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ICVTS on-line discussion A The safety of using millimolar doses of lidocaine as cardioplegia

Cardiac Surgery Department, St. Thomas' Hospital, London SE1 7EH, United Kingdom

Lidocaine-magnesium blood cardioplegia was equivalent to potassium blood cardioplegia in left ventricular function of canine heart

eComment: We read with interest the paper by Yamaguchi and colleagues [1] that studies the effect of lidocaine-magnesium blood cardioplegia in an in vivo canine model. The interest of this study lies in the fact that it addresses the safety issue of infusing millimolar doses of lidocaine as a cardioplegic agent. This is done by measuring the serum concentration throughout the procedure, but particularly around the time when cardiopulmonary bypass will be discontinued. There appeared, however, to be a very narrow margin of safety because it took 30 minutes for lidocaine to reach safe levels and this will be largely dependent on the renal clearance of the drug, which could be less effective during cardiopulmonary bypass. In reference 10 (incorrectly cited!) Corvera and colleagues [2] used lower lidocaine concentrations in combination with adenosine. Thus, it is possible that, in this study, the use of a higher magnesium concentration (possibly closer to the concentration used in the St. Thomas' Hospital cardioplegia of 32 mEq/L (16 mmol/l), which would act to block the L-type calcium channels) may have allowed a reduction in their lidocaine concentration. However, serum concentrations of lidocaine were not measured in the study by Corvera and coworkers.

Another point of interest is the formulation of the potassium cardioplegia used at the authors' institute; the calcium concentration stated is considerably higher than most cardioplegic solutions, at 8 mEq/L (4 mmol/l)! What was the reason behind this? In addition, why were the sodium and potassium concentrations in the Lidocaine-Mg solution so low? Moreover, there are numerous errors of fact throughout the manuscript. For example, the lidocaine concentration used in the maintenance infusion is cited as 0.65 mmol/l in Table 1 and 0.43 mmol/l in the discussion text. The lidocaine serum concentration is cited as mg/ml in Fig 3 and g/ml in the text. It is also surprising that statements made in the Introduction are not supported by references. These, and many other points, should have been brought to the attention of the authors by the reviewers so that they could be corrected or explained.

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1. Yamaguchi S, Watanabe G, Tomita S, Tabata S. Lidocaine-magnesium blood cardioplegia was equivalent to potassium blood cardioplegia in left ventricular function of canine heart. Interact CardioVasc Thorac Surg 2007; 6:172–176.[Abstract/Free Full Text]
2. Corvera JS, Kin H, Dobson GP, Kerendi F, Halkos ME, Katzmark S, Payne CS, Zhao ZQ, Guyton RA, Vinten-Johansen J. Polarized arrest with warm or cold adenosine/lidocaine blood cardioplegia is equivalent to hypothermic potassium blood cardioplegia. J Thorac Cardiovasc Surg 2005; 129:599–606.[Abstract/Free Full Text]

This Article Full Text (PDF) 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 Add to Personal Folders Download to citation manager Author home page(s): David J. Chambers Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Fallouh, H. B. Articles by Chambers, D. J. Search for Related Content PubMed PubMed Citation Articles by Fallouh, H. B. Articles by Chambers, D. J. Related Collections Related Article