this is something you definatley need to call your doctor that prescribed the medication for and not take our words for it. no one here knows what level your murmur is etc. best advice is call your Dr.
It can definitely affect your heart as side effect. from Mayo Clinic
Here's the link to side effects of Tramadol. It lists rapid heart beats, irregular heart beats amongst manySE.
http://search.mywebsearch.com/mywebsearch/redirect.jhtml?searchfor=tramadol+side+effects&cb=ZZ&n=77fc993c&qid=d7e437f1c21448d796e267741e3ada48&ptb=A453850F-AF68-4630-8E55-93D7C95C6F8E&si=CD9606&pg=GGmain&action=pick&ptnrS=^YO^sfr999^YY^us_YO^xdm128^YY^us&ss=sub&pn=1&st=tab&qs=&pr=GG&tpr=tabsbsug&redirect=mPWsrdz9heamc8iHEhldERQO5obxpZX46Q7pRLdIdo%2Fj9EIed7X%2FhAGqTiJRq8ywUBU%2Fb1eHg9xnpWtL%2BZldoBsKO2rQaPj55pOoCMfnZLvD6ERSdvi6v3Y1ksnQSry7&ord=1&ct=AR&