The Effects Of In Situ Coronary Venous Arterialization To Myocardial Mitochondrial Ultrastructure

BackgroundAs the increasing standard of living and the prolong of the average life-span, theincidence of CAD is increasing. CAD has been one of the main diseases that cause thedeath of middle age and old people in china. It is well known that the coronary arterybypass graft (CABG),as a effective therapy for coronary artery disease(CAD),hasbeen extensively accepted recently. But according to the materials, about 12-30 percentof the CAD patients can not accept the normal operation because of the poor conditionof target vessel caused by severe CAD. Surgeons often seem to be helpless whenfaceing such patients with end-stage coronary artery disease. Various methods havebeen tried, but eventually none of them widely used for various reasons such asincorrect effect or immature technology.Atherosclerosis is mainly caused by dyslipidemia, widely impacting on the humanarterial system, but this will not affect the venous system. As for the venous, smoothand gross compared to abnormal artery, can ensure an adequate flow and low flowresistance. So we will provide an excellent method to cure terminal CAD by ICVA.At present the researches for ICVA are focused on the condition of smooth and relief ofthe transplanted venous. But few studies is reported about myocardial ultrastructureafter ICVA. Mitochondrial is an crucial cellular organ that effects damage level of the cellsand shows whether the cells damage can be reversible or not.Mitochondrial has theimportant functions of persisting the alive cells' biochemistry,oxadation and theproduction of energy. The damage and apoptosis of mitochondrial reveal the integrityof the cell function. It is the sensitive index to evaluate cell function and importantevidence for molecular cytopathology check.According to the materials above, we established dog model of myocardialinfarct, and compared the change of the structure of the mitochondrial and thedamage before and after ICVA, and find the anatomical foundation of ICVA throughisolated heart visualization.Materials and MethodsDivided experimental groups:Twentyfour healthy dogs were randomly dividedinto two groups:(1)ischemia group;(2)ICVA group.Establish modle of myocardial ischemia and ICVA:The left anterolateralthoracotomy is performed after using 3％pentobarbital sodium(50mg/kg). Afterheparinization,a Prolene purse string is sutured at the ascending aorta.A catheter withpressure transducer used in cardiopulmonary bypass is placed through the pursestring,and continuously monitor perioperative hemodynamics.The near part of theposterior descending artery (PDA) in the ischemia group. In the ICVA group,we usethe great saphenous vein for the bypass graft. The arteriotomies were performed with aNo. 11 scalpel blade and fine vascular clip.The proximal anastomosis is performed onthe descending aorta in an end-to-side manner using arunning 6-0 Prolene suturetechnique.A similar anastomosis is performed to middle cardiac vein(MCV) with 7-0Prolene suture.After estalished the flow through the graft,Ligated the PDA and MCVin the same time.Utilize dopamine and nitroglycerin to control the blood pressure ofdogs.Observation the change of mitochondria ultrastructure:The blocks wereimmediately transfered into a 2.5％glutaraldehyde solution buffered to a PH of 7.05with 0.5M phosphate solution at 4℃. Each block was washed three times(each time for 30 min), and was fixed with 1％osmium for 2 hours. Then each block was washedthref: times(each time for 30 min)with PBS solution. The blocks were dehydrated ingraded series of ethanol and acetone(50％ethanol 30 min→70％ethanol 30 min→80％acetone→90％acetone→100％acetone 90 min), Finally blocks were rountinelyembedded in Epon for 48 hours at 60℃.70 nm ultrathin sections were made forobservation. Then the sections were stained with uranyl acetate for 15 min and leadcitrate for 20 min. Each section was observed under a JEM-1200EX electronmicroscope. The mitochondria under each specimen were evaluated according toFlameng score.Myocardium cell extraction and cell damage detection:Samples mentioned abovewere Cleaned, digested, centrifugaled and filterwd,then single myocardial cells wasgot.we store them in K-B liquid, color with Rhodamine123,then detection celldamagewith flow cytometry.Vasography:Removing canine heart rapidly after cut samples of ICVA group andperfusion meglumine imaging agent via vein bridge after perfusing coronary arterywith heparin,then vasography.Statistical analysis:All analysis were performed with the SPSS 13.0.Data wereexpressed as the Means±SD. t test were used to compare the significance between thegroups. P＜0.05 was considered significant.Results1. The change of mitochondria ultrastructure and cell damage of the ICVA group wassignificantly lower than the ischemia group.2. ex vivo vasography shows constrast medium can flow into ischemia myocardiumand the others return to the coronary sinus via capillary network and superficialvenous.Conclusion right coronary artery can be supplying blood nutrition by the bridge of ICVA.