Atoms can join together to form molecules, which in turn form most of the objects around you. Atoms are composed of particles called protons, electrons and neutrons. Protons carry a positive electrical charge, electrons carry a negative electrical charge and neutrons carry no electrical charge at all. The protons and neutrons cluster together in the central part of the atom, called the nucleus, and the electrons 'orbit' the nucleus.
Practice Essentials. Percutaneous coronary intervention (PCI), also known as coronary angioplasty, is a nonsurgical technique for treating obstructive coronary artery disease, including unstable angina, acute myocardial infarction (MI), and multivessel coronary artery disease (CAD). See the image below.
PCA: Commonly used abbreviation for patient-controlled analgesia. Analgesia simply means relief of pain. PCA is a method by which the patient controls the amount of pain medicine they receive. There are a number of different PCA systems. In the classic PCA system, the patient receives a preset dose of morphine by pressing a button on a computerized pump that is connected to an IV catheter. With PCA the patient may receive a small continuous flow of morphine and add more morphine as needed to provide a more constant level of comfort.