I have also had heart troubles while smoking weed as well as an irregular heart beat. It is at its worse when I smoke blunts. During the attacks I experience palpitations a heart rate around 120 bpm and a moderately high blood pressure. I have also been to the ER due to a panic attack and been alright and I have also been to a cardiologist and was told my heart was fine. Some advice that I would recommend that has worked for me is excersing regularly and maintaining a balanced healthy diet. Also lay off the caffiene or anything else that you may think to trigger your heart rate. Whenever I feel a panic attack coming for some reason it is very difficult to remain positive even though I know everything is going to be alright. What I try to do is keep my mind focused on something else and eventually I will forget about my heart and my heart rate will slow down. I feel the hardest part to get through is the initial panic attack but it may vary among others. Its also relieving to know that no one has ever died from marijuana and that it won't hurt your heart. The most important thing is to maintain a positive attitude and to have a good time. Hope this helps.