Objective: To accumulate and improve the electrophysiological parameters of pediatric heart in China by comparing the electrophysiological data obtained by Intracardiac Electrophysiologic Studies (IEPS) and Transesophageal Atrial Pacing (TEAP) in children with Supraventricular Tachycardia (SVT), in order to provide a scientific basis for the widespread implementation of TEAP The reliability of the electrophysiological parameters was reasonably evaluated to provide a scientific basis for the widespread development of pediatric noninvasive cardiac electrophysiological examinations.
METHODS: The examination results of TEAP and IEPS were compared and studied in 27 children with SVT hospitalized in the hospital from August 2000 to October 2008. 12 males and 15 females, aged 6-15 (mean 10.1±2.5) years, all had a clinical history of repeated multiple episodes of SVT. The sinus node recovery time (SNRT), corrected sinus node recovery time (CSNRT), and sinus node conduction time (SACTc) were measured by TEAP and IEPS methods, respectively; the ventromedial node block point and 2:1 block point were measured by atrial graded incremental method S1S1; the atrial effective nonresponse period (AERP) and atrioventricular anterior transmission effective The effective atrioventricular nonresponse period (AERP) and the effective atrioventricular anterior ejection period (AVERP) were measured with S1S1 programmed premature stimulation. All data were analyzed statistically using SPSS software.
Results: 7 of 27 children with SVT had AVNRT and 20 had AVRT, including 6 with left-sided collateral tract and 14 with right-sided collateral tract; all were successfully eradicated by RFCA. 96.3% of TEAP fractional diagnosis was met. The electrophysiological parameters obtained by TEAP and IEPS were 912.2±180.3ms and 930.2±174.9ms for SNRT, 304±79.7ms and 287.1±63.09ms for CSNRT, 84.3±21.8ms and 94.62±23.24ms for SACTc, respectively, and Wen’s point was 182±28.1ms and 187±24.94ms, 2:1 block point was 211±24.7ms and 220±19.27ms, AERP was 228±29.4ms and 223.5±21.71ms, and AVERP was 298.46±71.76ms and 277.7±57.5ms, respectively. for the two groups of data Statistical analysis was performed and the p-values were 0.05, and the differences were not statistically significant.
Conclusion: TEAP electrophysiological parameters are reliable, although it is easily influenced by subjective factors and has a lower diagnostic rate and accuracy than IEPS, but as a noninvasive cardiac electrophysiological examination method, it is simple, safe, and low cost, and it is worthy to be widely used in primary pediatric clinical units. Intracardiac Electrophysiologic Studies (IEPS) is currently recognized as the gold standard for obtaining cardiac electrophysiologic parameters, on the basis of which Radiofrequency Cardiac Ablation (RFCA) has been widely used at home and abroad for the eradication of pediatric tachyarrhythmias; however, as an invasive test, its technical content and hardware requirements are high, and it is difficult to perform in primary pediatric care. However, as a non-invasive cardiac electrophysiological examination method, it is easy, safe, inexpensive, and has a relatively high compliance rate, which makes it a good method for primary screening of tachyarrhythmias. There are few studies on the controlled analysis of cardiac electrophysiological parameters obtained by TEAP and IEPS, and even less have been reported in pediatrics. We compared the data of IEPS and TEAP examinations in 27 children with tachyarrhythmias admitted to our hospital to make a reasonable evaluation of the reliability of TEAP electrophysiological parameters in order to clarify its application value and facilitate its use among primary pediatric medical staff.
1. Data and methods
1.1 Study subjects
All 27 patients were admitted to our hospital from August 2000 to October 2008, 12 males and 15 females, aged 6-15 (mean 10.1±2.5) years. All of them had a history of recurrent SVT episodes with sudden onset and abrupt termination, which could not be controlled by medication; no organic heart disease was found by routine physical examination, X-ray chest radiograph, echocardiography, and other examinations. The indications for RFCA treatment of cardiac arrhythmias in children recommended by the Radiofrequency Ablation Therapy Group of the American Association of Pediatric Electrophysiology were referred to IEPS examination and RFCA for radical treatment.
