What is a "bigeminy arrhythmia" and is it serious?

Maybe: This is a rhythm where the natural pacemaker is causing a beat and then the ventricular innate pacemaker causes a premature beat giving a normal beat followed by a PVC and repeating this process over and over. This is sometimes present and not issues are identified and tolerated well. Others may have underlying cardiovascular disease and this could be a harbinger of a significant problem. C pcp.

PVC: Patients with frequent premature ventricular contractions such as bigeminy (every other heartbeat is a premature ventricular contraction), often report no symptoms. But in rare occasions they may report weakness, dizziness, or fainting. This is because frequent PVC can diminish the ability of the heart to pump blood to the other organs (diminished cardiac output), resulting in low blood pressure.

Bigeminy is: An extra beat every other beat & can arise from atrium or ventricle. How much are you having? Often not a serious thing if infrequent but talk to a cardiologist.