SGCB and angina pectoris: The NO-sGC-cGMP axis is essential for the regulation of the cardiovascular system and the improvement of cardiac function in heart failure (29–32); earlier studies have demonstrated that the exogenous NO drug nitroglycerin can ameliorate angina, but it has the disadvantage of high first-pass metabolism, a low half-life and no specific effect (33); Inhibition of phosphodiesterase (PDE) activity downstream of cGMP has emerged as a new strategy for the use of sildenafil treatment (32).