If Purkinje fibers produce the electrical impulse, what would the EKG show as a heart rate?

When Purkinje fibers generate an electrical impulse, they do so at a rate of 20 to 40 beats per minute (bpm). This is often described as a junctional or ventricular escape rhythm, which typically occurs in situations where the higher pacemakers (such as the sinoatrial node or atrioventricular node) are not functioning correctly or have become compromised.

In a healthy heart, the sinoatrial node is the primary pacemaker, driving the heart rhythm at 60 to 100 bpm. If the sinoatrial and atrioventricular nodes fail to maintain pacing, the Purkinje fibers take over, but they do so at a much slower rate. This lower heart rate reflects the body's compensatory mechanism to ensure minimal cardiac output during times of distress or in cases of certain cardiac pathologies.

Thus, when analyzing the EKG in this scenario where Purkinje fibers are responsible for impulse generation, one would expect to see a heart rate in the range of 20 to 40 bpm. This understanding is crucial for interpreting EKGs and recognizing different cardiac rhythms.