The Effect Of Implantation Of "Valve Up Valve" On Coronary Artery Blood Flow And Myocardial Perfusion In Animals With Acute Severe Aortic Regurgitation

BackgroundSymbas PJ et al’s statistical data showed that the incidence of cardiovascular damage caused by a variety of closed or open wounds was up to 30%.The common types of injuries include myocardial contusion hematoma,aortic rupture amputation,the tear of heart valves,some intracardiac shunt such as sinus of valsalva ruptured into the ventricle,and so on.Among the heart valve damages caused by trauma,the aortic valve is most commonly involved,which often results in acute aortic regurgitation(Acute Aortic Regurgitation,AAR).As these patients mostly suffered acute severe aortic regurgitation,combing with other trauma,which often obscured the valve laceration.Thus they were often neglected to check heart valves in the treatment process,resulting in misdiagnosis and missed diagnosis,which delayed treatment time and ultimately life-threatening.When the severe aortic regurgitation occurs,it should be timely performed surgery to correct aortic regurgitation.According to statistics,if these patients were not timely treated,the mortality rate was up to 80%.Some patients still had the possibility to die due to cardiac mortality factors even after the tide of acute trauma.For these patients,surgical emergency valve replacement surgery can not be carried out even they have the left ventricular function incomplete caused by severe aortic regurgitation.Although transcatheter valve replacement technology was increasingly applied in clinical year by year,it was more harder to treat patients with acute aortic regurgitation.Currently,the transcatheter aortic valve implantation has become a hot topic of interventional treatment of valvular heart disease.But the technology is mainly used for high-risk patients with severe aortic stenosis,acute aortic regurgitation,as it is not recommended to plant the valve stent in situ.In our previous animal studies of percutaneous aortic valve replacement,when the ascending aorta valve stent was placed transcatheterly in aortic regurgitation,with the prosthetic valve opening edge(valve above above)implanted in acute coronary animals,we accidently found that the animal can survive for three months.It suggested that " the flap flap " method had the possiblility to act the role of " bridge " in transition of patients with acute aortic regurgitationrole to surgery in patients.But researches have not yet assessed blood supply after the myocardial.This topic plans to conduct the research of the myocardial blood supply state with "valve above above" implantation of acute severe aortic regurgitation animals on the basis of the above.It aims to establish different degrees of acute aortic regurgitation regurgitation model by taking a scientific and feasible way.An appropriate size and shape’s he new valve stent was implanted in the animal’s coronary severe aortic regurgitation model of the upper edge of the opening.Then the coronary blood flow and myocardial perfusion changes "after the flap flap" implantion was observed by using imaging studies so as to provide experimental evidence for interventional treatment of acute severe aortic regurgitation method as well as establish a reliable and stable therapy.objective:According to the experimental canine aortic vascular size and morphology in the area to obtain the reasonable data,evelopment of transcatheter from bentonite on the aortic valve scaffold system,establish a scientific and feasible aortic valve return flow model,and use the system of aortic egurgitation model animals on the aortic valve implantation.Evaluate disc disc effects on coronary blood flow and myocardial perfusion.Provide the basis for further clinical research.Method:(1)The anatomical features of aortic valve and aortaSix healthy dogs’ vitro cardiac specimens were autopsied to observe the morphology of the aortic valve.The size of right coronary cusp are measured with calipers.12 experimental dogs were conducted aortic angiography examination in the X-ray by utilizing the thoracic echocardiography.Normal experimental canine heart imaging measurement data in the ascending aorta and aortic valve was selected via chest ultrasound cardiogram plane left for shaft section and aortic valve on imaging exposure position to the left 30,along with measuring coronary openings above the distance to the aortic arch and the diameter of ascending aorta.The blood vessel diameter of canine aorta,aortic arch and thoracic aorta,abdominal aorta and femoral artery was also measured.