Three-dimensional surface area of the aortic valve orifice by three-dimensional echocardiography: Clinical validation of a never index for assessmentof aortic stenosis

Background A direct and accurate method of assessing aortic valve area (AVA ) in patients with aortic stenosis (AS) is desirable because of the well-kn own theoretical and practical limitations of the currently available method s. We assessed the clinical feasibility and accuracy of a novel index, the 3-dimensional surface area (3-DSA) of the aortic valve orifice by 3-dimensi onal transesophageal echocardiography (3-DTEE) in patients with AS. Methods Intraoperative 3-DTEE was performed in 23 consecutive patients (mea n age 58 +/- 15 years) with valvular AS using a Toshiba SSA-380A system wit h a multiplane TEE probe and a TomTec EchoScan system. The 3-DTEE acquisiti on, processing and reconstruction were conducted and the aortic valve orifi ce presented using a "surgeon's aortotomy view" (aortic valve orifice as if viewed through on open aortic root). The 3-D images were videotaped and ca librated and the 3-DSA measured by planimetry of the inner surface of the a ortic valve leaflets at the maximal systolic opening using the dynamic 3-D images. For comparison, the 2-D cross sectional area (2-DCSA) of the aortic valve was also determined by 2-DTEE. The 3-DSA and 2-DCSA were compared wi th the AVA by the invasive Gorlin formula and the Doppler continuity equati on method by transthoracic echocardiography. Results The 3-DSA and 2-DCSA measurements were feasible in all but one pati ent. Both 3-DSA and 2-DCSA correlated moderately well with the AVA by the G orlin formula (n = 17, r = 0.66, standard error of the estimate [SEE] = 0.3 cm(2), P < .05 for 3-DSA and r = 0.61, SEE = 0.5 cm(2), P < .05 for 2-DCSA , respectively). They also correlated well with the AVA by Doppler continui ty equation method (n = 22, r = 0.90, SEE = 0.1 cm(2), P < .05 For 3-DSA an d r = 0.83, SEE = 0.3 cm(2), P < .05 for 2-DCSA, respectively). There was n o statistically significant difference between the 3-DSA and AVA by both th e Gorlin formula (Delta = 0.1 +/- 0.3 cm(2), P = .3) and the Doppler contin uity equation (Delta = 0.0 +/- 0.3 cm(2), P = .7). in contrast, the 2-DCSA significantly overestimated AVA by the Gorlin formula (Delta = 0.5 +/- 0.5 cm(2), P < .005) and by the Doppler continuity equation (Delta = 0.5 +/- 0. 6 cm(2), P < .0001). Conclusions Planimetry of 3-DSA of the aortic valve orifice by 3-DTEE is a clinically feasible and relatively accurate technique for assessment of AVA and is superior to 2-DCSA by 2-DTEE.