Mechanism, Morphology Of Flutter Wave In The Surface Electrocardiogram And Method Of Ablation Of Atrial Flutter

Objective (1) To study the relationship between morphology of flutter wave in the surface electrocardiogram and endocardiial atrial transmission sequence in patients with typical counterclockwise conduction (CCW AFL) and clockwise conduction atrial flutter (CW AFL). (2) To investigate the impact of trans-cavo-tricuspid isthmus(CTI) linear ablation of typical atrial flutter on activation sequence of atria. (3) To study the mechanism, surface electrocardiographic characteristics and catheter ablation of atypical right and left atrial flutter.Methods (1) We performed conventional, noncontract three-dimensional mapping, surface ECG analysis and ablation for 55 patients with typical atrial flutter with 63 episodes (47 males, 8 females; mean age 61.2 ±19.5 years). There were 38 patients with counter clockwise conduction, 9 with clockwise conduction and 8 with both counter clockwise and clockwise conduction. (2) 52 patient with typical atrial flutter were investigated during proximal coronary sinus (PCS) and lower lateral right atrium (LLRA) pacing before and after ablation. The measurement includes 1) activation time from proximal to distal coronary sinus(PCS-DCS) and difference of PCS-DCS ( A(PCS-DCS)), from LLRA to PCS(LLRA-PCS) and A(LLRA-PCS) ,from His bundle to PCS(His-PCS) before and after ablation during LLRA pacing; 2) activation time from PCS to LLRA (PCS-LLRA) and the difference of PCS-LLRA ( A(PCS-LLRA) during PCS pacing, and 3) morphology, duration and ratio of a positive terminal Pwave part and whole P wave amplitude changes of the paced P wave. Right atrial activation in 20 patients was visualized using a noncontract mapping system (EnSite-3000) for a three dimensional reconstruction of the endocardial depolarization. (3) We performed conventional, noncontract three-dimensional mapping, surface ECG analysis and ablation for 18 patients with 34 episodes of atypical right atrial flutter and 10 patients with 12 episodes of left atrial flutter.Results (1) Of the 63 episodes evaluated, 46 were CCW AFL, 17 were CW AFL. Four groups of CCW AFL were observed: Group 1 had purely negative F wave inferiorly with a proximal-to-distal pattern (PD) in coronary sinus recording (CS). Group 2 had small positive terminal deflections with PD pattern. Group 3 had broad positive terminal deflections or purely positive F wave with a distal-to-proximal pattern (DP) or fused pattern (F). Group 4 had almost flat-line recording with PD pattern. All groups of CCW AFL had a positive F wave in Vi lead. Three groups of CW AFL were observed: Group 1 had positive or notched positive F wave inferiorly with a PD or F pattern in CS. Group 2 had negative with PD pattern. Group 3 had almost flat-line recording with fused pattern. All group of CW AFL had negative F wave in Vj leads. (2) Banchmann's bundle and CSos can develop varying degrees of conduction delay and block, which can make connection between right and left atrium change consequentially. (3) The AVF/I flutter wave amplitude ratio was >2 .0 in CCW AFL but <2.0 in all CW AFL (4) The duration of the plateau in lead III correlated with strongly Cavo-tricuspid isthmus conduction time (r=0.96). (5) The decreased amplitude of F wave in inferior leads seems to relate to heart disease and left atrium enlargement. (6) Complete CTI block was achieved in 52 patients. During LLRA pacing, linear ablation at CTI results in a significant delay of activation in all coronary sinus recording sites with great extent at the ostium area. The A (PCS-DCS) was well correlated with results of CTI block and significantly longer in patient with complete than incomplete CTI block (30±17 vs. 10±ll ms p<0.001), thereby allowing avalue of 20 ms as a discriminative parameter to differentiate incomplete (<20ms) from complete (>20ms) CTI counterclockwise conduction block with a sensitive of 92% and a specificity of 85%. (7) PCS advanced His before ablation and then His advanced PCS after ablation, His-PCS was well-correlated counter clockwise block, allowing a value 35ms as a discriminative parameter to differentiate incomplete (<35 ms) from complete (>35ms) CTI block with a sensitive of 94% and a specificity of 90%. (8) A change of the terminal portion of the P wave towards a positive morphology in 48(92%) of 52 patients during PCS and LLRA pacing. These changes were predominantly observed in the inferior leads. Positive morphology changes of the terminal P wave portion and larger increment of ratio of P wave ratio (40±12ms) in the inferior leads indicating conduction block with a sensitive of 92% and a specificity of 90% were observed. An increment of 20ms or more in P wave duration during PCS and 15 ms or more during LLRA pacing indicates conduction block with a sensitivity of 90% and a specificity of 90%. (9) There were 18 episodes with low loop reentry atrial flutter(LLR) involved the low right atrium(RA), as early breakthrough in the low RA, wave-front collision in the high lateral RA or septum, and conduction through the CTI. Surface-ECG showed negative F wave in inferior leads as same as typical flutter with counter clockwise conduction. There were 4 episodes with upper loop reentry flutter (ULR) involved upper atrium and no conduction through CTI, positive F wave in inferior leads. (10) 12 episodes originating in right atrial free wall (RAFW), the surface ECG does not distinguish RAFW atypical atrial flutter from typical atrial flutter, but they can be differentiated by entrainment (or electroanatomic) mapping. (11) 10 patients with 12 episodes of left atrial(LA)flutter involved LA septal, LA posterior wall and mitral annulus. Surface ECG showed positive F wave in Vj lead and flat or isoelectric F wave in inferior leads.Conclusion (1) Polarity of the F wave in surface ECG inferior lead is determined by connection between two atria and activation sequence in...