Patient data
Sixty patients with paroxysmal atrial fibrillation undergone radiofrequency ablation in the First Affiliated Hospital of Wannan Medical College, Anhui, China, were consecutively included from February to October of 2021, and randomly allocated to conventional TSP group and Runthrough guidewire assisted group (Figure 1). All patients underwent esophageal ultrasound or computed tomography angiography (CTA)of the left atria to exclude thrombosis at left atrial appendage, and oral warfarin or a new anticoagulant for three to four weeks before operation. Fasting started about 4 to 6 hours prior to the procedure. Written informed consent was obtained from all patients. Exclusion criteria were as follows: 1)history of catheter ablation for atrial fibrillation in the past 6 months; 2)left ventricular ejection fraction<0.35; 3) New York Heart Association (NYHA) cardiac function III or IV; and 4) patent foramen ovale(PFO) confirmed by TEE.
Qualification of the physicians
Physicians participated in current study were those who had many years of clinic practice in interventional management of arrhythmia, and performed TSP in over 150 patients on average per year. Additionally, all providers were totally competent at estimating and managing the complications associated with therapeutic catheterization.
TSP procedure
Conventional TSP procedure with iodinated contrast agent
A 10-pole electrode catheter (Biosense-Webster Inc., Diamond Bar,CA, USA)was initially positioned at the coronary sinus (CS)via left subclavian vein or left femoral vein. Transseptal sheath with its dilator (SL1;size: 8.5F; Synaptic Medical Technology Co., Ltd. Beijing, China) was delivered into the superior vena cava through right femoral vein assisted by a long J-tipped guidewire(0.032 inch×180 cm; Synaptic Medical Technology Co., Ltd. Beijing, China), which was then replaced by a transseptal needle (Synaptic Medical Technology Co., Ltd. Beijing, China). Under the fluoroscopy by postero-anterior(PA) projection, the puncture assembly(including sheath–dilator and the transseptal needle)were then carefully withdrawn against the patient’s foot while observing the motions of catheter tip at fluoroscopy until two falls occurred, which indicated successful descent of the assembly from the superior vena cava and into the fossa ovalis.Next, the puncture assembly were gently adjusted at the right anterior oblique fluoroscopic(RAO) 30-45° projection. Once the right puncture location was decided, the transseptal needle was pushed through the fossa ovalis into left atrium. TSP was directly performed in patients undergoing conventional procedure after injecting 2-3ml of iodinated contrast agent via the transseptal needle. After confirming access to the left atrium, the transseptal needle was fixed, and the transseptal sheath with its dilator was advanced into the left atrium. The long J-tipped guidewire was introduced after withdrawal of the transseptal needle, and confirmed to be in place in the left superior pulmonary vein at PA projection and the left anterior oblique (LAO) projection (30-45°). Finally, the transseptal sheath with its dilator was introduced into left atrium under the protection of the guidewire.
TSP procedure assisted by Runthrough guidewire
After transseptal needle tip reaching left atrium through the fossa ovalis, a Runthrough guidewire(0.014 inch×180 cm, Terumo Corporation, Japan) was introduced and positioned without use of iodinated contrast agent. The Runthrough guidewire was driven into the left superior pulmonary vein by the same position(PA and LAO projection) as conventional TSP procedure. Upon confirming that the distal tip of the Runthrough guidewire was exposed into the left superior pulmonary vein and by the outside of the contour of the heart under fluoroscopy, the Runthrough guidewire was secured, and the transseptal needle and the transseptal sheath with its dilator were introduced into the left atrium under the protection of the guidewire (Figure 2). Then the Runthrough guidewire, the transseptal needle and the dilator were drawn out after the transseptal sheath was positioned and maintained in the left atrium.
The blood was drained through the sheath, and heparin was administrated immediately in dose of 80–100 U/kg. All patients received only one TSP and circumferential pulmonary vein isolation (CPVI) by Carto 3 system(Biosense-Webster Inc., Diamond Bar,CA, USA).
Imaging system and radiation dose measurement
Fluoroscopic imaging was performed using Simens single-plane pulsed system (SIEMENS Artis Zee Ceiling, Siemens Medical Systems NA.) at 6 frames/s, The total puncture time was defined as the time from withdrawal of the puncture assembly from superior vena cava to successfully positioning the transseptal sheath at the left atrium. The radiation dosage was measured by dose per unit area (uGym2), and the radiation length during puncture was recorded for each patient.
Study endpoint
The endpoints in current study consisted of: ① TSP duration(the time from retracting the puncture assembly from the superior vena cava to the transseptal sheath retained in the left atrium); ②radiation time(total fluoroscopy length during TSP); ③ radiation dose(the radiation dose automatically recorded by X-ray device during TSP) (uGym2); and④ complications(adverse events involved in TSP, including cardiac tamponade and aortic perforation).
Statistical analysis
All statistical data were analysed with software SPSS version 22.0(Inc. Chicago, IL). Measurement data were expressed as`x̄±S, and compared between groups using t-test. The counting data was presented as percentage, and compared between groups using χ2 test. P value < 0.05 was accepted as statistical significance.