Lidocaine-sensitive atrial tachycardia
Lidocaine-sensitive, rate-related, repetitive atrial tachycardia: a new arrhythmogenic syndrome
Pablo A. Chiale, MDa,
D. Alejandro Franco, MDa,
Horacio O. Selva, MDa,
Claudio A. Militello, MDa and
Marcelo V. Elizari, MD, FACCa
a Division of Cardiology, Ramos Mejía Hospital and Instituto Sacre Coeur, Buenos Aires, Argentina
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Figure 1 (A) Short runs of self-limited uniform atrial tachycardia recorded at rest in an asymptomatic 60-year-old man. Note that the atrial ectopic salvos are separated by sinus node pauses of 1010 ms. (B) Relationship between atrial ectopic activity and sinus node cycle length. After a mild exercise, with sinus node cycle lengths between 630 and 670 ms, no ectopic atrial beats are recorded. A slight increase of the sinus node cycle length to 680 ms causes the appearance of a single premature atrial beat. Post-extrasystolic sinus node pauses of 750 and 810 ms are also followed by single atrial extrasystoles (arrows), while a slightly longer pause (830 ms) triggers repetitive atrial discharges.
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Figure 2 Relationship between atrial ectopic activity and sinus node cycle length, as assessed in a baseline 24-h electrocardiogram Holter monitoring. The R-R interval trend graph (top) of time intervals selected from the continuous electrocardiogram recording shows that when the sinus node cycle length is short, or relatively short, no ectopic atrial premature impulses occur (left). A slight increase of sinus node cycle length (left arrow) is enough to trigger single (panel A) or repetitive (panel B) atrial premature impulses. This causes wide variations in the R-R intervals, with an apparent predominance of short (corresponding to atrial premature impulses) over long R-R intervals (corresponding to sinus node pauses following single or repetitive atrial impulses), which is denoted by the different densities of the superior and inferior lines in the graph. The right arrow indicates the disappearance of the arrhythmia, which occurs simultaneously with a critical shortening of sinus node cycle length. The arrhythmia is also absent when the sinus node rate slows down (right), during night sleep (panel C).
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Figure 3 The two different patterns of repetitive atrial tachycardia identified in the eight patients according to the behavior of ectopic atrial cycle length. Panels A and B are representative of the pattern observed in seven patients. The first atrial tachycardia cycle length is relatively long; the second is the shortest, and after that a gradual lengthening of the cycle length occurs until the end of the salvos. Panel C shows the erratic atrial tachycardia cycle length observed in only one patient. HRA = high right atrium electrogram.
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Figure 4 (A) Repetitive runs of atrial tachycardia observed at baseline in case 2. (B) Suppression of the arrhythmia by atrial pacing (A.P.) at a cycle length (C.L.) of 550 ms, which is longer than that of the atrial tachycardia. Note that a prolongation of only 10 ms in the paced atrial cycle length led to the reappearance of single and brief runs of ectopic atrial discharges (arrows). HRA = high right atrium electrogram.
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Figure 5 Suppression of repetitive atrial tachycardia by intravenous lidocaine in the same patient as in Figure 4. A small dose of the drug caused a progressive abbreviation of the salvos and, finally, restoration of normal sinus node rhythm (S.R.). The suppression of the arrhythmia was not the result of an increment of the sinus node rate, which is slower (97 beats/min) than the critical atrial rate (109 beats/min) required to eliminate the arrhythmia in Figure 4B. HRA = high right atrium electrogram.
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