Cardiology: Tachyarrhythmia Classification

Study Notes

Tachyarrhythmia

Definition: Any abnormality in the rate or rhythm of heart beats, with a normal heart rate of 60-100 BPM and a normal heart rhythm of sinus rhythm, passing through the AVN (atrioventricular node).

Classification of Tachyarrhythmia

Narrow complex tachycardia:
- Originating from above the AVN
- QRS duration < 120 ms
- Subclassified into:
  - Regular: Supraventricular tachycardia (SVT)
  - Irregular: Atrial fibrillation (AF)
Wide complex tachycardia:
- Originating from below the AVN
- QRS duration > 120 ms
- Subclassified into:
  - Regular: Ventricular tachycardia (VT)
  - Irregular: Ventricular fibrillation (VF)

Sinus Tachycardia

Heart rate > 100 BPM, sinus rhythm
Causes:
- Physiological: exercise, pregnancy, anxiety
- Pathological: pulmonary embolism, anemia, hyperthyroidism, acute heart failure, drug-induced
- Inappropriate sinus tachycardia: increased SAN automaticity
Presentation:
- Palpitation, chest pain, shortness of breath
Management:
- Treatment of the cause
- Withdrawal of offending drug
- Beta blockers
- Ivabradine
- SAN ablation (rare, in resistant cases)

Supraventricular Tachycardia (SVT)

Heart rate > 100 BPM, originating from above the AVN, outside the SAN
Classification:
- Atrial flutter
- Atrial tachycardia
- AVNRT (AV nodal reentrant tachycardia)
- AVRT (atrioventricular reentrant tachycardia)
Pathophysiology:
- Reentry due to presence of two pathways for conduction with different speeds of conduction and refractory periods through the AVN and accessory pathway, triggered by PAC
Presentation:
- Sudden onset palpitation
- Chest pain
- Dizziness
- Syncope
- Shock
Management:
- Acute management: see below

Atrial Fibrillation (AF)

Irregular rhythm caused by uncoordinated atrial electrical activation
Usually > 100 BPM, but controlled AF by medication may be < 100 BPM
The most common sustained arrhythmia in adults
Management:
- ABC pathway:
  - A: Anticoagulation/avoid stroke
  - B: Better symptom control (rate and rhythm)
  - C: Cardiovascular risk factors and concomitant diseases
- Anticoagulation:
  - Who should take anticoagulation: patients with prosthetic valves, moderate or severe mitral stenosis, high ischemic risk (CHADSVASC score)
  - Types of anticoagulation: Vitamin K antagonists (warfarin), Novel oral anticoagulants (NOACS)
- Rhythm control: selected for patients with normal left atrial dimensions and morphology, HCM, and persistent symptoms despite adequate rate control

Atrial Flutter

Characteristic saw-tooth appearance
May be regular (2:1, 3:1, 4:1, etc.) or irregular (flutter with variable block)
Same management as AF with more insistence on rhythm control

Ventricular Tachycardia (VT)

3 or more consecutive wide QRS complex beats
Originating from the ventricles
A rate > 100 BPM
VT and VF account for the most common causes of SCD

Ventricular Fibrillation (VF)

Requires urgent CPR

Description

Learn about the definition and classification of tachyarrhythmia, including normal heart rate and rhythm, and narrow complex tachyarrhythmias. This quiz is perfect for cardiology students and medical professionals.