The animal study of echocardiography-guided transthoracic laser ablation of the interventricular septum

Objective To investigate the safety and long-term efficacy of a new treatment, echocardiography-guided transthoracic laser ablation of the animal interventricular septum (IVS), for obstructive hypertrophic cardiomyopathy (HOCM). Methods Ten healthy sheep were randomly divided into two groups: experimental group: sheath puncture with laser ablation (energy: 3 W, 1000 J), sham control group: sheath puncture only without laser ablation. Echocardiography and electrocardiogram (ECG) were recorded before operation, immediately after operation, and 1, 3 and 6-month after the operation. Left ventricular systolic and diastolic function, longitudinal strain, difference of time to peak between the ablation segment and the surrounding segments were analyzed. Blood samples were collected before and one hour after the operation to examine the serological results. Results Immediately and 6 months after the operation, all animals survived with normal cardiac function. No severe complications such as cardiac tamponade or bundle branch block occurred. The Troponin I level was significantly elevated immediately after the operation(P<0.05). The thickness of the ablated IVS was significantly reduced 6 months after the operation compared with before the operation[(3.23±1.21)mm vs (8.53±0.44)mm, P<0.05]. M-mode echocardiography showed that the amplitude of movement of the ablated region of the experimental group 6 months after the operation was significantly decreased compared with the control group(P<0.05). Three dimensional strain analysis showed that for the experimental group, the longitudinal strain of the ablation segment was significantly reduced and the difference of time to peak was significantly delayed, compared with the control group(P<0.05). Conclusions Echocardiography-guided transthoracic laser ablation of IVS is a safe, effective, and minimally invasive method. It is capable to reduce the volume of IVS without influencing the cardiac function, which makes it a potential alternative for HOCM treatment. Key words: Echocardiography, transthoracic; Hypertrophic cardiomyopathy; Septal ablation; Laser ablation