Arrhythmia
Results:
Three High Risk ECGs and the Right Next Move
A 34 year old man presents with acute chest pain radiating to the left arm associated with diaphoresis. He has hyperlipidemia and a family history of early coronary disease. The…
T Wave Alternans
Key Points: T wave alternans is beat-to-beat alternation in T wave amplitude, polarity, or morphology with otherwise stable P waves and QRS complexes. Visible T wave alternans is a warning…
Sinus Node Dysfunction (Sick Sinus Syndrome & Bradycardia-Tachycardia Syndrome)
Key Points: A spectrum, not a single rhythm: Sinus node dysfunction includes inappropriate sinus bradycardia, sinus pauses or arrest, SA exit block, chronotropic incompetence, and alternating atrial tachyarrhythmias with bradycardia….
Sinus Arrest
Key Points: Definition: Sinus arrest occurs when the sinus node temporarily fails to generate an impulse. This produces an absence of the expected P wave and its associated QRS complex….
UMEM Cases, Part 4: When the Computer Misses the Rhythm and Flutter Fakes a STEMI
A 44-year-old man with severe cardiomyopathy, an LVAD, chronic amiodarone therapy, and an AICD presents with palpitations. His ECG shows a regular wide-complex tachycardia, but the rate is only 135….
UMEM Cases, Part 3: When the Diagnosis Seems Clear and When It Is Not
A 71-year-old man presents with shortness of breath, and his ECG is initially read as a junctional rhythm. On later review, it is even mistaken for atrial fibrillation. But the…
Junctional Tachycardia
Key Points: Junctional tachycardia is an uncommon supraventricular tachycardia arising from the AV junction, usually due to enhanced automaticity rather than reentry. It is usually a regular narrow-complex tachycardia, although…
Dysrhythmias in LVAD Patients
Key Points: Continuous-flow LVADs can mask cardiovascular collapse. Patients may remain awake during sustained VT or even VF because the pump can provide temporary flow. Treat the rhythm and the…
Unstable Bradyarrhythmias
Key Points: Unstable bradyarrhythmias cause poor perfusion which can rapidly progress to shock, irreversible organ injury, or cardiac arrest. Priority: Do not treat the heart rate alone. Treat clinical instability….
Junctional Rhythms
Key Points: Junctional rhythms arise from the AV junction, usually the AV node or proximal His bundle, when the sinus node slows, fails, or impulses do not reach the ventricles…
UMEM Cases, Part 2: When the ECG Conceals and When It Reveals
An 81-year-old woman presents with lightheadedness and marked bradycardia. Her ECG shows more P waves than QRS complexes, but the mechanism is not immediately clear. The key question is whether…
Supraventricular Tachycardias (SVTs)
Key Points: SVT in bedside emergency medicine usually refers to a rapid regular tachycardia arising above the ventricles, most commonly AVNRT, AVRT, or atrial tachycardia. Most SVTs are regular narrow-complex…
Polymorphic Ventricular Tachycardia (PMVT)
Key Points: Definition: Polymorphic ventricular tachycardia is VT with beat-to-beat variation in QRS morphology, axis, and amplitude. Clinical significance: PMVT is electrically unstable and can rapidly deteriorate into ventricular fibrillation…
Nonsustained Ventricular Tachycardia (NSVT)
Key Points: Definition: Nonsustained ventricular tachycardia is 3 or more consecutive ventricular beats lasting less than 30 seconds and terminating spontaneously. Rate: VT is usually faster than 120 bpm, but…
Occlusion MI in Ventricular Paced Rhythms: STEMI Equivalent Pattern
Key Points: Ventricular paced rhythms can mask acute coronary occlusion. Pacing alters depolarization and produces expected secondary ST-T abnormalities, so standard STEMI criteria are unreliable. Appropriate discordance is expected in…
Preexcitation Pitfalls (Part 4): Potpourri Cases & Final Teaching Points
A 49-year-old man arrives with palpitations and chest discomfort. The monitor shows an irregular, wide-complex tachycardia with varying morphology and rates nearing 250 to 300 bpm. The team debates polymorphic…
Atrial Flutter with Variable Conduction
Key Points: Mechanism: Typical atrial flutter arises from a large re-entry circuit in the right atrium. The atrial rate is usually near 300 beats per minute. ECG hallmark: Continuous “saw-tooth”…
Atrial Flutter 2:1 Conduction
Key Points: Atrial flutter is a macro-reentrant atrial tachycardia, most commonly typical cavotricuspid isthmus-dependent right atrial flutter, with an atrial rate usually near 300 bpm. With 2:1 AV conduction, the…
Atrial Flutter 1:1 Conduction
Key Points: Rare, high-risk rhythm. Atrial flutter with 1:1 conduction can produce ventricular rates of 240-320 bpm and may rapidly cause hypotension, ischemia, or collapse. Often mimics VT. The QRS…
Flutter Waves (F waves): Basics
Key Points: Flutter waves are caused by a macro-reentrant atrial circuit, most often typical right atrial flutter. Atrial rate is usually ~250-350 bpm, classically near 300 bpm. ECG shows continuous…
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