Which of the following is not listed as a trigger for tachycardia?

• A. Fever
• B. Anemia
• C. Hypervolemia
• D. Hypothermia

Answer: (D)

Tachycardia tends to occur when factors increase metabolic demand or stimulate the sympathetic nervous system. Fever raises metabolic rate and triggers sympathetic activation, pushing the heart to beat faster. Anemia reduces the blood’s oxygen-carrying capacity, so the heart speeds up to help deliver more oxygen to tissues. Hypervolemia increases venous return and the workload on the heart, which can also drive the heart rate up as part of compensatory mechanisms.

Hypothermia, by contrast, lowers metabolic activity and tends to slow the heart, leading to bradycardia rather than tachycardia. Because of that cooling effect on heart rate, hypothermia is not a trigger for tachycardia.