Ventricular bigeminy

ECG: Alternation between two QRS complexes: 1) a first complex of sinus origin (positive P wave in leads I, II, V5, V6 and negative in aVR) with normal PR interval (120 ms); wide QRS with right bundle branch block pattern; 2) a non-fragmented, premature ventricular complex, left delay; this electrocardiogram thus reveals a ventricular bigeminy with alternation between a conducted QRS and a monomorphic premature ventricular complex with fixed coupling interval;

Comments: Patients with premature ventricular complexes may be perfectly asymptomatic, the diagnosis being made at pulse taking with evidence of irregularity and premature beating. As in this patient, pulse measurement can lead to the diagnosis of bradysphygmia which corresponds to a slowing of the pulse due to the hemodynamic ineffectiveness of premature beats, with the pulse remaining normal if the premature complex is bigeminal. This effective bradycardia can cause an asthenia-like or exertional dyspnea-like symptomatology.

The number of premature ventricular complexes on a single day does not constitute a major prognostic factor (assessment of the risk of sudden death). On the other hand, it may have an impact on cardiac function. The bigeminy observed in this patient, if maintained long term, may be responsible for the development of heart rhythm disease. The characterization of the premature ventricular complex can therefore be supplemented by performing a 24-48 hour Holter-ECG which allows not only a quantitative assessment over 24-48 hours, but also a qualitative assessment including the evaluation of the number of different morphologies (monomorphic or polymorphic premature beats), coupling interval, existence of repetitive forms (presence of couplets, triplets, and/or bursts), the link with heart rate (catecholaminergic, vagal or undetermined mechanism), day-night alternation (nocturnal and daytime distribution). More than the absolute number of premature ventricular complexes, it would appear that the presence of repetitive activities with very short coupling interval allows identifying those patients most at risk.

Take-home message: Pulse measurement in a patient with premature complexes may give a false impression of bradycardia (bradysphygmia) or reveal an irregularity in the rhythm and amplitude of the felt beats (amplitude increased on the cycle following the post-extrasystolic pause due to increased diastolic time).