- Email: [email protected]
To The Editor—Response
120
7. 8.
Heart Rhythm, Vol 4, No 1, January 2007
trode study of the genesis of the monophasic action potential by contact electrode technique. J Cardiovasc Electrophysiol Dec 2002;13:1246 –1252. Olsson B, Varnauskas E, Korsgren M. Further improved method for measuring monophasic action potentials of the intact human heart. J Electrocardiol 1971;4:19–23. Holland RP, Arnsdorf MF. Solid angle theory and the electrocardiogram: physiologic and quantitative interpretations. Prog Cardiovasc Dis May-Jun 1977;19:431– 457.
To the Editor: In the August 2006 issue of Heart Rhythm, Undavia et al1 reported a nice case of swallowing-induced atrial tachycardia with successful radiofrequency ablation of an ectopic focus in right atrium. An in-depth review of the literature with all published case reports since 1925 was presented, and possible mechanisms of this rare form of tachycardia were discussed. We found in our paper files a case published some years ago with many interesting aspects.2 Briefly, a young female had palpitations while eating frozen yogurt and then experienced severe dizziness. ECG revealed atrial fibrillation with extremely rapid ventricular response related to preexcitation, finally requiring electrical cardioversion. Radiofrequency ablation of the bypass tract was performed. This case highlights that swallowing-induced atrial tachycardia may also reveal Wolff-Parkinson-White syndrome and in some cases may be associated with a high risk for sudden death. It suggests that vagal modulation may depend on the mode and type of swallowing, as the patient typically experienced symptoms while eating ice products. It also suggests that education may play a role in preventing recurrences in some cases if patients avoid fast and/or extremely cold swallowing. Of interest, the fact that the other case, which was published in a well-known journal, was not cited by Undavia et al probably is related to suboptimal indexing of the article. A MEDLINE search using the term “swallow” did not find this brief report published in 1994. Thus, use of appropriate rather than provocative words in the title and/or keywords is mandatory if investigators wish others to benefit from an interesting experience. Laurent Fauchier, MD, PhD [email protected] Dominique Babuty, MD, PhD Service de Cardiologie B et Laboratoire d’électrophysiologie Cardiaque Centre Hospitalier Universitaire Trousseau Tours, France
References 1. 2.
Undavia M, Sinha S, Mehta D. Radiofrequency ablation of swallowing-induced atrial tachycardia: case report and review of literature. Heart Rhythm 2006;3:971–974. Brodsky MA, Orlov MV, Allen BJ, Selvan A. Frozen yogurt near deep-freeze. Am J Cardiol 1994;73:617– 618.
To the Editor—Response: We thank Drs. Fauchier and Babuty for sharing another case of supraventricular tachycardia induced by the act of swallowing. After reviewing the case published,1 several im-
portant details that would confirm this diagnosis appear to be missing, most importantly, consistent reproducibility of the symptoms either by history or by use of Holter or event monitoring. We find the case to be a straightforward atrioventricular reentrant tachycardia probably triggered by a swallowing-induced atrial premature complex. Furthermore, details of the electrophysiologic study seem to be focused primarily on the presence of a right-sided bypass tract rather than induction of the tachycardia by swallowing-induced atrial premature complexes. On the contrary, patients in our case series had atrial tachyarrhythmia that was reproducibly induced by swallowing. Indeed, it is likely that the event described was triggered by a swallowing-mediated vagal reflex. We agree with the comment that scientific and article focused titles and key words should be used rather than provocative terms, thereby facilitating a more thorough literature search. Manish Undavia, MD [email protected] Davendra Mehta, MD, PhD Mount Sinai Medical Center New York, New York
Reference 1.
Brodsky MA, Orlov MV, Allen BJ, Selvan A. Frozen yogurt near deep-freeze. Am J Cardiol 1994;73:617– 618.
To the Editor: Coronel et al. reported in their recent article that there was a significant correlation between monophasic action potential (MAP) durations and activation-recovery intervals (ARIs) determined at the maximum positive slope of the positive T wave (conventional method).1 The authors acknowledged that significant correlation has also been demonstrated between MAP durations and ARIs determined at the negative slope of the positive T wave (alternative method) in other studies.2– 4 However, the authors had not directly compared the conventional and alternative methods of estimating ARIs at the same sites in their experiments. A possible explanation for the discrepancy in results is that MAP durations were measured at the steepest part of phase 3 in this study,1 and at MAP90% in other studies.2– 4 In figure 6A of Coronel et al’s study, the positive slope of the negative T wave would approximate with MAP90% (right panel), as would the negative slope of the positive T wave with the corresponding MAP (left panel), but the maximum dV/dt of the upslope of the positive T wave would only be approximately coincidental with MAP50%. Furthermore in Figure 7, the maximum dV/dt of the T wave upslope would correspond with the peak minimum and not the end of the Laplacian repolarization signal, suggesting that determination of ARI at the maximum dV/dt of the T wave would underestimate local repolarization by about 30 ms. We have shown by using Bland-Altman statistics that the conventional approach underestimates repolarization determination for the positive T wave compared with the alternative approach.2 This difference is significantly more pro-
7. 8.
