Cardiac Flashcards
1
Q
Quinedine
A
MOA
- Class 1a (active Na blocker)
- Prolong phase 0 and therefore refractory window = slowed HR
- anti muscurinic and anti alpha
SE
- ANS effects = increase HR
- anti muscurinic = prolonged QT/torsades
- anti alpha = hypotension
- cinchonism (GI distress, tinitis, oculuar, CNS effects)
2
Q
procainamide
A
MOA
- Class 1a (active Na blocker)
- prolong phase 0 and refractory window –> decrease HR
- anti muscurinic
SE
- slow acetylisers = SLE like syndrome
- haematotoxicity
- torsades
3
Q
lidocaine
A
MOA
- Class 1b (inactive Na blocker)
- holds fast Na channel in inactive state, preventing repolarisation (selective for hypoxic tissue)
- blocks slow Na channel and window current –> shorten action potential –> increase diastole, coronary blood flow and CO
SE
- seizures
- cardiotoxic
- IV (first pass metabolism)
4
Q
amiodarone
A
MOA
- Class III (K channel blocker)
- prolong phase 3 and APD/ERP –> decrease HR
- also has class I, II and IV effects
SE
- half life >80 days
- strong protein binding (iodination)
- pulmonary fibrosis
- thyroid dysfunction
- corneal deposits
- hepatotoxic
- smurf skin
5
Q
Non-dihydropyridine Ca channel blocker
A
Peripheral = verapamil Mixed = diltiazam
MOA (anti-arrhythmic)
- class IV
- L type calcium channel blockers
- slow phase 0 of SA and AV nodal cells –> prolong APD/ERP –> decrease HR
SE
- contraindicated in CCF
- AV block (beta blockers, digoxin)
- constipation
- flushing/headache/hypotension
- reflex tachy and gingival hyperplasia for nephidepine
6
Q
beta blockers
A
propanolol = non selective metoprolol = selective
MOA (anti-arrhythmic) Class II -blocks B1 receptor in nodal cells, preventing phosphorylation of K/Na/Ca --> decrease Na/Ca influx and K efflux ->Na flattens slope of phase 4 ->Ca flattens slope of phase 0 ->K flattens slope of phase 3 -decreases HR
SE
- sedation
- bronchospasm
- sexual dysfunction
- hyperadrenergic state in withdrawal
- suppress hypoglycaemic symptoms
7
Q
digoxin
A
MOA direct = -inhibition of cardiac Na/K ATPase -> increase intracellular Na and inhibit action of Na/Ca antiporter -> increases intracellular Ca -> increases contractility
indirect
- inhibition of neuronal Na/K ATPase
- > increase in ACh release and bradycardia –> increase diastole and EDV –> increase CO
- > increase NE release and positive inotropy
SE
- long half life (need loading dose)
- displaced by quinedine and verapamil
- cardiac (arrhythmias due to high Na)
- CNS (hallucinations, disorientation, dizziness)
- GI distress
8
Q
dobutamine
A
MOA
- B1 agonist
- > increase cAMP -> increase protein kinase A
- > phosphorylate Ca channels (increasing influx)
- > increase contractility
SE
- tachycardia
- hypertension
- headache
- dyspnoe
- GI distress
9
Q
Nitrates
A
nitroglycerine
MOA
- pro drug of NO
- increases cGMP
- smooth muscle relaxation (particularly large veins)
- > venodilation -> decrease preload -> decrease myocardial work -> decrease oxygen demand
- > decrease infarct size and improve mortality post MI
SE
- headache
- flushing
- palpitations
- orthostatic hypotension + reflex tachy
- peripheral oedema
- tachyphylaxis
Precautions
- contraindications
- > hypovolaemia/hypotension
- > raised ICP
10
Q
Arrhythmia treatment
A
Regular and Narrow Tachy
- ddx
- > sinus tachy/SVT/atrial tachycardia/atrial flutter
- Sinus tachy
- > treat underlying cause
- SVT
- > DC cardioversion if unstable
- > consider vagal maneuvers then adenosine if stable
- Atrial tachycardia
- > DC cardioversion if unstable
- > if stable, beta blockers/non dihyrdropyridine CCB
- Atrial flutter
- > treated liked AF
Irregular and Narrow Tachy
- ddx
- > AF/multifocal atrial tachy/atrial flutter variable conduction
- AF
- > unstable = DC cardioversion
- > stable = beta blockers/non dihydropyridine CCB
- > consider need for anticoagulation
- multifocal atrial tachy/atrial flutter variable conduction
- > usually underlying cardiac/pulmonary path
- > usually stable
- > treatment focused at addressing cause
Regular and Wide Tachy
- ddx
- > VT (until proven otherwise)
- VT
- > unstable = DC cardioversion
- > stable = amiodarone or lidocaine
Irregular and Wide Tachy
- ddx
- > polymorphic VT/VF
- Polymorphic VT
- > unconscious = DC cardioversion
- > baseline long QT (torsades) = magnesium sulfate
- > normal baseline QT (post MI) = beta blockers
- VF
- > ALS
Bradycardia
- only treat if shocked
- atropine while preparing for temporary pacing
- > atropine = 0.5mg
- > pacing = transvenous or transcutaneous
- consider dopamine or adrenaline if unsuccessful
