Study On Safety Of Myocardial Contrast Echocardiography

BACKGROUNGMyocardial Contrast Echocardiography (MCE) is a new technology of diagnosing myocardial microcirculation perfusion. For the past few years,MCE has maken a great breakthrough progress, it can be used for left ventricular opacificatio,detecting myocardial infarct area and ischemic area, measureing coronary flow reserve, evaluating the activity of cardiomyocyte and so on.But,which the domestic and foreign scholars worried is the bioeffect of inertial cavitation induced by contrast-enhanced ultrosound(CEUS) Cavitation is the gas hole in the fluid irradiated by ultrasound formate,grow up,burst.In low ultrosound field,the microbubbles expand and compress regularly,this is stable-cavitation or noninetial-cavitation.In high ultrosound field,the expandtion and compression unsymmetrically and gets bigger significantly,eventualy leads to the burst of the microbubbles which called inertial cavitation.There is much energey in the course of inertial cavitation which is the main course of its bioeffects.In 2004,the EMEA revoke the use of Sonovue in heart diseases in view of three fatal correlated with ultrosound contrast agent(UCA); In 2007,four fatal incidents which seems like correlated with UCA aroused people's attention again.Much exerimental studies and clinical trials had demonstrated that contrast-enhanced ultrosound is safe on the condition of diagnostic ultrosound,but the deathes incline to server heart diease,so The Food & Drug Administration (FDA) dropped a warning regarding of MCE in 2007:baning its use on patients with acute myocardial infarction etl server cardiopulmonary diease.This measure lead to a great disturbance in CECU workers.Is the condition of examiners really a important factors in ues of MCE? And the safty of MCE are influenced by imaging modes,agents?These questions has not been reported. So we investgates the influence of MCE on vascular permeability in myocardium,and on condition of different and different pathophysiological mouses,the bioeffects induced by contrast enhanced ultrosound are the same,to offerring guide for its clinical application.PartⅠThe impact of ultrasound mediated microbubbles on vascular permeability in myocardiumObjectiveTo investigate the impact and recovery time of vascular permeability induced by high MI (mechnical Index) myocardial contrast echocardiography (MCE) with a high dose of microbubbles.MethodsThirty rats were randomized into 5 groups (A-D were the MCE groups with the same condition, E was the control group). Evans Blue (EB) were injected at different time:10 seconds before MCE (A), immediately after the end of MCE (B), and 5 minutes (C) or 20 minutes after the end of MCE (D). In group E,QFX and EB were injected at the end of 5 minutes of ultrsound exposure. All rats were sacrificed 5 minutes after EB injection. The content of EB in the myocardium and the percentage of EB leakage area were calculated.Other two rats using the same MCE plan were injected EB one minute before MCE.The hearts were excised instantly and 20mins after MCE,the area of EB were used for electron microscope observation.ResultsThe percentage of EB leakage area in group A, B and C were significantly higher than in group E (P<0.05), while there was no difference between group D and E (P >0.05). The EB content in A,B groups were significantly higher than in group E (P <0.05), but there was no difference in both group C and D compared with group E (P>0.05). No change of the heart rates and premature beat numbers were observed during and after MCE (P> 0.05).The results of transmission electron microscope(TEM) showing that electron photomicrograph of the two times both showing the carpillaries are no dialation and congestion,bleeding,none of swelling and breakage of the endotheliocytes, myofibrils are well-arranged,Z-lines are clear, mitochondrial cristae are clear with no swelling and vacuolar degeneration.PartⅡThe influence of imaging modes,contrast agents and disease conditons on safety of MCEObjectiveTo investigate the safety of MCE on condition of different imaging modes,different contrast agents and different pathophysiological rats.Methods1. The influence of imaging modes on safety of MCE, this part was divided into two sections.1.1.The safety comparison of intermittent-triggered imaging and real time low MI imagingIntermittent-triggered imaging using a MI of 1.5,T wave 1:6 triggered imaging,low MI real time imaging using a low MI of 0.2 real time imaging,a high MI of 1.3 damaging the microbubbles. 