The nurse is knowledgeable about sinoatrial node dysrhythmias if she selects which of the following causes of sinus tachycardia?
• Sinus tachycardia is defined as a sinus rhythm with a rate of greater than 100 beats per minute. Causes of ST include: fever, emotional & physical stress, heart failure, fluid volume loss, hyperthyroidism, hypercalcemia, caffeine, nicotine, exercise, and some medications
• In the vast majority of cases, sinus tachycardia results from some underlying condition such as exercise, infection, or congestive heart failure, which alters the autonomic nervous system
• Sinus bradycardia may result from the following: Valsalva's maneuver, drugs like digitalis, MI, hyperkalemia, hypothyroidism, severe hypoxia, and increased ICP