(2)Research on transcatheter self-expandable stent system implanted on ascending arota.This flashing typed stent is moulded by thermal treatment,which is made from nickel titanium tube and is processed into a diamond net.The fresh pig pericardium is first tailored into valve leaflet and then sutured to the stent to form a decellularized scaffolds by damage free line.After anti calcification processing,in accordance with the stent size,the pig pericardium was cutted into corresponding tricuspid valves,The transporter is formed by three parts : the epitheca,the inner core and the controlling handle.(3)Construction of aortic regurgitation animal modelThe 12 exprimenting dogs are alloted into 3 groups according to the size of their sacculus,the minute sacculus group(2.5x15mm),the intermediate sacculus group(3.0x15mm)and the larger sacculus group(4.5x15mm)and each group includes 4 dogs.After being anesthetized,the experimenting dogs are implanted 6F vascular sheath by radial artery punctureing method to puncture the right femoral artery to put the moulded multi-functional 6F catheter to the root of the aorta.The head of the multi-functional catheter points to the right coronary sinus bicuspid valves.The non-selective radiography will locate the right coronary sinus.And the Runthrough godet hardhead will be delivered from the catheter.When the valve leaflet puncture is successfully implemented,the expanded sacculus puncture part will be delivered from it.The degree of the aortic regurgitation and the hemodynamic change will be valued by transthoracic ultrasonography and arterial blood pressure before and after the construction of the three models.After the evaluation,all the experimenting dogs’ right coronary valve will be expanded by 4.5 x 15 mm PTCA sacculus to construct severe aortic regurgitation model.(4)The influence of acute severe aortic regurgitation on coronary blood flow and myocardial perfusionThe following index CPV、AT、DT、VTI of coronary blood flow dynamics under normal and acute severe aortic regurgitation can be got by doppler coronary flow imaging technique.Myocardial perfusion will be reflected by both myocardial imaging time and myocardial imaging peak time implemented by myocardial contrast echocardiography.(5)Animal experiment on transcatheter aortic“valve up valve”implantation under condition of acute severe aortic regurgitationThe valved stent is implanted to the top of the ascending aorta of the coronary artery opening through the aortaventralis by TAVI.The influences of the stent on coronary blood flow will be valued by left ventricular angiography after the operation and aortic valve back flow and self-valve will be valued by ultrasound cardiogram.(6)The influences of “valve up valve” implantation on coronary blood flow and myocardial perfusionThe following index CPV、AT、DT、VTI of coronary blood flow dynamics under normal and acute severe aortic regurgitation can be got by doppler coronary flow imaging technique.Myocardial perfusion will be reflected by both myocardial imaging time and myocardial imaging peak time implemented by myocardial contrast echocardiography.The size and ejection fraction of the left ventricle will be valued by echocardiography after the operation and systolic blood pressure and diastolic blood pressure of the two valves and heart rate will be valved by invasive blood pressure and the degree of myocardial ischemia will be valued by electrocardiogram.StatisticsSPSS18.0 was used for statistical processing.Continuous datas were showed by mean±standard deviation.T test was used to Compare the mean differences between the two groups,and analysis of variance was used to compare the mean differences among the different groups,the statistically difference was different when P < 0.05.Result(1).The unfolding diameter of the tight coronary valve is(1.03±0.10)cm and the size of the left ventricle is(24.58±2.27)ml;the EF is(68.75±3.31)%;the systolic pressure is 150.83±7.49)mmhg;the diastolic pressure is(101.92±7.11)mmhg and the heart rate is(120.67±9.55)times per minute.The diameter of the aorta ascenden(A line)at the upper coronary artery opening is(24.6± 1.1)mm;the length of the aorta ascenden(B line)namely the length between the coronary artery opening and the near lateral margin of truncus brachiocephalicus opening is(38.5± 2.2)mm;the length(C line)from the near lateral margin of truncus brachiocephalicus opening to the opposite aorta wall is(33.0± 1.0)mm;the diameter of the arteria femoralis is(2.41±0.17)mm;the diameter of the lower abdominal aorta is(6.07±0.21)mm;the diameter of the thoracic aorta is(21.80±1.03)mm.And the 12-lead electrocardiogram indicates sinus rhythm or a normal electrocardiogram(2).This stent mainly contains two parts the upper aorta ascenden(the head)and the lower aorta ascenden(the body),and the body gets three kinds of specifactions 22、24、and 26 mm.The stent is delivered from 16 F sheathing canal,and located through the operation of the hand shank.Experiment out of body vindicates that the transporting system is reliable and the the pushing process makes no difference to the stent and the assisstant system exerts no damage to it either.