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Key Features

Essentials of Diagnosis

  • Fast, wide QRS complex on ECG

  • Associated with ischemic heart disease, particularly in older patients

  • In the absence of reversible cause, implantable cardioverter defibrillator (ICD) is recommended if meaningful life expectancy is longer than 1 year

General Considerations

  • Defined as three or more consecutive ventricular premature beats and classified as either

    • Nonsustained: lasting < 30 seconds and terminating spontaneously or

    • Sustained: a heart rate > 100 beats/min

  • VT is a frequent complication of acute myocardial infarction and dilated cardiomyopathy

    • May occur in chronic coronary disease, hypertrophic cardiomyopathy, myocarditis, and in most other forms of myocardial disease

    • Can also be a consequence of atypical forms of cardiomyopathies, such as arrhythmogenic right ventricular cardiomyopathy

    • However, idiopathic VT can also occur in patients with structurally normal hearts

  • Accelerated idioventricular rhythm

    • A regular wide complex rhythm with a rate of 60–120 beats/min, usually with a gradual onset

    • Occurs commonly in acute infarction and following reperfusion with thrombolytic medications

  • Torsades de pointes

    • A form of VT in which QRS morphology twists around the baseline

    • May occur in the setting of severe hypokalemia, hypomagnesemia, or after administration of a medication that prolongs the QT interval

Clinical Findings

  • Palpitations

  • Dyspnea

  • Lightheadedness

  • May be asymptomatic on rare occasion

  • Patients with underlying cardiac disease or other severe comorbidities can present with syncope or cardiac arrest

  • Episodes may be triggered by exercise or emotional stress

Diagnosis

Laboratory Findings

  • Comprehensive blood laboratory work should be performed as VT can occur in the setting of hypokalemia and hypomagnesemia

  • Cardiac markers may be elevated when VT presents in the setting of acute myocardial infarction or as a consequence of underlying coronary artery disease and demand ischemia

Diagnostic Studies

  • In patients with sustained, hemodynamically tolerated VT, a 12-lead ECG during tachycardia should be obtained

  • Cardiac evaluation with echocardiography or cardiac MRI, ambulatory ECG monitoring and exercise testing may be warranted depending on the clinical situation

  • In survivors of cardiac arrest or those with life-threatening ventricular arrhythmia, invasive coronary angiography is recommended to establish or exclude the presence of significant coronary artery disease

  • Invasive electrophysiology (EP) study

    • No general role in patients with sustained VT who otherwise meet criteria for implantable cardioverter defibrillator (ICD)

    • May provide important information in

      • Patients with structural heart disease and syncope of unknown cause

      • Situations in which the mechanism of wide complex tachycardia is uncertain

Differentiation of Aberrantly Conducted Supraventricular Beats From Ventricular Beats

  • Distinguishing VT from SVT with aberrant conduction on 12-lead ECG is important because of the differing prognostic and therapeutic implications of each type

  • Ventricular origin

    • AV dissociation

    • QRS duration exceeding 0.14 second

    • Capture or fusion beats (infrequent)

    • Left axis deviation with right bundle branch block morphology

    • Monophasic (R) or biphasic (qR, QR, ...

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