Modeling of main arteries restenosis in experimental cardiology

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Purpose To perform the model of main arteries restenosis and to study the arterial hemodynamics using the original device for modeling of intra-arterial circulation. Materials and methods We used an original device developed by us for modeling of intra-arterial circulation. The main part of the device is a prototype of human arterial vessel - rotameter glass tube 365 mm length, with inlet diameter more than outlet (20 mm vs 16.5 mm). An aqueous solution of glycerin is introduced inside closed system had the same viscosity as the human blood. Flexible silicone tubes are connected with rotameter and electric pump with various modes of work (imitation of pulse waves in regular rhythm (RR), extrasystoles (ES), atrial fibrillation (AF)). We hermetically installed in the rotameter imitation of arterial stent – metal construction with spiral oriented parts 68 mm long. Plastic diaphragms 15 mm long with stenosis of the internal lumen of 50%, 70%, and 90% were alternatively put inside the tube to study intra-arterial hemodynamics. 5 mm long silk thread was alternately installed inside the tube, an intravascular piezoelectric crystal pressure sensor connected to an oscilloscope was injected with a dye - clerical ink. Results When imitating AF after the long pause the speed of fluid flow through the diaphragms increased in comparison with the RR with the pendency: if longer pause was than more speed increased. So, with a stenosis of 50%: the speed with a RR was 2.09 m/s, with AF after the pause <1 s speed was 3.36 m/s, AF after the pause >1, but <2 s speed was 4.97 m/s, AF after the pause >2 s speed was 5.88 m/s; with 70% stenosis: the speed with a RR was 3.24 m/s with AF after the pause <1 s speed was 3.96 m/s, AF after the pause >1, but <2 s speed was 5.87 m/s, AF after the pause >2 s speed was 7.83 m/s; with 90% stenosis, the speed at RR 8.96 m/s, with AF after the pause <1 s speed was 9.46 m/s, AF after the pause >1, but <2 s speed was 11.17 m/s, AF after the pause >2 s speed was 13.45 m/s. The pressure measured by piezoelectrical probe increased proportionally to the speed. We observed the appearance of reflected, standing waves in the edge zones of the diaphragm and stent and a turbulent flow of liquid behind the diaphragm and stent. Conclusion These changes in hemodynamics are characterized by proposed concept of "hydraulic shock". Intense mechanical effect of the pressure waves after the long pauses between cardio cycles in AF in the marginal zones of the diaphragm and intra-arterial stent can cause the further growth, progression of atherosclerosis and restenosis in arterial vessels.