<s>[INST] My left side of my chest just started pulsating for just about 10-20 sec stopped for a few seconds then started again then stopped. I have a 3cm hole between the left and right ventrical of my heart so one chamber where the blood flows pushes into the other. I ve had it checked out within the last year and everything is good. My heart hasn t gotten bigger and the doctor said since I haven t had any problems its not wise to sew it up. Just wondering if this has anything to do with the pulsating? I have no pain, just curious because you can see my chest pulsate when im lying down. [/INST] What you described is a ventricular septal defect as you say, all if fine during last consultation.  Now here I would like to say much transient arrhythmia (heart rhythm problem s) are known to occur with VSD, doing an ECG at the time of such episode and if on daily basis its happening a 24 hour holder, if still rarer a loop recorder for a week, will help us know what is the type of such disturbance and if anything found can be treated with a small dose of medication.  Regards </s>