i have had a aortic valve replacement(mechanical) 3 years ago, I am now taking cardicor and 2 other blood pressure tablets,over the last 2 years i have developed with maintaining an erection but with viagra everything is fine,but now my doc won,t write me a script for anymore he has told me to stop taking cardicor for 2 days before i have sex,this is not working i now get an soft erection and am suffering premature ejaculation. please help.