Using Electrocardiographic Activation Time and Diastolic Intervals to Separate Focal From Macro–Re-Entrant Atrial Tachycardias
Jason P. Brown, MD,
David E. Krummen, MD,
Gregory K. Feld, MD, FACC and
Sanjiv M. Narayan, MB, MD, FACC*
University of California and Veterans Administration Medical Centers, San Diego, California.
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Figure 1 Identifying Tachycardia P or F Waves From Underlying ECG T Waves
The top panel shows sinus rhythm, and the lower panel tachycardia in the same patient. The RR and QT intervals are identified in each. Linear scaling from the sinus beat (top) was used to generate an "expected" T-wave at the tachycardia RR. This was compared to the actual tachycardia T-wave with superimposed P waves. The first derivative (dV/dt), shown for the X-lead, helped identify P (or F)-wave onset and offset (vertical arrows). Here, P-wave duration (3-axis mean) = 129 ± 17 ms. AT = atrial tachycardia; CL = cycle length; ECG = electrocardiogram.
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Figure 2 Quantifying ECG CL for Focal AT (Right Atrial) and Macro–Re-Entrant AT (Lower Loop Re-Entry)
Panels show (A) focal AT and (B) macro–re-entrant AT. (I) For each tachycardia, leads X (V5), Y (aVF), and Z (V1). The selected template was cross-correlated successively to the ECG to yield a correlation time series for each axis as shown. (II) Autocorrelation, or correlation of the series to itself with successive time-shifts. The first peak of the autocorrelation function indicates the time-shift required to bring the signal "back into phase." It thus estimates the CL, which was 258 versus 262 ms measured for the focal AT in (A) and 236 versus 239 ms measured for macro–re-entry in (B). (III) Spectral CL estimates were accurate for focal AT in (A) 3.78 Hz (=265 ms), but not for (B) macro–re-entry, 5.49 Hz (=182 ms). Abbreviations as in Figure 1.
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Figure 3 High-Resolution Mapping Confirms Atrial Activation Time
(A) Focal AT (lateral RA). The ECG dV/dt estimated P-wave duration is 127 ms; mapped atrial activation is 125 ms. The ECG autocorrelation CL (284 ms) closely estimated measured CL (274 ms). (B) Lower loop macro–re-entrant AT (same patient as in Fig. 2B). The ECG dV/dt-estimated F-wave duration is 171 ms and mapped atrial activation is 181 ms; ECG autocorrelation CL is 236 ms versus measured CL 239 ms (Fig. 2B). Abbreviations as in Figure 1.
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Figure 4 Training Study: ROC of P(F) Wave Duration for Focal AT
(A) X, (B) Y, (C) Z and (D) 3-axis mean, showing optimal cutpoint <160 ms. ROC = receiver-operating characteristic; other abbreviations as in Figure 1.
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Figure 5 Training Study: ROC of P(F) Wave Duration: CL Ratio for Focal AT
(A) X, (B) Y, (C) Z, and (D) 3-axis mean, showing optimal cutpoint <45%. Abbreviations as in Figures 1 and 4.
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Figure 6 Examples of AT and Macro–Re-Entrant AT
(A) Focal AT with P-wave durations of 72, 60, and 79 ms (X, Y, and Z axes, respectively) that were 20%, 17%, and 22% of actual CL 357 ms (estimated 358 ms); (B) focal AT with P-wave duration 125 ms (3-axis mean), 38% of CL 330 ms (estimated 323 ms); (C) macro–re-entrant AT with F-wave duration 237 ms (mean), 90% of CL 262 ms (estimated 258 ms); (D) macro–re-entrant AT with F-wave duration 224 ms (mean), 84% of CL 267 ms (estimated 270 ms). Abbreviations as in Figures 1 and 2.
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