Discussion

These are examples of irreversible cell injury.

It is difficult to define a "point of no return" but once changes to the nucleus take place (i.e. pyknosis, karyorrhexis and karyolysis) and cell membranes are disrupted the cell is on the path to irreversible injury and death.

In heart muscle, episodes of ischemia or reduced blood flow, if of short duration, may produce periods of pain and shortness of breath (angina), but if prolonged will result in death of the cardiac muscle cells and heart attack or myocardial infarction. The underlying cause is almost always due to narrowing of the coronary blood vessels due to atherosclerosis (as in this case).

In this case the injury to the liver and kidneys is secondary to the primary injury in the heart. Failure of the heart affects many other organs, most significantly liver and kidneys.
Irreversible cell injury in liver cells (hepatocytes).
In acute right-sided heart failure (as in this case) the hepatic veins and sinusoids are engorged resulting in a characteristic 'nutmeg' pattern. The periphery of the liver acinus (zone 3) is affected first. The cells from the perivenular area suffer from both mechanical hydrostatic pressure and lack of adequate oxygen supply.

Irreversible cell injury in kidney (renal tubular cells).
Ischemic ATN (acute tubular necrosis) is focal and affects the nephron at multiple points with large skip areas in between. ATN is a major cause of acute renal failure. The morphological changes of this type of injury (ischemic) in the kidney include (e.g. increased cytoplasmic eosinophilia, loss of RNA basophilia, denaturation of proteins & nuclear changes - pyknosis, karyolysis, and karyorrhexis).

These changes are not exclusive to circulatory failure due to heart falure, but may also occur in many other conditions, e.g. severe trauma, surgical operations, hemorrhage, pulmonary embolism. The extent of the changes can be related to the duration of the shock state. If less than 10 hours, lesions are unusual, but if existing for longer than 24 hours, hepatic cell necrosis is always present.