Heart

Question 1

Quinidine

Answer 1

• Class 1A Anti-arrhythmic (delays redepolarization)
• treats both supra/ventricular arrhythmias
• increases sympathetic tone-increase HR
• alpha adrenergic antagonist: vasodilation and negative inotropy
• mostly used for horses with atrial fibrillation
• contraindications: bradyarrhythmias and heart failure
• side effects: hypotension, GI effects

Question 2

Procainamide

Answer 2

• Class 1A anti-arrhythmic (delays redepolarization)
• less autonomic effects then quinidine
• used for atrial and ventricle tachyarrhythmias
• 2nd option for ventricular tachycardia
• contraindications : bradyarrhythmias
• fewer side effects then quinidine

Question 3

Lidocaine

Answer 3

• Class 1B anti-arrhythmic
• only used for ventricular tachyarrhythmias (first option)
• does not suppress contractility or vasodilation
• high first pass effect
• lower doses in cats and horses
• contraindicated for all bradyarrhythmias
• side effects are uncommon
• only IV

Question 4

Mexiletine

Answer 4

• Class 1B anti-arrhythmic
• PO
• same as lidocaine
• can combine with class 2 or 3 to increase effect

Question 5

Propranolol

Answer 5

• Class 2 anti-arrhythmic
• non selective B-blocker
• first generation B-blocker
• highly protein bound
• caution when giving to patients with respiratory disease or diabetes
• lipophilic

Question 6

Atenolol

Answer 6

-Class 2 anti-arrhythmic
-most common
second generation
-selective B1 blocker
-longer half life then propranolol
-hydrophilic

Question 7

Esmolol

Answer 7

• Class 2 anti-arrhythmic
• selective B1 blocker
• second generation
• VERY short half life, good because we use it for emergency situation and can give a better drug later
• only IV

Question 8

Amiodarone

Answer 8

• Class 3 anti-arrhythmic
• prolongs AP and increases refractory period for ALL cardiac tissue
• also exhibits class I,II,IV, and alpha 1 effects
• LOTS of side effects: pulmonary fibrosis (most common), skin discoloration (blue skin), CNS, GI, elevation of liver enzymes, corneal microdeposits, hypothyroidism
• clinical effects are delayed for several weeks, loading dose is usually needed
• contraindication : patients with long QT syndrome

Question 9

Sotalol

Answer 9

• Class 3 anti-arrhythmic
• prolongs AP and increases refractory period in myocardial cells
• also has potent non-selective class II effects(first generation Beta-blocker)
• side effects are rare
• used to prevent sudden death in boxers with arrhythmogenic right ventricular cariomyopathy, DADs, and re-entry

Question 10

Diltiazem

Answer 10

• Class 4 anti-arrhythmic
• potent on nodal tissue
• used for supra ventricular tachyarrthythmias
• minimal vascular effects

Question 11

Amlodipine

Answer 11

• Class 4 anti-arrhythmic
• minimal cardiac effects
• used for hypertension and after load reduction
• very good vasodilator

Question 12

Furosemide

Answer 12

• loop diuretic
• less Na loss
• used for acute pulmonary edema and congestive heart failure
• causes increase in renin secretion
• always give in combination with an ACE inhibitor
• sulfonamide diuretic
• decreases reabsorption of Na and Cl in thick ascending look of H by competing for Cl site –> leads to parallel decreased of Ca reabsorption
• used in cardiac, renal, and hepatic dysfunction, pulmonary edema
• can help in treatment of hyperCa
• many routes for intake

Question 13

Torsemide

Answer 13

• loop diuretic

- longer duration and 10x more potent then furosemide

Question 14

Spironolactone

Answer 14

• K sparing diuretic
• does not work on the luminal side
• competitive antagonist of aldosterone (which wants to re-absorb Na)
• blocks aldosterone stimulated Na reabsorption therefore also blocking K + H excretion in late distal tubule (bind to its receptor on late distal tubule to increase Na, Ca, H2O excretion and decrease K loss)
• weak when given alone, needs to be given with something else to achieve sequential nephron blockade

Question 15

Mannitol

Answer 15

• osmotic diuretic
• freely filtered
• imparts H2O reabsorption
• increases blood volume, never give on CHF patients

Question 16

Digoxin

Answer 16

• cardiac glycoside
• positive inotrope
• stop giving it if DAD is present
• block Na/K pump so cell has way too much Na inside -> cell exchanges Na for Ca -> more cytoplasmic Ca for contraction
• direct stimulation of vagal nuclei causing some parasympathetic actions (slower AV)
• used for systolic myocardial failure and AF
• dose is based on lean body weight–> does not go to fat, ascitic fluid (not predictable dose response)
• renal excretion
• narrow therapeutic window
• cardiac toxicity (when 60-70% of channels are blocked); CNS; GI
• predisposition to toxicity in cases of hypoK, azotemia
• serum levels should be checked constantly
• lower therapeutic levels then before

Question 17

Dopamine

Answer 17

• synthetic catecholamine/ Beta 1 agonist
• effects alpha, B1 and DA receptors depending on doses
• -> low doses: DA for vasodilation (mostly renal)
• ->med doses: B1 for positive inotropy
• ->high doses:alpha for vasoconstriction

Question 18

Dobutamine

Answer 18

• synthetic catecholamine/ Beta 1 agonist
• mostly beta 1 effects
• no renal change in BP since both B2 and alpha receptors are stimulated in peripheral blood
• better then dopamine in patients with pump failure

Question 19

Pimobendan

Answer 19

• Ca sensitizing agent
• does not increase O2 consumption so less arrhythmias
• also phosphodiesterase III activity: also systematic and pulmonary vasodilator (inodilator)

Question 20

Nitroglycerin

Answer 20

• venodilator (nitrate forms NO, decreases intracellular Ca)
• -> very short half life because fast conversion to NO
• hepatic metabolism
• heavy, colorless, oil, explosive liquid used in demolition and mining
• topical administration
• questionable effects on the heart

Question 21

Nitroprusside

Answer 21

• venodilator (nitrate forms NO, decreases intracellular Ca) AND arterial
• -> very short half life because fast conversion to NO
• hepatic metabolism
• very effective
• VERY expensive so not used a lot
• CRI

Question 22

Hydralazine

Answer 22

• arterialdilator
• decreases GMP by unknown mechanisms
• used for acute CHF
• can cause hypotension in high doses, and sub sequential reflex tachycardia

Question 23

Sildenafil

Answer 23

• used for pulmonary artery hypertension
• NO activates guanylate cyclase -> GTP converts to cGMP -> phosphodiresterase 5 inhibitor to stop breakdown of cGMP
• increases CO by 20%

Question 24

Enalapril

Answer 24

• ACE inhibitor to minimize RAAS effects
• converted to enalaprilat by liver
• side effects: vomiting, anorexia, and diarrhea are the most common. HyperK due to decrease in aldosterone, reversible renal injury

Question 25

Benazepril

Answer 25

• ACE inhibitor to minimize RAAS effects
• converted to benazaprilat by liver
• side effects: vomiting, anorexia, and diarrhea are the most common. HyperK due to decrease in aldosterone, reversible renal injury