2005 terni, università di medicina. corso di elettrofisiologia, l'ablazione del flutter atriale
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2005 terni, università di medicina. corso di elettrofisiologia, l'ablazione del flutter atriale
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2005 terni, università di medicina. corso di elettrofisiologia, l'ablazione del flutter atriale
- 1. Corso di “ELETTROFISIOLOGIA”Corso di “ELETTROFISIOLOGIA” Ablazione Transcatetere delAblazione Transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE Stefano Nardi, MD AZIENDA OSPEDALIERA SANTA MARIA TERNIAZIENDA OSPEDALIERA SANTA MARIA TERNI DIPARTIMENTO CARDIOTORACOVASCOLAREDIPARTIMENTO CARDIOTORACOVASCOLARE STRUTTURA COMPLESSA DI CARDIOLOGIASTRUTTURA COMPLESSA DI CARDIOLOGIA UNITA’ OPERATIVA DI ARITMOLOGIA CARDIACAUNITA’ OPERATIVA DI ARITMOLOGIA CARDIACA LABORATORIO DI ELETTROFISIOLOGIA ED ELETTROSTIMOLAZIONELABORATORIO DI ELETTROFISIOLOGIA ED ELETTROSTIMOLAZIONE
- 2. Flutter ectopic AT Tachicardia Atriale ORGANIZZATA • Tachicardia Atriale Ectopica “Focale” • Flutter tipico “istmo - dipendente” dipendente da un ralentamento nella regione compresa tra VCI e AT - flutter ORARIO - flutter ANTI-ORARIO - “LOWER-LOOP” • Flutter da MACRORIENTRO “non-istmo dipendente” - precedente CCH atriale o SCAR Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 3. FLUTTER comune Istmo-dipendente FO CS IVC SVC Shah Circ 96:3904, 1997; Olgin Circ 92:1365, 1995; Cosio Pace 19:841, 1996; Kalman Circ 94:398, 1996; Nakagawa Circ 94:407, 1996; Takahashi JACC 33:1996, 1999; Arenal et al Circulation 99:2771, 1999 AMPIE VIE DI RIENTRO AL DI FUORI DELL’ISTMO - Variabilità interindividuale - Via anteriore +/- posteriore a VCS - Area di BLOCCO lungo la CT - 17% dei pazienti presentano un BLOCCO PARZIALE (doppi potenziali) nell’ ISTMO Kalman et al Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 4. Tricuspid Valve FlA anti-ORARIO Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 5. Nel circuito: PP- interval = Lunghezza di ciclo del FlA “ENTRAINMENT” positivo in istmo CT ss s s Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 6. INTERRUZIONE del FlA durante ATRF Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 7. Tricuspid Valve Setto Anulus Tricuspidale VCI Flutter Atriale Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 8. Blocco della Conduzione nella regione ISTMICA VCI - AT • Dopo terminazione del Flutter Atriale durante applicazione di RF, spesso la conduzione attraverso l’istmo PERSISTE Schwartzman et al JACC 1996; 28:1519; Shah et al JACC 2000; 35: 1478 • Un rallentamento della conduzione spesso si verifica prima del blocco ISTMICO – Il rallentamento della conduzione può essere FREQUENZA DIPENDENTE • La ripresa della conduzione dopo un INIZIALE BLOCCO ISTMICO è un evento COMUNE Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 9. VERIFICA del BLOCCO della conduzione No block Block CS pacing Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE CS pacing
