The effect of depth of anesthesia on the severity of mitral regurgitation as measured by transesophageal echocardiography

Objective: The unloading effect of anesthesia on the left ventricle results in a downgrade of mitral regurgitation (MR) severity, which increases as anesthesia deepens. This study examined how the depth of anesthesia could affect the loading condition of the left ventricle and the severity of MR.

Design: A prospective study.

Setting: Cardiac operating room at a single institution.

Participants: Twenty patients with functional MR and 20 patients with organic MR.

Interventions: Different anesthetic depths determined by bispectral index (BIS) monitoring.

Measurements and main results: In patients with functional MR, maximal regurgitant jet area (JA), the vena contracta (VC) width, and the proximal isovelocity surface area (PISA) radius were significantly smaller at a low BIS than at a high BIS (JA, 2.4 cm(2), 1.9-4.7, v 5.0 cm(2), 3.4-6.7, p < 0.001; VC width, 2.7 ± 1.6 v 4.2 ± 1.4 mm, p < 0.001; PISA radius, 3.3 ± 2.3 v 5.6 ± 2.4 mm, p < 0.001). Similarly, in patients with organic MR, JA, VC width, and PISA radius were significantly smaller at a low BIS than at a high BIS (JA, 7.0 ± 2.4 v 9.7 ± 3.6 cm(2), p = 0.002; VC width, 5.7 mm, 4.1-6.6, v 7.1 mm, 5.4-8.4, p < 0.001; PISA radius, 9.0 ± 2.8 v 12.0 ± 3.3 mm, p < 0.001).

Conclusions: It may be helpful to measure the severity of MR at a shallower anesthesia depth guided by BIS monitoring to avoid a downgrade of MR under general anesthesia.