Completed History and Physical and Intro to Pediatric ECG

You have now completed the history and physical examination of an eighteen-year-old man with an innocent pulmonary flow murmur. Let us know consider whether our patient needs laboratory studies. Diagnostic procedures are not required for the evaluation of typical innocent murmurs.

Although not required to evaluate an innocent murmur, certain aspects of the electrocardiogram in children deserve emphasis. Special techniques are required ro record a suitable electrocardiogram from an infant. In addition to quieting the infant, a small electrode one half inch in diameter should be used for precordial leads. Either lead V3R or V4R should be taken routinely in infants to obtain more information about the right ventricle. These leads are placed on the right chest in a position analogous to V3 and V4 respectively. Precordial lead V3 or V4 may then be omitted. Similarly, lead V7 may be obtained instead of V5 in order to get more information about the left ventricle. Lead V7 is placed in the left posterior axillary line at the same level as V4.

Infants at birth demonstrate equal right and left ventricular pressures and, therefore, relative right ventricular dominance on the electrocardiogram. The mean QRS axis is rightward with dominant R waves and positive T waves in leads V3R and V1. Increased precordial leads QRS voltage is common in children and younger adults due to a variety of factors, including a thin chest wall producing closer proximity of the heart to the chest wall.

In children, the T waves in the limb leads are similar to those of the adult but, depending on age, the precordial T waves differ. T waves in the right precordial leads are positive at birth. After a week, as the right ventricular systolic pressure decreases, these T waves become negative, and this negativity may extend as far as V4. In fact, an upright T wave in precordial lead V1 in a child less than six years old indicates right ventricular hypertrophy. As the child grows older, T wave positivity shifts progressively towards the right. In an older child, as in the normal adult, an inverted T wave is common in lead V1, frequent in V2 and rare in V3. Inverted T waves in the anterior leads may persist into the third decade of life. This is called "persistent juvenile T-wave pattern" and it is more common in women. This is normal, as long as the depth of the T wave decreases as the leads progress across the chest.