Arrhythmias-Katz Flashcards
Components of the cardiac conduction system
SA node-atrial pathways-AV node-AV junction-Bundle of His-Left and Right Bundle-Purkinje fibers
How do medications that affect Na or K affect atrial, ventricular and nodal cells?
Don’t affect nodal cells depolarization. They are affected by calcium.
Which cardiac layer has the longest action potential?
Myocardial region is longer than epi or endocardium.
How is transverse conduction different from longitudinal conductino?
Transverse is higher axial resistance, slower conduction velocity, higher safety factor, shorter action potential duration.
How is transverse conduction related to left bundle branch block?
QRS is wider because bundle is missing and conductance is transverse through the right ventricle, not through the normal path.
How does anti-arrhythmia medication affect the myocardial refractory period?
Prolongs the absolute refractory period or reduced.
Definition of automaticity
Ability to generate an action potential. Mostly the SA node.
What phase of the action potential does the ANS affect?
Phase 4 (refractory period)
What are the two mechanisms of arrhthmigenesis?
- Abnormal impulse generation, 2. Abnormal impulse conduction (reentry)
What are the forms of abnormal impulse generation?
Automaticity (enhanced or abnormal), triggered (EADs and DADs)
What are the forms of abnormal impulse conduction?
Reentry (anatomic, functional, anisotropy)
What kind of impulse formation is Possibly accelerated ventricular rhythms after MI?
Abnormal automaticity
What kind of impulse formation is idiopathic and acquired long QT syndromes?
Early after depolarizations (triggered activity) or can be acquired, caused by antihistamines together with arithromycin
What kind of impuse formation is digitalis-induced arrhythmia?
Delayed after depolarization/triggered activity
What is triggered activity impulse formation?
Rare generation of AP at times and at parts that usually don’t generate an AP.
What phase in the action potential has a problem in Delayed After Depolarization?
Phase 4 in not pacemaker cells. Na inside the cell generating an action potential.
What phase in the action potential has a problem in Early After Depolarization?
Phase 3 due to failure of potassium channels may lead to overactivation of sodium channels, accumulation of calcium. May lead to an inadequate but spreadable AP.
How does digoxin cause depolarization of the cell?
The overload of the sarcoplasmic reticulum may cause spontaneous Ca2+ release during repolarization, causing the released Ca2+ to exit the cell through the 3Na+/Ca2+-exchanger which results in a net depolarizing current.
What is Torsades de Pointes?
Twisting or changing of axis, can be a lethal arrhythmia, can generate into vfib, dangerous. Can be caused by EAD and long QT syndrome from depolarization during the relative refractory period.
What type of block are SA, AV, bundle branch, Purkinje-muscle?
Bidirection or unidirectional without reentry
What type of block are reciprocating tachycardia in WPW syndrome, AV nodal reentry, VT due to bundle branch reentry?
Unidirectinoal block with reentry
What is the most frequent type of arrhythmia?
Reentry
How do refractoriness and conduction relate to reentry disorder?
Increased refractoriness and decreased conduction in an adjacent electrical pathways.
What is the trigger needed for reentry?
Extrasystole, early beat enters junction of two pathways, if too early will get into fast pathway during refractory period and won’t pass but will trigger impulse in slow pathway.
How does the impulse reenter the fast pathway?
Passes through slow pathway and by the time it circles around to fast pathway it has repolarizaed and impulse can go backwards.
Which cardiac layer has the longest action potential?
Myocardial region is longer than epi or endocardium.
How is transverse conduction different from longitudinal conductino?
Transverse is higher axial resistance, slower conduction velocity, higher safety factor, shorter action potential duration.
How is transverse conduction related to left bundle branch block?
QRS is wider because bundle is missing and conductance is transverse through the right ventricle, not through the normal path.
How does anti-arrhythmia medication affect the myocardial refractory period?
Prolongs the absolute refractory period or reduced.
Definition of automaticity
Ability to generate an action potential. Mostly the SA node.