1.1.1.The rats were randomized into QuanFuxian(QFX) intermittent triggered imaging group(IT) and its control group(ITN),QFX low MI real time imaging group and(RL) its control group(RN).The time of MCE lasted 5mins,the control group performed as follow,first,5mins ultrsound exposure,then injecting contrast agent,another 5mins later,the ras were sacrificed.In the course of experiment,the heart rate and number of arrhythmia in 3mins before and after MCE were recorded.1.1.2.Measurement of EB content and percentage of EB area in the heart:All the rats were injected with EB(50mg/kg) before MCE,the dose of contrast agents was 5×108 ind microbubbles/kg,determinated by Coulter Counter before experiment, bolus injection,5mins after MCE the rats were sacrificed,mearsuring the EB content and EB%。1.1.3.Measurement of cTnT:group of IT and RL giving another group did not accepting EB injection,sampling blood before and 6h after MCE for cTnT measurement.1.1.4.The hearts of other two rats of group IT and RL were excised 10mins after MCE,the area of EB were used for electron microscope observation.The heart of rat of group RL were excised according to the probe for TEM detection.1.1.5.Based on the EBcontent,EB%,cTnT and heart rate,arrhythmia numbers,pathological changes to evaluation the difference of Intermittent-triggered imaging and low MI real time imaging on MCE safety.1.2.In the course of real time imaging,the influence of,differeent power of damaging microbubbles on safety of MCE1.2.1. In the course of real time imaging,there is a high MI pulsation(a flash) damaging microbubbles,Using the rate of micbubbles refilling to evaluation the blood flow perfusion rate in myocardium.We would compare the difference of high MI damaging real time imaging(RH) and low MI damaging real time imaging(RL) on MCE safety.Both of them using a MI of 0.2 real time imaging,in addition to different flash,the other program is the same.The damaging MI of RH is 1.9,and the damaging MI of RL is 1.3.1.2.2. The rats were randomized into RH and RL group, The detection of EBcontent,EB%,and heart rate,arrhythmia numbers,pathological changes were the same as 1.1section.Based on these indexes to evaluation the difference of RH and RL on MCE safety.2. The influence of contrast agents on safety of MCE2.1. The rats were randomized into Sonovue intermittent triggered imaging group(S) and its control group(SN), QFX intermittent triggered imaging group(IT) and its control group(ITN),The MCE plan is the same with the the before(MI 1.5,1:6 T wave triggerd imaging). The dose of Sonove determined by Kurt count service that has the same number of microbubbles with QFX.(5×108ind microbubbles/kg).2.2. The detection of EBcontent,EB%,cTnT and heart rate,arrhythmia numbers,pathological changes were the same as 1.1 section. Based on these indexes to evaluation the difference of Sonovue and QFX on MCE safety.3.The influence of disease condition on MCE safety3.1.animal models:The cronic hyperlipidemia rats were the nomal rats feeded with high-fat diet for two months. Plasma lipid and hypersensitive CRP to detemined the success of the model.The myocardial ischaemia reperfusion model is made by ligateing antier anterior decending branch underside the left auricle for 30mins and reperfuse for 2 hours.3.2. The rats were randomized into normal rats QFX intermittent triggered imaging group(IT) and its control group(ITN);the cronic hyperlipidemia rats also were randmized into intermittent triggered imaging group(C) and its control group(CN);The myocardial ischemia-reperfusion rats also were randmized into intermittent triggered imaging group(I) and its control group(IN).3.3.MCE plan is intermittent triggered imaging,MI 1.5,T wave 1:6 electrocardiogram triggered imaging,the dose is 5×108ind microbubbles/kg,bolues injection.the control group performed as follows,the same power ultrasound exposure for 5mins,then moved away the probe,injecting microbubbles.3.4.Measurement of EB content and percentage of EB area in the heart:All the rats were injected with EB(50mg/kg) lmins before MCE, In the course of experiment,the heart rate and number of arrhythmia in 3mins before and after MCE were recorded,5mins after MCE the rats were sacrificed,mearsuring the EB content and EB%。