylephrine (selective alpha 1 agonist)
2 - NE (nonselective alpha agonist)
3 - Epinephrine (nonselective alpha agonist)
What direct and indirect sympathomimetics are vasoconstrictors?
ephedrine
pseudoephedrine
phenylpropanolamine (PPA)
When should you use nonselective alpha blockers as vasodilators?
emergency hypertension - 1 dose
penotalmine, phenoxybenzamine
Selective alpha blocker: ________
Vasodilator or Vasoconstrictor?
Prazosin
vasodilator
Presynaptic alpha 2 agonist: ______________
does it increase or decrease BP?
Clonidine
decreases BP
Nonselective Beta locker used as a vasodilator
Propanolol
A beta and alpha 1 blocker that is used as a vasodilator
Carvedilol
A selective beta1 blocker used as a vasodilator
Atenolol
Which ACE inhibitor is available in the USA?
Is it long or short acting?
Enalapril
short acting
What is the route of administration for ACE inhibitors?
oral or injectable
What are ACE inhibitors used to treat?
CHF
long term hypertension
chronic renal insufficiency
What are some adverse effects of ACE inhibitors?
hypotension
decreased GFR
Captopril may cause idiosyncratic glomerular disease in some dogs
What is Losartan?
an angiotensin II antagonist
T/F. Hydrazine only dilates arteries.
True
What are 2 direct acting vasodilators?
Hydralazine
Nitrates (make NO)
Verapamil, Diltiazem, Amlodipine, Nifedipine are…
Calcium channel blockers
How do calcium channel blockers act on blood vessels?
direct vasodilators by inhibiting myocardial contraction
Verapamil is a (+/-) chronotrope and a (+/-) inotrope.
negative chronotrope
negative inotrope
What are calcium channel blockers used to treat?
tachyarrhythmia
hypertension
myocardial hypertrophy (Ditiazem)
antianginal
Which drugs are best to use for treating hypertension in cats that do NOT have hyperthyroidism?
Calcium channel blockers (verapamil, diltiazem, amlodipine, nifedipine)
Which drugs should you use to treat a hypertensive cat with hyperthyroidism?
Beta blockers
Which calcium channel blocker is the best to treat myocardial hypertrophy?
Dilitiazem
Systolic and Diastolic Which do... Beta blockers treat? Calcium channel blockers treat? ACE inhibitors treat?
B-blockers: systolic and diastolic
Ca channel blockers: systolic and diastolic
ACE inhibitors: diastolic ONLY
