Written by epgonline.org - Last updated 29 May 2018
This category covers several different disorders, all of which represent a disruption to normal sinus cardiac rhythm. The disruption may result in a disordered rhythm or rate. Symptomatically they are highly variable; some dysrhythmias present with shock, chest pain, syncope and collapse while others, such as atrial fibrillation (AF), may present with palpitations or could be entirely asymptomatic. Even if asymptomatic, they can represent a significant risk for stroke, or other embolic disease.
The most common sustained dysrhythmia is AF; it is estimated to have a prevalence of 2–3% in Europe (including asymptomatic, previously undiagnosed disease), and although complete data are not available at present, this is likely to be representative of the USA. It is frequently asymptomatic, and represents malcoordinated electrical activity in the atria, which do not contract effectively. Ventricular contractions are coordinated from the atrioventricular node (AVN) onwards, but due to the disconnection from the sino-atrial node (SAN), these are irregular in nature. AF can be easily diagnosed via ECG, where absent P-waves, and irregularly occurring QRS complexes are hallmarks of the condition. Anticoagulation is one of the cornerstones of treatment, while rate and rhythm control are other management strategies, alongside cardioversion in the more acute setting.
Atrial flutter is a condition characterised by rapid atrial contraction as a result of a re-entrant rhythm. The atria may contract over 240 times per minute; the rate is slowed at the AVN and thus not transferred to the ventricles. Unlike AF, it is not a stable rhythm, and is unlikely to exist in a chronic state. It may also be asymptomatic in otherwise healthy individuals. Diagnosis is made by typical ‘sawtooth’ pattern, or by rapid atrial depolarisations on ECG. Management is largely similar to AF.
Other dysrhythmias covered in this section include:
- sick sinus syndrome – disruption of the SAN as a result of scarring or degeneration
- tachycardia – may be ventricular or supraventricular in origin
- bradycardias – may be as a result of numerous conditions or medications.