Sympathetic stimulation produces a greater increase in both transmural and spatial dispersion of repolarization in LQT1 than LQT2 forms of congenital long QT syndrome
Yasuko Tanabe, MD*,
Masashi Inagaki, MD ,
Takashi Kurita, MD*,
Noritoshi Nagaya, MD*,
Atsushi Taguchi, MD*,
Kazuhiro Suyama, MD, PhD*,
Naohiko Aihara, MD*,
Shiro Kamakura, MD, PhD*,
Kenji Sunagawa, MD, PhD,
Kazufumi Nakamura, MD, PhD ,
Tohru Ohe, MD, PhD, FACC,
Jeffrey A. Towbin, MD ,
Silvia G. Priori, MD, PhD|| and
Wataru Shimizu, MD, PhD*
* Division of Cardiology, Department of Internal Medicine, National Cardiovascular Center, Suita, Japan
Department of Cardiovascular Dynamics, National Cardiovascular Center, Suita, Japan
Department of Cardiovascular Medicine, Okayama University Medical School, Okayama, Japan
Department of Pediatrics (Cardiology), Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
|| Molecular Cardiology, Salvatore Maugeri Foundation, Pavia, Italy
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Figure 1 Twenty-four-lead ECGs (G–K: 2–6) that are expected to reflect the potential from the left ventricular free wall under baseline condition (A) and during epinephrine infusion (B) in a patient (pt) with LQT1 syndrome. A representative ECG (H4) is shown on the upper trace in each panel. The ECGs showed broad-based T waves commonly observed in LQT1 patients. Both the QTc-e and QTc-p were prolonged (603, 482 ms1/2) and the Tcp-e was increased (121 ms1/2) under the baseline condition (A). Epinephrine produced a prominent prolongation in the QTc-e (712 ms1/2), but a mild prolongation in the QTc-p (520 ms1/2), resulting in a dramatic increase in the Tcp-e (192 ms1/2) (B).
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Figure 2 Twenty-four-lead ECGs (G–K: 2–6) under baseline condition (A) and during epinephrine infusion (B) in a patient (pt) with LQT2 syndrome. A representative ECG (I4) is shown on the upper trace in each panel. The ECGs showed low-amplitude T wave with a notched appearance commonly seen in LQT2 patients. The QTc-e and QTc-p were prolonged (518, 414 ms1/2) and the Tcp-e was increased (104 ms1/2) under the baseline condition (A). Epinephrine produced a moderate prolongation in the QTc-e (618 ms1/2) and the QTc-p (494 ms1/2), resulting in a mild increase in the Tcp-e (124 ms1/2) (B).
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Figure 3 Twenty-four-lead ECGs (G–K: 2–6) under baseline condition (A) and during epinephrine infusion (B) in a control patient (pt). A representative ECG (H4) is shown on the upper trace in each panel. The QTc-e and QTc-p were much shorter (396, 314 ms1/2) and the Tcp-e was smaller (82 ms1/2) than those in LQT1 and LQT2 patients under the baseline condition (A). Epinephrine produced no significant changes in the QTc-e (410 ms1/2), the QTc-p (325 ms1/2), and the Tcp-e (85 ms1/2).
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Figure 4 Comparison of the differences before and after epinephrine in the mean QTc-e (A), QTc-p (B), Tcp-e (C), and Tcp-e/QTc-e ratio (D), which were averaged among 87-leads, in LQT1, LQT2, and control groups. The changes in the mean QTc-e with epinephrine were largest in LQT1 patients, intermediate in LQT2 patients, and were not significant in control patients (A), whereas changes in the mean QTc-p were not different among the three groups (B). As a consequence, the changes in the Tcp-e (C) and Tcp-e/QTc-e ratio (D) were largest in LQT1 patients, intermediate in LQT2 patients, and were not significant in control patients.
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Figure 5 Comparison of the differences before and after epinephrine in the max QTc-e (A), min QTc-e (B), QTc-eD (C), max QTc-p (D), minQTc-p (E), and QTc-pD (F), which were obtained from 87-leads, in LQT1, LQT2, and control groups. Changes in the max QTc-e with epinephrine were largest in LQT1 patients, intermediate in LQT2 patients, and were not significant in control patients (A), whereas changes in the min QTc-e were not different between LQT1 and LQT2 patients, but were significantly larger than those in control patients (B). As a consequence, changes in the QTc-eD were larger in LQT1 patients than those in LQT2 and control patients (C). In contrast, no significant differences were seen in the changes in the max QTc-p (D), min QTc-p (E), and QTc-pD (F) among the three groups.
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