There are two approaches used when inserting a pacemaker; the epicardial approach and the transvenous approach. Epicardial approach involves the opening the chest cavity and placing a lead on epicardial sac of heart while the transvenous approach involves accessing a vein and inserting an electrode into the vein. Epicardial approach for inserting pacemakers are divided based on approach to heart thoracotomy, upper abdominal or endoscopic.
The Phanerozoic eon is the eon of visible life. It started about 541 million years ago. It represents only 1/8 th of the time since Earth`s crust formed. Precambrian eon is older : it extends from 4.6 billion years ago to the Phanerozoic eon. Fossils in the Precambrian eon are rare. In the late Precambrian eon evolved the first multi-cellar organisms.
Answer:
B. There was no life in the Precambrian eon.
Patent fingerprints are made by a liquid or powder that sticks to the finger and then transfers to a surface, leaving an easily visible fingerprint behind. Substances that can leave patent fingerprints are ink, blood, dirt, flour, grease, etc.
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