Ischemia-reperfusion destabilizes rhythmicity in immature atrioventricular pacemakers: A predisposing factor for postoperative arrhythmias in neonate rabbits
Por:
Cici, CH, Sheng, XY, Dan, PL, Qu, Y, Claydon, VE, Lin, E, Hove-Madsen, L, Sanatani, S, Tibbits, GF
Publicada:
1 dic 2016
Resumen:
BACKGROUND Postoperative arrhythmias such as junctional ectopic tachycardia and atrioventricular block are serious postoperative complications for children with congenital heart disease. We hypothesize that ischemia-reperfusion (I/R) related changes exacerbate these postoperative arrhythmias in the neonate heart and administration of postoperative inotropes is contributory.
OBJECTIVE The purpose of this study was to study the effects of I/R and postischemic dopamine application on automaticity and rhythmicity in immature and mature pacemaker cells and whole heart preparations. METHODS Single pacemaker cells and whole heart models of postoperative arrhythmias were generated in a rabbit model encompassing 3 primary risk factors: age, I/R exposure, and dopamine application. Single cells were studied using current clamp and line scan confocal microscopy, whereas whole hearts were studied using optical mapping.
RESULTS Four responses were observed in neonatal atrioventricular nodal cells (AVNCs): slowing of AVNC automaticity (from 62 +/- 10 to 36 +/- 12 action potentials per minute, P < .05); induction of arrhythmicity or increased beat-to-beat variability (0.08 +/- 0.04 to 3.83 +/- 1.79, P < .05); altered automaticity (subthreshold electrical fluctuations); and disruption of calcium transients. In contrast, these responses were not observed in mature AVNCs or neonatal sinoatrial cells. In whole heart experiments, neonatal hearts experienced persistent postischemia arrhythmias of varying severity, whereas mature hearts exhibited no arrhythmias or relatively transient ones.
CONCLUSION Neonatal pacemaker cells and whole hearts demonstrate a susceptibility to I/R insults resulting in alterations in automaticity, which may predispose neonates to postoperative arrhythmias such as junctional ectopic tachycardia and atrioventricular block.
Filiaciones:
Cici, CH:
Child & Family Res Inst, Cardiovascular Sci, Vancouver, BC, Canada
Simon Fraser Univ, Mol Cardiac Physiol Grp, Burnaby, BC, Canada
Sheng, XY:
Child & Family Res Inst, Cardiovascular Sci, Vancouver, BC, Canada
Simon Fraser Univ, Mol Cardiac Physiol Grp, Burnaby, BC, Canada
Dan, PL:
Child & Family Res Inst, Cardiovascular Sci, Vancouver, BC, Canada
Simon Fraser Univ, Mol Cardiac Physiol Grp, Burnaby, BC, Canada
Qu, Y:
Child & Family Res Inst, Cardiovascular Sci, Vancouver, BC, Canada
Simon Fraser Univ, Mol Cardiac Physiol Grp, Burnaby, BC, Canada
Claydon, VE:
Simon Fraser Univ, Mol Cardiac Physiol Grp, Burnaby, BC, Canada
Lin, E:
Child & Family Res Inst, Cardiovascular Sci, Vancouver, BC, Canada
Simon Fraser Univ, Mol Cardiac Physiol Grp, Burnaby, BC, Canada
Hove-Madsen, L:
Hosp Sant Pau, Cardiovascular Res Ctr CSIC ICCC, Barcelona, Spain
Sanatani, S:
Child & Family Res Inst, Cardiovascular Sci, Vancouver, BC, Canada
Simon Fraser Univ, Mol Cardiac Physiol Grp, Burnaby, BC, Canada
Univ British Columbia, Div Pediat Cardiol, Vancouver, BC, Canada
Tibbits, GF:
Child & Family Res Inst, Cardiovascular Sci, Vancouver, BC, Canada
Simon Fraser Univ, Mol Cardiac Physiol Grp, Burnaby, BC, Canada
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