GOAL
To evaluate turbulent blood flow and kinetic energy consumption in patients with aortic stenosis
MATERIALS AND METHODS
58 patients with aortic valve stenosis (aortic valve stenosis) were examined. The average age of the patients was 74±8 years. All patients underwent transthoracic echocardiography (TEC) 3 days before and 7—12 days after surgery. The analysis included patients with mechanical prostheses only. For analysis, a series of dynamic images obtained from apical access were recorded in 2-, 3- and 4-chamber sections. The data was stored and analyzed on an EchoPAC workstation (GE), a Multivox workstation (Gammamed, RF). The ejection fraction (LVEF) of the left ventricle (LV), the final diastolic (CDW) and final systolic volumes (CSF) of the LV, and the pressure gradient (DR) on the AC were calculated with the calculation of the valve opening area. Based on the data of the anatomy of the ventricle and valvular apparatus, quantitative parameters and the structure of blood flows in the LV and aorta were evaluated in the Multivox program. Intraventricular blood flows (V) and pressure gradients per cardiac cycle were plotted with calculation of kinetic energy costs (KE).
RESULTS
The nature of blood flow in the LV and aorta is closely related to the mechanics of the valves and the movement of the myocardium. In patients with AS before surgery, during the period of isovolumic stress, there is a low blood flow rate in the apex area and a fairly high one in the basal region. The average velocity gradient was 0.21±0.4 m/s, which is 10 times higher than normal values. During the expulsion period, the blood flow velocity gradient averaged 0.04±0.01 m/s. The uneven intraventricular flow leads to an additional increase in the pressure gradient between the tip and the LV outflow tract, which increases energy consumption by more than 2 times. During systole, energy consumption was 28% higher than normal. Intraventricular flows and CE are closely related (r — 0.79). After prosthetics of the AC, blood flow rates in all parts of the LV approach normal values. During isovolumia, the average velocity gradient between the apex and the basal region was 0.03±0.01 m/s. During the expulsion period, the blood flow velocity gradient averaged 0.2±0.12 m/s.
CONCLUSION
Surgical correction of AS is an effective treatment method. The turbulent blood flow leads to an additional increase in the pressure gradient and the expenditure of kinetic energy between the tip and the external LV. The stress distribution and the dynamics of changes in the direction of blood flow vectors in the LV are important for determining the progression of the disease and evaluating the results of AS correction.
