Cardiovascular Flashcards
Quinidine mechanism of action
Blocks fast Na channels in open or active state
Increases Action potential duration and effective refractory period
Blocks K channels causing prolonged repolarization
Muscarinic receptor blockade which can increase HR and AV conduction
Vasodilation via Alpha block and possible reflex tachycardia
Quinidine used for
Orally effective used for many arrhythmias and atrial fibrillation
Need INITIAL DIGITALIZATION to slow AV conduction
Quinidine adverse affects
1) Cinchonism (GI, tinnitus, ocular dysfunction, CNS excitation)
2) Hypotension
3) Prolongation of QRS and increase in QT interval associated with Syncope (torsades)
4) Black water Fever
Quinidine drug interactions
Hyper K enhances effects and Hypo K decreases affects
Displaces Digoxin from tissue binding sites enhancing toxicity
Procainamide mechanism of action
Blocks fast Na channels that are open or activated
Incarease action potential duration and effective refractory period
Blocks K channels
Has less Muscarinic receptor block
Metabolized via N-acetyltransferase to N-acetyl procainamide, an active metabolite
Procainamide used for
Antiarrhythmia
Procainamide adverse affects
SLE - like syndrome in slow acetylators
Hematotoxicity causing thrombocytopenia and agranulocytosis
Torsades
Class 1A antiarrythmics drugs
1) Quinidine
2) Procainamide
Class 1A antiarrhythmics MOD
1) block fast, active Na Channels
2) Block K channels
3) Some Muscarinic receptor blockade
Increases APD and ERP
Affect Phase 0
Disopyramide action
Class 1A antiarrythmic with the most M blockade
Not used for arterial arrythmia
Used for VENTRICULAR arrhythmia
Drugs that cause SLE- like disease
1) Procainamide
2) Isoniazid
3) Hydralazine
Lidocaine mechanism of action
Block fast Na channels in inactivated state (damaged tissue)
Decrease APD due to block of SLOW Na “window” currents - increases diastole and extends the time for recovery
Give in IV to prevent First Pass metabolism
Lidocaine used for
Arrythmias due to:
1) post MI
2) Open-heart surgery
3) Digoxin toxicity
Lidocaine adverse affects
CNS toxicity causing seizures
Mexiletine mechanism of action
Blocks fast Na channels in inactivated state
Given orally
Same as Lidocaine
Tocainide mechanism of action
Blocks fast inactivated Na channels
Same as Lidocaine
Given orally
Tocainide adverse affects
can lead to agranulocytosis and decrease on other blood cells
Class 1B drugs
Lidocaine
Mexiletine
Tocainide
Class 1B drugs Mechanism of action
Blocks fast, inactivated Na channels
Blocks slow Na channels
Found in Ischemic tissue
Flecainide mechanism of action
Blocks fast Na channels in His-Purkinje tissue
Has no effect on APD
No ANS effect
Flecainide adverse affects
can cause sudden death post MI
Class 2 drugs
Beta blockers:
1) Propranolol (B1=B2)
2) acebutolol (B1)
3) Esmolol (B1 short acting for SVT)
Class 2 antiarrythmics mechanism of action
Prevent Beta receptor activation decreasing cAMP
Decrease SA and AV nodal activity
Decrease slope of phase 4 (diastolic current) in AP in Pacemaker
Amiodarone mechanism of action
Decreases K channel slowing phase 3 (repolarization) of AP
Increase APD and ERP
Mimics class 1, 2, 3, and 4 antiarrythmics
Large VD and multiple effects
Amiodarone adverse affects
1) Pulmonary fibrosis
2) blue pigmentation of the skin (Smurf Skin)
3) Phototoxicity
4) Corneal deposits
5) Hepatic necrosis
6) Thyroid dysfunction
Sotalol mechanism of action
Decrease conductance of K channels slowing phase 3
Non - selective Beta blockade - Beta 1 leading to decrease HR, AV conduction
Sotalol adverse affects
Torsades (the worst)
Class 3 drus
Amiodarone
Sotalol
Class 3 mechanism of action
Block K channels decrease phase 3
Verapamil and diltiazem mechanism of action
Class 4 antiarrythmics that block Ca Channels
Decrease phae 0 and phase 4
Decrease SA and AV nodal activity
Verapamil adverse affects
1) consitpation
2) dizziness
3) flushing
4) hypotension
5) AV block
6) Gingival hypoplasia
Diltiazem adverse affects
Same as Verapamil minus constipation
Class 4 drugs
Verapamil and Diltiazem
Ca blocks
Class 4 antiarrythmic drug interactions
Additive AV block with Beta blockers and Digoxin
Verapamil displaces Digoxin from tissue-binding sites, increasing Digoxin toxicity
How to treat Torsades
1) Control HypoK
2) Correct HypoMg
3) Discontinue drug causing prolonged QT
4) attempt to shorten APD with Isoproterenol or electrical paceing
Drugs causing QT prolongation (Torsades)
Class 1A and Class 3 drugs
Thioridazine
TCA
Adenosine Action
Causes Gi coupled decrease in cAMP
Decrease SA and AV nodal activity
Adenosine is DOC for
Paroxysmal supraventricular tachycardia
AV nodal arrhythmia
Adenosine adverse affects
1) Flushing
2) Sedation
3) Dyspnea
Adenosine interaction with Methylxanthines
Methyxanthines are Theophylline and caffeine
Adenosine antagonized by Methylxanthines
Methylxanthines will decrease affect of Adenosine
Stratagey for antihypertensives
Decrease TPR - CCB
Decrease CO - Beta blockers, CCB
Decrease body fluids - Diuretics, ACEI, ARB
Decrease BP
Clonodine and Methyldopa Mechanism of action
Alpha 2 agonist that decreases sympathetic outflow
Decreases TPR and HR
Clonodine used for
Mild to moderate hypertension
Opiate withdrawl
Methyldopa used for
Mild to moderate HT
Hypertensive managment in pregnancy
Issue with Clonodine
Can lead to MASSIVE rebound HT if stopped
Reserpine mechanism of action
Decreases presynamptic storage levels decreasing CO and TPR because of decreased Norepi, Dopamine and serotonin in CNS
Reserpine adverse affects
Depression (severe leading to suicide)
Edema
Increase GI secretion
Guanethidine mechanism of action
Inhibit NE release
Adverse affects of Alpha 1 blockers used for HT
1) First dose syncope (sudden fall of BP)
2) Orthostatic Hypotension
3) Urinary incontinence