On a cellular level, myocardial cells (heart muscle cells) will intake oxygen and release carbon dioxide like any other living cells in the body. Hence, it does undergo cellular respiration (the oxidative phosphorylation cycle in which oxygen is used to generate and gain net ATP in the mitochondria). So yes, the heart does require oxygenation. And if their blood supply (distributed by the coronary arteries) is blocked, it will generally result in myocardial cellular death (clinical definition of a heart attack). Ralph