Which descriptor is best associated with Reynaud's Phenomenon?

Reynaud's Phenomenon is best associated with arterial involvement because it primarily affects the small arteries that supply blood to the skin, especially in response to cold or stress. During an episode, these blood vessels spasmodically constrict, leading to reduced blood flow and typical changes in skin color and temperature (often resulting in pallor or cyanosis). The focus on arterial occlusion provides insight into the pathophysiological mechanisms at play, as these episodes illustrate how the arterial system responds to various stimuli.

The other descriptors—venous, unilateral, and painless—do not accurately capture the essence of Reynaud’s. While patients may experience pain during an attack due to ischemia, it is not a defining feature, and the phenomenon typically affects both hands or feet rather than manifesting unilaterally. Thus, the association with arterial involvement is the key attribute of Reynaud's Phenomenon.