- 10. PACING CS Block No block DOPPI POTENZIALI >100ms Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 11. Markers di blocco della conduzione • AUMENTATO tempo di conduzione attraverso l’istmo PACING differenziale Tada JACC 2001;38:750. Tai JICE 2002;7:77. Chen JICE 2002;7:67. Tada JCE 2001;12:393. Shah JCE 1999;10:662. Nakagawa Circ 1996;94:3204. Poty Circ 1996;94:3204 • DOPPI POTENZIALI 100 - 110 ms intervallo tra i potenziali nell’istmo CT lungo la linea di ABLAZIONE PACING differenziale • Stimolando dalla regione opposta alla linea di ablazione si osserva una INVERSIONE della polarita dell’ EGM • Modifica della morfologia dell’onda P stimolando LATERALMENTE alla linea di ablazione Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 12. Durante pacing dal CS: la conduzione attraverso la CT mediante la regione poseriore dell’ADx può suggerire falsamente la presenza di conduzione attraverso l’istmo, quando il BLOCCO è presente cs pacing Scaglione et al, J CV El 2000; 11:387 Anselme et al, Circulation 2001;103:1434 Crista shunt Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 13. s s s Gap in the RF line Pacing from lateral RA Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 14. CATETERE IRRIGATO (Sol. Salina raffreddata) Comparati ai cateteri standard con punta da 4 mm: Elettrocateteri IRRIGATI (rafreddati) - Riduzione del numero di lesioni richieste per il BLOCCO - Riduzione del tempo di fluoroscopia Elettrocateteri con punta da 8mm Tsai Circulation 1999; Jais Circulation 2000; Schreieck J Cardiovasc Electrophy 2002 Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 15. Linea SETTALE vs LATERALE EFFICACIA SIMILE RISCHIO AUMENTATO Per le linee settali: - CS TV IVC Anselme et al Am J Cardiol 2000 Ouali et al J Cardiovasc Electrophys 2002 Tai et al Circulation 2001;104:1501 septal lateral Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE - Alterazioni della conduzione attraverso il NAV in 5/36 pts con linea settale - RF in CS con Cat. Irrigato/8mm
- 16. 61 pz >1 episodio FlA e nessuna precedente tx AA Farmaci AA Sotalolo, Amiodarone Flecainide, Procainamide, Propafenone ABLAZIONE RF > 90% riduczione in ampiezza degli elettrogrammi lungo la linea di ablazione RECIDIVA FlA: Atrial Fibrillation: R.S.FU 36Mo: 93% 60% 36% 6% 29% 80% mean follow-up: 36 months Terapia AA vs ATRF primaria Natale et al J Am Coll Cardiol 2000 Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 17. INCIDENZA FA dopo ATRF di FlA n = 212 n = 121 Ricorenza di Flutter Atriale: 9% Hsieh et al J Interv Card Electrophysiol 2002;7:225 Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 18. Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 20. Clockwise Flutter Di quale ARITMIA si tratta? Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 21. Tachiaritmia con onde p non tipiche per FlA istmo.dipendente Flutter ectopic AT • Flutter “Istmo - dipendente” - precedente Chirurgia Atriale/scar - Trapianto Cardiaco • Flutter Atriale da macrorientro “non-istmo dipendente” - precedente Chirurgia Atriale o presenza di cicatrici - Flutte Atriale Sinistr • Tachicardia Atriale FOCALE Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 22. Palpitazioni 24 mesi dopo riparazione di DIA Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE
- 23. scar RPO scar Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE MAPPAGGIO EP e 3-D
- 24. 47 CIRCUITI in 20pts Flutter COMUNE- 18 Circuito sulla P. Laterale - 19 Circuito Settale - 8 Non identificato - 2 Successiva ATRF (ASSENZA DI RECIDIVA) - 80% follow-up a 46 mo FO CS IVC SVC POSSIBILI circuiti di RIENTRO post- CCH ASD patch Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE Delacretaz et al 2000
- 25. - onda P positiva V1 - onda P positiva in II, III, AVF Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE Jais et al Circulation 2000 FlA Sinistro: Di quale ARITMIA si tratta?
