This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map 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 De Ferrari, G. M. Articles by Schwartz, P. J. Search for Related Content PubMed PubMed Citation Articles by De Ferrari, G. M. Articles by Schwartz, P. J.

Circulation, Vol 89, 2126-2132, Copyright © 1994 by American Heart Association

ARTICLES

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

GM De Ferrari, F Nador, G Beria, S Sala, A Lotto and PJ Schwartz
Centro di Fisiologia Clinica e Ipertensione, Universita degli Studi di Milano, Italy.

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: Th1/2 (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 Th1/2 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 < .00001). At the peak effect of verapamil, the contraction pattern of all patients was normal. In healthy control subjects, verapamil did not significantly change either Th1/2 (from 17.6 +/- 2.5% to 18.5 +/- 3.5% of the cardiac cycle) or TSTh (from 0.92 +/- 0.47% to 1.17 +/- 0.74%). CONCLUSIONS: This study demonstrates that the wall motion abnormality of LQTS is completely abolished by verapamil. These results suggest that symptomatic LQTS patients may have an abnormal increase in the intracellular calcium concentration before relaxation has completed, possibly linked to an early afterdepolarization, and that the contraction abnormality may be the mechanical equivalent of an early afterdepolarization.

This article has been cited by other articles:

				L. Fabritz Drug-induced torsades de pointes -- A form of mechano-electric feedback? Cardiovasc Res, November 1, 2007; 76(2): 202 - 203. [Full Text] [PDF]

				D. J. Gallacher, A. Van de Water, H. van der Linde, A. N. Hermans, H. R. Lu, R. Towart, and P. G.A. Volders In vivo mechanisms precipitating torsades de pointes in a canine model of drug-induced long-QT1 syndrome Cardiovasc Res, November 1, 2007; 76(2): 247 - 256. [Abstract] [Full Text] [PDF]

				R. Tukkie, P. Sogaard, J. Vleugels, I. K.L.M. de Groot, A. A.M. Wilde, and H. L. Tan Delay in Right Ventricular Activation Contributes to Brugada Syndrome Circulation, March 16, 2004; 109(10): 1272 - 1277. [Abstract] [Full Text] [PDF]

				R. Tukkie and A.A.M. Wilde TDI-echocardiography: a new screening tool for long QT syndrome? Eur J Echocardiogr, September 1, 2003; 4(3): 157 - 158. [Full Text] [PDF]

				C Savoye, D Klug, I Denjoy, P.V Ennezat, T Le Tourneau, P Guicheney, and S Kacet Tissue Doppler echocardiography in patients with long QT syndrome Eur J Echocardiogr, September 1, 2003; 4(3): 209 - 213. [Abstract] [Full Text] [PDF]

				H Yamanari, K Nakayama, H Morita, K Miyazi, K Fukushima, H Matsubara, T Emori, and T Ohe Effects of cardiac sympathetic innervation on regional wall motion abnormality in patients with long QT syndrome Heart, March 1, 2000; 83(3): 295 - 300. [Abstract] [Full Text]

				S. G. Priori, C. Napolitano, and P. J. Schwartz Low Penetrance in the Long-QT Syndrome : Clinical Impact Circulation, February 2, 1999; 99(4): 529 - 533. [Abstract] [Full Text] [PDF]

				K Nakayama, H Yamanari, F Otsuka, K Fukushima, H Saito, Y Fujimoto, T Emori, H Matsubara, S Uchida, and T Ohe Dispersion of regional wall motion abnormality in patients with long QT syndrome Heart, September 1, 1998; 80(3): 245 - 250. [Abstract] [Full Text]

				D. M. Roden, R. Lazzara, M. Rosen, P. J. Schwartz, J. Towbin, and G. M. Vincent Multiple Mechanisms in the Long-QT Syndrome: Current Knowledge, Gaps, and Future Directions Circulation, October 15, 1996; 94(8): 1996 - 2012. [Abstract] [Full Text]

				G. M. De Ferrari, M. Viola, E. D'Amato, R. Antolini, and S. Forti Distinct Patterns of Calcium Transients During Early and Delayed Afterdepolarizations Induced by Isoproterenol in Ventricular Myocytes Circulation, May 15, 1995; 91(10): 2510 - 2515. [Abstract] [Full Text]