| Arrhythmia is a common disease in clinics. Mordern clinical cardiac electrophisiology is an important branch of cardiology,which aims on exploring the mechnism, diagnosis and treatment of arrhythmia.The electrophysiology examination and radiofrequency therapy require localization of cathetheter at target area in the heart using X-ray imaging, electronic mapping and 3-dementional mapping, such as electroantomic mapping, to perform diagnosis and treatment. During procedure, the image of heart is usually aquired by X ray imaging, and the location of a catheter is determined by multiple projection imaging and anatomic landmarks.Optimizing in-procedure X ray imaging may feacilitize locating anatomic structures and catheter in the heart, which will further decrease complication and improve procedure success rate. The variablity of cardiac anatomy, especially the rotation of the heart and related strctures such as inter-atrial septum, will cause imagingissues like shorterning images, which will confuse the localization consequently. Electrophysiologists have suggested many methods to improve and individualize X ray prjection, but these methods are basicly based on experience. Hence, studies on variablities of anatomy will provide us methods on predicting varability and individualized imaging. However, most relavent studies are based on bioposy,in which the anatomic relationship may differ from a living heart.Nowadays, the development on CT technology renders CT imaging more and more advanced temperal resolution and spacial resolution, which made CT studies aiming at cardiac anatomy practicible. Although some researchers have mentioned that cardiac CT is able to image cardiac conduction system, only limited studies are performed for anatomy analysis, especially for atrial septum and Triangle of Koch’s.The present study analyzed varability of cardiac electrophysiology-related anatomy structures, especially for their rotation and change in directions, and we made effort on correllating these varablities and anatomic landmarks sush as coronary sinus and its ostium, which is useful in individualized imaging.Section I:Anatomic study on intra-atrial septum rotation and its predicting—implication to electrophysiologists from CT studies.Methods:Data from 115 CT studies showing no structural heart diseases were collected and analyzed. The angulations describing the heart position, the IAS orientation and the CS direction were measured.The relationships between the IAS orientation and each of the other two were analyzed.Results:The mean IAS orientation shown in our study was 36.8±7.3degree ranging from 10.1 to 53.6 degree. No correlation was revealed between the IAS orientation and the heart position(P=0.86). The IRA orientation tends to change as CS direction changes(slope=1.03; 95%CI= 0.95 to 1.1; P < 0.01;y=-2.01+1.03x; r2=0.86).Section II:Developing strategies for accurately determining the anatomy of the Triangle of Koch using Computed TomographyMethods:Data from 104 patients undergoing coronary computed tomography(CT) angiography with no evidence of cardiac structural disease were collected and analyzed. Angulationsdescribing the orientations of upper and lower regions of the TK as well as the CS ostium direction were measured and the relationships between these parameters were subsequently analyzed. Differences between the TK orientation and different projection angles(RAO30, RAO45, and CS direction) were determined. A Bland-Altman statistical analysis was performed to validate the use of CS ostium direction to evaluate the TK orientation.Results:The mean orientations of the upper and lower regions of the TK were 57.2 ± 9.5°(range 33.2-77.7) and 58.2 ± 9.1°(range31.7-78.7) respectively, with no significant difference within a given patient(P > 0.05). Linear regression showed a significant correlation between CS ostium direction and TK orientation(r=0.883, P < 0.001). The CS ostium direction predicted the TK orientation to within a less than 15? difference in 99% of the cases compared with only 6.7% and 58.7% when RAO30 and RAO45 were used respectively, respectivelysuggesting the CS ostium is a better predictor of TK variability. Bland-Altman statistical analysis showed that the difference between the CS ostium direction and the TK orientation was 5.88±4.29?(95% limits of agreement-2.53?to 14.29?).Conclusion:In patients without structural heart diseases, the CS direction should be a reliable predictor for the IAS rotation, and could serve an assistant approach during invasive electrophysiology procedures. Further studies are still needed to clarify the association between the IAS orientation and the heart position.In patients without structural heart disease, the direction of the CS ostium may be a reliable predictor of TK variability, and may serve as a valuable reference for clinicians during invasive electrophysiological procedures.CT studies renders analysis on in-vivo living heart anatomy praticible, which can hopefully provide us more support on individualized procedures. |
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