ABSTRACT
Objective:To investigate the effect of mid-ventricular obstruction (MVO) on left ventricular systolic function in patients with hypertrophic cardiomyopathy(HCM) by four-dimensional automatic left ventricular quantitation technology(4D Auto LVQ).Methods:Fifty-seven hypertrophic obstructive cardiomyopathy patients were selected from December 2020 to October 2022 in the First Affiliated Hospital of Zhengzhou University. According to the presence of MVO, HCM patients were divided into two groups: HCM 1 group, HCM without MVO ( n=34); HCM 2 group, HCM with MVO ( n=23). In addition, 25 healthy subjects in the same period were selected as the control group. Conventional ultrasound parameters were collected, and 4D Auto LVQ technology was used to obtain the mechanical parameters of left ventricular myocardium, including left ventricular longitudinal strain (GLS), circumferential strain (GCS), area strain (GAS), radial strain (GRS), segmental longitudinal strain (SLS) and area strain (SAS). The differences of these parameters among the three groups were compared. Results:①Compared with the control group, the thickness of the maximum basal segment of interventricular septum, the thickness of the middle segment of the maximum interventricular septum, the thickness of the apical segment of the interventricular septum, the thickness of the left ventricular posterior wall and left atrium diameter were significantly increased. Six-minute walk distance and the left ventricular end-diastolic diameter was decreased in the two groups of HCM(all P<0.05). Left ventricular outflow tract gradients in HCM 1 group was higher than HCM 2 group( P<0.05), but there was no significant difference in left ventricular ejection fraction among the three groups( P>0.05). There was significant difference in the incidence of left ventricular apical aneurysm among the three groups( P<0.05). ②Compared with the control group, the GLS in both HCM groups was lower, and it was lower in the HCM 2 group than in the HCM 1 group(all P<0.05) the GRS and GAS in both HCM groups were lower than in the control group ( P<0.05), and there was no significant difference between the two groups of HCM, and there was no significant difference in GCS among the three groups(all P>0.05). ③Compared with the control group, the SLS of basal segment, middle segment, apical cap, posterior septum, inferior wall and lateral wall in HCM group were significantly lower than those in control group. The SLS of apical segment of posterior septum, anterior septum, anterior wall, posterior wall, inferior wall and apical segment of posterior septum, lateral wall and inferior wall in HCM 2 group were significantly lower than HCM 1 group(all P<0.05), but there was no significant difference in SLS of posterior septum, anterior septum, anterior wall, lateral wall and inferior wall between the two groups(all P>0.05). ④Compared with the control group, the SAS of posterior septal basal segment, middle segment, anterior septal middle segment, anterior wall basal segment, middle segment, apical segment, lateral wall basal segment, middle segment, apical segment, posterior wall basal segment, middle segment, inferior wall basal segment, middle segment and apical cap in HCM groups were significantly lower than the control group(all P<0.05), but there was no significant difference in SAS between the two groups of HCM( P>0.05). Conclusions:4D Auto LVQ can quantitatively evaluate the damage of MVO on the left ventricular systolic function in patients with HCM, especially for the evaluation of local myocardial function damage in the medial segment and apical segment.