European Journal of Cardio-Thoracic Surgery, Vol 5, 183-189, Copyright © 1991 by European Association for Cardio-thoracic Surgery
Detrimental effects of multidose hypothermic cardioplegia in the neonatal heart: the role of the frequency of cardioplegic infusions
T Murashita, M Avkiran and DJ Hearse
Cardiovascular Research, Rayne Institute, St. Thomas' Hospital, London, UK.
In the neonatal rabbit heart, multidose crystalloid cardioplegia is
protective against normothermic ischemia, but its beneficial effects are
lost under hypothermia. In order to determine the relationship between
myocardial protection and the number of cardioplegic infusions administered
during the ischemic period, we examined the effects of an increasing number
of infusions on postischemic recovery at three temperatures (37 degrees, 20
degrees, or 10 degrees C). Isolated working hearts from rabbits aged 7-10
days were perfused aerobically (37 degrees C) for 20 min before infusion of
St. Thomas' Hospital cardioplegic solution at the selected temperature. At
each temperature, the cardioplegic solution was given either as a single
2-min infusion (single-dose) or as repeated 2-min infusions (multidose) at
various intervals. Following the ischemic period, hearts were reperfused
(15 min Langendorff, 20 min working) before assessment of the recovery of
function. Ischemic durations (selected to result in approximately 55%- 70%
recovery in the single-dose group at each temperature) were 1, 10, or 18 h
at 37 degrees, 20 degrees, and 10 degrees C. At 37 degrees C, there was a
positive correlation between postischemic recovery and the number of
infusions during the ischemic period. However, at 20 degrees or 10 degrees
C the relationship was reversed and recovery was depressed with increasing
number of infusions.(ABSTRACT TRUNCATED AT 250 WORDS)
