Hi friend, Welcome to Health Care Magic This description points to possible abnormal nerve paths in the heart (bypass tracts). It is very likely to be Supra Ventricular Tachycardia (SVT) - it is not usually so threatening as it looks. TMT excludes ischemia. ECHO excludes many structural abnormalities. These are advanced techniques of investigations – Electro Physiological Studies (EPS) it resembles angio – a catheter is put inside the heart / electrical activity recorded / stimulation and suppression tests are carried out / suitable medicine tested and so on. Though the test is the gold standard, it is INVASIVE and has a risk (though minimal) and is not generally done unless there are compelling indications. This super-speciality expert is called ELECTRO-PHYSIOLOGIST. The treating doctor may suggest them depending on need, based on his assessment of the situation. Take care Wishing speedy recovery God bless Good luck