1 The Romans also used a 12 hour clock. 2  The 12 hour dial became popular with mechanical clocks during the 15th and 16th centuries and this has continued to this day.  The abbreviations for am and pm are often also written as a.m. and p.m. or AM and PM.
Stress Testing/Stress Echocardiogram. A stress echocardiogram is a non-invasive test that combines two tests--a treadmill stress test (TST) and an echocardiogram (ECHO). This test is used to see how the heart muscle contracts during rest and during exercise. A stress echo is made up of three parts: a resting echo study, a stress test, and a repeat echo while the heart is beating fast. (See also Drug Induced Stress Test or Nuclear Stress Test--below)
A dobutamine stress echocardiogram may utilize one or more of four special types of echocardiography, as listed below: M-mode echocardiography. This, the simplest type of echocardiography, produces an image that is similar to a tracing rather than an actual picture of heart structures.f exercise on a treadmill is not an option (too much stress on the heart) due to a personâs medical condition, a doctor may use an intravenous medication called dobutamine. Dobutamine causes the heart to beat faster and will mimic the effects of exercise on the heart.