The Evaluation Of Left Ventricular Function And Its Relationship With The Severity Of Coronary Artery Stenosis By Using64-MDCT

Coronary atherosclerotic heart disease (also known coronary artery disease) is a kindof heart disease caused by the stenosis, the obstruction or the vasospasm of coronaryarteries, or as the result of the accumulation of atheromatous plaques within the walls ofthe coronary arteries, which could lead to myocardial anoxia, ischemia or necrosis. Itsmorbidity and mortality is closely related to the volume and systolic function of leftventricle. Accurate evaluation of left ventricular function can provide valuableinformation for the prevention, treatment and risk stratification for coronary heart disease.There are a variety of methods for assessment of left ventricular function: such as leftventriculogrphy, echocardiography, cardiac magnetic resonance imaging and computedtomography. Echocardiography is used commonly to assess left ventricular volume andsystolic function. Among all kinds of echocardiography, the M-mode is most widely used,but when irregular shape of the left ventricle or regional wall motion abnormalities occurs,a significant error will produce. Although the evaluation of left ventricular volume usingreal-time three-dimensional echocardiography does rely on actual shapes to measure thevolume and function of the left ventricle,it has some disadvantages in the the clinical practice,such as the limited vision, lack of quantitative analysis and no color Doppler.Cardiac MRI is considered to be the gold standard of the assessment of left ventricularfunction. But its clinical application is limited by the long scanning time, and also cardiacMRI does not apply to patients with pacemakers and claustrophobia. In recent years,applications of multi-detector computed tomography(MDCT) and CT cardiovascularimaging increased gradually, the value and reliability of the diagnosis of coronaryatherosclerotic heart disease using MDCT has been recognized by clinicians. With thedevelopment of temporal and spatial resolution of MDCT, with retrospective ECG gating,patients need to hold a breath just for about10seconds to complete the CT coronaryangiography (CT coronary angiography, CTCA) examination, and it is reliable tocomplete both the measurement of coronary stenosis and evaluation of left ventricularfunction.Objectives To evaluate the feasibility and accuracy of analysis of the globalleft-ventricular (LV) function by using64multi-detector computed tomography (MDCT)and the differences of left ventricular function parameters measured by reconstruction of5%R-R intervals and10%R-R intervals.Materials and methods Thirty patients (15male,15female; age range37~69years,mean58years) with suspected coronary heart disease were recruited in this study. All thepatients received M-mode echocardiography and64-MDCT coronary angiography within48hours before or after the CT examination.64-MDCT was performed using a ToshibaAquillion64system. An initial non-enhanced ECG-gated scan was performed for calciumscoring. For the contrast-enhanced scanning, nonionic contrast medium was administeredin the right dorsal hand vein, with a amount of70to80mL, and a flow rate of4.0~5.0mL/s(ioversol320mgI/mL).Automate peak enhancement detection in theascending aorta was used for tracing of the bolus contrast materials using a threshold of180Hounsfield Units. Patients with a heart rate>75beats/min received an oral dose ofBeteloc25to50mg1hour before MDCT scanning.20phases and10phases MDCT data,respectively, for the measurement of LV end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), and ejection fraction (EF) were reconstructed at every5%(20phases) and10%(10phases) step through the R-R interval. All the reconstructedimages were analyzed with a imaging software using an automated contour detectionalgorithm of LV endocardial contours and by manual tracing. The data were comparedwith those obtained via M-mode echocardiography as the standard of reference，whichwas performed with the Philips corporation echocardiography iE33.Results No significant differences were found when comparing the reconstructionsamong the measurements of every5%and10%step through the R-R interval（Usingautomated contour detection algorithm,CT5%vs CT10%：EDV=108.00±14.56mL vs106.54±14.08mL， ESV=32.85±9.24mL vs32.00±8.50mL， SV=75.15±14.53mL vs74.54±15.89mL，EF=69.38±8.36%vs69.62±8.57%；Using manual tracing,CT5%vsCT10%： EDV=107.85±14.43mL vs106.92±14.32mL， ESV=32.15±8.26mL vs32.15±8.26mL， SV=75.69±14.37mL vs75.61±15.03mL， EF=70.08±7.83%vs70.46±8.01%）, and showed a good correlation (r=0.948~0.995,all P<0.05). EDV, ESV,SV and EF of the LV derived from an automated contour detection algorithm were notstatistically significantly different from manual tracing, and evidenced an excellentcorrelation as well(r=0.978~0.988, P<0.05). The LV functional parameters obtained byusing64-MDCT were markedly correlated with those acquired by M-modeechocardiography, and there was no statistically significant difference between the twomethods.Conclusion64-MDCT is a reliable assessment of LV function. Within MDCT, using10%R-R interval reconstruction is sufficient to evaluate LV volumes and EF, and is moretime-effective than5%R-R interval reconstruction. Objectives To investgate the relationship between severity of coronary lesions and leftventricular function.Materials and Methods From September2011to April2012,41patients (13male,28female; age range40~86years,mean68years),who were given positive results of stenosisof coronary artery after undergoing CTCA examination were recruited in this study.14ofthem completed conventional coronary angiography(CCA) in two weeks.Quantitativeanalysis of the severity of coronary lesions was performed with the Gensini ScoringSystem.10phases MDCT data for the measurement of LVEF, EDV, ESV, SV andmyocardial mass(MM) were reconstructed at every10%step through the R-R interval.The measurements of EF, EDV, ESV and SV were analyzed with a imaging softwareusing an automated contour detection algorithm of LV endocardial contours.The results ofMM were obtained by manual tracing.According to Gensini score,the correlationsbetween the severity of coronary lesions and left ventricular function were analyzed.Results The range of Gensini Score is2to82scores. only the person with82scoreshowed a decrese of left ventricular function(EF=47%, EDV=123mL, ESV=65mL).Gensini score level as a categorical varible ordering was grouped by quartilevalues,41patients were divided into four groups,respectively group1(GS≤7scores),group2(7scores＜GS≤15.5scores),group3(15.5scores＜GS≤26scores)，group4（GS＞26scores）.There were no significant differences in EF, EDV, ESV, SV and MM among thegroups with different Gensini scores and the normal group. Compared Gensini score withSpearman correlation analysis, Gensini score was not correlated withEF(r=0.053,P=0.741),EDV(r=0.011,P=0.944),ESV(r=-0.024,P=0.882),SV(r=0.030,P=0.854) and MM(r=0.104,P=0.518).Conclusion Mild stenosis of coronary arteries is not correlated with the decrease of leftventricular function;with the aggravation of severity of coronary lesions,the left ventricular function may decrease.