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Figure 1 Calcium during demand ischemia. Ischemia (decreasing coronary perfusion pressure [CPP] to 20 mm Hg) reduced left ventricular systolic pressure (LVSP) to 70 mm Hg and left ventricular end-diastolic pressure (LVEDP) to 13 mm Hg. Tachycardia increased isovolumic LVEDP to 20 mm Hg, indicating increased diastolic chamber stiffness. A 14 mmol/L calcium (14 mM Ca++) imposed after tachycardia during sustained ischemic diastolic dysfunction increased LVSP from 60 to 110 mm Hg, indicating increased intracellular calcium concentration. However, LVEDP did not simultaneously increase (but in this example decreased from 20 to 18 mm Hg), suggesting that during ischemic diastolic dysfunction, calcium resequestration mechanisms remained intact and that the upward shift in LVEDP during tachycardia was not calcium-driven. Left ventricular systolic pressure recovered subsequent to infusion.
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