- 26. Tachicardia Atriale da macrorientro SCAR-dipendente (INCISIONALE) • L’ECG può NON essere AFFIDABILE per la diagnosi di SEDE Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE • ATRF spesso particolarmente COMPLESSA – E’ comune riscontrare CIRCUITI MULTIPLI – DIFFICOLTA’ a definire correttamente l’ISTMO critico – DIFFICOLTA’ ad ottenere un BLOCCO attraverso l’istmo • Il MAPPAGGIO è facilitato dai sistemi di ricostruzione TRIDIMENSIONALI • PERCENTUALI di SUCCESSO con ATRF: 50–88% Akar, et al.2001,Chan, et al.2000,Delacretaz, et al.2001, Nakagawa, et al.2001,Triedman, et al.1997 Jais, et al.2000,Saoudi, et al.2001,Tai, et al.2001,Thomas, et al.2000
- 27. • Terapia di PRIMA LINEA per Flutter Atriale tipico ricorrente – eccellente efficacia, bassi rischi Ablazione transcatetere delAblazione transcatetere del FLUTTER ATRIALEFLUTTER ATRIALE • In seguito FA si verifica nel 20-30% dei pts • Flutter Atriale “Non-istmo dipendente” si verifica quale complicanza TARDIVA nei pts precedentemente sottoposti a chirurgia atriale – L’efficacia è inferiore CONCLUSIONI
- 28. POSIZIONAMENTO ELETTROCATETERI ATRF del FLUTTER ATRIALE Catheter Ablation forCatheter Ablation for Cardiac ArrhythmiasCardiac Arrhythmias
- 29. Catheter Ablation forCatheter Ablation for Cardiac ArrhythmiasCardiac Arrhythmias
- 30. Catheter Ablation forCatheter Ablation for Cardiac ArrhythmiasCardiac Arrhythmias
- 31. Ablazione del Flutter Atriale • Il FLUTTER ATRIALE è una aritmia molto STABILE che che si verifica per la presenza di un CIRCUITO di MACRORIENTRO all’interno dell’ ATRIO DESTRO. Cosio FG. Am J Cardiol. 1993;71:705-709. Catheter Ablation forCatheter Ablation for Cardiac ArrhythmiasCardiac Arrhythmias • Affinchè sia possibile la PERPETUAZIONE del FlA è richiesta pa presenza di AREE CRITICHE di CONDUZIONE all’interno dell’ ATRIO DESTRO • L’ INTERRUZIONE della conduzione all’interno di tali aree critiche (VCI – AT) elimina il FlA.
- 32. Interruzione flutter durante RF Cosio FG. Am J Cardiol. 1993;71:705-709. Catheter Ablation forCatheter Ablation for Cardiac ArrhythmiasCardiac Arrhythmias
- 33. Catheter Ablation forCatheter Ablation for Cardiac ArrhythmiasCardiac Arrhythmias TV VCI
- 34. Catheter Ablation forCatheter Ablation for Cardiac ArrhythmiasCardiac Arrhythmias VCI TV
- 35. Catheter Ablation forCatheter Ablation for Cardiac ArrhythmiasCardiac Arrhythmias VCI TV
- 36. - Aritmia da rientro relativamente FREQUENTE - Notevole STABILITA’ del CIRCUITO che la rende assai resistente ai tentativi di interruzione mediante farmaci AA (ed alla CVE) - ATRF PRIMA SCELTA (preceduta dall’ETE) allo scopo di alterare stabilmente il circuito di rientro (localizzato fra VCI e AT). Ablazione TranscatetereAblazione Transcatetere delle Aritmie Cardiachedelle Aritmie Cardiache FLUTTER ATRIALE CONSIDERAZIONI
- 37. • Elevata percentuale di successo in acuto (95%) anche se si riduce nel FU a medio termine (80%). • Complicanze assai limitate. • Classe 1 nei pz nei quali l'aritmia tende a recidivare nonostante il miglior regime di profilassi AA. Ablazione TranscatetereAblazione Transcatetere delle Aritmie Cardiachedelle Aritmie Cardiache FLUTTER ATRIALE CONSIDERAZIONI
Editor's Notes
- A classification of organized atrial tachycardias is shown on this slide. There are focal ectopic atrial tachycardias that originate from a point source activation spreads out from that source. Typical isthmus dependent atrial flutter is dependent on conduction through the isthmus formed by the tricuspid valve annulus and the inferior vena cava. This includes common clockwise flutter as the circuit is viewed from the right ventricle and looking up at the tricuspid valve annulus. The wavefront circulates down the septum, through the isthmus, up the lateral wall, and across the roof of the right atrium. Counter-clockwise flutter has a circuit revolving in the opposite direction. Lower loop re-entry involves propagation across the posterior wall of the right atrium, across the crista terminalis, and then through the common flutter isthmus. There is a large group of macro re-entrant non-isthmus dependent atrial flutters, most commonly these involve re-entry in the lateral wall of the right atrium. They can occur anywhere including in the left atrium. They are often associated with areas of scar, such as from prior repair of congenital heart disease or the mitral valve.
