Evaluation of fluid field of left ventricle outflow tract in hypertrophic obstructive cardiomyopathy with fluid models based on three-dimensional echocardiography with inverted grey values / 中华超声影像学杂志

ABSTRACT

Objective:To explore the effect of systolic anterior motion (SAM) of mitral valves on the morphology and function of left ventricular outflow tract (LVOT) in patients with hypertrophic obstructive cardiomyopathy (HOCM) using computer fluid dynamics based on three-dimensional echocardiography with inverted grey values.Methods:A total of 40 patients with hypertrophic cardiomyopathy were divided into SAM group (24 cases) and non SAM group (16 cases) in Renmin Hospital of Wuhan University from April 2016 to October 2019. Two dimensional and three-dimensional echocardiographic data of the patients were collected. The LVOT morphological model was constructed based on the post-processing of three-dimensional echocardiography data, and the LVOT flow field model was constructed based on the time-volume curve of left ventricle. LVOT peak velocity was obtained to assess the agreement with echocardiography measurements. Area of LVOT, average velocity, flow rate and iso-surface area of vortex of different levels were obtained and compared between the two groups.Results:There was a good correlation between cardiac fluid model and echocardiographic measurement ( r=0.943, P<0.01). The Bland-Altman consistency interval was -75.0-111.3, and 92.5% of the points were within the consistency limit. Compared with non-SAM group patients, the peak velocity of LVOT increased, the area of LVOT decreased, the flow rate decreased and the area of vortex increased in SAM patients (all P<0.01). In the SAM group, in 16 patients the double orifice LVOT was observed due to the contact between mitral valve and septum, in 1 patient the single orifice LVOT structure was observed with contact between mitral value and septum, and in 7 patients, single orifice LVOT without contact between mitral value and septum. In SAM patients, compared with single orifice LVOT, patients with double orifice LVOT were observed with higher LVOT velocity, smaller LVOT area and higher vortex area with high level(all P<0.05). Conclusions:Accurate fluid models can be obtained using three-dimensional echocardiography with inverted grey values. In SAM patients, contact between mitral valve and septum leads to the formation of double orifice structure and the increase of vortex level in LVOT.