(3).It takes(24.5±3.7)min to construct this model and exposureing time to the X ray is(5.7±1.2)min.The regurgitant volume of the minute sacculus group is(1.50±0.58)ml,the intermediate sacculus group(3.00±0.00)ml and the larger sacculus group(4.25±0.50)ml,reaching the degree of mild moderate and severe aortic valvular regurgitation respectively.(4).All the experimental dogs are examined by coronary arteriography which indicates no severe coronary vascular abnormalities.Electrocardiography indicates sinus rhythm.Compared to the electrocardiography before the operation,Lead V1-3 T wave in the after operation electrocardiography is a little low and the ventricular rate increases significantly.The variation of coronary blood flow indexes CPV、AT、DT、VTI examined by ultrasonic cardiogram between normal condition and severe aortic valve regurgitation conditon make statistic significance.Afer the examination of myocardial contrast echocardiography,visual grading method shows that the contrast agent is sacttered averagely on the myocardial perfusion area,all the segmental myocardial imaging deserveing 1 socre.The variation between myocardial imaging time and myocardial imaging peak time at normal condition and severe aortic valve regurgitation conditon makes statistic significance.(5).Of the twelve experimental dogs,four die during the operation and eight survive.Two experimental dogs(number one and number two)die immediately because the lower implanted stent blocks off the opening of the coronary.The number four dog dies because the backward implanted stent and the number seven dog die after escaping the breathing machine because of the shallow anesthesia.The operation lasts(54.50±4.89)min and the exposure time is(12.58±1.62)min.It is measured from the operation that the diameter of the ascending aorta is(24.57±1.09)mm and the average diameter of the the stent is(23.17±1.59)mm.When the guide wire and sheathing canal enter the left ventricle,the electrocardiogram monitor reflects transient ventricular arrhythmia,and when the stent is implanted and the guide wire and sheathing canal are withdrawed,the electrocardiogram monitor reflects normal wave.Two experimental dogs die because of massive haemorrhage when sutureed the abdominal aorta after operation.After successfully implanted the stent,the 6 surviving experimental dogs reflects normal and stable hemodynamics.And color doppler ultrasound indicates a normnal open and close function of the manmade stent and no evident constriction or insufficiency can be detected.The stent makes no influence to the self aortic valve either.(6).The 8 experimental dogs were successfully performed stent implantation,the immediately left ventricular volume of which were(30.00±1.77)ml,the left ventricular ejection fraction were(64.75±1.67%).Compared to normal group,the left ventricular volume of which were(24.88±2.42)ml,the left ventricular ejection fraction were(74.38±2.50%),the difference was statistically significant.the systolic/diastolic blood pressure of the operational group were(115.50±7.07)/(33.75±3.11)mmHg,While the figures of normal group were(150.50±7.13)/(101.38±8.16)mmHg,the difference was statistically significance.Compared to normal group,the value of CPV/AT/DT/VTI in operational group were much lower,the difference was statistically significance.Compared to the severe AR group,the value of CPV/DT in operational group were higher,the difference was statistically significance.Though the value of AT/VTI in operational group were higher,but without statistically significance.Myocardial contrast echocardiography showed cardiac development time and time to peak myocardial opacification was significantly longer than those in the normal group,and was significantly shorten than those in the severe AV group,the difference were both statistically significant.Stenting ECG results suggest that sinus rhythm,V1-3 leads T wave height returned to normal preoperative state.ConclusionThe method under the guidance of the aortic valve puncture and balloon dilatation of the multifunctional catheter to establish acute aortic regurgitation model is feasible,which has the advantages of controllability and repeatability.According to the shape and size of the aortic,the valve stent was developed,the stent was implanted into the ascending aorta through the abdominal aortic approach,which is more simpler and feasible than TAVI.When the acute severe aortic regurgitation was happened,valve stent’s implantation can significantly reduce aortic regurgitant volume,although there is some effect on coronary blood flow and myocardial perfusion,which can be fully compensated,heart function has got improved too.