Sustained Monomorphic Ventricular Tachycardia: Clinical findings
Sustained Monomorphic Ventricular Tachycardia
A wide QRS complex tachycardia originating from the ventricles lasting > 30 seconds. Common mechanisms include re-entry (e.g., scar-mediated) or a ventricular ectopic focus with increased automaticity. Refer to Sustained Monomorphic Ventricular Tachycardia: Pathogenesis slide for more details.
Authors: Rahim Kanji Reviewers: Stephanie Happ, Raafi Ali, Derek Chew* * MD at time of publication
The sinoatrial node continues to depolarize the atria while the ventricles depolarize independently and more rapidly
Heart rate > 100 beats per minute
The re-entrant circuit/ectopic focus uniformly and consistently depolarizes ventricular myocytes
Occasionally, a sinoatrial impulse conducts to the ventricles
Loss of coordination between the contractions of the atria and ventricles
ECG Finding: AV Dissociation
The impulse conducts normally through the His-Purkinje pathway and coincides with abnormal ventricular depolarization
ECG Finding: Fusion beat
Patient feels a forceful and rapid heart rate
Palpitations
Right atrium periodically contracts against a closed tricuspid valve
Cannon A waves (intermittent irregular jugular venous pulsations with large amplitudes)
↓ Ventricular filling time
↓ Preload
↓ Stroke volume cardiac output
Inadequate perfusion to organs
ECG Finding: Uniform morphology of QRS complexes
Direct myocyte-to- myocyte spread of the electrical impulse proceeds slower than an impulse conducted via the His-Purkinje pathway
ECG Finding: Wide QRS complexes (≥ 120 milliseconds)
The impulse conducts normally through the His-Purkinje pathway in between abnormal ventricular depolarizations
ECG Finding: Capture beat
Muscles and other organs
General malaise
Heart
Chest pain
Brain
Presyncope/ syncope
Inability to adequately respond to increased cardiac demand
Shortness of breath
Hemodynamic collapse
Sudden cardiac arrest
Death
Hypotension
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published October 22, 2023 on www.thecalgaryguide.com