Syllabus · Current · V5 (2025) · Cardiovascular System
D2 · Electrical Properties of the Heart
D2.i · Cardiac Electrophysiology
Explain the ionic basis and processes involved in the following: a. automaticity of cardiac pacemaker cells, b. excitation and relaxation of cardiac pacemaker cells, c. excitation and relaxation of cardiac muscle cells.
Written examination
SAQ history
Cardiac Electrophysiology — Cardiac Conduction
2 exam appearances
(a) Describe the action potential of the cardiac pacemaker cells including the ionic events (60%). (b) Explain how excitation then propagates through the conducting pathway of the heart, including mechanisms to prevent abnormal conduction (40%).
69%
Outline normal impulse generation and conduction in the heart. Describe the features present in a normal heart that prevent generation and conduction of arrhythmias.
33%
Cardiac Electrophysiology — SA–Ventricular APs
5 exam appearances
(a) Describe the action potential of the following: (i) the sinoatrial node (35% of marks) (ii) the cardiac ventricular muscle cells (35% of marks) Include in your answer the phases and ionic events involved with each action potential. (b) Explain the implications of the differences between these action potentials (30% of marks).
83%
Describe and compare the action potentials from cardiac ventricular muscle cells and the sino-atrial node.
72%
Describe and compare the action potentials from cardiac ventricular muscle and the sinoatrial node
95%
Describe and compare the action potentials from cardiac ventricular muscle and the sinoatrial node.
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Cardiac Electrophysiology — Sodium Channels
1 exam appearance
Outline the structure of fast cardiac sodium channels and describe in detail how they work.
18%
Oral examination
VIVA history
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2026A · VIVA 5
Relevant examiner prompts
Explain the effect of high serum potassium on the ventricular action potential?
How is the SA node action potential changed by high serum potassium?
Relate those changes in the action potential to the changes on the ECG (in hyperK)?
How does vagal stimulation affect the action potential?
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2021B · Day 3 · VIVA 6
This viva will assess your knowledge of the cardiac action potential and anti-arrhythmic drugs. This image shows the phases of the cardiac muscle action potential. Describe the electrophysiological processes responsible for each phase. (Image removed from report).
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2020B · Day 1 · VIVA 1
This viva will explore your knowledge of anti-arrhythmic agents and the electrocardiogram. Briefly describe the phases of an action potential of the SA nodal / pacemaker cell. (Image removed from report.)
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2019A · Day 1 · VIVA 4
This viva is about the ECG and important electrical currents in the heart. Relate the phases of the ventricular myocyte action potential to the normal ECG. (Image removed from report.)
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2018A · Day 1 · VIVA 2
This viva will examine pacemaker cells and antiarrhythmic drugs. Explain the ionic currents responsible for spontaneous electrical activity of sinus node pacemaker cells.
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2013B · VIVA 5
This Viva explored knowledge of the control of the heart rate. It assessed knowledge of the origin of the heart rate, its regulation, and catecholamines. Most candidates performed well. Anatomical location of the SA node, ionic currents related to the action potential, structure-activity of catecholamines and dobutamine pharmacokinetics were areas of weakness.
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2011B · VIVA 6
This viva is about principles of electrophysiology in relation to the heart. Q 1 Draw the cardiac action potential for a ventricular muscle cell. Subsequent questions sought knowledge of what is the Resting Membrane Potential and how is it created, to describe ionic mechanism for each of the phases of the ventricular action potential, to draw the SA node action potential, compare and contrast the ventricular and SA node action potentials, and which pharmacological agents affect the different phases of the pacemaker potential.
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2011A · VIVA 7
This Viva will test your knowledge of renal physiology and potassium regulation Q 1. Briefly outline the functions of the kidney? This viva tested, briefly, knowledge of renal function, as well as covering hyperkalaemia in some depth. Candidates had a general knowledge related to hyperkalaemia, but struggled to explain the cardiac consequences as they related to the cardiac action potential and as they reflected upon the ECG.
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2009A · VIVA 3
This viva will assess your knowledge of the action potential of the ventricle, sinus node and the atrioventricular node. It will also assess knowledge of anti-arrhythmic drugs. From where does this action potential arise?
Sources: objective text from the relevant CICM syllabus; historical SAQ and VIVA wording from CICM examiner reports.