Ventricular arrhythmia is a term encompassing various forms cardiac rhythm abnormalities originating from the ventricular system. Electrocardiography is used to confirm the diagnosis and the type of arrhythmia, but a detailed morphological and biochemical workup is necessary in order to determine the underlying cause, as most severe forms, such as ventricular fibrillation, can be fatal.
Presentation
The clinical presentation depends on the underlying subtype of arrhythmia [1] [2]:
- Outflow tract arrhythmia (OTA) - Developing on the grounds of aberrant cyclic adenosine monophosphate (cAMP) activity, this type is most frequently encountered in individuals between 20-40 years, with a slight predilection toward female gender [1]. Symptoms seem to be aggravated by emotional stress or exertion, most common being palpitations, dyspnea, chest pain and syncope [1]. Cardiac arrest has been rarely associated with OTA [1].
- Ventricular tachycardia (VT) - Defined as 3 or more ventricular beats at a heart rate of more than 120 beats per minute [3], VT is strongly associated with heart disease (eg. myocardial infarction, cardiomyopathies), while electrolyte abnormalities (hypokalemia or hypomagnesemia) or metabolic changes, including acidosis or hypoxemia, can also induce VT [3]. Monomorphic or polymorphic (the ectopic beat arises from one or multiple foci) and sustained or nonsustained subtypes exist. Nonsustained forms may be asymptomatic, as they are of short duration, but sustained VT is universally symptomatic, manifesting with palpitations, hemodynamic instability, and sudden cardiac death [3], which is not uncommon in severe structural heart disease (SHD).
- Long QT and Brugada syndromes - Two ventricular arrhythmias induced by genetic events present usually in early life (mean onset of symptoms in long QT syndrome is 12 years of age) manifest through syncope, seizures, palpitations, and cardiac arrest [1] [3]. The nocturnal appearance of symptoms is characteristic of Brugada syndrome [3].
- Ventricular fibrillation - Considered as the most severe form of arrhythmia, chaotic ventricular conduction leads to immediate syncope and death within minutes without adequate therapeutic measures [3].
Workup
Prompt diagnostic workup is mandatory in defining the exact type of arrhythmia, starting with a thorough physical examination and a detailed patient history that could reveal the presence of comorbidities, use of pro-arrhythmogenic drugs, structural heart disease, or positive family history [4]. A 12-lead electrocardiogram (ECG) should be performed immediately in patients who present with symptoms suggestive of arrhythmia, followed by a transthoracic echocardiogram in order to evaluate cardiac structure and exclude structural heart disease as a possible cause [4] [5]. ECG findings may include a widened QRS complex (both prolongation and change in shape), ST elevation and inversion of T waves in the case of ventricular tachycardia and fibrillation, while prolonged QT intervals and coving of the ST-segment are seen in long QT syndrome and Brugada syndrome, respectively [1] [4] [5]. In addition to ECG and echocardiography, laboratory workup should comprise a complete blood count, cardiac markers (troponin, creatine kinase MB, and myoglobin), serum electrolytes (potassium, sodium, magnesium, calcium) and renal function tests, to determine optimal therapy and perform electrolyte correction [3] [4]. If symptoms appear in childhood, genetic testing to confirm mutations characteristic for Brugada or long QT syndromes is necessary [4]. If the cause of arrhythmia remains unresolved, coronary arteriography, exercise stress testing and cardiac magnetic resonance imaging (MRI) have been suggested as additional diagnostic methods [4].
Treatment
Prognosis
Etiology
Epidemiology
Pathophysiology
Prevention
References
- Prystowsky EN, Padanilam BJ, Joshi S, Fogel RI. Ventricular Arrhythmias in the Absence of Structural Heart Disease. J Am Coll Cardiol. 2012;59(20):1733-1744.
- Roberts-Thomson KC1, Lau DH, Sanders P. The diagnosis and management of ventricular arrhythmias. Nat Rev Cardiol. 2011;8(6):311-321.
- Hebbar AK, Hueston WJ. Management of common arrhythmias: Part II. Ventricular arrhythmias and arrhythmias in special populations. Am Fam Physician. 2002;65(12):2491-2496.
- Pedersen CT, Kay GN, Kalman J, Borggrefe M, Della-Bella P, Dickfeld T, et al. EHRA/HRS/APHRS expert consensus on ventricular arrhythmias. Europace. 2014;16(9):1257-1283.
- Porter RS, Kaplan JL. Merck Manual of Diagnosis and Therapy. 19th Edition. Merck Sharp & Dohme Corp. Whitehouse Station, N.J; 2011.