Clinical Applications of Myocardial Metabolic Imaging
To maintain mechanical function, the heart requires a high rate of oxygen intake in order to give enough energy to balance the mechanical function's demands. When the oxygen supply is insufficient to meet the demand, metabolic alterations can occur, both reversible and permanent. In Coronary Artery Disease (CAD), where oxygen delivery is restricted due to severe stenosis or occlusion of major coronary arteries, such an imbalance is most common. Energy is also necessary to preserve the potential to regulate ion concentration in the cells in the membrane. The myocardium's principal energy sources are glucose and free fatty acids, both of which require enzyme conversion before being broken down. The term "substrate" can be used to denote "heart fuel." The heart's ability to absorb various substrates is influenced by the fuel's arterial concentration. Due to the suppression of glucose oxidation in the fasting state, where plasma free fatty acids are high, free fatty acid absorption in the heart is similarly high. When glucose and/or insulin levels are high, such as in the post-prandial state, glucose oxidation increases but fatty-acid utilisation is suppressed. Chemical energy is converted into mechanical energy by the myocardium . Because metabolism and heart function are intricately intertwined, energy substrate metabolism could be a possible target of such innovative medicines to enhance failing heart function .