Potential influence of the status of a stenotic side branch on the healing of a main branch stenosis treated with percutaneous intervention and stent placement. Simultaneous stenting of the side branch may create disturbed flow patterns at the lateral wall opposite the side branch orifice, which are associated with amplified inflammatory responses and restenosis (upper panel). In the continued presence of stenosis and decreased flow in the side branch, the hemodynamic environment in the stented main branch may be similar to that in a nonbranching arterial segment with nondisturbed, laminar flow (lower panel). Laminar flow, in general, has anti-inflammatory and growth-inhibiting effects on the arterial wall and facilitates healing. While hypothetical, this figure illustrates that opening of a side branch in the setting of a stented main branch may have untoward effects on the outcome of the primary treatment target.