Clinical Presentation: Ventricular Arrhythmias

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Monomorphic Ventricular Tachycardia

Symptoms associated with MVT include:

• Palpitations, often described as pounding, racing, or fluttering
• Chest pain or tightness
• Dyspnea
• Presyncope or syncope
• Cardiac arrest

Signs on exam:

• achycardia with narrow QRS complex on ECG (rate usually 140-250 bpm)
• Hemodynamic instability – hypotension, acute heart failure

Associated risk factors and conditions:

• Structural heart disease – prior myocardial infarction, cardiomyopathy
• Electrolyte abnormalities – hypokalemia, hypomagnesemia
• Drugs that prolong QT interval
• Congenital syndromes – long QT syndrome, Brugada syndrome
• Men are more commonly affected than women
• Mean age of presentation is 65 years old

MVT can present across a spectrum from asymptomatic ectopy to unstable rhythms causing syncope, chest pain, shortness of breath, hypotension, or sudden cardiac death. It is crucial to obtain a 12-lead ECG, which will demonstrate a regular, monomorphic wide complex tachycardia. Hemodynamic instability warrants urgent electrical cardioversion.

Polymorphic Ventricular Tachycardia

• Symptoms associated with polymorphic VT include palpitations, lightheadedness, syncope, and chest pain. Hemodynamic instability with hypotension, altered mental status, and shock can occur.

• Polymorphic VT often presents with a rapid ventricular rate between 150-250 beats per minute.

• The ECG shows a irregular, continuously changing QRS morphology and axis – the complexes appear to twist around the isoelectric line.

• Prolongation of the QT interval is usually seen prior to initiation of polymorphic VT episodes.

•  Risk factors include structural heart disease, electrolyte disturbances (hypokalemia, hypomagnesemia), drugs that prolong QT interval, bradycardia, pauses, congenital long QT syndromes.

• More common in older adults but can occur at any age. Slight male predominance.

• Sudden cardiac death can be the initial presentation in patients with undiagnosed congenital channelopathies.

• Syncope, cardiac arrest, or sudden death can occur if polymorphic VT deteriorates into ventricular fibrillation.