Tall T waves during metabolic acidosis without hyperkalemia: A prospective study

The specific ECG characteristics of metabolic acidosis have not been satisfactorily defined in man. We addressed this question by prospectively studying 14 consecutive patients admitted with metabolic acidosis and without hyperkalemia. Arterial blood gas analysis and serum potassium determinations were performed during acidosis and after its correction. ECGs were recorded at the same times. Mean pHa increased from 7.11 ± 0.05 to 7.40 ± 0.01 (p < .001) in response to an increase in total CO2 content from 6.8 ± 1.4 to 21.2 ± 0.7 mmol/L (p < .001). Serum potassium concentration decreased only slightly after correction of the acidosis from 4.2 ± 0.1 to 3.9 ± 0.14 mmol/L (p < .05). T waves were taller during acidosis than after correction (0.68 ± 0.1 vs. 0.28 ± 0.04 mV. p < .001 and 0.64 ± 0.08 vs. 0.38 ± 0.04, p < .005, in precordial leads V2 and V3, respectively). Moreover, the amplitude of T waves in V2 was correlated positively with the arterial concentration of H (r = 786, p < .001) and negatively with the arterial total CO2 content (r = -.71, p < .005). In addition to their augmented amplitude, T waves were peaked and symmetrical with a narrow base (“tent-shaped”). Thus, metabolic acidosis may be accompanied by an increase in the amplitude of T waves, even in the absence of hyperkalemia.