What happens to cardiac muscle if it does not receive oxygen due to a blockage?

When cardiac muscle does not receive oxygen due to a blockage, the primary consequence is that the muscle cells begin to deteriorate. Oxygen is essential for the production of ATP, which is the energy currency of the cells, including cardiac muscle cells. Without sufficient oxygen, the cells can enter a state of ischemia, leading to impaired function and, eventually, cell death if the deprivation continues.

This process can result in various problems for the heart, including decreased contractility, arrhythmias, and in severe cases, myocardial infarction (heart attack). If a significant portion of the heart muscle is affected and not revived, it could lead to cardiac arrest, where the heart stops pumping blood effectively. Thus, the deterioration and the risk of cardiac arrest reflect the critical role oxygen plays in maintaining heart health and function.