Heart Rhythm, Vol 4, No 1, January 2007
trode study of the genesis of the monophasic action potential by contact electrode technique. J Cardiovasc Electrophysiol Dec 2002;13:1246 –1252. Olsson B, Varnauskas E, Korsgren M. Further improved method for measuring monophasic action potentials of the intact human heart. J Electrocardiol 1971;4:19–23. Holland RP, Arnsdorf MF. Solid angle theory and the electrocardiogram: physiologic and quantitative interpretations. Prog Cardiovasc Dis May-Jun 1977;19:431– 457.
To the Editor: In the August 2006 issue of Heart Rhythm, Undavia et al1 reported a nice case of swallowing-induced atrial tachycardia with successful radiofrequency ablation of an ectopic focus in right atrium. An in-depth review of the literature with all published case reports since 1925 was presented, and possible mechanisms of this rare form of tachycardia were discussed. We found in our paper files a case published some years ago with many interesting aspects.2 Briefly, a young female had palpitations while eating frozen yogurt and then experienced severe dizziness. ECG revealed atrial fibrillation with extremely rapid ventricular response related to preexcitation, finally requiring electrical cardioversion. Radiofrequency ablation of the bypass tract was performed. This case highlights that swallowing-induced atrial tachycardia may also reveal Wolff-Parkinson-White syndrome and in some cases may be associated with a high risk for sudden death. It suggests that vagal modulation may depend on the mode and type of swallowing, as the patient typically experienced symptoms while eating ice products. It also suggests that education may play a role in preventing recurrences in some cases if patients avoid fast and/or extremely cold swallowing. Of interest, the fact that the other case, which was published in a well-known journal, was not cited by Undavia et al probably is related to suboptimal indexing of the article. A MEDLINE search using the term “swallow” did not find this brief report published in 1994. Thus, use of appropriate rather than provocative words in the title and/or keywords is mandatory if investigators wish others to benefit from an interesting experience. Laurent Fauchier, MD, PhD [email protected] Dominique Babuty, MD, PhD Service de Cardiologie B et Laboratoire d’électrophysiologie Cardiaque Centre Hospitalier Universitaire Trousseau Tours, France
References 1. 2.
Undavia M, Sinha S, Mehta D. Radiofrequency ablation of swallowing-induced atrial tachycardia: case report and review of literature. Heart Rhythm 2006;3:971–974. Brodsky MA, Orlov MV, Allen BJ, Selvan A. Frozen yogurt near deep-freeze. Am J Cardiol 1994;73:617– 618.
To the Editor—Response: We thank Drs. Fauchier and Babuty for sharing another case of supraventricular tachycardia induced by the act of swallowing. After reviewing the case published,1 several im-
portant details that would confirm this diagnosis appear to be missing, most importantly, consistent reproducibility of the symptoms either by history or by use of Holter or event monitoring. We find the case to be a straightforward atrioventricular reentrant tachycardia probably triggered by a swallowing-induced atrial premature complex. Furthermore, details of the electrophysiologic study seem to be focused primarily on the presence of a right-sided bypass tract rather than induction of the tachycardia by swallowing-induced atrial premature complexes. On the contrary, patients in our case series had atrial tachyarrhythmia that was reproducibly induced by swallowing. Indeed, it is likely that the event described was triggered by a swallowing-mediated vagal reflex. We agree with the comment that scientific and article focused titles and key words should be used rather than provocative terms, thereby facilitating a more thorough literature search. Manish Undavia, MD [email protected] Davendra Mehta, MD, PhD Mount Sinai Medical Center New York, New York
Reference 1.
Brodsky MA, Orlov MV, Allen BJ, Selvan A. Frozen yogurt near deep-freeze. Am J Cardiol 1994;73:617– 618.
To the Editor: Coronel et al. reported in their recent article that there was a significant correlation between monophasic action potential (MAP) durations and activation-recovery intervals (ARIs) determined at the maximum positive slope of the positive T wave (conventional method).1 The authors acknowledged that significant correlation has also been demonstrated between MAP durations and ARIs determined at the negative slope of the positive T wave (alternative method) in other studies.2– 4 However, the authors had not directly compared the conventional and alternative methods of estimating ARIs at the same sites in their experiments. A possible explanation for the discrepancy in results is that MAP durations were measured at the steepest part of phase 3 in this study,1 and at MAP90% in other studies.2– 4 In figure 6A of Coronel et al’s study, the positive slope of the negative T wave would approximate with MAP90% (right panel), as would the negative slope of the positive T wave with the corresponding MAP (left panel), but the maximum dV/dt of the upslope of the positive T wave would only be approximately coincidental with MAP50%. Furthermore in Figure 7, the maximum dV/dt of the T wave upslope would correspond with the peak minimum and not the end of the Laplacian repolarization signal, suggesting that determination of ARI at the maximum dV/dt of the T wave would underestimate local repolarization by about 30 ms. We have shown by using Bland-Altman statistics that the conventional approach underestimates repolarization determination for the positive T wave compared with the alternative approach.2 This difference is significantly more pro-