Biomechanical Analysis Of Ultra-fine Zinc Particles On Cardiovascular Effects Of HFpEF Rats

In recent years,the deterioration of air quality has become a global problem.Many studies have shown that small pollution particles have greater cardiovascular hazards due to their high content of organic chemicals and strong oxidation capacity.Therefore,ultrafine particles such as metal particles in haze are one of the important components that need attention.Ejection fraction retention heart failure(HFp EF)is on the rise in morbidity and mortality.The ultra-fine particles in polluted air enter the human blood through respiration and cause cumulative damage to the vascular endothelium,resulting in vascular intima thickening,vascular stenosis and atherosclerosis and other diseases.However,there is a lack of research on the effect of inhalation of ultra-fine particles on HFp EF patients.Dahl salt sensitive(DSS)rats are a good experimental model for high blood pressure induced HFp EF.In this study,ultra-fine zinc particles were inhaled by high-salt-fed DSS rats as the logical starting point,and the hemodynamic mechanism of HFp EF deterioration caused by air pollution was explored in combination with biomechanical calculation.In the experimental part,salt-sensitive rats aged 7 weeks were divided into the low-salt group,the high-salt group and the high-salt haze absorption group.The rats were fed in the same environment for 7 weeks,and the high-salt haze absorption group was subjected to regular and quantitative inhalation of ultra-fine zinc particles in the last 4 weeks.In the in vitro experiment,the morphology and blood flow velocity of the ventricle,abdominal aorta and carotid artery were measured by Doppler ultrasound equipment,and the strain,strain rate and displacement changes of the left ventricle were calculated by Vevo software.In vivo,blood flow,blood pressure and left ventricular indoor pressure were measured by inserting a probe into the aorta.At histological level,the changes of cell number and morphology were observed by confocal microscopy.In the calculation part,based on the Windkessel model,peripheral impedance,vascular compliance and pulse wave velocity(PWV)of carotid artery and abdominal aorta were calculated.The flow velocity profiles within the carotid and abdominal aorta were reproduced by Womersley formula and the relevant hemodynamic parameters were calculated.Through the calculation and analysis of ultrasonic images,the changes of strain and strain rate of endocardium and epicardium of rats in the high-salt group and the high-salt haze group were obtained compared with those in the low-salt group.Based on the measurement of blood flow and blood pressure in vivo,the changes of cardiac output,ventricular pressure,endsystolic and end-diastolic blood pressure,etc.,can be obtained through statistical analysis.Through programming calculation,the effects of inhalation of ultra-fine zinc particles on peripheral vascular impedance,vascular compliance and PWV of HFp EF rats can be obtained,and the internal mechanism of increasing vascular hardness can be revealed.Finally,the conjecture of this study was verified,namely,inhalation of ultra-fine zinc particles could further worsen the local myocardial dysfunction of left ventricle and peripheral hemodynamic environment of HFp EF rats.This study will be of great significance in revealing the mechanism of cardiovascular injury caused by air pollution.