What phase of the action potential does the ANS affect?
Phase 4 (refractory period)
What are the two mechanisms of arrhthmigenesis?
- Abnormal impulse generation, 2. Abnormal impulse conduction (reentry)
What are the forms of abnormal impulse generation?
Automaticity (enhanced or abnormal), triggered (EADs and DADs)
What are the forms of abnormal impulse conduction?
Reentry (anatomic, functional, anisotropy)
What kind of impulse formation is Possibly accelerated ventricular rhythms after MI?
Abnormal automaticity
What kind of impulse formation is idiopathic and acquired long QT syndromes?
Early after depolarizations (triggered activity) or can be acquired, caused by antihistamines together with arithromycin
What kind of impuse formation is digitalis-induced arrhythmia?
Delayed after depolarization/triggered activity
What is triggered activity impulse formation?
Rare generation of AP at times and at parts that usually don’t generate an AP.
What phase in the action potential has a problem in Delayed After Depolarization?
Phase 4 in not pacemaker cells. Na inside the cell generating an action potential.
What phase in the action potential has a problem in Early After Depolarization?
Phase 3 due to failure of potassium channels may lead to overactivation of sodium channels, accumulation of calcium. May lead to an inadequate but spreadable AP.
How does digoxin cause depolarization of the cell?
The overload of the sarcoplasmic reticulum may cause spontaneous Ca2+ release during repolarization, causing the released Ca2+ to exit the cell through the 3Na+/Ca2+-exchanger which results in a net depolarizing current.
Which cardiac layer has the longest action potential?
Myocardial region is longer than epi or endocardium.
How is transverse conduction different from longitudinal conductino?
Transverse is higher axial resistance, slower conduction velocity, higher safety factor, shorter action potential duration.
How is transverse conduction related to left bundle branch block?
QRS is wider because bundle is missing and conductance is transverse through the right ventricle, not through the normal path.
How does anti-arrhythmia medication affect the myocardial refractory period?
Prolongs the absolute refractory period or reduced.
Definition of automaticity
Ability to generate an action potential. Mostly the SA node.
What phase of the action potential does the ANS affect?
Phase 4 (refractory period)
What are the two mechanisms of arrhthmigenesis?
- Abnormal impulse generation, 2. Abnormal impulse conduction (reentry)
What are the forms of abnormal impulse generation?
Automaticity (enhanced or abnormal), triggered (EADs and DADs)
What are the forms of abnormal impulse conduction?
Reentry (anatomic, functional, anisotropy)
What kind of impulse formation is Possibly accelerated ventricular rhythms after MI?
Abnormal automaticity
What kind of impulse formation is idiopathic and acquired long QT syndromes?
Early after depolarizations (triggered activity) or can be acquired, caused by antihistamines together with arithromycin
What is Torsades de Pointes?
Twisting or changing of axis, can be a lethal arrhythmia, can generate into vfib, dangerous. Can be caused by EAD and long QT syndrome from depolarization during the relative refractory period.
What kind of impuse formation is digitalis-induced arrhythmia?
Delayed after depolarization/triggered activity
What type of block are SA, AV, bundle branch, Purkinje-muscle?
Bidirection or unidirectional without reentry
What is triggered activity impulse formation?
Rare generation of AP at times and at parts that usually don’t generate an AP.
What type of block are reciprocating tachycardia in WPW syndrome, AV nodal reentry, VT due to bundle branch reentry?
Unidirectinoal block with reentry
What phase in the action potential has a problem in Delayed After Depolarization?
Phase 4 in not pacemaker cells. Na inside the cell generating an action potential.
What is the most frequent type of arrhythmia?
Reentry
What phase in the action potential has a problem in Early After Depolarization?
Phase 3 due to failure of potassium channels may lead to overactivation of sodium channels, accumulation of calcium. May lead to an inadequate but spreadable AP.
How do refractoriness and conduction relate to reentry disorder?
Increased refractoriness and decreased conduction in an adjacent electrical pathways.