Which of the following factors does NOT affect thresholds?

Understanding which factors can influence pacing thresholds is essential for effective cardiac device management. Ejection fraction, while a critical parameter in assessing heart function and clinical status, does not directly influence the thresholds for pacing.

Pacing thresholds refer to the minimum electrical stimulus required to consistently depolarize the myocardial tissue and achieve capture with a pacing lead. Several physical and technical factors play a significant role in this phenomenon.

Lead integrity is crucial because it ensures that the lead maintains good contact with myocardial tissue and is not damaged. If there is an issue with lead integrity, the pacing response may change, leading to variations in thresholds.

The placement of the lead within the heart significantly affects pacing thresholds as well. Different locations on the myocardium yield different thresholds due to variations in tissue impedance and local myocardial characteristics.

Medications can alter the cardiac electrical activity and change the excitability of the myocardium. For example, some antiarrhythmic drugs can influence the pacing threshold by affecting myocardial conductivity.

In contrast, ejection fraction primarily provides insights into the functional status of the heart and the efficiency of its contraction but does not have a direct impact on how much electrical stimulation is required for effective pacing. Thus, while it is a vital parameter for clinical assessment, it is not