Arrythymia 2 Flashcards
Two arrythymia starts
Impulse Generation and Impulse Conduction
Impulse generation refers to….
Automaticity- spontaneous impulse generation in latent pacemaker cells
Impulse conduction refers to…
Re-entrant arrhythmias- indefinite propagation of the impulse and continued activation of previously refractory cells
Examples of AUtomaticity Arrythymias
sinus tachycardia – Cells other than the SA node depolarize faster than the SA nodal cells and take control as the pacemaker
multifocal atrial tachycardia –> Transient membrane depolarizations that occur during repolarization (relative refractory period)
Conduction requirementsfor re-entry arrythymia
Two pathways for impulse conduction
An area of unidirectional block (prolonged refractoriness)
Slow conduction in the other pathway
Antiarrthymic Meds
Class 1 all works all Na+ channels
2 –> beta blockers
3 –> K+ channels (Amiodarone does them all)
4 –> Ca2+ channels
Class I
A –> Lowers automaticity
B –> Lidocaine –> Shortens repo;arization
C - Depolarization occurs for longer
Class III
Block potassium channels thereby prolonging the refractory period
CCB
Slow conduction, prolong refractoriness, and decrease automaticity of calcium dependent cells in the SA and AV nodes
Digoxin
Inhibitor of Na+/K+ -ATPase
Increases vagal tone, which reduces conduction velocity (decrease the herat rate)
Increases AV node refractoriness
Bradycardia Definition
Heart Rate Less Than 60 bpm
Bradycardia sx occur when? What are they?
Usually, patients won’t have symptoms unless heart rate is dropping below 50 bpm
Symptoms can include fatigue, lightheadedness, palpitations, or syncope (pass out)
What is AV block?
Conduction delay or “block” in an area of the AV conduction system
Not beta blocker
Degrees of AV block
First degree (least severe- prolonged PR interval)
Second degree
Third degree (most severe- absence of AV conduction)
Tx Brady
Treatment for chronic symptomatic AV block is a pacemaker
Sick Sinus SYndrome
Pauses or dropped beats due to SA node dysfunction
Usually caused by degenerative changes due to age
Leave it alone, unless symptomatic, then pacemaker
Tachycardia
Heart Rate Greater Than 100 bpm
Supraventricular Tachycardia Cause
Usually caused by re-entry mechanisms
SVT Sx
palpitations, fatigue, lightheadedness, neck fullness, chest pain (blood not getting where it needs to do)
SVT tx
For narrow QRS complex: first line treatment is vagal maneuvers
Second line is adenosine, or IV beta-blocker or calcium channel blocker if needed
Type sof ventricular tacyyartythmia
Premature Ventricular Complexes (PVCs)
Benign, common (structuaral heart dx (recent MI’s))
Ventricular tachycardia (VT)
Potentially fatal, life threatening
Eventually leads to V-fib No blood circulated to the body
Ventricular fibrillation (VF)
Fatal, medical emergency
PVC’s tx
Often asymptomatic, can occur in healthy individuals
Usually don’t require any treatment
VT TX
Sustained VT, unstable patient: First line is direct current (DC) cardioversion
Stable patient: medication can be used, IV procainamide, amiodarone, lidocaine
Maintainenece tx VT
Once acute VT terminated, possibility of recurrence
Amiodarone is most effective as maintenance therapy to prevent VT recurrence
Sotalol also option for maintenance therapy
Ablation can be considered if medication therapy fails
VF TX
More common in people with acute MI, drug overdose, hypoxemia (not perfusing the tissues)
Terminal event unless corrected Not perfusing
DC cardioversion first line, IV amiodarone if unsuccessful
Torsade Des Pointes
Life threatening form of VT
Associated with long QT interval on ECG
Treatment: Magnesium sulfate 2g IV (stabilize cardiac membrane), DC cardioversion
Outcome of QT prolongation
Amiodarone???
- Does not affect renal system
ALOT of SIDE effects
Qt prolong, phosens, hyperthyroid, blue-grey skin, Liver enzyme increase, vision changes, pulmonary toxicity, cough, fveer, dyspnea
QT risk? Higher when? Why?
Risk higher with antiarrythmic medications due to their potassium channel blocking properties
Sotalol risk of TdP around 4%
QTc prolongation? Definition?
Females- greater than 480 msec
Males- greater than 470 msec
Need to become worried if QTc exceeding 500 msec
Tisadle Score
