Changes in T wave morphology during hypercalcemia and its relation to the severity of hypercalcemia

Not all ST-segment changes are myocardial injury: hypercalcaemia-induced ST-segment elevation

“…The equilibrium of the outward K flow through the delayed rectifier potassium channel and the inward calcium flow through the L-type calcium channels are the likely aetiology 36. Another possible mechanism noted by Ashizawa et al involves how hypercalcaemia can lead to a biphasic or flattened T wave appearing as ST-segment elevation 37 38. The aetiology of these specific ECG changes is due to hypercalcaemia's effect on action potential repolarisation or its effect on other cations that transfer across the myocardial cell membrane 37 38…”

High [Ca2+]o-induced electrical heterogeneity and extrasystolic activity in isolated canine ventricular epicardium. Phase 2 reentry.

“…Clinical hypercalcemia, whether secondary to hyperparathyroidism, neoplastic disease, or other causes, is usually characterized by a prolongation of A-V conduction time, widening of the QRS interval, the appearance of a J wave or Osborne wave, abbreviation of the ST segment, and, particularly in patients with extreme hypercalcemia (> 16 mg/dL; normal value, 8.2 to 10.4 mg/dL), changes in the morphology (biphasic, notched), polarity (inverted), and amplitude (flat) of the T wave of the surface ECG. 56 Most if not all of these changes can be explained based on the differential effects of high calcium in canine ventricular epicardium and endocardium. The calcium-induced accentuation of the action potential notch in epicardium can account for the appearance of a J wave, the slight slowing of conduction for the widening of the QRS, and the disparate effects on APD90 in epicardium and endocardium for the inversion or flattening of the T wave.14 Possible Limitations of the Study Although some of the results of the study are discussed in terms of changes in intracellular calcium levels, we clearly have not demonstrated an increase in Ca, in either epicardium or endocardium after exposure to high [Ca'2+] and rapid pacing.…”

Severe Hypercalcemia Mimicking ST-Segment Elevation Myocardial Infarction

“…It is important to note that hypercalcemia may cause other electrocardiographic abnormalities that can mimic myocardial ischemia including inverted, biphasic, notched, or flattened T waves. 11,25 Figure 2 demonstrates a characteristic flattened T-wave as the elevation of the ST segment resolved. In addition to hypercalcemia there are other important causes of ST segment elevation (Table 4).…”