Cardiovascular research
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Cardiovascular research · Aug 1994
Determinants of frequency domain measures of heart rate variability in the acute and convalescent phases of myocardial infarction.
Low heart rate variability after acute myocardial infarction is associated with an increased risk of cardiac mortality. The aim of this study was to investigate the determinants of frequency domain measures of heart rate variability in acute myocardial infarction. ⋯ The frequency domain measures of heart rate variability are mostly determined by the location of myocardial infarction in the early phase, whereas a correlation between heart rate variability and left ventricular function and arrhythmic propensity is more obvious in the convalescent phase.
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Cardiovascular research · Aug 1994
Brief perfusion with diluted whole blood after global myocardial ischaemia increases reperfusion injury.
In vivo studies indicate that blood components, especially leucocytes, contribute to reperfusion injury after myocardial ischaemia. This study was designed to: (1) develop a small animal heart model of ischaemia-reperfusion that demonstrates the contribution of blood to reperfusion injury; (2) determine when the presence of blood in the heart--that is, during ischaemia or during early reperfusion--caused greater dysfunction; and (3) attempt to limit the blood contribution to reperfusion injury by leucocyte depletion. ⋯ Thirty min of global, normothermic ischaemia caused significant cardiac dysfunction early during reperfusion. Perfusion with unstimulated blood for a limited period further impaired the recovery of function and enhanced myocardial oedema. Dysfunction was particularly evident when diluted whole blood was perfused during the first minutes of reperfusion. The leucocyte depletion studies suggest that leucocytes are necessary, but may not be sufficient, to demonstrate the blood contribution to reperfusion injury.