2025 – PAGE 120 – CARDIOLOGY
NORMAL HEART RATES
Normal heart rates in children are not well defined, so use these values as a guideline:
- NEONATES: 70–160 is considered normal. Slower means bradycardia, and faster means tachycardia.
- OLDER CHILDREN: 50–120 can be considered normal.
SINOATRIAL NODE (SA NODE), ATRIOVENTRICULAR NODE (AV NODE) and VENTRICULAR INTRINSIC RATES
- The sinoatrial node firing rate is AGE DEPENDENT. The rate is higher in young children and decreases to an intrinsic rate of approximately 80 beats/minute in adults.
MNEMONIC:
- The atrioventricular node (AV node) intrinsically fires at 60 beats/minute.
- The ventricle intrinsically fires at 40 beats/minute (so you could see a rate of 40 in a patient with 3rd degree AV Block).
MNEMONIC: The “S” of SA node looks like the “8” of 80 beats/minute: “8A node.” From higher up to lower (SA to AV to Ventricle), the intrinsic rates decrease by 20 from 80 to 60 to 40 beats/minute. Keep “8A Node beating at 80 beats/minute” in mind, and you should be fine.
ARRHYTHMIAS
PEARL: Studying arrhythmias in too much detail has been low-yield in recent years. This is likely due to the importance placed on congenital heart disease, murmurs, and septal defects. Even though the information presented in this section is fairly complete, consider reading it for a “high level” understanding only.
BRUGADA SYNDROME
Brugada syndrome is usually found in adults but may occur in children. It is characterized by sudden death associated with certain ECG patterns. Look for a right bundle branch block (RBBB) + ST segment elevation in the precordial leads (V1–V3). This example shows normal ST segments on the left (A) and ST segment elevation on the right (B).
