Irregular heartbeats are common and usually harmless. You re describing a preventricular contraction -- the skipped beat followed by the strong beat. This is probably the most common cardiac arrhythmia. There are a LOT of PVC triggers (anxiety, lack of sleep, too much caffeine) and most of them are easily remedied. Only a few are related to heart disease. You needn t see your doctor about it unless you begin to experience shortness of breath, difficulty breathing, dizziness and so forth.