Arrythmias Flashcards
Rhythm
Movement or procedure with uniform or patterned recurrence of a beat, accent, or the like
Cardiac Arrhythmia
Heartbeat is irregular, too fast, or too slow
What does the P wave represent?
Atrial depolarizaiton
What does the QRS complex represent?
Ventricular depolarization
What does the T wave represent?
Ventricular repolarization
Contraction of the atria does what?
Moves blood into the ventricles
Contraction of the right ventricle does what?
Sends O2 depleted blood to the lungs
Contraction of the left ventricle does what?
Sends O2 rich blood to the body
What coordinates cardiac muscle contraction?
Electrical signals
Trace the circulation of blood through the heart
Vena cava –> R atrium –> R ventricle –> Pulmonary artery –> Lungs –> L atrium –> L ventricle –> Aorta –> rest of the body
Trace the electrical current through through the conducting system through the heart
SA node –> AV node (signal pauses) –> AV bundle branches –> Purkinje fibers
Where is the signaling velocity slowest in the heart?
AV node
Where is the signaling velocity fastest in the heart?
Purkinje fibers
What creates the EKG?
The sum total of action potentials traveling through the heart
What does the PR interval describe?
The time it takes for the impulse to travel from the Sinus node through the AV node
What does the ST segment represent?
The time the ventricles are depolarized
What does the U wave represent?
Repolarization of the intraventricular septum
What is the QT interval?
The speed of the heart beat
What are the four main types of arrhythmias?
Extra beats
Supreaventricular tachycardias
Ventricular arrhythmias
Bardyarrhythmias
Extra beat arrhythmia types
Premature atrial contraction
Premature ventricular contractions
Supraventricular tachycardia types
Atrial fibrilation
Atrial flutter
Paroxysmal supraventricular tachycardia
Ventricular arrhythmia types
Ventricular fibrilation
Ventricular tachycardia
Bradyarrhythmias
Slow heartbeat
What are the classifications of arrhythmias by site of origin?
Atrial
Ventricular
Juncitonal
AV Heart Blocks
Atrioventricular Blocks
Conduction between the atria and ventricles is blocked or slowed
Can be primary, secondary, tertiary
Primary AV Block
PR interval is lengthened beyond 0.2 seconds
Secondary AV block
Disturbance, delay, or interruption of atrial impulse conduction through the AV node to the ventricles
Tertiary AV block
aka Complete heart block
Impulse generated in SA node does not propagate to the ventricles
How will a primary AV block look on an EKG
PR interval is lengthened
How will a secondary AV block look on an EKG
There will be QRS complexes dropped
How will a tertiary AV block look on an EKG?
None of the p waves conduct to ventricles - P-P and QRS-QRS are independent
What are the causes of arrhythmias?
Cardiac ischemia
Excessive discharge or sensitivity to autonomic neurotransmitters
Exposure to toxic substances (smoking, alcohol, Rx meds, caffeine, nicotine)
Unknown etiology
What occurs in phase 0 of cardiac action potential
Na goes into the cell (depolarization)
What occurs in phase 1 of cardiac action potential?
K and Cl leave the cell
What occurs in phase 2 of cardiac action potential?
Ca goes into the cell
K goes out of the cell
Plateau phase
What occurs in phase 3 of the cardiac action potential?
K goes out of the cell
Repolarization
What are the classes of Anti-Arrhythmic Drugs?
Class I
Class II
Class III
Class IV
Class I Anti-arrhythmic drugs
Block Na channels
What are the different classes of Class I anti-arrhythmic drugs and when are they used?
Ia
Ib
Ic
Class II Anti-arrhythmic drugs
B-adrenoceptor antagonists
Diminish phase 4 depolarization - depressing automaticity, prolonging AV conduction, decreasing HR and contractility
Can diminish both Na and Ca currents
Class III Anti-arrhythmic drugs
K channel blockers
Delay the ventricular AP (specifically repolarization)
Prolong refractory period
Class IV Anti-arrhythmic drugs
Ca channel antagonists
Decrease Ca inward current, decreasing phase 4 spontaneous depolarization
Slow conduction and increase the refractory period
Ia Na channel blockers
Lengthen the duration of the AP
Bind more selectively to the open state of the channel
Dissociates from the channel with intermediate kinetics (1-10 seconds)
Ib Na channel blockers
Shorten the duration of the AP
Bind primarily to inactivated state of the channel
Dissociates from the channel with rapid kinetics (
Ic Na channel blockers
Minimal effect on the duration of the action potential
Bind more selectively to the open state of the channel
Dissociate from the channel with slow kinetics (>10 seconds)
What are Class II Anti-arrhythmias used to treat?
Useful in treating tachyarrhythmias caused by increased sympathetic activity
Also used for atrial flutter and fibrillation
T/F - Class II and Class III compound, but Class I and Class III do not
True
What are Class III Anti-arrhythmias used to treat?
Ventricular arrhythmias - especially ventricular fibrillation or tachycardia
What phase of the Ventricular AP do Class I Anti-arrhythmic drugs effect?
Phase 0
What phase of the Ventricular AP do Class II Anti-arrhythmic drugs effect?
Phase 4
What phase of the Ventricular AP do Class III Anti-arrhythmic drugs effect?
Phase 3
What phase of the Ventricular AP do Class IV Anti-arrhythmic drugs effect?
Phase 2
