Objectives:To investigate the relationship between pelvic landmarks on body surface and the trajectory of S2 alar-iliac(S2AI)screws in populations of different genders and body mass indexes.Methods:A retrospective analysis was conducted on 150 patients who underwent pelvic CT scans in the Affiliated Hospital of Southwest Medical University between February 2022 and February 2024.Basic demographic data including age,gender,weight,and height were collected.Pelvic models were reconstructed by CT,and screw trajectories were simulated on the models.The screw trajectories were extended to intersect with the skin sur-face,and the intersection points of the safe trajectories with skin formed a safety zone on the body surface.The shortest distances from the anterior superior iliac spine(ASIS),anterior inferior iliac spine(AIIS),and greater trochanter(GT)to the safe zone were measured.The length of the line connecting ASIS and GT on the surface,length of such line intersecting with the safety zone,length from ASIS to the safety zone along such line,length from GT to the safety zone along such line were measured.Group comparisons were performed based on gender and BMI[underweight group(BMI＜18.50kg/m2),normal group(18.50kg/m2≤BMI＜24.00kg/m2),overweight group(24.00kg/m2≤BMI＜28.00kg/m2),obese group(BMI≥28.00kg/m2)].Results:In males,the shortest distances from ASIS,AIIS,and GT to the safe zone were 19.87±3.66mm,33.66±3.33mm,and 39.53±3.56mm,respectively;In females,they were 19.31±3.41mm,33.23±3.45mm,and 38.74±3.23mm,respectively.No statis-tically significant differences were observed between gender groups(P＞0.05).The shortest distance from ASIS,AIIS,GT to safety zone was 14.03±1.64mm,26.79±1.15mm,43.68±1.32mm in the underweight group,17.67±2.36mm,31.73±1.77mm,41.18±2.43mm in the normal group,21.85±1.37mm,35.78±1.76mm,36.80±1.68mm in the overweight group,and 25.66±0.84mm,38.75±0.88mm,and 36.80±1.68mm in the obese group,respec-tively.Intergroup comparisons between the four groups were statistically significant(P＜0.05),and pairwise com-parisons within groups were statistically significant(P＜0.05).In males,the length of the line connecting ASIS and GT was 129.43±6.42mm,the length of the line intersecting with safety zone was 30.72±5.27mm,the length from ASIS to safety zone along the line was 33.61±8.82mm,and the length from GT to safety zone a-long the line was 69.14±11.46mm;In females,such lengths were 109.83±8.99mm,32.32±4.94mm,35.77±11.26mm,and 43.75±7.62mm,respectively,with significant differences between the two gender groups(P＜0.05);In the underweight group,such distances were 119.40±12.21mm,30.72±3.83mm,25.42±7.75mm,and 65.64±14.79mm;In the normal weight group,they were 122.98±10.91mm,30.29±4.29mm,35.01±10.22mm,and 60.58±13.43mm;In the overweight group,they were 117.52±13.70mm,32.12±6.27mm,36.92±8.27mm,and 51.42±18.38mm;In the obese group,they were 120.52±13.95mm,35.65±3.29mm,29.58±11.67mm,and 60.93±15.13mm.The length of the line connecting ASIS and GT showed no statistically significant difference be-tween weight subgroups(P＞0.05).However,the length of the line intersecting with the safety zone,the length from ASIS to the safety zone along the line,and the length from GT to the safety zone along the line exhib-ited statistically significant differences between subgroups(P＜0.05).Conclusions:All the S2AI screw safety channels targets a specific area on the body surface,and the line connecting the anterior superior iliac spine and greater trochanter(GT)passes through this safety zone,which can serve as an auxiliary landmark for plac-ing the S2AI screw.

Objectives:To investigate the relationship between pelvic landmarks on body surface and the trajectory of S2 alar-iliac(S2AI)screws in populations of different genders and body mass indexes.Methods:A retrospective analysis was conducted on 150 patients who underwent pelvic CT scans in the Affiliated Hospital of Southwest Medical University between February 2022 and February 2024.Basic demographic data including age,gender,weight,and height were collected.Pelvic models were reconstructed by CT,and screw trajectories were simulated on the models.The screw trajectories were extended to intersect with the skin sur-face,and the intersection points of the safe trajectories with skin formed a safety zone on the body surface.The shortest distances from the anterior superior iliac spine(ASIS),anterior inferior iliac spine(AIIS),and greater trochanter(GT)to the safe zone were measured.The length of the line connecting ASIS and GT on the surface,length of such line intersecting with the safety zone,length from ASIS to the safety zone along such line,length from GT to the safety zone along such line were measured.Group comparisons were performed based on gender and BMI[underweight group(BMI＜18.50kg/m2),normal group(18.50kg/m2≤BMI＜24.00kg/m2),overweight group(24.00kg/m2≤BMI＜28.00kg/m2),obese group(BMI≥28.00kg/m2)].Results:In males,the shortest distances from ASIS,AIIS,and GT to the safe zone were 19.87±3.66mm,33.66±3.33mm,and 39.53±3.56mm,respectively;In females,they were 19.31±3.41mm,33.23±3.45mm,and 38.74±3.23mm,respectively.No statis-tically significant differences were observed between gender groups(P＞0.05).The shortest distance from ASIS,AIIS,GT to safety zone was 14.03±1.64mm,26.79±1.15mm,43.68±1.32mm in the underweight group,17.67±2.36mm,31.73±1.77mm,41.18±2.43mm in the normal group,21.85±1.37mm,35.78±1.76mm,36.80±1.68mm in the overweight group,and 25.66±0.84mm,38.75±0.88mm,and 36.80±1.68mm in the obese group,respec-tively.Intergroup comparisons between the four groups were statistically significant(P＜0.05),and pairwise com-parisons within groups were statistically significant(P＜0.05).In males,the length of the line connecting ASIS and GT was 129.43±6.42mm,the length of the line intersecting with safety zone was 30.72±5.27mm,the length from ASIS to safety zone along the line was 33.61±8.82mm,and the length from GT to safety zone a-long the line was 69.14±11.46mm;In females,such lengths were 109.83±8.99mm,32.32±4.94mm,35.77±11.26mm,and 43.75±7.62mm,respectively,with significant differences between the two gender groups(P＜0.05);In the underweight group,such distances were 119.40±12.21mm,30.72±3.83mm,25.42±7.75mm,and 65.64±14.79mm;In the normal weight group,they were 122.98±10.91mm,30.29±4.29mm,35.01±10.22mm,and 60.58±13.43mm;In the overweight group,they were 117.52±13.70mm,32.12±6.27mm,36.92±8.27mm,and 51.42±18.38mm;In the obese group,they were 120.52±13.95mm,35.65±3.29mm,29.58±11.67mm,and 60.93±15.13mm.The length of the line connecting ASIS and GT showed no statistically significant difference be-tween weight subgroups(P＞0.05).However,the length of the line intersecting with the safety zone,the length from ASIS to the safety zone along the line,and the length from GT to the safety zone along the line exhib-ited statistically significant differences between subgroups(P＜0.05).Conclusions:All the S2AI screw safety channels targets a specific area on the body surface,and the line connecting the anterior superior iliac spine and greater trochanter(GT)passes through this safety zone,which can serve as an auxiliary landmark for plac-ing the S2AI screw.

