Exploring the hemodynamic changes of the ascending aorta before and after interventricular septal myocardial resection in obstructive hypertrophic cardiomyopathy by CMR 4D Flow technology / 中国医师杂志

ABSTRACT

Objective:To investigate the hemodynamic changes in the ascending aorta (AAo) before and after interventricular septal myocardial resection in obstructive hypertrophic cardiomyopathy (HOCM) using cardiac magnetic resonance four-dimensional blood flow (CMR 4D Flow) technology.Methods:HOCM patients who underwent interventricular septal myocardial resection at Guangdong Provincial People′s Hospital from May 2021 to September 2022 were prospectively included. Age and gender matched healthy volunteers (control group) were included during the same period. Both the control group and HOCM patients underwent CMR examination (including cine sequence and 4D Flow sequence) before and 6 months after surgery. CMR 4D flow technology was used to evaluate changes in AAo preoperative and postoperative blood flow patterns (eddy currents, spiral flow), maximum energy loss (EL max), and average energy loss (EL avg). HOCM patients underwent laboratory tests, including N-terminal pro-brain natriuretic peptide (N-pro BNP) and high-sensitivity troponin T (hsTnT). At the same time, the correlation between postoperative energy loss in HOCM patients and the degree of improvement in laboratory biomarkers was explored. Results:A total of 15 HOCM patients and 15 healthy volunteers were included. (1) In terms of blood flow patterns, the preoperative spiral flow degree of HOCM patients was significantly higher than that of the control group ( P=0.001), but the postoperative difference was not statistically significant ( P=0.059). The degree of eddy currents in HOCM patients before and after surgery was higher than that in the control group (all P<0.05). (2) In terms of energy loss, the preoperative EL max [21.17(14.30-28.10)mW vs 10.17(7.66-13.07)mW, P<0.001] and EL avg [4.87(3.46-5.77)mW vs 2.27(2.19-2.27)mW, P=0.023] of HOCM patients were higher than those of the control group, but there was no statistically significant difference between the postoperative and control groups (all P>0.05). Compared with preoperative, the postoperative EL max [12.33(8.70-17.41)mW] and EL avg [3.10(2.25-4.40)mW] of AAo in HOCM patients were significantly reduced (mean P=0.001). (3) Correlation analysis showed that there was a positive correlation ( r=0.587, P=0.021) between the EL max of AAo and the degree of improvement in hsTNT after interventricular septum myocardial resection, but no significant correlation ( r=0.229, P=0.413) with the degree of improvement in NT-pro BNP. Conclusions:The degree of postoperative AAo blood flow disorder in HOCM patients is reduced, and EL max and EL avg are significantly reduced. The EL max of postoperative AAo is positively correlated with the degree of improvement in hsTNT, suggesting that EL max may be applicable for prognostic evaluation of patients.