Indexes for ventricular repolarization abnormality: Re-evaluation of QT interval.

Q: What does this research mean for the field?

The characteristic ECG change during the occurrence of Torsades de Pointes is a significant increase in U wave amplitude that leads to the fusion of T and U waves, distinguishing it from the normal pharmacological prolongation of the QaTc interval caused by class Ia antiarrhythmic drugs. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Takahisa Maruyama; Tohru Ohe; Yoshiaki Okano; Takashi Kurita; Naohiko Aihara; Shiro Kamakura; Mokuo Matsuhisa; Katsuro Shimomura

doi:10.5105/jse.12.327

January 1, 1992Japanese Journal of ElectrocardiologyOpen Access

Indexes for ventricular repolarization abnormality: Re-evaluation of QT interval.

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Why the study?

How do specific ECG indices of ventricular repolarization change with class Ia antiarrhythmic drugs and during TdP occurrence?

Structured PICO

How do specific ECG indices of ventricular repolarization change with class Ia antiarrhythmic drugs and during TdP occurrence?

P

Population

23 subjects total: 15 healthy subjects and 8 patients with Torsades de Pointes (TdP)

I

Intervention

Class Ia antiarrhythmic drugs (including quinidine)

C

Comparator

Before administration (for healthy subjects) and non-administration period (for TdP patients)

O

Outcome

ECG indices of ventricular repolarization (QaTc and U-wave amplitude)surrogate

Torsades de Pointes is characterized by an increase in U-wave amplitude causing T-U wave fusion, suggesting U-wave evaluation is critical in repolarization abnormalities.

Implication

May support U-wave monitoring for TdP risk with class Ia drugs; leaves open prospective validation before clinical adoption.

Abstract

心室再分極異常はしばしば重篤な不整脈と関連し, 体表面心電図では従来「QT延長」と表現される.しかしT波の終点の決定が曖昧なまま扱われているという問題がある.本研究ではT波とU波を厳密に区別して再分極過程の体表面心電図上の諸指標を設定し, 健常群 (15名) においてIa群抗不整脈薬投与前後で比較した.さらにTorsades de Pointes (TdP) 群 (8名) においてTdP発生時と非投与時とで比較した.健常群では, Ia群抗不整脈薬投与によりQaTc (QRSの始まりからT波の頂点までの時間をBazett's formulaで補正) が有意に延長し, その変化度はキニジン血中濃度と相関した.したがってQaTcの延長は通常の薬理学的な反応と考えられた.TdP群では, U-amp (U波の振幅) が有意に増大した.すなわち, 異常時 (TdP発生時) の変化の特徴はU波の増大であり, これがT波とU波の融合をもたらしている.

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Cite This Study

Maruyama et al. (1992) studied this question.

synapsesocial.com/papers/6a1c840e973ffece4bc3ed37 https://doi.org/10.5105/jse.12.327

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Indexes for ventricular repolarization abnormality: Re-evaluation of QT interval.

Structured PICO

Implication

Abstract

Discussion

Cite This Study

Indexes for ventricular repolarization abnormality: Re-evaluation of QT interval.

Structured PICO

Implication

Abstract

Discussion

Cite This Study

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