The influence of acute alterations in coronary blood flow on left ventricular diastolic compliance and wall thickness.

The extent to which alterations in the coronary blood flow influence left ventricular (LV) diastolic compliance and wall thickness was studied in isolated, isovolumic (balloon in LV), blood perfused dog hearts. Studies were performed at a ventricular volume which was associated with an LV systolic pressure of 100 mm Hg and changes in LV diastolic pressure (at this constant volume) were taken as changes in LV diastolic complicance. When coronary perfusion pressure was reduced to zero (5 min of global ischemia), LV diastolic wall thickness fell from 9.9 +/- 0.9 mm to 9.2 +/- 0.7 mm (P less than 0.01) and LV diastolic pressure fell only 1.3 mm Hg (from 5.5 +/- 1.0 mm Hg to 4.2 +/- 1.1 mm Hg P less than 0.01). In contrast to these findings in 'near normal' ventricles, global ischemia in severely injured hearts (with unphysiologically high diastolic pressures) resulted in marked reductions in diastolic pressure. Thus, moment to moment changes in coronary blood flow can result in alterations in the diastolic properties of the LV. However, these are extreme interventions, and in the clinical setting, changes in coronary dynamics are unlikely to cause significant changes in LV diastolic pressure.