Title What is baseballâs âmodern eraâ? The start of the 20th century might not seem particularly modernâafter all, there were only 45 states in the Union, hardly anyone owned a car (the Model T didnât debut until 1908) and William McKinley, a Civil War vet, occupied the White House.
Sinus tachycardia is a normal increase in the heart rate. How it happens. The sinoatrial (SA) node --- the heart's natural pacemaker-sends out electrical signals faster than usual. The heart rate is fast, but the heart beats properly.inus tachycardia is a normal increase in the heart rate. How it happens. The sinoatrial (SA) node --- the heart's natural pacemaker-sends out electrical signals faster than usual. The heart rate is fast, but the heart beats properly.
If the heart beats more rapidly than normal, this arrhythmia is called tachycardia. An unpleasant sensation in the heart, whether rapid or slow, regular or irregular, and of which one is consciously aware, is called a palpitation. Physical Causes of Rapid or Irregular Heart Rate. 1  arrhythmia.  postmyocardial infarction.