| ObjectiveTo investigate the image features of the significant structures in the right atrium and interatrial septum relevant to interventional elecrtophysiologic techniques with 64-Detertor CT.Methods and methods①GE advanced work station ADW4.4 was used to evaluate the image features of in 100 patients(58men,42women;mean age,58.4 years)with contiguous examination by ECG gating for 64-detector CT of the coronary arteries, and corresponding parameters were measured. The shot-axis view show the crista terminalis extends from the superior vena cava (SVC) to the inferior vena cava(IVC).A line was drawn from the right margin of SVC junction and the right margin of IVC junction and then drawn a perpendicular line from the midpoint to the crista terminalis.The cross point was the target point for modification of the sinus node as a treatment for inappropriate sinus tachycardia, which was closely related to the ceista terminalis.The distance from the SVC junction to the IVC junction, the distance from the SVC junction and the IVC junction to the target point and the length of the perpendicular line were measured, respectively. View was magnified and the thickness of the crista terminalis at the target point was measured. The length of the cavotricuspid isthmus (CTI) was measured along the three parallel levels as the paraseptal isthmus,the central isthmus and the inferolateral isthmus at the 75% of the R-R interval of the cardiac cycle(ventricular diastole), and the depth of the central isthmus was also measured. The same parameter was also measured in 24 patients(15men,9women;mean age,61.8 years)at the 0%(atrial contraction) and 35%(ventricular systole) of the R-R interval of the cardiac cycle. Central isthmus depth was classified as straight(≤3mm),concave(>3mm,≤5mm),or pouchlike(>5mm).The depth of subthebesian recess and the thickness of Eustachian ridge were also measured form shot-axis view and four-chamber view, respectively.②CT date in 201 patients(122 men,79 women;mean age,58.05 years)with contiguous examination by 64-detector CT of coronary arteries were reviewed for PF O morphologic feature.The length and diameter of the opening of the PFO tunnel,presence of atrial septal aneurysm(ASA),and PFO shunts were evaluated. A left-to-right shunt was assigned a grade according to length of contrast agent jet(gradel,≤1 cm;grade2,>1 to2cm;grade3,>2cm).Results①The average distance between the right margin of superior vena cava junction and the right margin of inferior vena cava junction was 48.9mm±6.9 mm, while the average verticalis distance from the midpoint of this line to the target point was 37.9mm±5.6mm.The distance from the right margin of superior vena cava junction and the right margin of inferior vena cava junction to the target point were28.3mm±5.2mm and 28.6mm±5.7mm, respectively. The average thickness of the crista terimal was 3.8mm±1.8mm.The average length of paraseptal isthmus was16.2mm±3.2mm;The length of septal isthmus was 9.8mm±2.6mm;The central isthmus was 7.3mm±3.1mm,The depth of central isthmus greater than 5mm in 72 patients;The lateral isthmus was 24.8mm±4.8mm.The septal isthmus was shorter than the paraseptal isthmus,the paraseptal isthmus was shorter than the central isthmus and the central isthmus was shorter than the lateral isthmus(p<0.05).The shortest CTI measurements were observed at atrial contraction and the longest were observed during ventricular systole.A thick Eustachian ridge (>4mm)was seen in 24 patients.A distinct eustachian valve arising from the eustachian ridge (a thick eustachian ridge with a valve) was also seen in 22 patients. Within the 100 patients,A subthebesian recess greater than 5 mm in depth was identified in 54 patients.The mean depth was 7.9 mm±2.7mm.②A free flap valve, seen in 80(39.80%) patients, was patent at the entry into the right atrium (PFO) in 63 patients (78.75% of patients with flap valve,31.34% of total patients).A left-to-right shunt was detected in 52(25.87% of total)patients (grade 1, 34.62%; grade 2,48.08%; grade 3,7.69%).Mean length of PFO tunnel was 6.77mm±3.97 mm in patients with a shunt and 10.01mm±5.17 mm in patients with a flap valve without a shunt (p<.05).In patients with a tunnel length of 6 mm or shorter, 82.76% of the shunts were seen. ASA was seen in 10(4.96%) patients;of these patients, a left-to right shunt was seen in 8 patients(80%). Conclusion64-detector CT was a powerful tool to display the exact structure and image features of the significant structures in the right atrium and interatrial septum relevant to interventional elecrtophysiologic techniques, which would be useful for the operation. |
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