<unk> s may be found incidentally on cardiac tests such as a 12-lead electrocardiogram (ECG/EKG) performed for another reason. In those with symptoms suggestive of<unk><unk>  complexes, the ECG/EKG is the first investigation that may identify<unk> s as well as other cardiac rhythm issues that may cause similar symptoms. If symptoms are infrequent, other forms of continuous heart beat recording may be used, such as a 24- or 48-hour Holter monitor. The advantage of these monitors is that they allow a quantification of the amount of abnormal beats ("burden") and ensure that there are no heart arrhythmias present that might require attention, such as<unk>  tachycardia. If symptoms are associated with exercise, a supervised cardiac stress test may be required to reproduce the abnormality. Specifically, if this shows exercise-induced<unk>  tachycardia this would require specific treatment. If<unk> s are suppressed by exercise, this is an encouraging finding. On electrocardiography (ECG or Holter)<unk> s have a specific appearance of the QRS complexes and T waves, which are different from normal readings. By definition, a<unk>  occurs earlier than the regular normally conducted beat. Subsequently, the time between the<unk>  and the next normal beat is longer as the result of a compensatory pause.<unk> s can be distinguished from<unk>  atrial contractions because the compensatory pause is longer following<unk> s, in addition to a difference in QRS appearance. In some people,<unk> s occur in a predictable pattern. Depending whether there are one, two, or three normal beats between each<unk> , the rhythm is called bigeminy, trigeminy, or quadrigeminy. If 3 or more<unk> s occur in a row it may be called<unk>  tachycardia. The precise shape of the QRS can give an indication as to where precisely in the heart muscle the abnormal electrical activity arises. If someone has<unk> s that all have the same appearance, they are considered "monofocal", if<unk> ’s have different appearance, they are considerevole “multifocal” .
Premature ventricular contraction
Premature atrial contraction
Benign early repolarization
Pre-excitation syndrome
Ectopic beat
Ectopic pacemaker
Premature junctional contraction
Drug-induced QT prolongation