The Infant with Heart Disease.

Yearly cheeks on radiation output of equipment should be carried out. When isotopes are used for indicator dilution studies to determine shunts and cardiac output, rapidly excreted ones should be employed with low activity and short half-life. Recent developments in the recording of the electrical events of the heart beat indude a battery-operated miniaturized radio broadcasting system which permits the recording of the electrocardiogram signal without the use of wires. The sender is attached to the patient and the receiver can be located as far away as 1,500 feet. The signal can be recorded on any appropriate device including magnetic tape. The technique permits the taking of the electrocardiogram during exercise and other procedures where wires would interfere. Currently, normal children and those with heart disease are being studied under conditions of play, work, and other physical activity. Vectorcardiography may give additional information to that obtained in the electrocardiogram by way of identifying chamber hypertrophy, conduction disturbances, and myocardial infarction. The threedimensional presentation of the electrical events of the heart is mediated through an oscilloscopic recording and then photographed. Time and voltage relationships of the cardiac forces are thereby depicted as a loop in contrast to the scalar representation on the conventional electrocardiogram. For over 20 years the functional status of the heart and great vessels has been investigated by cardiac catheterization techniques. Through catheters it has been possible to record the intracardiac pressures and remove blood samples for oxygen analysis. More recently indicator dilution techniques have been utilized during cardiac catheteri-