Figure 7.

Central illustration: the effect of pressure loading on myocardial energetics. In comparison with the normal heart (A) energetic impairment occurs in the presence of pressure loading from aortic stenosis (AS) and is established by moderate AS (B). Although creatine kinase (CK) capacity reduces (green line) as AS severity increases (blue line) to severe (C) and is lowest in systolic failure (D), ATP delivery (CK flux, red line) at rest does not alone fall lower than that seen in moderate AS. As ATP demand increases with increasing AS severity and left ventyricular hypertrophy (black dotted line), this exceeds prevailing ATP delivery. In summary, energetic impairment in the CK system is present early in AS, and although it does not appear alone to be sufficient for transition to systolic decline in AS, it may nevertheless increase susceptibility to failure as ATP turnover demands increase.