The pulse is fast and slow, commonly in patients with pulse dystocia, and may occur in patients with arrhythmias such as atrial fibrillation. In patients with atrial fibrillation, the ventricular rate is definitely irregular and the hypocardial sounds are unequal in strength on auscultation. Patients may exhibit a heart rate greater than the pulse rate, and the pulse may exhibit a pulse dystocia. Atrial fibrillation arises from ectopic rhythms in the atria, which originate from different pacing points and manifest as a loss of regular, orderly atrial electrical activity, replaced by rapid, disordered fibrillation waves. In atrial fibrillation, which is a severe disturbance of atrial electrical activity, it usually manifests as an irregular and rapid rhythm.