1.2 Apparatus
The esophageal atrial pacing apparatus was a DXT5 multifunctional cardiac electrophysiological pacing apparatus manufactured by Suzhou Sino-American Electronic Instrument Factory; the intracardiac electrophysiological examination was performed with a dual C-arm DSA apparatus manufactured by SIMENS and a multi-channel electrophysiological recorder and radiofrequency ablation apparatus manufactured by GE.
1.3 Methods
The following data were measured by TEAP and IEPS methods: Sinus Node Recovery Time (SNRT), Corrected Sinus Node Recovery Time (CSNRT), Sinoatrial Conduction Time (SACTc), Atrioventricular Node block and 2:1 block. point and 2:1 block point, Atrial Effective Refractory Period (AERP), and Atrioventricular Effective Refractory Period (AVERP).
1.3.1 Esophageal electrophysiological examination The 6F four-stage esophageal electrode was inserted through the nasal cavity, fixed when the esophageal ECG showed bidirectional high P waves, with a cannulation depth of 20-35 cm, pulse width of 3-7 ms, pacing voltage of 15-25 volts, programmed scanning with programmed stimulation mode (scanning wavelength ±10 ms), and SVT was evoked with atrial graded incremental or continuous incremental programmed premature stimulation (consistent with the usual onset graph). The electrophysiological data of the esophageal leads were measured asynchronously (consistent with the usual seizure pattern). A fractional diagnosis was made and then tachyarrhythmia suppression was performed using short bursts of prodromal stimulation [3, 6].
1.3.2 Intracardiac electrophysiological examination Local anesthesia with lidocaine is used in older children or those who can cooperate with the procedure, while intravenous anesthesia with ketamine or isoproterenol is chosen in younger ones who cannot cooperate. The femoral vein and left subclavian vein were routinely punctured, and a 10-pole electrophysiological marker catheter was placed into the coronary sinus (CS), and two or three 4-pole electrode catheters were placed in the high right atrium, His bundle (His), and right ventricle (RV) sites, respectively. 200m/s, detailed recording of body surface ECG, His, CS, RV electrograms, confirming the diagnosis of AVNRT and AVRT according to IEPS results, and marking the bypass site.
1.4 Radiofrequency ablation (all ablations were performed using temperature-controlled catheters)
1.4.1 Ablation of AV node double pathway The ablation slow pathway method is used. During ablation, the ablation catheter is marked between His bundle and CS to small A and large V waves with no H waves in between, and discharges at sinus rhythm with a power of 10-25 watts, and the junctional rhythm appears within 5-10 seconds as effective discharge, and continues to consolidate the discharge until 30-60 seconds. The indicator of successful ablation is: repeat IEPS, if the atrial program stimulates the disappearance of AH interval jump prolongation, or although there is AH jump prolongation or occasional atrial echo, intravenous isoproterenol cannot induce AVNRT, the ablation is considered successful.
1.4.2 Bypass ablation The ablation of the right bypass was performed in a left anterior oblique position at 45 degrees, and the location of the bypass was first marked initially at the tricuspid valve with a large-tipped catheter placed at the ablation electrode in sinus rhythm; the left bypass was performed using a retrograde aortic path or by puncturing the interatrial septum and placing the marking catheter at the mitral annulus, and the location of the bypass was marked initially at a right anterior oblique position at 45 degrees under the guidance of the coronary sinus electrode, and then the target point was carefully marked. The earliest ventricular excitation point was found for the dominant bypass; the earliest atrial excitation point was found for the occult bypass under ventricular pacing. Determination of ablation target: ① complete fusion of A and V waves; ② V wave is more than 25-30 ms earlier than the ECG preexcitation wave; try to ablate by discharge for 10-15 seconds at the target point determined by the marker test, and if it is effective, extend the discharge time to 90-120 seconds. The criteria for successful ablation were: (1) disappearance of the preexcitation wave on the body surface ECG; (2) termination of SVT during VA separation or discharge during ventricular stimulation; (3) failure to induce SVT and disappearance of collateral conduction when the electrophysiological examination was repeated after 30 minutes of observation.
1.5 Statistical analysis
The statistical significance in the data of the two groups of TEAP and IEPS was studied by SPSS software with paired data t-test comparison.
