These are caused by the premature discharge of a ventricular ectopic focus
which produces an early and broad QRS complex.
Extrasystoles are usually
normal, being common in middle age. The patient may feel an occasional missed
Patients with no ischaemic heart disease or cardiomyopathy have an
Ventricular extrasystoles after myocardial infarction
are associated with increased mortality.
They may be the presenting feature
of viral myocarditis.
Ventricular ectopics are common and usually of no
clinical significance (1):
- often arise from specific sites such as the right ventricular outflow tract
and can affect people of all ages
- may be completely asymptomatic and discovered incidentally on a routine
ECG or they are experienced as 'missed beats'
- in structurally normal hearts, they are not dangerous and can be difficult
to suppress with medication which is thus best avoided
- in the presence of significant structural heart disease, frequent ectopy
marks an increased risk of sudden cardiac death and specialist advice
should be sought (1)
- rarely they have the potential to induce ventricular fibrillation particularly
if they coincide with the T wave of a preceding beat - this is described
as the 'R on T phenomenon'
- ventricular bigeminy
- this occurs when a ventricular premature beat follows each normal beat
- ventricular trigeminy
- occurs when there is a ventricular premature beat following two normal
- BHF Factfile (March 2005). Ventricular Arrhythmias.