The availability and marketing of new therapies for erectile dysfunction have greatly increased public awareness of this problem. buy viagra online . buy cialis online . Ain't love grand? (NaturalNews) Fears that men with chronic heart failure might risk their lives by having sex are overblown, and even those taking Viagra may be safe engaging in sexual activity if they are receiving the proper medical care, according to a study published in the journal Mayo Clinic Proceedings. Reduced blood flow to the penis and nerve damage is the most common physical causes.