Electrocardiographic findings in 130 hospitalized neonatal calves with diarrhea and associated potassium balance disorders

Abstract

Background: Hyperkalemia in neonatal diarrheic calves can potentially result in serious cardiac conduction abnormalities and arrhythmias.

Objectives: To document electrocardiographic (ECG) findings and the sequence of ECG changes that are associated with increasing plasma potassium concentrations (cK⁺ ) in a large population of neonatal diarrheic calves.

Animals: One hundred and thirty neonatal diarrheic calves (age ≤21 days).

Methods: Prospective observational study involving calves admitted to a veterinary teaching hospital.

Results: Hyperkalemic calves (cK⁺ : 5.8-10.2, blood pH: 6.55-7.47) had significantly (P < .05) longer QRS durations as well as deeper S wave, higher T wave, and higher ST segment amplitudes in lead II than calves, which had both venous blood pH and cK⁺ within the reference range. The first ECG changes in response to an increase in cK⁺ were an increase in voltages of P, Ta, S, and T wave amplitudes. Segmented linear regression indicated that P wave amplitude decreased when cK⁺ >6.5 mmol/L, S wave amplitude voltage decreased when cK⁺ >7.4 mmol/L, QRS duration increased when cK⁺ >7.8 mmol/L, J point amplitude increased when cK⁺ >7.9 mmol/L, and ST segment angle increased when cK⁺ >9.1 mmol/L. P wave amplitude was characterized by a second common break point at cK⁺ = 8.2 mmol/L, above which value the amplitude was 0.

Conclusions and clinical importance: Hyperkalemia in neonatal diarrheic calves is associated with serious cardiac conduction abnormalities. In addition to increased S and T wave amplitude voltages, alterations of P and Ta wave amplitudes are early signs of hyperkalemia, which is consistent with the known sensitivity of atrial myocytes to increased cK⁺ .

Keywords: acidemia; calves; electrocardiography; hyperkalemia; hypokalemia.