3.5.Measurement of cTnT:because of the basic cTnT of myocardial ischemia-reperfusion rats might be high,the level of 6h after MCE contineously increased.so the sham MCE group as the control,measuring cTnT 6h after MCE to compared the influence of MCE on cTnT.That was MCEgroupand its control group both measuring cTnT before and 6h after MCE. 3.6 Based on the EBconten,EB%,cTnT and heart rate,arrhythmia numbers,pathological changes to evaluation the difference of different disease conditions on MCE safety.Results1.The influence of imaging modes on safety of MCE1.1.The safety comparison of intermittent-triggered imaging and real time low MI imagingThe EB content and percentage of EB leakage area in group IT were significantly higher than its control group (P<0.05), while there were no difference between group RL and its control group (P>0.05), There was no difference between before and after MCE in cTnT both in group IT and RL(P>0.05), No change of the heart rates and premature beat numbers were observed before and during MCE (P> 0.05).The TEM graphs of IT group showing that a carpillary with a erythrocyte,none of swelling and breakage of the endotheliocytes,myofibrils are well-arranged,Z-lines are clear, mitochondrial cristae are clear with no swelling and vacuolar degeneration.The group seen in the TEM graphs were the same as IT group.1.2.In the course of real time imaging,the influence of,differeent power of damaging microbubbles on safety of MCEThe EB content and percentage of EB leakage area in group RH were significantly higher than RL group (P<0.05), No change of the heart rates and premature beat numbers were observed before and during MCE (P>0.05).The group seen in the TEM graphs were the same as IT group.2. The influence of contrast agents on safety of MCEThe EB content and percentage of EB leakage area in group S were significantly higher than its control group (P<0.05), There was no difference between before and after MCE in cTnT(P>0.05), No change of the heart rates and premature beat numbers were observed before and during after MCE (P>0.05). The EB content and percentage of EB leakage area in group S was not different from group IT (P>0.05).This group seen in the TEM graphs were the same as IT group.3.The influence of disease condition on MCE safetyThe EB content and percentage of EB leakage area were all significantly higher than their control group in group IT,C,I(P<0.05), There were no difference among group IT,C and I in EB% increaseing induced by MCE (P>0.05).The EB content increasing in group I was significantly than group C and IT,But there was no difference among group IT,C and I in EB increaseing rate induced by MCE (P> 0.05).There was no difference between before and after MCE in cTnT(P>0.05); No change of the heart rates and premature beat numbers were observed before and during after MCE (P>0.05).The EB content was not correlated with hs-CRP (P>0.05).Conclusion1. Microvascular leakage increase may be induced by high MI MCE with a high contrast dosage,this is instaneous, and it can recover in 20 minutes after the MCE.2.Both of the intermitent triggered imaging and low MI real time imaging have no influence on heart rate. numbers of arrhythmia, cTnT and myocardial ultrastructure.Comparing with low MI real time imaging, the intermitent triggered imaging could indue more sinificant microvascular leakage increase.so low MI real time imaging is a related safe imaging mode which should be choosed first in clinical.3.Both of real time imaging,the different damaging MI lead to differtent MCE safety.The Ebcontent and EB% in group RH both significant higher than in group RL. But there was no difference in heart rate,numbers of arrhythmia and myocardial ultrastructure between before and after MCE.This including that the damaging power is a important factor of its safety.4,In the condition of intermitent triggered imaging mode,Sonovue has the same safety as QFX in nomal rats.5.Cronic hyperlipidemia rats and myocardial ischemia-reperfusion rats have no difference with normal in the safety indexes.This suggests that disease condition hsve the same influenced on safety of MCE...