Atrial flutter and atrial fibrillation result primarily from which of the following?

Atrial flutter and atrial fibrillation are both types of arrhythmias, which are irregular heart rhythms stemming from abnormal electrical activity in the heart's atria. In atrial flutter, there is a reentrant circuit commonly involving the right atrium, leading to a rapid but organized rhythm. In contrast, atrial fibrillation is characterized by disorganized electrical impulses that result in a rapid and irregular heartbeat.

The primary issue in both conditions is indeed the irregular heart rhythms that arise from these disturbances in the heart's electrical conduction system. This can lead to various symptoms, including palpitations, shortness of breath, and fatigue, as well as an increased risk of thromboembolic events such as stroke. Thus, the focus on irregular heart rhythms as the underlying factor is accurate, distinguishing these arrhythmias from conditions like bloody loss, cardiac arrest, or cardiomyopathy, which do not specifically address the nature of atrial flutter and atrial fibrillation.