MSCT Coronary Venography: Morphology Features And Application Value In The Cardiac Electrophysiology Treatment Study

IntroductionThe anatomy of coronary venous system (CVS) has become more and more important with the development of cardiac electrophysiological treatment such as cardiac resynchronization therapy, radiofrequency ablation and so on. In left ventricular (LV) pacing, the proper coronary vein is needed for transvenous LV lead placement, which is achieved by positioning the LV lead in one of the tributaries of the coronary sinus ( CS). Although the success ratio for this operation is relatively high, it fails in about 10-15% of patients because of the inability to insert catheters in the CS and the lack of suitable side branches. Knowledge of the CVS anatomy before these procedures may facilitate LV lead position. In addition, there are myocardial fibers on the surface of MCV, PVLV or CS diver-ticula. These fibers can connect with ventricle and become the pathway between CS and ventricle, which is named as EpiAP. In about two thirds of the patients, coronary artery situates within 2mm of the ideal ablation sites of EpiAP. So the ablation there may injure the coronary arteries and even cause acute myocardial infarction. Thus, the knowledge of relationship between CV and CA is very important before the ablation.Although imaging of the CVS has been attempted by angiography, echocar-diography and electron -beam computed tomography (CT), there havent been an ideal non - invasive method that can detect and evaluate the CVS in detail. In recent years, multi - slice CT ( MSCT) has been widely used to depict vascular structure and has become an important non - invasive method in diagnosis of coronary artery disease. However, little work has been done on the depiction ofCVS by MSCT. So the aim of this study is as follows:To assess the effect of injection rate of contrast on the imaging of CVS and determine the optimal protocol for coronary venography on 64 - slice CT.To evaluate the value of MSCT in coronary venography using the results of CVG as gold standard.To study the CT characteristics of CVS and its value in cardiac electrophys-iological treatment.Materials and Methods1. Twenty - five patients without heart disease underwent coronary CT venography on a 64 — slice CT ( Sensation 64;Siemens, Germany ) with colli-mation of 0.6mm. They were divided randomly into group A(n = 13) and group B(n = 12) with injection rate of 3. 5ml/s and 4. 5ml/s respectively. Firstly, a small bolus test was done on the level of coronary sinus to define the circulation time from coronary arteries to coronary sinus. Secondly, bolus - tracking technique was used to trigger the MSCTCV scanning with the ROI placed the ascending aorta. The triggering threshold was 100HU. Transition delay (TD) was e-qual to the coronary circulation time. The quality of the Rotation relative arteries (LCX, LP, PDA) was evaluated using a 0 ~ 3 point scale and was compared between the two groups.2. Both MSCT and CVG were obtained in 46 patients (26 men;age 52 ± 10 years) during the same period. All the images were studied retrospectively. The display rate of CS and its branches were calculated with the result of CVG as gold standard. The diameter of coronary sinus ostium (CSO) , middle cardiac vein ostium (MCVO) and left posterior vein ostium were measured, and the distance between the main branches was also determined on CT. The correlation between the data acquired on MSCT and CVG were evaluated.3. 300 patients underwent MSCT coronary venography and 3D reconstruction was done to evaluate the morphology, position, number, diameter and an-gulation of the CS and its tributaries. All the patients were divided into several groups according to their age, sex and kind of coronary heart disease. And thediameter of CS, MCV, PVLV in different groups were compared with ANOVA.Results1. The CT value of the coronary vessels was higher in group B than in group A with the mean value of CV 165.02 56.07 and 137.31 31.07 HU, and that of CA 283.71 56.63 and 236.55 70.34 HU respectively. There was a significant difference in the CT value of GCV, MCV, PVLV and LP (P <0. 05) between the two groups.2. The display rate of the LP and PDA was 84.6% (11/13) and 61.54% (8/13)for group A;100% (12/12)and 83. 33% (10/12) for group B. There was no statistical difference between the two groups.3. The average score of CV and CA was 2.75, 2.18 in group A and 2.96, 2. 53 in group B. Group B had an better display quality of CV and CA (P =0. 041, 0.029) than group A statistically.4. All of the coronary veins and their major branches could be seen on MSCT using CVG as gold standard. The course of the vessels in MSCT was in full accordance with CVG. 2 patients had deformity of permanent vena cava superior on the left and 1 patient had a CS diverticulum. The diameter of coronary veins in the two methods had a high positive linear correlation, with the correlation coefficient 0. 89 for CS, 0.83 for MCV and 0.95 for PVLV respectively (p<0.001).5. The CS, GCV and MCV could be seen in all the patients. 1-3 branches of PVLV could be visualized in most of the patients. SCV and MV were found in 18.7% and 8% of the cases respectively. 3 patients had permanent vena cava superior on the left and 1 patient had a CS diverticulum. Hie MCV and PVLV entered the CS at an angle of 90 approximately.6. No significant difference existed in the antero - posterior diameter of CS ostium , MCV and PVLV(P>0.05) in different groups. The superoinferior diameter of CS ostium had a statistical difference between male and female ( P < 0.05).7. Domination of right coronary artery was found in 277 cases, while domi-. 7 .nation of left coronary artery was found in 15 cases and co - domination in 8 cases. PDA accompanied MCV in 189 cases and intersected with MCV in 96 cases (32% ). LP was concomitant with CS in 146 cases (48.7% ). LCX went along with CS in 122 cases(40.67% ) , intersected with MCV in 15 cases (5% ) , and intersected with PVLV in 104 cases (34.67% ).Conclusion1. The injection rate of 4.5ml/s is superior to 3.5ml/s in depiction of coronary veins and their relationship with adjacent coronary arteries on 64 - slice CT. But 3. 5ml/s is more suitable for patients with severe heart failure.2. MSCT can display the coronary venous system clearly and has a good correlation with CVG in measurement of vessel diameter. It is better than CVG in showing the relationship between CV and adjacent CA. So MSCT is an effective and non - invasive method in depiction of coronary venous system.3. MSCT coronary venography shows that the variance of CVS structure is marked in the Chinese people. In most cases, there are concomitant coronary artery and its branches within 3 mm of coronary veins. This feature will make the LV lead placement and radiofrequency ablation more difficult.