Isotopes are atoms of the same element (that is, with the same number of protons in their atomic nucleus), but having different numbers of neutrons. Most (66 of 94) naturally occurring elements have more than one stable isotope.here are 80 elements that have at least one stable isotope and 38 that have exclusively radioactive isotopes, which decay over time into other elements. Iron is the most abundant element (by mass) making up the Earth, while oxygen is the most common element in the crust of the earth.
This test, often called an echo, shows your heart's movement. During this exam, your doctor places a wand on the surface of your chest. It sends ultrasound waves that show pictures of your heart's valves and chambers. Those images let your doctor look at how well your ticker is pumping. Your doctor may combine an echocardiogram with tests called Doppler ultrasound and color Doppler to check blood flow across your heart's valves. Ejection fraction (EF). It's a measure of how much blood is pumped out of your heart each time it beats.
An ejection fraction is most commonly measured during an echocardiogram. This painless and noninvasive test uses high-frequency sound waves (ultrasound) to get a picture of the four heart chambers and the four heart valves.