The Mechanism of Pause-Induced Torsade de Pointes in Long QT Syndrome

Jinqiu Liu, M.D.; Kenneth R. Laurita, Ph.D.

Disclosures

J Cardiovasc Electrophysiol. 2005;16(9):981-987. 

In This Article

Conclusion

In the present study, we found that the pause associated with a short-long cycle length sequence significantly increased mean APD and dispersion of repolarization under conditions of LQT2 and LQT3, but not control. In addition, enhanced local repolarization gradients were causally related to the occurrence of unidirectional block. Spontaneous EADs, EAD-induced triggered activity were only observed under condition of LQT3 and occurred more frequently following a pause. Interestingly, the breakthrough site of triggered activity always occurred where local repolarization gradients were largest, not where APD was longest or shortest. As a result, unidirectional block occurred against the repolarization gradient (towards longest APD). These data suggest that the pause associated with a short-long cycle length sequence promotes EAD-induced triggered activity and large repolarization gradients caused by M-cells.

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