Final answer:
A 7-month-old with a heart rate of 58 bpm and a history of an atrial ventricular defect is experiencing pathologic bradycardia. This condition is serious and indicates that the heart may not be pumping sufficient oxygenated blood, necessitating immediate medical intervention.
Step-by-step explanation:
The condition of a resting heart rate dropping below 60 beats per minute (bpm) in adults is known as bradycardia. Since the 7-month-old patient has a heart rate of 58 bpm and a history of an atrial ventricular defect, this can be considered as pathologic bradycardia, a concerning form of the condition that could be due to intrinsic cardiac issues related to the defect. This bradycardia is potentially serious, since a baby's normal heart rate should be much higher than an adult's, typically around 130 bpm. The low heart rate, especially when combined with an altered mental status and history of cardiac defect, suggests that the heart may not be delivering enough oxygenated blood to the body, which requires immediate medical attention.