Bigeminal rhythm
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby, M.D. [2]
Synonyms and keywords: Bigeminy, bigeminal beat
Overview
Bigeminy is a type of cardiac arrhythmia in which abnormal heart beats occur every other concurrent beat. The abnormal heart beat can originate from the atrium, AV node or the ventricle. A typical example is bigeminal rhythm resulting from premature ventricular beats, also known as a premature ventricular contractions/complexes (PVC). Following the PVC there is a pause and then the normal beat returns, only to be followed by another PVC. The continuation of this pairing of beats is an example of bigeminy. Other forms of abnormal beats include PAC, escape beats and parasystole.
Classification
- Atrial bigeminy
- Junctional bigeminy
- Ventricular bigeminy
- Concealed bigeminy
- Escape capture bigeminy
Pathophysiology
Differential Diagnosis
| Bigeminal premature ventricular contractions | Normal, PVC, Normal, PVC... |
| Trigeminal premature ventricular contractions | Normal, Normal, PVC, Normal, Normal, PVC... |
| Quadrageminal premature ventricular contractions | Normal, Normal, Normal, PVC; Normal, Normal, Normal, PVC... |
| Occasional escape complexes | Normal, Normal, Normal, Normal, Pause, Escape... |
| Bigeminal Couplets | Normal, Normal, PVC, PVC, Normal, Normal, PVC, PVC... |
| NS-VT | Normal, Normal, PVC, PVC, PVC, PVC, Normal, Normal, PVC... |
Diagnosis
ECG
Shown below is an EKG depicting atrial bigeminy. The EKG shows a regularly irregular rhythm at a rate of about 75/minute. There are two P wave morphologies best seen in lead V1.
Copyleft image obtained courtesy of ECGpedia,http://en.ecgpedia.org/wiki/Main_Page
Shown below is an EKG depicting bigeminy. The pacemaker is an atrial pacer set at 30/min. Note the marker channel documenting atrial pacing and then sensing of the QRS in the refractory period of the pacemaker. The paced atrial beats seem to stimulate a normal sinus beat and hence create the bigeminal rhythm.
Copyleft image obtained courtesy of ECGpedia,http://en.ecgpedia.org/wiki/Main_Page