To explore the feasibility and validity of preoperative evaluation of Liwen procedure for obstructive hypertrophic cardiomyopathy using 3D printing cardiovascular model.

A retrospective study was conducted on eight patients with obstructive hypertrophic cardiomyopathy who were treated at Xijing Hospital, Air Force Military Medical University from October 2018 to May 2019. Liwen procedure was successfully performed. CT imaging data were collected before operation, and the data were imported into Mimics software for reconstruction. The patients' whole-heart anatomical models were made by 3D printing technology for preoperative imaging evaluation. Ultrasound-guided percutaneous intramyocardial septal radiofrequency ablation was monitored and evaluated by transesophageal echocardiography during the operation. Follow-up observations were carried out at 1, 3, and 6 months after the operation during the first year and every year thereafter. Postoperative evaluation was made by combining imaging and 3D printing techniques. The data including left ventricular ejection fraction, maximum thickness of interventricular septum, and mitral regurgitation before and after operation were compared by paired t test. The data including pressure difference of left ventricular outflow tract and after loading were compared by Wilcoxon signed-rank test.

Liwen procedure was successfully performed in eight patients with obstructive hypertrophic cardiomyopathy. The cardiac function, ventricular septal hypertrophy, and left ventricular outflow tract obstruction were significantly improved after operation. The 3D printing model could accurately reproduce the individual anatomical structure of the patients and assist the preoperative evaluation of Liwen procedure. The intraoperative and postoperative 3D printing models were consistent with the actual operation. Compared with the value before operation, the left ventricular ejection fraction increased significantly at 6 months after operation [(58.36±6.21)% vs (46.25±7.62)%, t=7.998, P=0.015], and the maximum thickness of interventricular septum [(13.92±3.56) mm vs (25.42±4.93) mm, t=14.539, P=0.005] and the mitral regurgitation [(1.04±0.41) ml vs (10.14±3.72) ml, t=4.726, P=0.041] decreased significantly. The pressure difference of left ventricular outflow tract [90.45 (90.00, 110.00) mmHg vs 7.00 (6.00, 10.00) mmHg, Z=2.521, P=0.012] and the pressure difference of left ventricular outflow tract [141.00 (89.25, 150.00) mmHg vs 16.50 (15.00, 17.85) mmHg, Z=2.521, P=0.012] decreased significantly after loading. There were three cases with NYHA class Ⅳ and five cases with NYHA class Ⅲ before operation, while there were six patients with NYHA class I and two patients with NYHA class Ⅱ at 6 months after operation.

3D printing technology is feasible and effective in preoperative evaluation of Liwen procedure for obstructive hypertrophic cardiomyopathy.