I've read several threads on SDN and other sites about the physiology of T-wave inversions in myocardial ischemia, but have a few lingering questions I hoped someone could answer (and correct errors in my thinking).
To my understanding, the positive morphology of T-waves is a product of two factors.
1) Repolarization occurs in a reverse fashion, with the epicardium repolarizing before the endocardium. This results in a net negative charge traveling away from your positive leads and resulting in a net positive deflection
2) The septum and deep endocardium have a longer depolarization, and subsequently repolarize later than the apex, leading to a net "upwards" direction of repolarization of lateral ventricular walls --> apex --> septum, resulting in a negative charge moving away from the electrode and a positive deflection on the ECG.
Ok, so if all this is true (feel free to correct if not), help me with the following...
Ischemic events primarily affect endocardium, and in essence switch the direction of net intramural repolarization from outwards --> inwards to inwards --> out. This would result in the net negative charge of repolarization moving towards the positive electrode, resulting in the inverted T-wave pattern.
BUT
How about point #2? Wouldn't overall repolarization still proceed in an upwards fashion? If so, I'd think that would still result in a positive T-wave. What exactly leads to the inverted T-wave morphology? And why do you not see concordance in the early precordial leads?
Thank you in advance!
To my understanding, the positive morphology of T-waves is a product of two factors.
1) Repolarization occurs in a reverse fashion, with the epicardium repolarizing before the endocardium. This results in a net negative charge traveling away from your positive leads and resulting in a net positive deflection
2) The septum and deep endocardium have a longer depolarization, and subsequently repolarize later than the apex, leading to a net "upwards" direction of repolarization of lateral ventricular walls --> apex --> septum, resulting in a negative charge moving away from the electrode and a positive deflection on the ECG.
Ok, so if all this is true (feel free to correct if not), help me with the following...
Ischemic events primarily affect endocardium, and in essence switch the direction of net intramural repolarization from outwards --> inwards to inwards --> out. This would result in the net negative charge of repolarization moving towards the positive electrode, resulting in the inverted T-wave pattern.
BUT
How about point #2? Wouldn't overall repolarization still proceed in an upwards fashion? If so, I'd think that would still result in a positive T-wave. What exactly leads to the inverted T-wave morphology? And why do you not see concordance in the early precordial leads?
Thank you in advance!
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