Effects of combined sildenafil-nitric oxide donor on defibrillation efficacy
Shinlapawittayatorn, K.; Chattipakorn, S.; Sungnoon, R.; Chattipakorn, N.
Journal of the Medical Association of Thailand 90(10): 2143-2149
2007
ISSN/ISBN: 0125-2208 PMID: 18041435 Document Number: 2989
Background. A previous study demonstrated that supra-therapeutic concentration of sildenafil citrate attenuates defibrillation efficacy. However the effect of combined sildenafil and NTG administration on defibrillation efficacy is not known.Objective: The present study investigated whether sildenafil administration at the therapeutic level increases the defibrillation threshold (DFT) when combined with NTG.Material and Method. Twenty-four pigs (20-25 kg) were randomized into four groups. After the control DFT was obtained, a stock solution of 50-mg (group 1, therapeutic concentration) and 100-mg (group 2, supratherapeutic concentration) of sildenafil, and 100-mL of saline (groups 3 and 4) were infused at 2 mL/min. Then, NTG was administered in groups 1-3 at 5 mu g/min, with an increment of 5 mu g/min every 5 min. The DFT was determined again after NTG was infused for 20 minutes.Results: In group 1, the DFT (402 +/- 33 V 11 +/- 2J) was not different from the control (404 +/- 28 V 11 +/- 2J). In group 2, the DFT (521 +/- 18 V 19 +/- IJ) was higher (p < 0.004) than that in the control group (444 +/- 31 V 14 2J). Saline did not alter the DFT either individually or in combination with NTG.Conclusion: Supratherapeutic dose of sildenafil-NTG combination significantly increased the DFT (17% of peak voltage, 37% of total energy). This effect on DFT appears to be driven by sildenafil and not NTG.
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