An In Vitro Model to Simulate Left Ventricular Contraction of Isolated Porcine Hearts for Mitral Valve Reconstruction

Background: In mitral valve insufficiency reconstruction of the valvular structures is a common and successful procedure, but challenging due to the complex spatial composition of the mitral valve apparatus and its movements during the cardiac cycle. In-vitro functional evaluation of surgical methods were actually done with either isolated mitral valves fixed on special holders or in apically perfused hearts, however, none of these models provide both, anatomical and physiological behaviors of the native mitral valve. In this regard, aim of this study was to develop a novel in vitro model which simulates a physiologically and anatomically fitted contraction of the left ventricle by means of an adapted external compression of the myocardium of porcine hearts.

Method: Porcine hearts were dissected, leaving the ascending aorta, the arch and a short portion of the descending aorta for connection to the afterload. The right ventricle was dissected to allow for direct forcing onto the septal muscle and also the left atrium to get access to the mitral valve. A felt skirt was sutured to the remaining left heart at the valvular level for fixation. The subjacent part was placed in the pressurization chamber in a form-fitted silicone bag which provides a tight sealing against the chamber and allows for a specific regional compression of the left heart by customized segments. Pressurization was done by an external pump providing a range of heart specific volume displacements at different frequencies; the afterload was set to 80 mm Hg diastolic. Resulting compression of the ventricle was determined by the difference the systolic and diastolic diameters at the basal, medial and apical level and the length of the vertical axis taken from video documentation in three aspects. External, left ventricular and aortic pressures were measured as well as ventricular volume ejection. Following these data different segmentations of the silicone bag were investigated with random porcine ventricles for stepwise optimization.

Results: In the actual configuration diameter deviations were 12.9% (basal), 13.5% (medial) and 20.0% (apical) and 7.6% in length, resulting in an ejection volume of 40.9 ± 0.2 mL with a physiological shaped aortic flow course.

Conclusion: With the latest model a close simulation of a left ventricular contraction could be achieved, allowing for investigations of mitral valve procedures. Model will be further optimized for different sizes and hemodynamic conditions.

Publication History

Article published online:
03 February 2022