Core
Results:
PR Segment: Basics
Key Points Definition: The PR segment is the flat line from the end of the P wave to the beginning of the QRS. It reflects conduction through the AV node,…
Preexcitation Syndromes
Key Points Terminology: WPW pattern = ECG evidence of pre-excitation without symptoms. WPW syndrome = pattern plus symptomatic tachyarrhythmia (e.g., AVRT, pre-excited AF). Mechanism: An atrioventricular accessory pathway (e.g., Kent;…
Waveforms, Segments, & Intervals: Basics
Key Points ECGs display voltage changes across the cardiac cycle, captured as waveforms, segments, and intervals. Waveforms represent depolarization or repolarization events. Segments are baseline connections between waveforms, usually representing…
TP Segment: Basics
Key Points Definition: The TP segment is the isoelectric interval from the end of the T wave to the start of the P wave. It reflects electrical diastole when the…
U Wave: Basics
Key Points Definition and origin: The U wave is a small deflection following the T wave, best seen in V2–V3. It likely reflects late ventricular repolarization or Purkinje repolarization. Normal…
T Wave: Basics
Key Points Definition: The T wave reflects ventricular repolarization. Measure amplitude from baseline to peak and identify the end of T to help define the QT interval. Normal appearance: Upright…
S Wave: Basics
Key Points Definition and measurement: The S wave is the first negative deflection after the R wave within the QRS. Measure depth in mm from baseline to nadir; width contributes…
Hyperacute T Waves: OMI Pattern
Key Points: Complexity of ACS: Arteries can spontaneously reperfuse or re-occlude. Understanding early ECG patterns of early acute ischemia can help detect dynamic changes and prompt rapid interventions. ECG Pattern…
Dysrhythmias in LVAD Patients
Key Points Continuous-flow LVADs can mask shock: patients may talk through VT/VF because pump flow maintains some perfusion. Treat the rhythm, not the appearance. First steps in any unstable LVAD…
Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)
Key Points Rare, inherited ventricular arrhythmia triggered by adrenergic stress during exertion or emotion. Classically presents in children or adolescents with syncope or cardiac arrest despite a normal resting ECG…
Takotsubo Cardiomyopathy vs STEMI: DDx
Key Points Takotsubo (stress) cardiomyopathy is a transient, non-ischemic LV dysfunction—classically apical ballooning with basal hyperkinesis—often after emotional or physical stress. Presentation mimics occlusion MI (chest pain, ECG changes, elevated…
Altered Mental Status Emergencies
Key Points Always get a 12-lead ECG in altered or confused patients. The ECG is a great triage and risk stratification tool and can reveal reversible, life-threatening causes when history…
Metabolic Emergencies
Key Points A Simple Yet Powerful Tool: With just a piece of paper and some ink, the ECG can be the earliest clue to life-threatening metabolic disease when labs are…
Artifact vs Ventricular Rhythms: DDx
Key Points Artifact is a common source of misdiagnosis for serious arrhythmias such as polymorphic ventricular tachycardia (PVT), torsades de pointes, or ventricular fibrillation (VF). Always correlate the ECG findings…
Monomorphic Ventricular Tachycardia
Key Points Monomorphic ventricular tachycardia (MMVT) is the most common sustained VT. It shows a single, uniform QRS morphology throughout. Classified as sustained if lasting > 30 seconds or associated…
Inverted U Waves
Key Points Definition: A negative deflection after the T wave (a true U wave) that is ≥0.5 mm deep in a lead where the T wave is upright. Why it…
Wide QRS Complex: DDx
Key Points A QRS duration greater than 120 ms indicates abnormal ventricular depolarization. A wide QRS can signal conditions that range from benign to immediately life-threatening. Developing a focused differential…
Artifact vs STEMI: DDx
Key Points Not all ST elevation is ischemia. The most common mimics at the point of care are atrial activity riding on the ST segment, motion or lead artifact, early…
VT vs SVT with Aberrancy: DDx
Key Points ECG alone cannot reliably distinguish VT from SVT-aberrancy in many cases. Use ECG features to rule in VT, not to exclude it. Default: treat regular WCT as VT…
Bidirectional Ventricular Tachycardia (BiVT)
Key Points BiVT is a regular wide-complex VT with beat-to-beat alternation of QRS axis and/or bundle-branch pattern (often alternating RBBB/LBBB or 180° frontal-plane axis shift). Most common cause is severe…
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