What 3 main ion currents dominate and at which parts of the cardiac cycle?
Phase 0 – Sodium Channel
Phase 1 – Sodium and Potassium Channel
Phase 2 – Potassium and Calcium Channels
Phase 3 – Potassium Channel
Phase 4 – Potassium Channel and Funny Current
What are the 4 classes of antiarrhythmatic meds?
•Class I: Sodium channel blockers
–Inhibit depolarization/slow conduction velocity
•Class II: Beta-blockers
–Slow sinus node and AV node
•Class III: Potassium channel blockers
•Class IV: Calcium-channel blockers
–Slow SA node (some) and AV node (more)
•Others: Digoxin, Adenosine, Atropine
Where do you place EKG leads --where on chest/body?
What are the 3 limb unipolar leads?
Use "ground" as composite as the major negative pole
aVR, aVF, aVL
What are the 3 bipolar limb leads?
Where you subtract the difference between two leads:
I = R arm (-) --> L arm (+)
II = R arm (-) --> leg (+)
III = L arm (-) --> leg (+)
What is the axial reference system?
Shows you the angle from which you are looking at each lead
What is the count off system for calculating HR?
Count how many small boxes there are between peaks
Which leads indicate problem with inferior potion of heart i.e. pathological Q wave? Which artery is this?
II, III, aVF
Which leads indicate problem with anteroseptal potion of heart? Which artery is this?
Which leads indicate problem with anteroapical potion of heart? Which artery is this?
Which leads indicate problem with anterolateral potion of heart? Which artery is this?
V5, V6, I, AVL
Which leads indicate problem with posterior potion of heart? Which artery is this?
V1, V2 (tall R, not Q wave)
AVNRT: what is it and treatment
Atrioventricular nodal tachycardia
Blip in p wave at end of QRS due to self perpetuating loop in tissue secondary to atrial premature beat
Treat w vagal maneuvers
AVRT: what is it and treatmnet
Atrioventricular reentry tachycardia
Bypass tract --> signal can reach ventricles faster = wolff-parkinson white syndrome
short PR, delta wave in QRS, wide QRS
Treat with vagal maneuvers
Atrial tachycardia: what is it and treatmnet
Many p waves, with diff morphologies
Beta blockers, Ca channel blockers, IA, IC, and II antiarrhythmic drugs
AFib: what is it and treatment
Chaotic depolarization of atria --> irregular Ventricular rate
Anticoags to prevent stroke (CHADS2 score)
No cardiac disease: meds or catheter ablation
Coronary disease: don't use Class IIC meds (propafenone, flecanide= worse outcome)
Htn, can't use sotalol, dofetilide (Class III)
CHF: ablation, amiodarone, dofetilide only (Class III)
Macro re-enterance loop --> sawtooth patterns, more organized rhtyhm than AFib
3 or more ventricular premature beats
Doesn't respond to vagal maneuvers
Treat with beta blockers, amiodarone & solatol (palliative), ICD, ablation
Torsades des Points
Associated with Long QT
Long QT- causes and treatment
Congenital, hypokalemia, hypomagnesia, drugs
Withdraw med that causes it, give Mg/K, pace the heart to make it faster, lidocaine, defibrillation
Long term: genetic testing, beta blockers, ICD, avoid meds that prolong QT
What med do you give to treat sinus bradycardia?
Atropine: blocks action of Ach at parasympathetic sites
What are the 4 types of atrial bocks? Treatment?
1st degree: longer PR interval
2nd degree Mobitz type 1/Wenckebach: progressive PR elongation with eventual nonconduction of a p wave
2nd degree Mobitz type 2: normal PR intervals with a sudden failure of p wave to conduct
3rd degree: complete AV dissociation
Treat all with pacemaker
Junctional excape rhythm
QRS not preceeded by p wave
Rhythm arises from below atria = slow 40-60 bpm
Ventricular escape rhtyhm
widened QRS complexes
Slower rates 30-40 bpm