Doppler ultrasound uses sound waves to measure blood flow and diagnose conditions like blood clots and heart issues. It is less invasive than tests like arteriography and venography. The Holter monitor records heart activity through electrodes attached to the chest over hours or days to detect irregular rhythms and diagnose conditions like atrial fibrillation. Thrombolytic drugs like t-PA and streptokinase are used to treat strokes and heart attacks by dissolving blood clots, but will not be given if the patient has recent bleeding, surgery, pregnancy or other exceptions.