Q-oTc interval and blood calcium levels in newborn infants.

The interval from the beginning of the Q wave to the origin of the T wave (Q-oTc interval) and total and ionized serum calcium levels were measured in 27 full-term and 77 premature infants. The correlation between Q-oTc and total and ionized calcium levels was significant in both full-term and normal premature infants. No correlation was found in a group of critically ill premature infants, most of whom had evidence of CNS involvement. Constant infusion of calcium gluconate in a number of infants belonging to the latter group produced a significant shortening of the Q-oTc interval. It is speculated that the lack of correlation of Q-oTc interval and total or ionized calcium levels in sick premature infants could be explained on the basis of a dysfunction in cardiac sympathetics or alternatively by marked variations in serum catecholamines.