Saudi heart 2013 SHA 24
Tachycardia • Approach • Clinical • Mechanism • ECG analysis
Clinical • Stable vs unstable
Mechanism • Reentrant • Automatic (ectopic focus fire by its own) • Triggered automatic (needs stimlus )
ECG analysis • • • •
Narrow vs wide Fast vs slow Regular vs irregular Atrial and ventricular relationship (linked or not) • P wave axis and morphology
Two concepts • Sequential depolarization • ECG records Vector of electrical current • Positive • Negative • biphasic
Automatic • • • •
Ectopic atrial focus; abnormal automaticity Abnormal P-wave morphology/axis Structurally normal hearts Tachycardia-induced cardiomyopathy
Reentrant • Accessory Connection between atrium and ventricle
Types of AP • Manifested vs concealed • Bidirectional vs unidirectional • Fast conducting vs slow
Manifested pathway • Conduct Antegrade – From atrium to ventricle – recognized by presence of delta wave on ECG
Ventricular Pre-excitation depends on competition between AV node and AP
How serious is the AP ? • Depends on:
–Conduction velocity –Refractory period
Concealed pathway • Conduct retrograde – From the ventricle to atrium – No delta wave
Orthodromic
AVRT
Slow concealed pathway
Antidromic
AV Node Reentrant Tachycardia distinct pathways – “slow” and “fast” • Typical – Down slow, up fast • Atypical – Down fast, up slow
Atrial Tachycardia (Reentrant) • Atrial Flutter – rapid, regular flutter waves (“saw tooth”) – variable AV conduction • Atrial fibrillation – absence of discrete Pwaves – “irregularly irregular” ventricular response
Examples
Atrial tachycardia
AVRT
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