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(Circulation. 2004;109:e205-e206.)
© 2004 American Heart Association, Inc.

Images in Cardiovascular Medicine

Life-Threatening Neonatal Arrhythmia

Successful Treatment and Confirmation of Clinically Suspected Extreme Long QT-Syndrome-3

Hans-Gerd Kehl, MD; Wilhelm Haverkamp, MD; Georg Rellensmann, MD; T. Mesud Yelbuz, MD; Thomas Krasemann, MD; Johannes Vogt, MD; Eric Schulze-Bahr, MD

From the Department of Pediatric Cardiology, University Children’s Hospital (H.-G.K., G.R., T.M.Y., T.K., J.V.); the Department of Cardiology and Angiology, University Hospital of Münster (W.H., E.S.-B.); and the Institute for Arteriosclerosis Research, Molecular Cardiology, University of Münster (E.S.-B.), Münster, Germany.

Correspondence to Hans-Gerd Kehl, MD, Department of Pediatric Cardiology, University Children’s Hospital, Münster, Albert Schweitzer Str. 33, D-48149 Münster, Germany. E-mail kehl{at}uni-muenster.de

Here, we demonstrate the electrophysiological findings for a preterm baby who was referred to our center for therapy of persistent complex arrhythmia with heart rate (HR) varying between 60 and 300 bpm. The ECG showed polymorphic ventricular tachycardia (HR 280 bpm), including short runs of torsade de pointes alternating within a few seconds with bradycardia due to third-grade atrioventricular (AV) block (HR 78 bpm, atrial rate 135 bpm), together with broad QRS complexes of 90 ms^1/2 (Figure 1 and Data Supplement). During bradycardia, an extreme prolongation of the normalized QT interval (QTc 760 ms^1/2) was present (Figure 2). To control tachycardia, treatment with propranolol was given intravenously, resulting in a predominant 2:1 AV block (HR 68 bpm) and fewer episodes of nonsustained ventricular tachycardia (Figure 3 and Data Supplement), although QTc remained unchanged (740 ms^1/2). Because of the persisting unstable hemodynamic condition, the extreme QTc prolongation combined with AV block, and the QRS and T-wave morphology, a sporadic defect in the Na⁺Ch-encoding SCN5A gene was suspected. Thus, an additional treatment with the Na⁺Ch blocker mexiletine was initiated. With this medication, sinus rhythm occurred within 90 minutes. Furthermore, within 3 hours, a significant improvement of QTc (760 to 480 ms^1/2) and of the intraventricular conduction delay (QRS 90 to 50 ms^1/2) occurred (Figure 4). Genetic examination of the child confirmed the suspected long-QT syndrome-3 with proof of a de novo SCN5A gene defect (P1332L) close to the central opening of the Na⁺ channel.

View larger version (12K): [in this window] [in a new window]   Figure 1. Six-lead ECG of a hemodynamically compromised preterm baby showing polymorphic ventricular tachycardia with a torsade de pointes pattern coupled with bradycardic episodes.

View larger version (14K): [in this window] [in a new window]   Figure 2. Six-lead ECG of the same patient during a bradycardic episode in which extreme prolongation of QT interval (as long as 760 ms1/2) is detectable. The third-grade AV block (HR 78 bpm, atrial rate 135 bpm) is due to the ventricular refractoriness. Polymorphic QRS complexes resulting from variant intraventricular conduction delays lead to different QRS durations up to 90 ms1/2.

View larger version (10K): [in this window] [in a new window]   Figure 3. Monitor recording of a single-lead ECG of the baby after administration of propanolol showing a predominant 2:1 AV block (HR 68 bpm) by which the QT interval remains unchanged (740 ms1/2).

View larger version (15K): [in this window] [in a new window]   Figure 4. Six-lead ECG of the same patient after administration of mexiletine. A, Acute response after 90 minutes showing a significant reduction in QT duration with shortening of the ventricular refractoriness, allowing the establishment of a regular sinus rhythm. Note the fusion of T and the consecutive P wave and the monomorphic QRS complexes (50 ms1/2). B, Follow-up ECG tracing recorded after 15 months of therapy. Note further reduction in QT duration, which could be achieved only with a high-dose treatment of mexiletine (16 mg/kg per day in 3 doses).

Our ECG tracings and the child’s clinical course (further details are given in the Data Supplement) confirmed the concept that the Na⁺Ch blocker mexiletine is capable of shortening the prolonged ventricular refractoriness below the P-P interval in extreme long-QT syndrome-3 with life-threatening arrhythmia.

Footnotes

Movies I and II are available in the online-only Data Supplement at http://www.circulationaha.org.

The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.

Circulation encourages readers to submit cardiovascular images to the Circulation Editorial Office, St Luke’s Episcopal Hospital/Texas Heart Institute, 6720 Bertner Ave, MC1-267, Houston, TX 77030.

(Circulation. 2004;109:e205-e206.)

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This Article Full Text (PDF) Data Supplement Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kehl, H.-G. Articles by Schulze-Bahr, E. Search for Related Content PubMed PubMed Citation Articles by Kehl, H.-G. Articles by Schulze-Bahr, E. Related Collections Electrophysiology Clinical genetics Cardiovascular Pharmacology Electrocardiology CPR and emergency cardiac care Arrhythmias, clinical electrophysiology, drugs