The first experience of intraoperative myocardial elastography in cardiac surgery patients

Abstract

The goal the work was to study the possibility of using elastography on an open heart to determine the stiffness of the left ventricular myocardium. Material and methods. Intraoperative elastography was performed in 6 patients with isolated aortic stenosis and dissecting aneurysm of the ascending aorta with aortic insufficiency. Three patients underwent surgery to replace the aortic valve with mechanical prostheses (SIM-19) and three were operated to replace the ascending aorta with an artificial prosthesis with aortic valve replacement (David’s operation). The average age of the patients was 42±9 years (42–53) years. All patients underwent surgery under conditions of artificial blood circulation. Initially, elastography was evaluated on a working heart, and then on full artificial circulation. The study was performed on a VK 5000 ultrasound device with an intraoperative «stick» type sensor at a frequency of 7.5–15 Mhz, gain of 1.6 Db, resolution of 127 hz. The deformation coefficient was evaluated. The imaging program was exposed as for neurosurgery with a frequency of 15 Mhz. Visualization was performed in B-mode, followed by obtaining shear wave elastography with calculation of the deformation coefficient. Results. Wave elastography was evaluated for various heart pathologies with different myocardial thickness. It was found that the stiffness in the studied areas of the myocardium is different. Thus, in patients with atherosclerotic aortic stenosis and a pressure gradient of more than 100 mmHg, the deformation coefficient was increased, in accordance with the thickness of the myocardium and amounted to 3.81–4.06, and in patients with aortic root dilation and aortic insufficiency, the deformation coefficient was 1.64–2.9. Conclusion. Intraoperative assessment of the left ventricular myocardial deformation coefficient is possible only on a stopped heart and gives an idea of the state of the heart muscle with the possibility of soft and hard areas. Shear wave elastography provides information about the elasticity and hardness of the tissue, which indirectly reflects the viscosity of the myocardium. This study was aimed at verifying the methodology for assessing the characteristics of the elasticity of the left ventricular myocardium for myocardial overload by pressure (aortic stenosis) and volume in case of a dissecting aortic aneurysm with aortic insufficiency.