Antonio Goicolea

Radiofrequency ablation of the inferior vena cava-tricuspid valve isthmus in common atrial flutter

Endocardial mapping has suggested that common atrial flutter (AF) is based on right atrial reentry surrounding the inferior vena cava (IVC). The isthmus between the IVC and the tricuspid valve (TV) appears essential to close the circuit. To test this hypothesis, radiofrequency was applied to the IVC-TV isthmus, with catheter electrodes, in 9 patients with AF. Mapping confirmed a right atrial circuit surrounding the IVC in all. In 4 patients another type of AF was induced that followed the circuit in the opposite direction. Radiofrequency interrupted AF in all patients. Multiple endocardial recordings showed that interruption was due to activation block at the point of application. Radiofrequency produced very brief or sustained, atrial fibrillation in 2 patients, which resulted in sinus rhythm. AF recurred in 4 patients with the same activation pattern and was interrupted again with radiofrequency in the IVC-TV isthmus in 3. AF was noninducible in 7 patients after 1 to 4 sessions. AF-free periods of 2 to 18 months without drugs were observed after radiofrequency, but 2 patients had paroxysmal atrial fibrillation. These results confirm that the IVC-TV isthmus is an essential part of the AF circuit. Ablation of this area may be of therapeutic value, but technical improvements are needed. Long-term efficacy of the procedure is uncertain.

Validation of double-spike electrograms as markers of conduction delay or block in atrial flutter☆

Recent mapping studies of atrial flutter have shown that fragmented electrograms can be found in most cases from the posterior, posteroseptal and posterolateral walls of the right atrium. The fragmentation pattern most often consists of a double spike. To further assess double-spike electrograms as a possible marker of conduction delay, bipolar electrograms were continuously recorded during atrial overdrive pacing of common flutter from the right atrium (7 patients) and from the proximal coronary sinus (5). Baseline double-spike separation of 50 to 130 ms was unchanged in 1 patient and slightly increased (5 to 25 ms) in 4 by coronary sinus pacing. The electrogram sequence was unchanged and the surface morphology was similar to that of basal flutter. Right atrial pacing decreased double-spike separation by 25 to 85 ms from basal values of 45 to 175 ms (23 to 83%), suggesting fusion in the area of fragmented electrograms. These findings suggest that double-spike electrograms represent activation on both sides of a conduction delay zone. The changes induced in these electrograms by pacing from the anterior right atrium and the coronary sinus are consistent with flutter circuits rotating counterclockwise (frontal plane) in the posterior right atrial wall in common atrial flutter.

Mechanisms of entrainment of human common flutter studied with multiple endocardial recordings.

BACKGROUND The mechanisms of common atrial flutter entrainment have not been directly studied in humans. METHODS AND RESULTS Endocardial mapping in six cases of common flutter showed large right atrial (RA) reentry circuits. Activation was craniocaudal in the anterolateral right atrium and caudocranial in the septum. The inferior vena cava-tricuspid isthmus (IVC-TV) closed the circuit. The high right atrium was paced at progressively shorter cycle lengths (CLs) in all, and the IVC-TV was paced in three cases. We recorded six to eight simultaneous RA electrograms from septum and anterior wall. Transient entrainment was recognized from all sites by capture of all electrograms at two or more paced CLs, with total or partial preservation of baseline flutter sequence and return to baseline after pacing. Antidromic circuit penetration was documented in five cases during high RA pacing and in one with IVC-TV pacing. Short CLs induced orthodromic conduction delays that resulted in a postpacing pause longer than basal flutter CL. ECG fusion with high RA pacing correlated poorly with antidromic septal penetration. This was related to overlap of orthodromic septal activation with anterior wall activation of the following cycle. Pacing disorganized flutter into a brief irregular rapid rhythm in two cases and atrial fibrillation in one case. In two cases, complete antidromic septal penetration led to sudden flutter interruption, and in another case it led to circuit inversion. CONCLUSIONS Direct recordings confirm orthodromic and antidromic penetration of flutter circuits by high and low RA pacing. Short CLs modify the circuit. Disorganization is the most common mode of flutter interruption.

Atypical flutter: a review.

