What does a 1 mV calibration signal look like on a standard ECG tracing?

It should produce a 10 mm vertical deflection, confirming standard gain calibration.

Which ECG leads show a septal myocardial infarction?

Septal changes are assessed in contiguous leads V1 and V2.

How can Mobitz type I and Mobitz type II AV block be distinguished on ECG?

Mobitz I shows progressive PR prolongation before a dropped QRS; Mobitz II has fixed PR intervals with sudden dropped QRS complexes.

Free Course Image ECG Interpretation and Clinical Application: Electrocardiogram Essentials

Free online course ECG Interpretation and Clinical Application: Electrocardiogram Essentials

Duration of the online course: 9 hours and 21 minutes

New

Build confident ECG interpretation skills with a free online course covering rhythm, ischemia, MI and conduction blocks—practice clinically and earn a certificate.

In this free course, learn about

What an ECG measures and how it’s used in clinical practice
Cardiac conduction system basics and how depolarization produces ECG waveforms
12‑lead ECG system: lead groups, contiguous leads, and correct chest lead placements (e.g., V4)
How to record/calibrate an ECG (1 mV = 10 mm) and ensure proper patient preparation/ID
ECG waveforms/intervals/segments; why deflections are positive vs negative in a lead
Vector ECG principles and QRS axis by quadrant method (e.g., lead I−, aVF+ = right axis)
Action potentials to arrhythmias; bypass tracts and classic pre-excitation ECG findings
Drug and electrolyte effects on ECG, especially QT prolongation and ST/QT interval changes
Systematic approach to brady- and tachyarrhythmias; wide-complex criteria (QRS ≥120 ms)
Diagnosing AV blocks and bundle branch blocks (Mobitz I vs II key distinguishing features)
ECG signs of chamber enlargement/heart failure, including LVH voltage criteria
Ischemia/injury/MI pathophysiology and key ECG patterns for ischemia vs infarction severity
Miscellaneous critical patterns: pulmonary embolism specificity and pacemaker rhythms/magnet effects

About the free online course

Electrocardiograms are among the fastest, most accessible clinical tests, yet many learners feel uncertain when faced with real tracings. This course helps you turn the 12-lead ECG from a confusing collection of lines into a practical tool for bedside decision-making. You will strengthen the fundamentals that make interpretation reliable, then connect those basics to common presentations such as chest pain, palpitations, syncope, and dyspnea.

You will start with how the heart generates electrical signals and how those signals appear on paper, building a clear mental model of depolarization, repolarization, and the meaning of each waveform, interval, and segment. From there, you will learn how the lead system views the heart from different angles, why proper electrode placement matters, and how calibration and recording technique can change what you think you are seeing. With this foundation, concepts like vectors and axis become easier to understand and apply.

The course emphasizes clinical application. You will practice recognizing normal sinus rhythms and the patterns that define bradyarrhythmias, tachyarrhythmias, AV blocks, and bundle branch blocks, including how to distinguish look-alike findings that often cause errors. You will also connect physiology to pathology, exploring how action potential changes lead to arrhythmias, and how ischemia and injury evolve into myocardial infarction on an ECG. Beyond acute coronary syndromes, you will learn to spot changes linked to chamber enlargement, heart failure, electrolyte disturbances, and the QT effects seen with many medications.

Throughout, the included questions reinforce pattern recognition and reasoning, helping you move from memorization to structured interpretation. By the end, you should feel more prepared to analyze an ECG systematically, communicate findings clearly, and understand when an abnormal tracing suggests urgency. As a free online learning option in health and medical topics, it is well suited for students, nurses, paramedics, and clinicians who want a practical, step-by-step approach to ECG essentials and real-world clinical relevance.

Course content

Video class: Introduction - Electrocardiogram - Interpretation and application in clinical practice 04m
Exercise: Which description best summarizes the electrocardiogram (ECG) as presented in the course introduction?
Video class: Basic Conduction of Heart 29m
Exercise: Which ECG waveform primarily represents ventricular depolarization?
Video class: ECG Lead system 23m
Exercise: Which group of ECG leads are considered contiguous septal leads in the standard 12‑lead system?
Video class: Recording of a Standard ECG (Lead placements 26m
Exercise: When calibrating a standard ECG machine, what should a 1 mV calibration signal produce on the ECG paper?

Video class: Waveforms, inervals and segments 37m
Exercise: In ECG interpretation, what determines whether a depolarization wave is recorded as an upward (positive) or downward (negative) deflection in a given lead?
Video class: Vector Electrocardiography 28m
Exercise: Using the quadrant method for QRS axis determination, what does it suggest when the QRS complex is negative in lead I and positive in lead aVF?

Video class: From Action Potentials to Arrhythmias 21m
Exercise: In accelerated conduction due to a paranodal (bypass) tract, what is the classical ECG finding?

Video class: Pathophysiology, Myocardial Ischemia / Injury 42m
Exercise: Which change most directly reduces subendocardial coronary blood flow during tachycardia, increasing the risk of myocardial ischemia?
Video class: Myocardial Infarction (MI), Pathophysiology 33m
Exercise: Which mechanism accounts for about 90% of myocardial infarctions?

Video class: Drug effects on ECG 37m
Exercise: Which ECG change is most characteristically associated with many non-cardiac medications (e.g., certain antibiotics, antifungals, antidepressants, antipsychotics)?
Video class: Patient identification , preparation and interpretation of ECG 17m
Exercise: Which chest lead placement is correct for V4 in a standard 12-lead ECG?

Video class: Sinus rhythms and Bradyarrythmias 20m
Exercise: Which ECG finding best differentiates sinoatrial (SA) exit block from sinus pause?
Video class: Approach to tachyarrhythmias 30m
Exercise: Which QRS duration criterion defines a wide-complex (broad-complex) tachyarrhythmia?
Video class: AV Blocks and Bundle Branch Block 26m
Exercise: Which ECG feature best differentiates Mobitz type 1 (Wenckebach) from Mobitz type 2 second-degree AV block?

Video class: Chamber enlargement and Heart Failure 29m
Exercise: Which ECG voltage criterion supports a diagnosis of left ventricular hypertrophy (LVH)?
Video class: Electrolyte Abnormalities on ECG 32m
Exercise: Which electrolyte abnormality most directly affects the ST segment and thereby alters the QT interval?

Video class: Recognizing signs and ECG changes in Myocardial Ischemia/Injury 24m
Exercise: Which ECG pattern most strongly favors myocardial ischemia rather than a normal variant?
Video class: ECG changes in myocardial infarction 36m
Exercise: Which ECG finding suggests a more severe non-ST elevation myocardial infarction (NSTEMI) that warrants early intervention?
Video class: Miscellaneous ECG findings 32m
Exercise: In acute pulmonary embolism, which ECG finding is described as the most specific?

Video class: Pacemaker Rhythms 26m
Exercise: In pacemaker electrocardiography, what does applying a magnet over a pacemaker typically do?

Learn aboutCardiology

Explore free online cardiology courses and build essential knowledge of heart health, cardiovascular diseases, diagnosis, treatment, ECG interpretation, and patient care. Learn at your own pace with accessible lessons for students, healthcare professionals, and lifelong learners, and earn a free certificate upon successful course completion.

Free online courses on Cardiovascular Physiology

Learn aboutCardiovascular Physiology

Explore free online Cardiovascular Physiology courses and build a deeper understanding of heart function, blood flow, cardiac cycles, circulation, and vascular regulation. Learn at your own pace with accessible lessons designed for students, healthcare professionals, and curious learners, and earn a certificate upon completion.