• Resuscitation · Aug 2011

    Heart rate reduction with ivabradine increases ischaemia-induced ventricular fibrillation threshold: role of myocyte structure and myocardial perfusion.

    • Fanny Vaillant, Leila Dehina, Alejandro Mazzadi, Jacques Descotes, Philippe Chevalier, Alain Tabib, Bernard Bui-Xuan, Cécile Riera, Dalila Belhani, and Quadiri Timour.
    • INSERM ERI22, Université Claude Bernard de Lyon, 8 Avenue Rockefeller, 69373 Lyon cedex 08, France. fanny.vaillant45@gmail.com
    • Resuscitation. 2011 Aug 1;82(8):1092-9.

    AimsWe showed previously that ivabradine (IVA), a selective inhibitor of the cardiac pacemaker I(f) current, achieved protection against ischaemia-induced ventricular fibrillation (VF) in pigs by increasing the VF threshold (VFT). This was correlated to the heart rate reduction (HRR), the limitation of monophasic action potential shortening and the reduction of the hypoxic area. This study investigated myocyte ultrastructure and regional myocardial blood flow (RMBF), potentially involved in these cardioprotective effects of IVA.Methods And ResultsMyocardial ischaemia was induced in pigs by total 1-min occlusion of the left anterior descending coronary artery following i.v. administration of saline (n=6) or IVA (0.25 mg/kg, n=6). Electrophysiological and haemodynamic parameters, the hypoxic area and the presence of myocyte ultrastructural lesions were evaluated. The RMBF was assessed using positron emission tomography following ischaemia/reperfusion in IVA (0.25 mg/kg, i.v., n=6) or vagal stimulation (n=4) groups. Compared with saline, IVA induced a 32% HRR (p<0.01), a 2.9-fold increase in the VFT (p<0.001) and a reduction of the hypoxic area without any change in left ventricular dP/dt(max). IVA preserved cardiomyocyte morphology, particularly mitochondrial ultrastructure. Compared with baseline, RMBF during reperfusion was increased in the hypoxic area following IVA administration (+218% vs. +97%, p<0.05) or vagal stimulation (+195% vs. +127%, p<0.05). This increase was sharply reduced by atrial pacing in IVA-group.ConclusionIVA exerts a cardioprotection from ischaemia-induced VF by increasing RMBF and preserving cardiomyocyte and mitochondrial ultrastructure, which opens new perspectives regarding potential targets that would be involved in the anti-ischaemic effects of IVA.Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

      Pubmed     Full text   Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…