The repolarization-excitability relationship in the human right atrium is unaffected by cycle length, recording site and prior arrhythmias
Frank Bode, MD*  ,
Michael Kilborn, MD*,
Pamela Karasik, MD, FACC* and
Michael R. Franz, MD, PhD, FACC*
* Veteran Affairs Medical Center and Georgetown University, Washington, DC, USA
Medizinische Klinik II, Universitaetsklinikum, Luebeck, Germany
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Figure 1 Simultaneous measurement of effective refractory period (ERP) and action potential duration at 70% repolarization (APD70) and 90% repolarization (APD90) with the combination catheter. S1 and S2 denote the basic and extrastimulus artifacts. Repolarization levels (n%) at which extrastimuli are superimposed onto the preceding repolarization phase are visualized.
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Figure 2 Ratio between effective refractory period (ERP) and action potential duration at 70% (APD70) and 90% repolarization (APD90) at different right atrial sites. Ratios exhibited no significant site-specific differences.
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Figure 3 (A) Correlation between effective refractory period (ERP) and action potential duration at 70% repolarization (APD70) and (B) between ERP and action potential duration at 90% repolarization (APD90). Measurements were obtained at 12 different right atrial sites and different steady state cycle lengths in nine patients.
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Figure 4 Ratio between effective refractory period (ERP) and action potential duration at 70% (APD70) and 90% repolarization (APD90) as a function of basic cycle length (BCL). Ratios showed no significant cycle length-dependent changes.
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