Experimental Study On Renal Blood Flow In Dogs With Acute Cardiac Insufficiency

Objectives:Acute cardiac insufficiency(ACI) is a clinical common disease.Renal blood flow(RBF) declines and renal dysfunction occurs due to decreased cardiac output(CO) of ACI. Renal insufficiency also makes ACI severe.It is of a signifiance to study the mecanhism of the kidney microcirculation in ACI which remains unclear .Up till now, seldom means to study renal mircirculation exist.Contrast-Enhanced Ultrasound (CEU) is ideal for measuring microcirculatory flow because of its good spatial and temporal resolutions and because it utilizes tracers that have intravascular rheology similar to that of red blood cells.So we design the experimental study with main puroses as follows:(1)making a canine model of ACI induced by coronary artery occulsion and tachycardiac stress. (2) To quantify renal microcirculatory flow in dogs with ACI. (3) To assess the effect of captopril(CPT) on kidney microcirculation in dogs with ACI.Methods:1.Making a canine model of ACIStudies were performed in anerthetized,mongrel dogs.Cardiogram,mean arterial pressure(MAP),arterial oxygen saturation(SaO2 ) were monitored.Swan Ganz catheter was inserted into a femoral vein and advanced into the pulmonary artery to measure mean right atrial pressure(mRAP) and mean pulmonary capillary wedge pressure(mPCWP).A pacing lead was attached to the right ventricular wall.An ultrasonic flow probe was placed around the assending aorta to monitor cardiac output after the chest was opened. CO reduction was expected using rapid ventricular pacing after the left anterior decending coronary(LAD) was ligated.As CO was reduced to 75% and 50% of the base, MAP, SaO2, mRAP, mPCWP, and systemic vascular resistance(SVR) were acquired.Echocardiography was used to examine cardiac size .Blood sample was obtained for examination of plasma renin activity(PRA) and endothelin(ET).2.To quantify renal microcirculatory flow in dogs with ACIThe left subcostal space was entered to exposed the left renal artery An ultrasonic flow probe was placed to monitor instantaneous changes in renal blood flow. Quanfuxian(a contrast agent consisting C3F8 microbubbles) was injected intravenously for CEU of the kidney at the base?75%CO?50%CO stages respcectfully,and CEU images were recorded by intermittent harmonic imaging technique and stored for offline analysis. The offline software presents values of A and automatically.Urine output (UO)?serum creating (Scr) and creating clearance(Ccr) were also measured.3. To assess the effect of captopril on kidney microcirculation in dogs with ACICaptopril(CPT) was injected at the dose of 1mg/Kg at the time 15minuntes after CO decreased to 50% of the base. 1 hour later, 2mg/Kg CPT was adminstrated.CEU of the kidney was performed before and 1 hour after the adminstration of CPT,and CO?RBF?MAP?SaO2?mRAP?mPCWP? SVR were record at the same time. CEU images were recorded and stored for offline analysis.Results:1.Making a canine model of ACICO was reduced steadily to 75% and 50% of the base after right ventricular pacing following ligation of LAD. MAP SaO2 decreased while mRAP, mPCWP SVR, PRA, ET increased significantly The cardiac cavity became larger while LVEF decreased.2.To quantify renal microcireulatory flow in dogs with ACIRBF changed to(72.50 32.4)ml/min and (44.1 ?17.2)ml/min from the base of (107.5 35.7)ml/min (P<0.05) following 25% and 50% CO reduction.Contrast appeared in the renal cortex (CX) then in the outer to inner medulla (MD) after CEU at the base. Notable difference of Values of A(CX120.3 vs MD110.8,P<0.05) . (CX1.39 vs MD 0.54,P<0.05)?A (CX167.4 vs MD59.5,P<0.05)existed between CX and MD.There is also marked difference between ratio of CX-to-MD and ratio A of CX-to-MD (ratoio & 0.612vs ratio A 0.078 P<0.05).In the CX, no significant changes in A value were observed when CO decreased to 75% while it decreased notablly when CO was 50% of the base(106.9 vs 120.3 ,P<0.05) Both and A value decreased markedly following 25% and 50% CO reduction.In the MD, there were no obvious changes in A value while distinct chang...