Basics & Fundamentals

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Pseudo-Wellens Waves

Key Points: Pseudo-Wellens waves are anterior T-wave patterns that mimic the biphasic or deeply inverted T waves of true Wellens syndrome but are caused by non-LAD, non-ischemic physiology. These normal-variant…

Wellens Waves

Key Points Wellens waves are anterior precordial T wave abnormalities (biphasic or deeply inverted) most often in V2–V3, occasionally extending to V1 and V4–V6. They signal a high likelihood of…

Ventricular Tachycardia (VT): Core Overview

Key Points: VT is a ventricular-origin rhythm: ≥3 consecutive ventricular beats, QRS >120 ms, rate usually 120–250 bpm. Types include monomorphic VT, polymorphic VT, torsades (PMVT with long QT), ventricular…

Prominent Upright T Wave in V1

Key Points: Normal T Wave in V1: The normal ECG typically shows a flat or inverted T wave in lead V1 in sinus rhythm. An upright T wave in V1 can…

Premature Atrial Complexes (PACs)

Key Points PACs are early atrial depolarizations from an ectopic focus that create a premature P wave with a different morphology and axis than the sinus P wave, usually followed…

Atrial Fibrillation (AFib)

Key Points Prevalence: The most common sustained cardiac arrhythmia, particularly prevalent among elderly individuals, associated with increased stroke, heart failure, and mortality risks. Mechanism: Caused by chaotic, multiple reentry circuits…

Premature Junctional Complexes (PJCs)

Key Points PJCs are premature impulses from ectopic foci in or near the AV junction. ECG hallmark is a narrow premature beat with an absent or retrograde P wave. Retrograde…

J Point: Basics

Key Points The J point is the junction where QRS ends and the ST segment begins. It is a location, not a waveform. ST deviation is judged at the J…

Blocked Premature Atrial Complexes (PACs)

Key Points Definition: early ectopic atrial beats that do not conduct to the ventricles. You see a premature P wave with no following QRS and a pause that is usually…

J Wave: Basics

Key Points Definitions: The J point is the QRS–ST junction (a location). A J wave is an added deflection at or just after that point (notch or slur).  Why it…

Premature Complexes (PACs, PJCs, & PVCs) Overview

Key Points: Premature complexes are early depolarizations arising from the atrium, AV junction, or ventricle which interrupt the expected sinus rhythm. Rapid classification by origin: look for a P wave…

Osborn (J) Wave: Basics

Key Points An Osborn wave is a notch or slur at the J point that becomes more prominent as core temperature falls. Most visible in inferolateral and precordial leads; can…

Premature Ventricular Complexes (PVCs)

Key Points PVCs are early ventricular depolarizations that produce a wide QRS with secondary ST-T changes and are usually followed by a full compensatory pause. No preceding P wave. A…

Spontaneous Coronary Artery Dissection (SCAD)

Key Points SCAD Definition: A spontaneous, non-atherosclerotic tear in the coronary artery wall, often affecting young, otherwise low-risk women (including peripartum patients). SCAD presents similarly to ACS and is an…

ECG Lead Misplacement

Key Points: Lead misplacement is common and can mimic ischemia, MI, conduction blocks, and arrhythmias. Always verify placement when ECG and clinical picture do not match. V1 and V2 placed…

Proper ECG Electrode Placement

Key Points A diagnostic 12‑lead ECG is only as good as your electrode placement. Misplacement can mimic MI, BBB, or poor R‑wave progression and trigger unnecessary workups. A standard 12‑lead…

Cerebral T Waves

Key Points What it is: Dramatic ECG repolarization abnormality from acute brain injury. Classic pattern is deep, symmetric T-wave inversions with prolonged QTc, often most prominent in anterolateral leads. Why…

Accelerated Idioventricular Rhythm (AIVR)

Key Points: Definition: AIVR is a transient, usually benign ventricular rhythm often seen after reperfusion of an acute myocardial infarction (AMI), whether spontaneous or post-intervention (PCI or thrombolysis). Rate Differentiation:…

Atrioventricular Nodal Reentry Tachycardia (AVNRT)

Key Points: AVNRT is a paroxysmal, regular, usually narrow-complex SVT caused by a reentry circuit within or adjacent to the AV node. Dual-pathway physiology is typical. Bedside hallmark is a…

Atrioventricular Reciprocating Tachycardia (AVRT)

Key Points: AVNRT is a paroxysmal, regular, usually narrow-complex SVT caused by a reentry circuit within or adjacent to the AV node. Dual-pathway physiology is typical. Bedside hallmark is a…

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