Approach to the interventricular septum with transection and restoration of the fibrous ring of aortic valve (experimental study)

 Septal myectomy is one of the most reliable methods of treating obstructive forms of hypertrophic cardiomyopathy. Most often, this operation is performed using a transaortic approach. Good immediate and long-term results of the operation are observed in more than 90% of cases. The limited visualization of interventricular septum through the aortic valve orifice is one of the reasons for myectomy ineffectiveness and some complications. This problem can be solved by using an extended transaortic approach to the interventricular septum, implying the intersection of the  fibrous ring of aortic valve.

Aim. To assess the effectiveness of extended transaortic approach to the interventricular septum by dissecting and restoring the fibrous ring of aortic valve in the commissural zone with subsequent assessment of its obturator function in the experiment.

Material and Methods. Cadaveric porcine hearts were used as experimental models. The aortic root was exposed; the coronary arteries were ligated. A total of 30 experimental dissection operations were performed, followed by a restoration of one commissure of the native aortic valve. The effect of investigated method for the commissural restoration of the diameter to the fibrous ring of the aortic valve was evaluated. The obturator function of the aortic valve after the restoration of annulus fibrosus was studied using a special device by performing water test with a maximum pressure of 200 mm Hg and regurgitant volume estimation.

Results. The aortic wall suture variant for the restoration of native aortic valve commissure was theoretically substantiated and studied in the experiment. When assessing the sufficiency of aortic valve after the dissection and restoration of commissure, no significant regurgitation on the aortic valve was observed in all cases. Direct measurements showed no significant decrease in the diameter of the annulus fibrosus of aortic valve after the reconstruction. The diameter of annulus fibrosus did not change
in 26 (87%) cases; the diameter after correction decreased by 1 mm in 4 (13%) cases (p = 0.570).

Conclusion. The experiment showed a possibility of the dissection and successful restoration of the annulus fibrosus of aortic valve in the commissural zone without disrupting its function and significantly changing the diameter of annulus fibrosus. This technique can become a key one in the development of both extended transaortic approach to the  interventricular septum and new options for the valve-sparing interventions at the aortic root. 

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