Myocardial capture is primarily determined by which factors?

Myocardial capture is crucial for effective pacing, as it refers to the successful stimulation of the myocardium by the pacing device, resulting in a contraction. The primary factors that determine myocardial capture are amplitude and pulse width.

Amplitude refers to the strength of the electrical signal generated by the pacemaker. A sufficient amplitude ensures that the electrical impulse can reach the myocardial tissue and trigger a depolarization, which is necessary for muscle contraction. Pulse width is the duration of the electrical pulse. A longer pulse width allows more time for the depolarization process, which can enhance myocardial capture, especially in tissues that may have decreased excitability.

While other factors, such as lead integrity, can influence pacing performance, they are not the primary determinants of myocardial capture. Lead integrity ensures the pacing system is functional and connected, and though electrode characteristics play a role, they are not as directly related as amplitude and pulse width are in ensuring effective myocardial capture.