The pacemaker may have one to three leads, depending on the type of pacemaker needed to treat your heart problem. There are different types of pacemakers: Single-chamber pacemakers use one lead in the upper chamber (atria) or lower chamber (ventricles) of the right side of the heart.
The MexicanâAmerican War, also known as the Mexican War, the U.S.âMexican War or the Invasion of Mexico, was an armed conflict between the United States of America and the United Mexican States from 1846 to 1848.
Home > Timelines > Mexican-American War Timeline. Mexican-American War Timeline. Timeline Description: The Mexican-American War was fought between the United States and Mexico between 1846 and 1848. The war started with the U.S. annexation of Texas and was the result of disagreement over where the Mexican-American border should be.