Assessment Of Myocardial Perfusion And Microvascular Endothelial Inflammation By Intravenous Myocardial Contrast Echocardiography--An Experimental Study

Part OneExperimental Study on Myocardial Perfusion with Myocardial Contrast Echocardiography by Intravenous Perfluorocarbon-Exposed MicrobubblesWith the development of new-generation contrast agents and ultrasound imaging technique. Myocardial contrast echocardiography (MCE) transfer from direct intracoronary injection of sonicated microbubbles to intravenous injection, noninvasively. Perfluorocarbon-exposed sonicated albumin microbubbles cleared the pulmonary microcirculation, could opacify the myocardium, also produce higher video intensity with intravenous injection of microbubbles. Studies demonstrated that there is the linear relationship between coronary flow and myocardial video grey-scale peak intensity. But myocardial opacification was not visually striking now, also the optimal dose of MCE is not known. The purposes of this study were to assess the safety of perfluorocarbon-exposed sonicated albumin microbubble contrast agent-Quan Fuxian, and whether a new method of ultrasoundimaging (intermittent second-harmonic ultrasound imaging) could improve the myocardial contrast after intravenous injection of perfluorocarbon-exposed sonicated microbubble contrast agent in dogs. The optimal dose of intravenous MCE was also investigated in the present study.Materials and methodsObjectives: Seven mongrel dogs were used for the study.Methods: The dogs were anesthetized with intravenous sodium pentobarbital, intubated and placed on a respirator. The right femoral artery was exposed and a 6F pigtail catheter was advanced into the ascending aorta for arterial pressure monitoring. The right femoral vein was exposed and sheath was inserted for injection of contrast agents. The left lateral thoracotomy were performed, and the heart were suspended in a pericardial cradle. Ultrasound images in seven dogs were obtained using a 2.1-4.2 MHz ultrasound transducer connected to a commercially available scanner, Hewlett-Packard Sonos 5500. The transducer were placed in a warm-water bath overlying the anterior surface of the heart and positioned to produce a short-axia view of the left ventricle at the mid-papillary muscle level. Myocardial contrast echocardiography imaging were obtained under intermittent second-harmonic technique by intravenous injection of 0.005ml/kg and 0.01 ml/kg two doses, respectively. The myocardial videointensity were measured off-line at end-systole from high-fidelity videotape images. The visual measurements were determined by comparing myocardial contrast intensity at baseline and after MCE as assessed by two independent experimenced observers. Gray-scale software (Acoustic Densitometry) quantifying videointensity versus time were used to measure the contrast intensity.Statistical analysis: Data were expressed as mean value ?standard deviation, and were assessed by the paired student t test. Categorical data comparison were performed by the Chi-Square test. All statistics were carried out in IBM computer with SPSS 10.0 software. A probability value <0.05 (or p <0.05 ) was considered as statistically significant.ResultsThe intravenous contrast agent- "Quan Fuxian" in the doses given produced no hemodynamic changes and no significant side effects in any dogs. Overall, the myocardial contrast imaging produced were significantly greater after intravenous injection of contrast agents than at baseline harmonic ultrasound imaging, average myocardial videointensity were 51.50±28.62 vs 6.65±1.82 (p<0.001). The posterior wall and left ventricular cavity were not satisfied because of ultrasound attenuation when injection with 0.01ml/kg. Conclusions1. Hemodynamic variables and regional myocardial blood flows remained stable when "Quan Fuxian" were injected at two different doses. Myocardial contrast echocardiography using intravenous perfluorocarbon-containing microbubbles is a safe method to assess myocardial perfusion.2. Intermittent second-harmonic ultrasound imaging produces significantly better myocardial contrast in dogs.3. The far-dista...