Objective To explore the value of transseptal puncture for left-sided accessory pathway in radio-frequency catheter ablation in children with paroxysmal supraventricular tachycardia(PSVT). Methods Thirty-three patients with PSVT who had underwent radiofrequency catheter ablation in the First Affiliated Hospital,Sun Yat-Sen University from January 2012 to December 2017 were retrospectively analyzed. All the cases were treated by transaortic approach(transaortic group)or transseptal approach(transseptal group). The immediate success rates,total fluoroscopy time and radiation exposure between 2 groups were compared,and the perioperative complications and recurrence rates were observed between 2 groups. Results Thirty-three cases of children were enrolled,22 cases were male and 11 cases were female. Nineteen cases were treated by transaortic approach(transaortic group),while 18 cases were treated by transseptal approach(transseptal group),including 4 recurrent cases in the transaortic group who were switched to transseptal approach because of previous treatment failure. The age was(10. 16 ± 3. 06)years and(10. 67 ± 2. 20) years,and the weight was(37. 68 ± 14. 28)kg and(37. 33 ± 8. 64)kg,respectively. There were no significant diffe-rences in age and weight statistics between 2 groups(all P>0. 05). The total fluoroscopy time was(20. 16 ± 11. 41) minutes and(12. 56 ± 5. 23)minutes,and the median dose of radiation exposure was 67. 0 mGy and 33. 5 mGy,re-spectively. The postoperative recurrence rate was 21%(4/19 cases)and 0(0/18 cases),respectively. There were sig-nificant differences in total fluoroscopy time,radiation exposure and recurrence rate statistics between 2 groups( t ＝2. 627,Z＝ -2. 31,χ2 ＝4. 249,all P<0. 05). No complications were found in both 2 groups. Conclusions It is safe and feasible by transseptal puncture for left-sided accessory pathway in radiofrequency catheter ablation in children with PSVT. Radiofrequency catheter ablation by transseptal approach could significantly reduce the postoperative recu-rrence rate,and should be the first choice for left-side accessory pathway in children.

Objective To explore the development and interaction of left and right ventricular function in healthy children using tissue Doppler imaging.Methods Healthy children aged 0-15 years and adolescents were recruited,then children were divided into 6 groups:0-1 year,＞ 1-3 years,＞ 3-6 years,＞ 6-9 years,＞ 9-12 years,＞ 12-15 years.Healthy adolescents aged ＞ 15-25 years were also recruited.Every subject underwent echocardiography including cardiac dimension measurements,atrio-ventricular valvular velocity and early-diastolic flow velocity(E)/late-diastolic flow evlocity(A) ratio measured by pulsed color Doppler,atrio-ventricular annular myocardial velocity (including systolic velocity (s),early diastolic velocity (e) and late diastolic velocity (a)),time intervals (including isovolumic contraction time,ejection time and isovolumic relaxation time),isovolumic acceleration (ⅣA) and Tei index measured by tissue Doppler imaging.Results were compared among different groups,the correlations with age and other factors were explored.Furthermore,comparison was done between left and right ventricular functional parameters.Results Left ventricular Tei index and isovolumic contraction time were significantly lower during puberty.From infancy to pre-school stage,left ventricular E/A (flow velocity) and e/a(tissue velocity) increased accordingly,then presented with no significant changes among the following age groups(P ＞ 0.05).There were no significant differences in right ventricular Tei index,ⅣA,E/A (flow velocity) and e/a (tissue velocity) among the 6 groups (P ＞ 0.05).Left ventricular systolic myocardial velocity (s) and ⅣA were significantly lower than right ventricle (all P ＜ 0.001).However,left ventricular E/e(flow velocity) and e/a(tissue velocity) were significantly greater than right ventricle (all P ＜0.001).Conclusions In healthy children,left ventricular systolic function enhances during puberty,diastolic function increases from infancy to pre-school stage,then keeps stable till adolescents.Right ventricular systolic and diastolic function present with no significant changes during growth.Left ventricular diastolic function is greater than right one,however,right ventricular longitudinal systolic function is greater than left one.