This document discusses various diagnostic tests used in electrocardiography. It describes the placement of the 12 precordial leads on the chest and the 3 limb leads used in ECG. It also discusses Holter monitoring, stress testing, echocardiography including M-mode, 2D and Doppler echocardiography. Laboratory investigations discussed include cardiac markers like CK-MB, troponins and LDH along with serum lipids. Invasive hemodynamic monitoring techniques are also summarized including central venous pressure monitoring, intra-arterial blood pressure monitoring and pulmonary artery catheterization.