- The re-entry circuit for common isthmus dependent flutter is shown here. The circulating flutter wave fronts are indicated by the yellow arrows. Propagation occurs up the septum, across the roof, and down the lateral wall of the right atrium forms a counter-clockwise circuit. Conduction is also occurring from the septum posteriorly around behind the inferior vena cava. It is likely that conduction is slow in the direction perpendicular to the Crista terminalis. In fact, conduction may be blocked here. This prevents short-circuiting of the re-entry circuit. The mechanism has been well defined. There is patient to patient variability in the course of the path, which is outside of the common isthmus. It may involve the lateral wall or come around posterior in a lower loop fashion. Some patients have a figure-eight circuit with both of these loops involved in the circuit. There can be areas of block along the Crista terminalis or there may be conduction through portion of the Crista terminalis. Some patients have small areas of conduction block present in the common flutter isthmus indicated by the presence of double potentials. There is also a great deal of variability in the anatomy of the common flutter isthmus. There can be thick pectinate muscles, which make ablation difficult or deep recesses, which can be difficult to get to access so that a catheter positioned for ablation may have problems. There may be areas of cooling from blood flow so with low power only small lesions are created.
- The approach to common counter-clockwise atrial flutter, which is shown on this slide. We typically use a deflectable 20-pole electrode catheter and place this so that the proximal electrodes are in the high right atrium and the catheter then swings down along the lateral wall of the right atrium, through the common flutter isthmus, and the tip electrodes are in the coronary sinus. This facilitates rapid recognition of the typical counter-clockwise atrial flutter activation sequence as shown. Occasionally, we will use more detailed activation sequence maps, as shown on the right where the activation sequence is displayed in a color-coded inner red beam earliest and then progressing to yellow, green, blue, and purple. Of course, since re-entry is a complete circle there is not a truly earliest or latest region and in the lower right-hand portion of this figure the earliest activation meets latest activation that is typical for re-entry. The additional colors in between the purple and the orange are interpolated by the mapping system in this case. Now when you have this activation sequence, the odds are very high that the rhythm you are dealing with is atrial flutter. However, left atrial arrhythmias and even focal atrial tachycardias can mimic this activation sequence on occasion. With left atrial tachycardias, there may be activation over Bachmann’s bundle conducting across the roof of the right atrium and then down the lateral wall. So, a limited mapping sequence will appear to be similar to that of counter-clockwise flutter so we need to do a bit more to sort this out and what our approach is, is to use entrainment mapping in this regard.
- This slide shows pacing from the lateral right atrium electrodes 15 and 16 on a 20-pole mapping catheter. You can see that the cycle length of the tachycardia is 260 milliseconds. We paced slightly faster than that to accelerate all of the electrograms to the paced cycle length. The post-pacing interval has been measured from the last stimulus. This entrains the tachycardia to the next activation at the pacing site. This is 270 milliseconds, only 10 milliseconds longer than the tachycardia cycle length. So we now know that the lateral right atrium is in this flutter circuit. The next thing that we do is pace from another site typically down in the flutter isthmus or at the medial side of isthmus and also confirm that that site is in the flutter circuit. If those two regions are both in the tachycardia circuit, then you can be very confident that this arrhythmia is indeed isthmus dependent flutter. If only the lateral right atrium is in the circuit, you may be dealing with one of those macro re-entrant flutters, which are not isthmus dependent. If the lateral right atrium is remote from the circuit with a long post-pacing interval relative to the tachycardia cycle length, you could even be dealing with a left atrial flutter. This takes just a moment to do and then you have got your re-entry circuit location confirmed.
