Effect of calcium channel block on the wall motion abnormality of the idiopathic long QT syndrome

Gaetano M. De Ferrari, Filippo Nador, Gabriella Beria, Sergio Sala, Antonio Lotto, Peter J. Schwartz

Research output: Contribution to journalArticle

Abstract

Background: We recently showed the frequent occurrence of an unusual ventricular wall motion abnormality, assessed by echocardiography, in patients with the idiopathic long QT syndrome (LQTS). Two new quantitative indexes were developed: Th( 1/2 ) (time needed to reach half of the maximal systolic thickening), which was smaller in LQTS patients than in controls; and TSTh (time spent at a very low thickening rate before rapid relaxation), which was much greater in LQTS patients, indicating the presence of a slow contraction in the late thickening phase. This marked late systolic 'plateau,' either rectilinear or with a peculiar double peak pattern, was significantly more frequent in patients with a history of syncope or cardiac arrest. The mechanism underlying this puzzling phenomenon remained unexplained. Methods and Results: The present study assessed the effects of the calcium channel blocker verapamil on the contraction pattern in 10 LQTS patients (9 females and 1 male; mean age, 19±7 years) with a marked plateau pattern and in 6 healthy controls (4 females and 2 males; mean age, 28 ± 5 years). Either verapamil (0.1 mg/kg) or saline was randomly injected over 2 minutes. Saline had no effect. In LQTS patients, verapamil increased Th( 1/2 ) by 27%, from 16.9±3.2% to 21.4±3.9% of the cardiac cycle (P=.005), and dramatically reduced TSTh by 92%, from 13.7 ± 5.3% to 1.08±0.6% of the cardiac cycle (P

Original languageEnglish
Pages (from-to)2126-2132
Number of pages7
JournalCirculation
Volume89
Issue number5
Publication statusPublished - May 1994

Keywords

  • death, sudden
  • depolarizing
  • echocardiography
  • torsade de pointes
  • verapamil

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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