硝普钠、酚妥拉明和咪噻芬等血管扩张药能降低后负荷,增加心排出量,并使增高的左室充盈压减低,可用于治疗心力衰竭,但这些药物只能静脉注射,不能口服。口服硝酸盐虽亦可降低后负荷,但主要作用于静脉血管床,减轻肺充血,而对于心排出量则不能恒定地增加。口服肼苯哒嗪可增加心排出 Vasodilators such as sodium nitroprusside, phentolamine and miciphenvate reduce postload, increase cardiac output, and increase increased left ventricular filling pressure, which can be used to treat heart failure but these drugs can only be administered intravenously oral. Although oral nitrate can also reduce the post-load, but mainly in the venous bed, reduce pulmonary congestion, and cardiac output can not be constant increase. Oral hydralazine can increase cardiac discharge