Cardiac Electrophysiology Practice Test

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• What is the equilibrium potential for potassium (EK)?
• Specialized cells within the His-Purkinje system exhibit typical fast responses, but may also undergo what during phase 4?
• What causes a cell to have a negative voltage on the inside relative to the outside?
• Ion concentration gradients contribute to the membrane potential primarily because which process occurs?
• AV block results in distal pacemaker sites generating the
• Sympathetic activation is an example of which chronotropic effect on heart rate?
• Which statement best describes global reentry?
• Which factors generate membrane potentials in cardiac cells?
• Which mechanism can trigger tachycardia or other abnormal rhythms such as ectopic beats?
• Which statement correctly describes KATP channels?
• Bundle branch blocks can take place in which structures?
• Negative dromotropy is best described as which of the following?
• What anatomical feature facilitates rapid activation of the ventricles?
• Which statement describes Em?
• Which are examples of ventricular ectopic foci?
• Which ion channel primarily mediates the fast upstroke (phase 0) in non-nodal cardiac cells?
• Which current predominates during phase 0 in pacemaker cells?
• Which condition is associated with decreased pacemaker activity and heart rate?
• Which ion concentration is higher inside the cell under resting conditions?
• Which of the following are chemical examples that can cause abnormal conduction?
• AV block can occur at which level of the conduction system?
• L-type channel is described as
• Which categories can cause abnormal conduction?
• During cardiac action potential propagation, sodium channel activation is typically of what duration?
• Electrogenic ion transport contributes to membrane potential due to what capability?
• Which component of the conduction system introduces a delay between atrial and ventricular activation to facilitate ventricular filling?
• Do non-pacemaker cells have a resting potential?
• Which of the following is an example of a functional abnormality affecting conduction?
• Phase 3 repolarization in pacemaker cells is due to
• Are cardiac action potentials initiated by nerves and neurotransmitters?
• Fast Na+ channels are responsible for which phase in non-pacemaker cardiac action potentials?
• First degree AV block is characterized by
• In AV nodal cells, decreased phase 0 slope decreases conduction velocity due to which mechanism?
• Current leakage from one cell depolarizes what?
• Membrane potential is influenced by ion conductances mainly through which mechanism?
• Which phase of the non-pacemaker action potential is the plateau phase with high Ca++ currents?
• Ca2+ diffusion results in which change to the intracellular charge?
• Which statement correctly describes conduction pathways between AVN and ventricles?
• Which tissue has the fastest conduction velocity?
• Sympathetic activation affects pacemaker activity by which change in phase 4 and Ca++ entry?
• Which cells are pacemaker cells?
• Parasympathetic activation also opens which channels resulting in hyperpolarization?
• Where is the Ca2+ concentration lower?
• Non-pacemaker action potentials arise in which cells?
• Low resistance gap junctions allow for what crucial phenomenon in cardiac tissue?
• Local reentry within the atria or ventricles causes which type of tachycardia?
• Which statement best contrasts non-pacemaker and pacemaker cell action potentials?
• Removal of overdrive suppression can permit these cells to display slow spontaneous action potentials that can drive ventricular rate. Which option best describes these potentials?
• Which statement best describes the relationship between AV nodal conduction and ventricular activation?
• Among EK, ENa, and ECa, which is the most negative value?
• Sodium channel activation is triggered by which event?
• Calcium-activated channels open in response to
• Which statement best describes the action potential of non-pacemaker cardiac cells?
• Which phenomenon is a known mechanism for generating tachyarrhythmias via reentry?
• Excessive vagal activation of the AV node leads to what effect on conduction velocity?
• Ectopic foci generate action potentials that do not follow normal conduction pathways. What is a consequence for ventricular depolarization?
• When KATP channels are open, which ion movement predominates?
• In the gradient described, in which direction does the Ca2+ ion tend to move?
• Reentry must occur beyond which physiological period?
• Acetylcholine-activated channels couple to which G-protein?
• Changes in autonomic function can do what to reentry?
• Na+ ion will move
• How does cardiac action potential duration compare to skeletal muscle and nerve?
• Ischemic injury can contribute to arrhythmia by promoting what mechanism?
• Local reentry within the AV node leads to which arrhythmia?
• Vagal activation is an example of which chronotropic effect on heart rate?
• Abnormal conduction can be caused by which mechanism?
• In non-nodal cells, decreased phase 0 slope decreases conduction velocity due to which mechanism?
• Under sympathetic activation, what is the combined effect on time to threshold and AP duration in pacemaker cells?
• What does negative chronotropy refer to?
• Which statement best describes gap junctions in cardiac tissue?
• What type of response and typical bpm do Purkinje fibers generate?
• Em is known as what?
• Which statement about AV blocks is true?
• Junctional rate is typically
• Reentry circuits can cause tachyarrythmias. Which of the following is a tachyarrythmia?
• Slow Na+ channels underlie which pacemaker current in nodal tissue?
• The resting membrane potential of a cardiac cell is approximately how many millivolts?
• Which structure has the slowest conduction, delaying conduction into the ventricles?
• In diffusion, the K+ ion tends to move from
• Na/Ca exchanger moves calcium in relation to sodium at what ratio and direction?
• T-type channel is described as
• Reentry occurs when there is which condition in a conduction pathway?
• Which ion movement contributes to more negative charges on the inside during resting membrane potential?
• Specialized conduction pathways between AVN and ventricular muscle ensure what?
• If Na+ diffuses into the cell, the interior becomes more
• During sympathetic activation, norepinephrine mainly binds to which receptor to increase heart rate and contractility?
• [Na+] inside vs outside
• Which phase of the non-pacemaker action potential is the rapid depolarization phase with high Na+ and Ca++ currents and low K+ currents?