2, Results
Twenty-seven children were diagnosed by IEPS, 7 with AVNRT and 20 with AVRT, including 6 with left-sided collateral tract and 14 with right-sided collateral tract; all were successfully eradicated by RFCA. Only one case was misdiagnosed as right-sided by-pass by TEAP, and the rest were consistent with IEPS, with a staging rate of 96.3%.
The electrophysiological parameters obtained by TEAP and IEPS were compared (see Table 1), and the P values were 0.05, with no statistically significant differences.
Table 1 Comparison of electrophysiological parameters obtained by TEAP and IEPS (unit: ms) SNRTCSNRTSACTc
Wen’s point 2:1 blocking point AERPAVERPTEAP912.2±180.3304±79.784.3±21.8182±28.1211±24.7228±29.4298.46±71.76IEPS930.2±174.9287.1±63.0994.62±23.24187± 24.94220±19.27223.5±21.71277.7±57.5P-value 0.13660.40610.06750.45430.15530.11970.3988
Note: P-value < 0.05, statistical difference exists; P-value > 0.05, no statistical difference.
3. Discussion
It has been nearly a century since the first esophageal lead electrocardiogram by Cremer et al. in 1906, and TEAP, as a noninvasive cardiac electrophysiological examination method, has become one of the indispensable auxiliary diagnostic tools in cardiac arrhythmology today with its advantage of high and large P waves in the esophageal electrocardiogram. Because of its simplicity, safety and low cost, it has been more widely used in pediatric clinics; in recent years its clinical application has evolved from simply detecting cardiac function to studying the pathogenesis of arrhythmias and explaining certain special electrocardiographic phenomena: such as cleft phenomenon, cicada phenomenon, hyperconductivity phenomenon, foldback phenomenon, etc., and treating and rescuing certain critically ill patients. Even in the current situation where IEPS and RFCA are widely carried out, TEAP still plays an important role in preoperative screening of cases, etc. It can be used to evaluate sinus node function, determine AVNRT and atrioventricular bypass, especially in the case of preexcitation syndrome, sometimes the preexcitation wave is not obvious on the body electrocardiogram, TEAP can make it clear, or even present the full preexcitation waveform, which is beneficial to the determination and localization of bypass.
From the clinical data about arrhythmias at home and abroad, TEAP is more commonly used, and IEPS and RFCA for radical treatment of pediatric tachycardia have been widely carried out. However, there have been few studies with controlled analysis of the cardiac electrophysiological parameters obtained by TEAP and IEPS, and even fewer have been reported in the pediatric community. The accuracy of TEAP for the diagnosis and staging of SVT has been reported in the national literature. In a controlled comparison of the results of TEAP and IEPS in 192 patients with SVT, it was found that the 2 electrophysiological examinations had a positive effect on the dual atrioventricular node pathway (DAVNP), atrioventricular node fold tachycardia (AVNRT), atrioventricular fold tachycardia (AVRT), common cis-atrial fold tachycardia (OAVRT), left atrioventricular collateral tract (LAP), right atrioventricular paravalvular tract (RAP), but TEAP has a lower diagnostic rate for AVRT with septal paravalvular tract (SAP) involvement with atrial tachycardia (AT) than intracardiac electrophysiological examination. The results of this paper showed that the TEAP fractionation diagnostic compliance rate: 96.3%, and the electrophysiological parameters obtained by TEAP and IEPS respectively were compared with a P value of 0.05, with no statistically significant difference and similar diagnostic value.
This shows that TEAP has similar value to IEPS in the diagnosis and typing of common SVT, and has the characteristics of non-invasive, simple and low cost. However, at the same time, we also see that TEAP has certain limitations, such as the existence of certain limits in the electrophysiological examination of preexcitation syndrome, which cannot be accurately localized, the retrograde function of the collateral tract cannot be directly evaluated, and the presence of retrograde function can only be inferred by the presence or absence of atrioventricular folding, so the diagnosis of occult preexcitation cannot be confirmed. However, in general, TEAP has excellent practical value for primary care hospitals in the diagnosis and treatment of SVT and is worth promoting.