- This is recorded during RF application. There is termination of the atrial flutter. You see that immediately prior to block there is a bit of slowing of conduction in the isthmus. Electrograms between poles 5, 6, and 3, 4, which is the septal side of the isthmus in this case show gradually prolongation of the conduction interval between these sites. Then block occurs after de-polarization at electrode 3, 4. So we are making our ablation lesion on the septal side of that.
- Once we know we are dealing with atrial flutter, then we select a place to make an ablation line. This slide shows the electroanatomic map of the flutter circuit. If we tilt it up, we see tricuspid annulus at the top, inferior vena cava at the bottom, and activation proceeding from lateral to medial. That is simply a matter of placing a continuous series of ablation lines through the isthmus to result in conduction block.
- Now once we have terminated atrial flutter, we are not necessarily finished because conduction commonly persists through the isthmus after termination of the flutter. Pacing on either side of the isthmus may easily show this. Conduction slowing in the isthmus often occurs prior to block. If you stop at this point with the resolution of edema from the additional ablation lesions, there will be some recovery and a high risk of recurrence of atrial flutter.
- So, you need to do a bit more and at this point. What we typically do is to begin pacing from either the coronary sinus electrodes or the lateral right atrium to assess conduction through the isthmus. This schematic shows what happens with pacing from the coronary sinus. As you will see, you have conduction up and around the lateral wall as well as through the isthmus with fusion in the lateral wall and no block. On the right hand side of the figure after block is achieved, activation comes down the lateral wall with no evidence of fusion. Double potentials will be recorded along the line of block.
- Nice examples of this are illustrated here in the publication from Tada and co-workers. In the left hand figure labeled incomplete block, you see the nice V-shaped activation of the lateral wall indicating fusion as the wave front comes down from E8,E7,E6 and up from the coronary sinus and E1, E2, and E3. On the right hand panel, after complete block is achieved, activation of the lateral wall is from high to low. The presence of double-potentials, there is also very instructive during pacing from either side of that region of block. In this case when there is incomplete block, you see that the two arrows under the ablation electrodes identify two potentials, which are separated by 94 milliseconds. Once block is achieved, these become more widely separated 132 milliseconds. This could be shown in the double-potentials separated by greater than 100 milliseconds is relatively specific for complete conduction block through the isthmus. The electrogram polarity of the signal recorded on the side opposite from the pacing site of the flutter line is also of interest. It can indicate conduction block. We see that when there is incomplete block the second potential labeled by the arrow at the ablation site is a QR kind of complex. After conduction block is achieved, the second potential develops more of an S-wave consistent with activation of by a wave front, which is traveling completely towards that site. Reversal of polarity of the potential on the side opposite the pacing site from the block is another marker of conduction block in the isthmus.
- This slide summarizes potential markers of conduction block in the common flutter isthmus. First, an increase in trans-isthmus conduction time with differential pacing so that after block is achieved, pacing on one side results in a long conduction time to the opposite side. If you move the pacing site a little bit further from the line of block, you will see that the conduction time to the opposite side decreases when you have block. This increases when there still slow conduction through the flutter isthmus. Secondly, double-potentials, as we discussed, with a relatively long interval of more than 100 to 110 milliseconds between the two potentials. We like to see this present along the entire ablation line. If we move our pacing site a little bit further from the line of block, then the conduction time from the pacing site to the potential generated by the wave front activates the distal side of the line becomes shorter and that to the proximal side becomes a little bit longer and the opposite occurs if there is still conduction through the isthmus. Thirdly, reversal of the electrogram polarity on the opposite side of the line of block, when block is achieve, and finally one can also look for changes in P-wave morphology when pacing in the low lateral right atrium on the free wall side of the line of block and these are all reviewed nicely in the references listed at the bottom of this slide. On a daily basis, we find that interpreting the double-potentials and simply doing differential pacing is quite useful. There are times where the double-potentials are not easily detectible in the common isthmus, particularly if you have had to do a lot of RF and you have low amplitude signals everywhere through the isthmus. Then it is useful to have some of these other markers to help confirm when you have conduction block.
