Arrhythmia Patho Flashcards
hERD channel
-K channel
-avoid in drug targeting
Membrane potential at rest
-70mV in cell (attracts positive ions)
-0mV out of cell
-higher potassium inside
-lower Na, Ca, Cl inside
-consider concentration and voltage for diffusion
Cardiac action potential
-phase 0: depolarization (Ca and Na influx) membrane potential inc
Phase 1: Na channels close at peak
-phase 2 (Ca inc K dec) plateau
-phase 3: repolarization (K dec , Ca channel close) membrane potential dec
-phase 4: resting potential and leaky K channels
Action potetial graph differences (pacemake cell vs myocyte)
-pacemaker:
-high automaticity
-Ca dependent spikes
-mV = -50
-myocyte:
-contractile
-Na dependent spikes
-mV -70
Which drug classes effect pacemaker cells
-B-blockers
-Ca channel blockers
which drug classes effect myocytes
-Na channel blockers
-K blockers (prolong refractory period)
beta blocker effect on pacemaker
-graph moves right
-longer time to threshold
=dec HR
-inc PR
Ca channel blocker effect on pacemaker cell
-shift right and shorter peak
-longer refractory
-inc PR
B blockers
-esmolol
-arrhythmias involving catecholamines
-atrial arrhythmias
CCBs for antiarrhythmics
-diltiazem and verapamil
-block AV node and protect rate
Class IA antiarrhytmics
-Quinidine
-procainamide
-prolong QT
-shift myocyte graph right
Class IB antiarrhythmics
-lidocaine
-mexiletine
-no clinically significant effect on ECG
-slope down gets shifted left a little
Class 1C antiarrhytmics
-propafenone
-flecainide
-widen QRS
-dec initial slope
Class 3 antiarrhythmic drugs
-amiodarone, dronedarone, ibutilide, sotalol, dofetilide
class 3 moa
-prolong QTc
-longer plateau on myoctye graph
-later T wave
-K blocker
drugs effect on action potential
-phase 0: class I Na blockers
-phase 2: class IV CCBs
-phase 3: class III K channel
-Phase 4: class II BB
