Internal Diseases and Therapy · MU Sofia

31. Rhythm abnormalities: ventricular arrhytmias – classification, hemodinamics, clinical

Covers ventricular arrhythmias, from premature ventricular contractions to ventricular tachycardia and fibrillation, starting with definitions and the ESC sudden cardiac death criteria. It then gives classification tables by ECG form and by haemodynamic tolerance, plus the historical Lown grading, followed by aetiology, pathogenesis and haemodynamic effects. Clinical features and ECG recognition come next, including long QT causes, Brugada and inherited channelopathies, and a VT versus SVT-with-aberrancy comparison table with the Brugada algorithm. It ends with complications and prognosis.

Inside: 10 sections · 5 labelled pictures · 4 tables · 16 flashcards · 15 min

Topic 31 of 139 in the MU Sofia syllabus for Internal Diseases and Therapy (Medicine, Years 4 and 5). The free AceMed note covers it in 10 sections, about 1,721 words (15 min of reading), with 16 flashcards.

In this note

  1. Definition
  2. Classification
  3. Aetiology
  4. Pathogenesis
  5. Haemodynamics
  6. Clinical features
  7. ECG recognition
  8. Differential diagnosis: VT or SVT with aberrancy
  9. Complications
  10. Prognosis and risk

Definition

  • Ventricular arrhythmias (VA): rhythms that arise below the bifurcation of the His bundle, in the ventricular myocardium or the Purkinje network.
  • The impulse spreads slowly from cell to cell, not through the conduction system, so on the electrocardiogram (ECG) the QRS is broad (≥ 120 ms) and bizarre, with the ST–T opposite to the main QRS deflection.
  • They range from harmless premature ventricular contractions (PVCs) to ventricular tachycardia (VT) and ventricular fibrillation (VF), the main mechanism of sudden cardiac death (SCD).
  • SCD (European Society of Cardiology, ESC 2022 ventricular arrhythmias guideline): an unexpected natural death of presumed cardiac cause within 1 hour of the onset of symptoms if witnessed, or within 24 hours of last being seen well if unwitnessed.

Classification

By ECG form and duration

By haemodynamics

  • Haemodynamically tolerated (patient conscious, adequate blood pressure); unstable (shock, syncope, acute heart failure, ischaemic chest pain); pulseless = cardiac arrest (pulseless VT and VF are the "shockable" rhythms).

By substrate

  • Structural heart disease (scar, cardiomyopathy): most sustained VT and VF, worse prognosis. Structurally normal heart: idiopathic VT and the channelopathies (long QT, Brugada, CPVT, short QT, early repolarisation).

Lown grading of PVCs (historical, still asked)

The risk depends mainly on the underlying heart disease, not on the grade.

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