Atrial Incision And Pulmonary Vein Isolation Postoperative Atrial Flutter Electrophysiological Characteristics And Catheter Ablation

Part One:The electrophysiological characteristics and ablation strategy of the post-atriotomy atrial flutterObjective:The purpose of this study was to evaluate the electrophysiological mechanisms and characteristics of the post-atriotomy atrial flutter (AFL) and summarize its clinical effects of catheter radio frequency ablation.Methods:One hundred and eight consecutive patients (male59, mean age41years) with AFL after atriotomy procedure were treated with catheter ablation strategy. The underlying heart diseases and surgeries were:repair of atrial septal defect (ASD)30, repair of ventricular septal defect (VSD)24, mitral valve replacement17, radical correction of Tetralogy of Fallot (TOF)12, mitral valvoplasty8,, excision of left atrial myxomas5, anomonous pulmonary venous drainage combined with ASD (Fontan procedure)3, Ebstein's anomaly (tricuspid valve replacement)3, transposition of the great arteries (TGA, Mustard procedure)2, tricuspid valvoplasty2, tricuspid atresia (Fontan procedure)1, single ventricle1. No AFL was found before the surgery. AFLs occurred at24(1～300) months after the surgery and the duration was8(1～34) months. Coronary sinus (CS) catheter and Halo catheter encircling the tricuspid annulus (TA) were inserted through veins under local anesthesia. Activation from CS catheter was set as reference and90%of the cycle length of the tachycardia was set as the window of interest. Right atrium (RA) and/or left atrium (LA) were mapped to create the electroanatomic and activation maps of the atriums. Superior vena cava (SVC), inferior vena cava (IVC), CS ostium, TA, scar area and surgery incision (double potential) were also labeled. Entrainmnet mapping was performed at target site. Focal or linear ablation was performed with the preset of43℃,30-40W for3.5mm irrigated ablation catheter. Success endpoint was defined as:①tachycardias were terminated by ablation,②complete block of the ablation line was achieved,③no tachycardias could be induced by atrial stimulation. In addition,20cavotricuspid isthmus-dependent (CTI-dependent) AFL patients without the history of atriotomy were enrolled as controlled group. Its' length, conduction time and conduction velocities in CTI, atrial septum and free wall were measured respectively, and we compared it with that of the patients of AFL after atriotomy.Results:Ninety-nine patients had chronic AFLs and sustained AFLs were induced in the other9patients in sinus rhythm during the procedures with a mean cycle length of246±31(208～400) ms. In the first procedure, a total number of127AFLs were found with121in the RA and6in the LA. In the121RA AFLs, CTI participated the circuit and act as a critical part in88AFLs (73%). Sixty AFLs were merely CTI-dependent AFL and were all treated with CTI ablation successfully. Thirty-five AFLs were merely surgery incision or scar related AFL encircling the right anterior wall (33) or right atrial septum (2), and were all treated with linear ablation from the inferior boarder of the scar to IVC successfully. Twenty-three AFLs were figure of8reentrant,22of them encircling both the TA and the scar and terminated after ablation of the CTI and the scar to IVC sequentially. One AFL encircled both the SVC and IVC was terminated after ablation of the IVC and SVC to the scar sequentially. In the6LA AFL,4encircled the mitral annulus (MA),1encircled the incision of the left atrial appendage and1encircled the scar in the post wall. Five LA AFLs were after mitral valve replacement, and its incidence in mitral valve replacement is30%(5/17). In ablation of these LA AFLs,4were successful and2failed. All the2failure cases were the AFL encircled the MA after mitral valve replacement. There was no complication during the procedures. Nine cases recurred during a mean follow up of36(3～70) months and8acquired success in a second ablation procedure. The failure one had atrial ventricular junction blocked by ablation since the patient had implanted a dual chamber pacemaker. One patient showed (?)us node region isolation and implanted a dual chamber pacemaker. In addition, conduction time and conduction velocities in CTI in experimental group were longer and slower than that in controlled group, whereas the parameter in free wall was on contrary in the two groups.Conclusions:Ninety-five percent of the AFL after atriotomy was RA AFL, CTI participate the circuit and act as a critical part in73%.8figure of reentry is not uncommon. It accounts for21.3%of the RA AFL and90%of