Shinlapawittayatorn, KrekwitChattipakorn, SiripornSungnoon, RattapongChattipakorn, Nipon2009-05-272009-05-272007-10-29Shinlapawittayatorn K, Chattipakorn S, Sungnoon R, Chattipakorn N. Effects of combined sildenafil-nitric oxide donor on defibrillation efficacy. Journal of the Medical Association of Thailand. 2007 Oct; 90(10): 2143-9http://imsear.searo.who.int/handle/123456789/42700Chotmaihet Thangphaet.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 microg/min, with an increment of 5 microg/min every 5 min. The DFT was determined again after NTG was infused for 20 minutes. RESULTS: In group 1, the DFT (402 +/- 33V, 11 +/- 2J) was not different from the control (404 +/- 28V, 11 +/- 2J). In group 2, the DFT (521 +/- 18V, 19 +/- 1J) was higher (p < 0.004) than that in the control group (444 +/- 31V, 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.engAnimalsElectric CountershockHeart Ventricles --drug effectsHemodynamics --drug effectsMyocardiumNitric Oxide --pharmacologyNitroglycerin --pharmacologyPhosphodiesterase Inhibitors --pharmacologyPiperazines --pharmacologyPurines --pharmacologySulfones --pharmacologySwineVentricular Fibrillation --physiopathologyJournal Article