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.
A rapid or fast heartbeat is when your heart is beating faster than normal. A normal heart rate is 60 to 100 beats per minute. Tachycardia is considered a heart rate of greater than 100 beats per minute.If you are exercising, or performing any kind of activity, your heart will normally beat faster. For rapid heart rates that are caused by shortness of breath, you may have trouble lying flat in bed, and you may have to sleep on 2 or more pillows. 2  Your shortness of breath may cause you to wake up in the middle of the night.