Understanding of typical flutter circuits led the way to the study of other forms of macroreentrant tachycardias of the atria, and to their treatment by catheter ablation. It has become evident that the ECG classification of atrial flutter and atrial tachycardia by a rate cutoff and the presence or absence of isoelectric baselines between atrial deflections is not a valid indicator of tachycardia mechanism. Macroreentrant circuits where activation rotates around large obstacles are the most common arrhythmias found in patients with atypical forms of flutter or atrial tachycardia, especially after surgery for congenital heart disease, however, focal mechanisms can also be found. Large areas of low voltage electrograms, suggestive of severe myocardial damage (fibrosis or infiltration) can be found in many atypical macroreentrant tachycardias at the center of the circuit. Many of these circuits can be mapped precisely, critical isthmuses can be defined, and effective catheter ablation can be performed. The need to match activation maps with anatomy precisely, makes computer assisted, anatomically precise mapping a useful tool. Entrainment techniques have to be used sparingly to avoid tachycardia interruption. In complex cases, ablation can be done in sinus rhythm, after definition of conducting channels between low voltage areas and scars or anatomic obstacles. Long‐term prognosis is uncertain and depends on the underlying pathology. (PACE 2003; 26:2157–2169)

Catheter Ablation of Atrial Flutter Circuits

Atrial flutter (AF) mapping has shown circular activation in the right atrium (RA), wilh a “counterclockwise” rotation in a frontal view. The myocardial isthmus between the inferior vena cava and the tricuspid valve (IVC‐T) closes the activation circuit in its caudal end. The reproducibility of this activafion pattern, and the fact that some “rare” AF with a “clockwise” rotation of activation use the same circuit, suggests that reentry is greatly facilitated by the anatomical arrangement of the caudal end of the RA. This suggested that ablation of the IVC‐T isthmus may interrupt AF and prevent its recurrence. We have applied radiofrequency (RF) current to the IVC‐T isthmus in nine patients, producing sudden interruption of activation at this point in five (all those treated with large surface electrode catheters). in three others, RF produced acceleration or disorganization, leading to interruption. Preliminary follow‐up data suggest a favorable effect on AF recurrence, either by preventing it, or by making antiarrhythmic drugs effective.

Ablación de flúter auricular. Resultados a largo plazo tras 8 años de experiencia

Objetivo Desde su invencion, a principios de los anos 90, la ablacion con radiofrecuencia del fluter auricular ha evolucionado en sus metodos y resultados. Hemos estudiado la evolucion de 62 pacientes con fluter, tratado con ablacion con radiofrecuencia entre 1990 y 1997. Pacientes y metodos Cincuenta varones y 12 mujeres de 22-78 anos de edad (57 ± 12). El fluter, recurrente tras cardioversion y farmacos antiarritmicos, era tipico (comun) en 59 casos y de giro invertido (horario) en 3. En 14 no habia cardiopatia, 10 tenian bronconeumopatia, 9 enfermedad coronaria, 6 miocardiopatias y el resto otros procesos. En 5 casos con antecedentes de cirugia cardiaca, se trato ademas una taquicardia por reentrada en torno a la atriotomia auricular derecha. La ablacion con radiofrecuencia se hizo en el istmo cavotricuspideo en el fluter tipico o invertido y en otro istmo entre la cicatriz en la auricula derecha lateral y la cava inferior, en las taquicardias por atriotomia. Los 24 casos hasta 1995 forman el grupo 1. A partir de 1995 se trataron 38 pacientes (grupo 2), con cateteres especiales e intentando bloquear el istmo cavotricuspideo. Resultados La ablacion con radiofrecuencia interrumpio el fluter en 61 de 62 casos (98,4%) y la taquicardia por cicatriz en los 5. El numero de aplicaciones en el grupo 1 fue 18,6 ± 10,1 frente a 12 ± 10 en el grupo 2 (p Conclusiones La ablacion con radiofrecuencia es un tratamiento eficaz del fluter y la taquicardia por atriotomia. Avances en la metodologia han mejorado significativamente los resultados. La fibrilacion auricular puede ser un problema en un 20-25% de los pacientes tras el control del fluter.

Intracardiac Coiling of Permanent Atrial Leads

We have observed intracardiac movement of permanently implanted atrial pacing leads in two patients with AAI pacemakers. This resulted in looping of the lead body into (he right atrium and ventricle, without displacement of the tip or changes in the pacing or sensing thresholds. At surgery only a single fixation ligature was found and allowed sliding of the lead through the suture sheath, in both cases. The position was corrected by gently pulling the lead. Multiple ligature fixation may avoid this complication.