For patients with functional mitral regurgitation, there needs to be sufficient leaflet tissue for mechanical coaptation. This is evaluated by TEE from the 4-chamber view by measuring the coaptation length and depth. For optimal results, coaptation depth must be ≥ 2 mm and coaptation depth ≤11mm (Figure 30). While an initial assessment may be performed with TTE, these parameters, particularly coaptation length, typically require TEE for precise measurement (Figure 31).