• Non-pacemaker cells are what type of response?
• After Purkinje activation, how is the impulse distributed to the rest of the heart?
• Which condition markedly delays AV nodal conduction?
• Which factors regulate SAN pacemaker activity and conduction velocity?
• Which statement is true regarding secondary pacemaker sites?
• AV blocks can take place in which structures?
• The ERP in non-pacemaker action potential spans which phases?
• Positive dromotropy refers to a change in conduction velocity in response to autonomic activity. Which statement is correct?
• Sympathetic stimulation increases pacemaker rate by enhancing which channels?
• Sympathetic activation of the AV node and ventricular conduction pathways has what effect on conduction velocity and ERP?
• Pacemaker cells are what type of response?
• In electrophysiology, E is known as what?
• Circulating catecholamines will have what effect on conduction velocity?
• Global reentry is between which chambers and can cause SVT?
• Inward rectifier channels contribute to which aspects of the action potential?
• Sodium channel activation in fast response cardiac cells occurs during which phase of the action potential?
• Which conduction system component has the fastest intrinsic firing rate?
• Which stimulus increases ERP in AV nodal tissue?
• The junctional rhythm originates from which region?
• What is the equilibrium potential for calcium (ECa)?
• How are cardiac action potentials conducted in both nodal and non-nodal tissues?
• Acetylcholine slows heart rate by activating which mechanism in pacemaker cells?
• Which statement best describes third-degree AV block?
• What best describes pacemaker cells' resting state?
• Where do the left and right bundle branches originate in the conduction system?
• Which factor shortens ERP by sympathetic activation?
• Which phase of the non-pacemaker action potential corresponds to repolarization with high K+ currents and low Na+ currents?
• In a pacemaker action potential, the effective refractory period (ERP) spans which phases?
• Vagal (parasympathetic) activation affects pacemaker cells by which change in threshold and AP duration?
• What is the effect of sympathetic tone on heart rate?
• L-type calcium channels in nodal cells contribute to which phases?
• Vagal activation of the AV node has what effect on conduction velocity and ERP?
• Acetylcholine-activated channels are
• K+ diffusion results in
• What is the primary pacemaker site that initiates the cardiac impulse in normal rhythm?
• Local reentry is located within which structures and leads to which tachycardias?
• Abnormal pacemaker sites such as ectopic foci illustrate which kind of conduction issue?
• How would you describe the resting state of non-pacemaker versus pacemaker cells?
• Which heart structures contain pacemaker cells?
• What is the key distinction of cardiac action potentials compared to nerve action potentials?
• Inward rectifier channels help maintain which aspects of the cardiac action potential?
• T-type channels contribute to which feature in SA and AV nodal cells?
• Local reentry within the AV node causes which arrhythmia?
• Which phase of the non-pacemaker action potential is the resting potential with high K+ currents and low Ca++ and Na+ currents?
• Which sequence correctly lists the pacemaker action potential phases from left to right?
• Ventricular rate is typically
• Equilibrium potential is defined as the membrane potential at which an ion would not diffuse across the membrane. Which term describes this?
• Pacemaker action potentials are generated in which cells?
• Among EK, ENa, and ECa, which has the most positive equilibrium potential?
• What is the net charge movement across the membrane during Na/K-ATPase activity?
• Delayed rectifier channels are responsible for which part of cardiac action potential?
• Slow Na+ channels are associated with which current in cardiac nodal tissue?
• What type of response and typical bpm does the AV node generate?
• Transient outward channels contribute to which phase of non-pacemaker APs?
• What is the effect of vagal tone on heart rate?
• Changes in phase 0 slope will have what effect on conduction velocity?
• What is the equilibrium potential for sodium (ENa)?
• Phase 4 pacemaker potential currents are best described by
• Which cells are primarily responsible for contraction of atria and ventricles in the heart?
• The Na/Ca exchanger operates with a stoichiometry of 1 calcium to 3 sodium and can move ions in either direction. Which statement best describes this?
• Which ion channel type is most associated with maintaining a negative resting membrane potential during diastole in ventricular tissue?
• SA nodal firing rate is primarily controlled by which autonomic inputs?
• Which ion concentration is higher outside the cell under resting conditions?
• Which statement correctly ranks conduction velocities from fastest to slowest among Purkinje fibers, AV node, atrial myocardium, and ventricular myocardium?
• Which description best fits a ventricular escape rhythm rate?
• Sodium channel resting state occurs during which phase?
• Which statement correctly identifies pacemaker locations?
• Which phase of the non-pacemaker action potential is repolarization with high K+ currents?
• Ectopic foci can be described as impulses that originate from where compared to the SA node?
• Ventricular ectopic foci cause a wide QRS complex on the ECG because which of the following occurs?
• Cardiac conduction system activation pathway: which sequence is correct?
• What is functional syncytium?
• Under vagal activation, what happens to funny channels and calcium channels, and what is the net effect on pacemaker slope?
• Which cells are considered non-pacemaker cells?
• What type of response and typical bpm does the SA node generate?
• Third degree AV block is described as
• Which agent is most likely to shorten ERP in AV nodal tissue?
• Severe hyperkalemia affects conduction by causing what change in cell resting state?
• Na/K-ATPase exchanges ions how?
• Which is NOT listed as a factor generating the cardiac membrane potential?
• Na+ diffusion will result in
• Sympathetic activation produces positive chronotropy. What does this mean for heart rate?
• Which statement best describes the action potential of pacemaker cells?
• Do pacemaker cells have a resting potential?
• Second degree AV block is defined by
• During parasympathetic (vagal) activation, acetylcholine binds to which receptor subtype to slow heart rate?