Tricuspid Annulus And Interventricular Septum Normal Anatomical Features Of Wpw Syndrome Radiofrequency Ablation In The Right Atrioventricular Impact Studies

Objective: to investigate the normal anatomical characteristics of tricuspid annulus and atrioventricular septum ,and provide basis for the radiofrequency catheter ablation used in surgical procedure in patients with right atrioventricular accessory pathway.Methods: 30 normal hearts preserved by formalin were selected. All the valves were in diastole naturelly. Then the configuration,size,position of tricuspid commissures and it's exterior projections,circumference of tricuspid annulus,length of the attached margins of the tricuspid valve,relationship between the attached margins of the tricuspid valve and tricuspid annulus,relationship between the right side of interventricular septum and septal leaflet and other adjacent structures were studied. The length,width and area of membranous septum,the ratio of atrial and ventricular portion to the total areas of membranous septum were assessed. Radiofrequency catheter ablation were applied in 40 patients in our hospital with Wolff -Parkson -White syndrome.Results: The results of the normal anatomical characteristics:1 the tricuspid annulus is approximately triangular in shape. The length and width are 31.25±3.21mm and 21.30±2.14mm respectively. The area of tricuspid annulus is 798.6±107.0mm~2;with a 1.8±0.35mm in width fibrous ring aroud the orifice. 2 The anteroseptal commissure projction on the exterior of the heart lies bewteen the right and anterior wall of aorta root and base of right auricle,along the longital axis of ascending aorta,30 degree rotation at sagittal section. The anteroinferior commissure lies at the middle of the lower margen of right auricle,11-17mm underneath vertically. The inferoseptal commissure lies 7-9mm from the right side of atrioventricular intersection.3.The circumference of the tricuspid annulus is 112.02±9.80mm,the attached margins of each valve are 43.24±5.42mm (anterior),37.12±5.79mm(inferior),30.31±5.96mm(septal),and the ratios of each atatched margen to the circumference of the tricuspid annulus are 0.387±0.060 (anterior),0.331±0.066 (inferior),0.286±0.065 (septal). 4. The maximum downward displacement of septal leaflet is 6.12±0.87mm in adult. The root of the septal valve at the interventricular septum is 6.87±2.61mm lower than that of the anterior valve of mural valve. 5. The right side of the interventricular septum is devided into atrioventricular and interventricular portion by the front 1/4-1/5 of septal leaflet and posterior end of anterior leaflet in 22 cases(73.33%).Of them,atrioventricular portions greater than that of interventricular were in 10 cases(45.45%),atrioventricular portions less than that of interventricula in 8 cases(36.36%),atrioventricular portions approximately close to that of interventricula in 4 cases(18.19%). All the right side of membranous interventricular septum were below the attached margin of septal leaflet,with atrioventricular portion defects. Six cases were with mere interventricular portion(20.00%). Tow cases that all the right side of membranous interventricular septum were above the attachment,with with interventricular portion defects(6.67%). The anerosuperior margin of atrioventricular portion lies beneath aorta prominentia,connecting posteroanteriorly to right fibrous body, across the atached margin of the right part of the right-posterior aorta annulus. 6. The area of interventricular, atrioventricular, and total membranous portion is respectively 48.0mm~2, 35.4mm~2, and 84.4mm~2. The ratio of atrial and ventricular portion to the total areas of membranous septum is 0.386 and 0.584. The results of radiofrequency catheter ablation: of the 40 patients, 32 cases were dominant type, 8 were opaque type. Thirty-eight were of single type, 2 were of double type. Five of them were complicated with atrio-fibrillation, associated with pathway forward conduction. One was with atrioventricular type of Mahaim pathway. One was with right-posterior septal slow pathway, one with Ebstein anomaly.There were 42 atrioventricular pathways. Thirty-seven were succesfully ablated at first time.The success rate was 92.5%. there were 4 recurrence.Conclusion: 1.the position , size and the exerior projection of each commissure of the tricuspid valve is critical for accurate tricuspid annulus locating by x-ray. 2. the extend of downward replacement of the septal leaflet, provides anatomical basis for right atrioventricular accessory pathway of Wolff-Parkson-White syndrome complicated with Ebstein anomaly, raises success rate of the radiofrequency catheter ablation used in surgical procedures in patients with right atrioventricular accessory pathway. 3. the relationship between atriovetricular septum and septal leaflet, the position of the right side of atriovetricular septum, provides anatomical basis to reduce injury to atriovetricular node and His bundle in the radiofrequency catheter ablation.