This report describes the case of a 52-year-old male patient who exhibited suspicious pulsation patterns during pulpal blood flow assessment using Doppler ultrasound. Initially, he was not aware of his cardiovascular problem; however, after referral to a medical clinic, he was diagnosed with atrial fibrillation. The patient was injured in a motor vehicle accident and referred to our clinic for management of multiple traumatized teeth. On clinical examination, several teeth exhibited negative responses to cold and electrical sensibility tests. For accurate diagnosis, pulpal blood flow assessment using a Doppler ultrasound device was performed. During the tests, irregular pulsation patterns were detected, indicating the possibility of a cardiovascular problem. As he denied any history of cardiovascular problems, he was recommended to visit a medical doctor for further evaluation. The following day, he visited a medical clinic, and a 12-lead electrocardiogram was performed. He was ultimately diagnosed with atrial fibrillation with idioventricular rhythm, and was started on anticoagulant medication for prevention of thrombogenesis, which is a possible complication of atrial fibrillation. As presented in this case, Doppler ultrasound can provide useful information, not only about blood flow in the dental pulp, but also about an individual's pulsation rhythm. When a patient presents with irregular pulsation patterns in certain situations, the possibility of cardiovascular problems should be considered.