The correct diagnosis is atrial flutter with variable block (Figure 2). The rhythm is regular at a rate of 150 beats/min; however, there are two long RR intervals (↔). The QRS complex is narrow (0.08 ...

When your electrical system is working normally, the two upper chambers of the heart (atria) contract and pump blood into the two lower chambers (ventricles) in a well-coordinated way. This results in ...