Investigation of ventricular pre-excitation electrocardiographic pattern in two horses: clinical presentation and potential causes.

This research article discusses the study of two horses exhibiting an irregular heart pattern, ventricular pre-excitation, possibly due to low magnesium levels. The study found reduced occurrences of this aberrant cardiac rhythm following magnesium supplementation.

Background and Purpose of the Study

• The study was conducted on two horses that were brought for unrelated health issues to the Unitat Equina, Fundació Hospital Clínic Veterinari, Universitat Autònoma de Barcelona. Both horses didn’t have any known history of cardiac disorders.
• The horses displayed an irregular heart rhythm, specifically an intermittent ventricular pre-excitation electrocardiographic pattern, during their hospital stay.
• The researchers aimed to understand the clinical implications of this heart pattern and its potential causes.

Research Findings

• Both horses were found to have decreased plasma total and ionized magnesium concentrations. No other significant electrolyte imbalances were detected.
• An abnormal movement of the wall separating the two ventricles of the heart, associated with ventricular pre-excitation beats (VPBs), was identified in both horses through M-mode echocardiography.
• Using pulsed-wave tissue Doppler imaging, the likely location of an accessory pathway (AP), an abnormal electrical heart pathway, was determined in the second horse. This was detected in the left anterior paraseptal location.
• A decrease in the frequency of the VPB was noticed when the horses were given magnesium supplementation and their plasma magnesium levels were restored to normal.

Conclusion

• The researchers concluded that the irregular heart pattern observed in the horses was probably due to the greater sensitivity of the AP to low magnesium levels.
• Magnesium supplementation was found effective in reducing the occurrence of this heart rhythm disorder.

Significance

• This study is significant because it links hypomagnesemia (lower magnesium levels) with ventricular pre-excitation, an abnormal heart rhythm. This finding can have important implications for the diagnosis and treatment of heart rhythm disorders in horses.
• The research also highlights the therapeutic potential of magnesium supplementation in managing these disorders.