Which statement best describes epicardial leads?

Epicardial leads are specifically designed to be applied directly to the surface of the heart. This technique usually involves attaching leads to the epicardial surface during surgeries, such as a cardiac surgery procedure where access to the heart is obtained directly. This direct placement allows for effective pacing and sensing because the leads are in close proximity to the myocardial tissue.

These leads are particularly useful in certain clinical situations, especially in pediatric patients or in cases where transvenous access may not be feasible due to anatomical or medical limitations. The connection to the heart surface enables them to provide reliable electrical stimulation, which is essential for therapeutic pacing.

Other options describe different characteristics that do not accurately capture the function and placement of epicardial leads. For instance, leads that are implanted through the veins refer to transvenous leads, not epicardial leads. The idea of stimulating multiple areas of the heart simultaneously typically pertains to specific types of pacing strategies or devices, rather than a defining feature of epicardial leads. External pacing would involve leads that are placed outside the body, further differentiating it from the internal, direct application of epicardial leads.