them encircle both the TA and the scar. Although the incidence of LA AFL is relatively low in patients with AFL after atriotomy,30%of AFL after mitral valve replacement is LA AFL and successfully ablation of them is usually very difficult, especially in AFL encircling the MA. Electrocardiogram (ECG) and Halo catheter are very important in guiding successful ablation. The three dimensional electroanatomic mapping, entrainment mapping and irrigated ablation catheter are the three sharp weapon in cured the AFL after atriotomy. The CTI is more a critical anatomical isthmus than an electrophysiological isthmus (?) AFL after atriotomy, and the slow conduction in the free wall is the basic electrophysiological substrate for this type of AFL Part Two:The electrophysiological characteristics and ablation strategy of the atrial flutter after pulmonary vein isolationObjective:The purpose of this study was to evaluate the electrophysiological mechanisms and characteristics of the AFL after pulmonary vein (PV) isolation and summarize its clinical effects of catheter radio frequency ablation.Methods:Thirty consecutive patients (male23, mean age55years) with AFL after PV isolation were treated with catheter ablation strategy. No AFL was found before the PV isolation. AFL occurred at80(1～1100) days after the PV isolation. Before transseptal catheterization, right atrial CTI-dependent flutter is excluded. PV isolation is confirmed, and reisolation is performed if necessary. If AFL was not terminated after PV isolation, activation and entrainment mapping was performed to identify its circuit and critical isthmus for ablation target. Focal or linear ablation was performed with the preset of43℃,20-40W for3.5mm irrigated ablation catheter. Success endpoint was defined as:①tachycardias were terminated by ablation,②complete block of the ablation line was achieved,③no tachycardias could be induced by atrial stimulation. In addition, the surface ECG characteristics of each patient during AFL were analyzed.Results:The conduction between LA and PV was found in all the30patients, of which single side of PV in12patients (right in3and left in9) and both sides of PV in18patients. Five types of reentry were found:①Four CTI-dependent AFLs with a mean cycle length of234±16ms, and all of them were counterclockwise and were all successfully ablation in CTI. Except ECG showed atypical flutter in one AFL,3AFLs showed typical flutter.②Thirteen gap-related AFLs with a mean cycle length of271±49ms showed10in the left and3in the right. A single radio frequency application at the exit in6patients and at the entrance in7patients successfully terminated the tachycardia, and achieved PV isolation in the entrance and exit ablation respectively. AFL F wave morphology was positive in V1in all patients, and positive in the inferior leads in8patients with exit at the superior portion of the previous ablation circuit and negative in5patients with exit at the inferior portion of the previous ablation circuit.③One roof-dependent AFL with cycle length of220ms showed descend sequence in the post wall and was cured through linear ablation between the right and left superior PV. ECG showed positive F wave in the inferior leads and V1, flat in I and negative in avR and avL.④Two AFLs encircled the left atrial appendage with cycle length of288ms and294ms respectively, and all were successfully ablation in the rim between the left superior PV and the left atrial appendage. ECG showed positive F wave in the inferior leads, flat in I and avL, and biphasic in V1.⑤Ten AFLs around the MA with a mean cycle length of228±22ms showed counterclockwise in2and clockwise in8. Eight of the10AFLs were cured through9procedures, and2failed. In the two counterclockwise MA AFLs, ECG showed positive F wave in the inferior leads and V1and negative in avL in all the2AFLs, and M shape and flat in I respectively. In the8clockwise MA AFLs, ECG showed negative F wave in the inferior leads, positive in V1, and positive or flat in I and avL. The total incidence of③,④, and⑤AFL in the atrial fibrillation type (paroxysmal or persistent) in the first ablation procedure was no statistically difference.Conclusions:The incidence of AFL after pure PV isolation is2.7%. There are5types of reentry mechanism to explain these AFL. Conduction between LA and PV plays a critical role in the formation of these AFL, which not only participate in reentry but also act as a triggering factor. ECG is very useful in identifying the circuit. Additional linear lesions in the LA to prevent these AFLs is rarely necessary in this atrial fibrillation population.