Atrial activation mapping in sinus rhythm in the clinical electrophysiology laboratory: observations during Bachmann's bundle block.

INTRODUCTION: The high posterolateral right atrium (RA) is considered the "sinus node area," but we lack information on endocardial atrial activation in sinus rhythm. We studied RA and left atrial (LA) endocardial activation in the electrophysiology laboratory. METHODS AND RESULTS: Thirty-five patients (21 men) aged 47 +/- 16.4 years (mean +/- SD) underwent RA mapping (22.2 +/- 3.8 points). In 21 patients, LA activation was mapped (11.1 +/- 3.9 points) through the coronary sinus (CS), right pulmonary artery, and/or a patent oval foramen. Fourteen patients had atrial arrhythmias, and 3 an ECG pattern of Bachmann's bundle block. Endocardial RA activation preceded P wave in 5 (-14 +/- 4.2 ms), coincided in 11, and followed P onset in 18 (16.7 +/- 6.6 ms). Location of the zero point varied from the superior vena cava to the low RA and from lateral to paraseptal RA. In 19 patients, activation started simultaneously in 2 to 5 points located >or=1 cm apart. RA activation was descending in most, but in 3 with low onset there was collision in the anterior and septal walls. In 15 of 21 patients, descending LA activation dominated, ending in the mid CS in 12, proximal CS in 1, and simultaneously throughout the CS in 2. In 3 with Bachmann's bundle block, CS activation was ascending and in 2 double potentials were recorded from the LA roof. CONCLUSION: During stable sinus rhythm, RA activation can start in different areas or simultaneously over large areas resulting in different activation patterns, both in the RA and the LA. LA activation is predominantly descending, but in Bachmann's bundle block it becomes ascending, and double potentials suggest a location of block in the LA roof.

[Electrophysiological and clinical characterization of left atrial macroreentrant tachycardia]. / Caracterización electrofisiológica y clínica de la taquicardia macrorreentrante auricular izquierda.

BACKGROUND AND OBJECTIVE: We are reporting the characteristics of 9 patients with left atrial macroreentrant tachycardia, an arrhythmia not well studied in man. PATIENTS AND METHOD: Mean age was 60 years and 7 were men. Tachycardia was spontaneous in 6 and induced in 3. Two had no heart disease, 2 sick sinus syndrome, 3 aortic prosthesis, 2 hypertension, 1 cardiomyopathy and 1 chronic bronchitis. Simultaneous recordings from right atrial, coronary sinus and right pulmonary artery were obtained at baseline and with atrial pacing. Macroreentrant tachycardia was diagnosed when entrainment with fusion was documented. RESULTS: Cycle length was 230-440 ms (287 67). The ECG showed atypical flutter in 3 patients and P waves with flat baseline in 6. Coronary sinus activation was distal to proximal in 7. Right atrial activation was circular in 3 with previous typical flutter ablation. Entrainment from the right atrium produced long return cycles in the right atrial recordings, but equal to basal tachycardic cycle in coronary sinus recordings. Entrainment from the coronary sinus produced local return cycles equal to basal cycle in 8 and prolonged in 1. After stimulation, 4 recovered sinus rhythm, 4 went to atrial fibrillation and 1 had no change. After a follow-up of 9-19 months 5 remain in sinus rhythm treated with antiarrhythmic drugs and/or atrial pacing. CONCLUSIONS: Left atrial macroreentrant tachycardia is associated with organic heart disease. The ECG most frequent pattern tends to show P waves with flat baseline at a relatively slow rate. Most circuits turn clockwise in anterior view. Atrial stimulation is not very effective for cardioversion to sinus rhythm. The prognosis of long term rhythm is uncertain.

Caracterización electrofisiológica y clínica de la taquicardia macrorreentrante auricular izquierda / Electrophysiological and Clinical Characterization of Left Atrial Macroreentrant Tachycardia

Introducción y objetivos. Describimos las características de 9 pacientes con taquicardia macrorreentrante auricular izquierda, un tipo mal conocido de arritmia. Pacientes y método. La edad media de los pacientes era 60 años y siete eran varones. La taquicardia fue espontánea en 6 casos e inducida en tres. En 2 enfermos no había cardiopatía, tres tenían una prótesis aórtica, dos disfunción sinusal, dos hipertensión arterial, uno miocardiopatía dilatada y uno bronquitis crónica. Se obtuvieron registros simultáneos de la aurícula derecha, el seno coronario y la arteria pulmonar derecha. Se diagnosticó taquicardia macrorreentrante en presencia de encarrilamiento con fusión en los registros endocavitarios. Resultados. La longitud de ciclo era 230-440 ms (287 ñ 67) y el patrón de ECG de aleteo era atípico en 3 pacientes y onda P con línea isoeléctrica en seis. El seno coronario se activaba de distal a proximal en 7 casos. La activación de la aurícula derecha era circular en 3 enfermos con ablación previa de aleteo típico. El encarrilamiento desde la aurícula derecha puso de manifiesto pausas de retorno largas en los registros de la aurícula derecha e iguales al ciclo de la taquicardia en el seno coronario. El encarrilamiento desde el seno coronario evidenció una pausa local igual al ciclo basal en 8 pacientes y prolongada en uno. Con la estimulación, 4 enfermos pasaron a ritmo sinusal, cuatro a fibrilación auricular y uno no cambió. Un total de 5 pacientes se mantuvieron en ritmo sinusal entre 9-19 meses con fármacos antiarrítmicos y/o estimulación auricular. Conclusiones. La taquicardia macrorreentrante auricular izquierda se asocia a cardiopatía. El patrón más frecuente es de onda P con línea isoeléctrica y frecuencia relativamente lenta. La mayoría giran en sentido 'horario' en visión anterior. La estimulación es poco eficaz para restablecer el ritmo sinusal. El pronóstico del ritmo a largo plazo es incierto (AU)