Irregular spikes on an EKG due to muscle movement are called?

Irregular spikes on an EKG that are caused by muscle movement are specifically referred to as a somatic tremor. This phenomenon occurs when voluntary or involuntary muscle activity interferes with the electrical signals being recorded by the EKG machine, leading to an artifact that may mimic or distort the actual heart rhythm being studied. Somatic tremors can result from factors such as patient movement, muscle spasms, or even tremors caused by conditions like Parkinson's disease.

While artifacts can generally refer to any distortion on an EKG from external sources (such as movement, poor lead placement, or electrical interference), the term "somatic tremor" specifically emphasizes the connection to muscle movement. The other terms listed, while relevant to cardiac activity, do not describe the irregular spikes from muscle movement. Sinus tachycardia refers to a specific increase in heart rate from a normal sinus rhythm, and premature contractions indicate early heartbeats that do not stem from muscle interference.