- This slide diagrams one of the more common misleading findings that mimics failure to achieve conduction block and this is a Crista shunt. Typically, what happens is pacing from the coronary sinus you have conduction posterior to the inferior vena cava breaking through the Crista terminalis and activating that low lateral aspect of the flutter isthmus earlier than you anticipate if there is complete block. One sees activation in the low lateral right atrium a bit earlier than activation at the electrodes just superior to that. You think that you don’t have block. There are two ways to sort this out. One is you can pace from the coronary sinus and do a detailed activation map. However, that is somewhat time consuming. Another method described by Anselme and co-workers is in the references listed. Pacing from the posterior wall of the right atrium you may see conduction through the Crista terminalis. Pacing posterior to the coronary sinus on the posterior wall shortens the conduction time to the lateral right atrium. It would lengthen it if there is still slow conduction through the common flutter isthmus.
- This illustrates the importance of assessing conduction up and down across the flutter line. It is not unusual to have gaps in conduction. One may see widely split double-potentials at one end of the line and narrow double-potentials in these regions of gaps as illustrated. Additional RF applications may be required.
- There are a number of tools now available to try and create bigger lesions, which help facilitate achieving block in the common flutter isthmus. A saline irrigated ablation catheter cools the tip electrode allowing greater power delivery before maximal temperature is achieved. This catheter is approved for use in ventricular tachycardia. However, it has been studied for use in atrial flutter ablation. A catheter which is available in Europe, but investigational in the US, uses an external irrigation system with small holes in the end of the catheter. Saline flows out these holes. This has been used in atrial flutter. There is an improved 8 mm electrode catheter. This operates on the same principle as the irrigated catheters as in that large electrode tip is cooled by circulating blood. It allows for greater power delivery. These catheters can create conduction block in the common flutter isthmus with a smaller number of RF applications. They can facilitate the procedure.
- I would sound a note of caution. When ablating on the septal side of the isthmus, there is some risk of injuring AV conduction. The reason for this is not completely clear. It may be damage to the AV nodule artery or a catheter malposition, but it has been reported. Secondly, if you are in the orifice of the coronary sinus with one of these cool tip or large tip electrode catheters, there is some possibility of damage to the right coronary artery in that location. Therefore, when using a large tip catheter be very careful to apply our lesions outside of the coronary sinus. We prefer to be on the more lateral side of the flutter isthmus although that is a little bit wider region and may requires additional RF applications. In general, however, the efficacy is similar - ablating on either the septal side isthmus or the lateral side of the isthmus. The site is really selected by ease of catheter manipulation and avoiding any very high voltage areas that may indicate big thick pectinate muscles.
- These data from a nice study by Natale and co-workers really makes the point that catheter ablation should be first-line therapy for recurrent atrial flutter. They randomized treatment in sixty-one patients who had had recurrent atrial flutter and who had not failed prior antiarrhytmic drug therapy. Randomized treatments were antiarrhytmic drugs shown versus catheter ablation. During an average follow-up of twenty-two months, atrial flutter recurred in over ninety percent of the drug treated patients and almost two-thirds of them had atrial fibrillation. In contrast, atrial flutter recurred in only six percent of those treated with catheter ablation and fewer than a third had atrial fibrillation during follow-up. Eighty percent were in sinus rhythm at last follow-up. Complications of atrial flutter ablation are quite infrequent. They are often no more than minor groin hematomas. Many of our flutter ablations are performed as out-patient procedures. However, it is important to manage anticoagulation in a fashion similar to that which you would use for a cardioversion. If the patient is in atrial flutter at the time of the procedure, follow guidelines developed for anticoagulation of atrial fibrillation.
