-Jim,  by your web search, I am sure you have already discovered that arrhythmia is a very non-specific term for a variety of cardiac maladies ranging from very benign to  serious.  Your situation needs to be evaluated by a cardiologist and your doc did the right thing by sending you. If he is experienced, his comment of "it's probably nothing" is encouraging.  The echocardiogram is an ultrasound test to check the function of valves and chambers.  Good luck in your workup. Rick