Irreversible cellular injury and membrane damage

[Cardiochick]

Hello
So I'm studying cellular injury and something just doesn't click in my head
One of the examples for irreversible cellular injury is when the plasma membrane of the cardiac cells get damaged and as a result the cardiac enzyme troponin and other enzymes will be released into the blood! its clearly stated in the Pathoma lectures that this is a sign for irreversible damage!
Now my question is then how is it that in the initial hours of MI the damage can be reversed by PCI or thrombolytic therapy and during these initial hours we have a positive troponin test??!
Does it mean that when we have a positive troponin test we can't reverse the damage??!
Appreciate any feedback

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[aspiringmd1015]

you cant reverse any Irreversible cellular injury, it says it in the name. If the damage is reversible, then obviously you can reverse it. By giving fibrinolytic rx/ptca you prevent further damage, and prevent reversible damage from going to irreversible.

 

[Cardiochick]

you cant reverse any Irreversible cellular injury, it says it in the name. If the damage is reversible, then obviously you can reverse it. By giving fibrinolytic rx/ptca you prevent further damage, and prevent reversible damage from going to irreversible.

Thanks for the input, and while I do agree with you and I think we can say that when we say irreversible that means IRREVERSIBLE!
But my question is that while the above point is a fact! But I just can't correlate it with MI !
Since as a protocol for managing MI we have to do cardiac enzyme testing after Ecg
And classically there should be a positive troponin test then in that case that means irreversible damage has occurred! Then why bother doing PCI or giving thrombolytic therapy?!

 

[aspiringmd1015]

To break the thrombus/other thrombi that caused the damage.

 

[Transposony]

Thanks for the input, and while I do agree with you and I think we can say that when we say irreversible that means IRREVERSIBLE!
But my question is that while the above point is a fact! But I just can't correlate it with MI !
Since as a protocol for managing MI we have to do cardiac enzyme testing after Ecg
And classically there should be a positive troponin test then in that case that means irreversible damage has occurred! Then why bother doing PCI or giving thrombolytic therapy?!

As you said irreversible injury cannot be reversed since those cells have spilled their guts and died.
The aim of PCI / thrombolytic therapy is to save the cells which have not yet reached the point of no return i.e. reversible injury since cells are in different stages of ischemia at a given time due to alternative blood supply. For example, the cells at the center of the area supplied by the occluded artery are more likely to sustain an irreversible injury compared to the myocytes at the periphery since there is always an overlap in the blood supply from the adjacent areas. However, that blood supply is only "buying some time" and is not sufficient for them to survive over a long period of time. That's why there is a door-to-balloon time of <90 min since the MI is still "evolving" at this stage.
Cardiac enzymes will still be raised by those cells which have sustained the irreversible damage but that doesn't mean that all the cells supplied by the occluded artery are dead.

 

[Cardiochick]

Thanks for the clarification Transposoy!

 

[Cardiochick]

Thanks aspiringmd1015