- These data from Hsieh et al demonstrates that atrial fibrillation is the biggest problem following flutter ablation. Patients who have had prior atrial fibrillation have a substantial risk of arrhythmia recurrence over the next couple of years, of fibrillation typically and not flutter. Patients who have not had fibrillation prior to ablation have a lower risk. However, with long follow-up, it is likely we are going to see more than twenty percent back with episodes of atrial fibrillation. In their study, recurrence of atrial flutter occurred in nine percent of patients during long-term follow-up.
- Now, as catheter ablation is becoming the first line treatment for atrial flutter, we are increasingly asked whether an arrhythmia that has a somewhat atypical appearance on the surface electrocardiogram is atrial flutter. In some cases, the only way to know is to do the electrophysiology study. So in this electrocardiogram is it flutter? Well, the P-waves are very small amplitude and are difficult to see. Certainly, the ventricular rate is organized and the activation sequence map of this arrhythmia on the insert panel shows an activation sequence consistent with clockwise flutter. Entrainment confirmed that indeed this was the case.
- Atypical electrocardiographic patterns are often seen when the atria are very diseased. Although the P-wave morphology may not be typical of an isthmus dependent flutter in someone who has had prior repair congenital heart disease or prior valve surgery, in fact isthmus dependent flutter is still the most common macro reentrant atrial arrhythmia that you will encounter in those patients. It is often worth a look at electrophysiologic study. It is important to keep an open mind in the approach to these patients. Some of the arrhythmias will be macro reentrant and non-isthmus dependent. They can still be ablated. Occasionally, one encounters a focal atrial tachycardia that mimics an activation sequence of common atrial flutter.
- This slide shows an electrocardiogram from a patient with prior ASD repair. The P-wave amplitude is very low, but you can see positive P-waves in II, III, and F. The rate is relatively slow. One might be suspicious on a focal atrial tachycardia.
- Intracardiac tracings confirm that indeed there is an atrial tachycardia. The activation sequence revealed a double-loop reentry circuit, as shown. The right atrium is seen from a right posterior oblique position here with wave-front circulating around to regions of scar. This is the most common location for scar related macro reentry - non-isthmus dependent following cardiac surgery.
- Our experience with these arrhythmias is summarized from our publication a few years ago by Etienne Delacretaz. In twenty patients with prior cardiac surgery for congenital heart disease, he identified forty-seven reentry circuits. The most common were isthmus dependent common flutters seen in eighteen and lateral wall circuits seen in nineteen cases. Septal reentry circuits were relatively infrequent. Left atrial circuits were also infrequent.
- Finally, atypical electrocardiographic appearances can also be left atrial flutter. Left atrial flutter is more difficult to ablate. The risk of approaching this arrhythmia are, of course, greater requiring left atrial access and more rigorous attention to anticoagulation. One can suspect you are dealing with a left atrial circuit when you find long post-pacing intervals (not at the tachycardia cycle length) in the right atrium. There are some P-wave clues as wel. These are summarized here in this nice article by Jais and colleagues in Circulation from 2000. A completely positive P-wave in V1 with atypical morphology for isthmus dependent flutter in the limb leads is often a clue that you are dealing with a left atrial flutter.
- In summary, you cannot reliably distinguish scar related or incisional macro reentry atrial tachycardias that are not isthmus dependent from those that are isthmus dependent based only on the electrocardiogram in many patients. Ablation of these arrhythmias is more difficult. They often are associated with multiple potential reentry circuits. It can be difficult to define a critical isthmus and to achieve block and an advanced mapping system is useful for guiding ablation in these patients. Employing these technologies success rates are improving in probably in the range of up to eighty percent or so, recurrences are more common than with isthmus dependent atrial flutters.
- In summary, catheter ablation in atrial flutter is an excellent first-line therapy for patients with recurrent isthmus dependent atrial flutter. It has excellent long-term efficacy and low risk. Atrial fibrillation occurs in twenty to thirty percent of patients during long-term follow-up, but this is usually somewhat easier to manage than the initial atrial flutter. Non-isthmus dependent flutter is occasionally encountered particularly in patients with prior atrial surgery and occasionally in patients with atrial scarring of unclear etiology and ablation of these is a bit more difficult.