An Exploratory Study on Vectorcardiographic Identification of the Site of Origin of Focally Induced Premature Depolarizations in Horses, Part II: The Ventricles.
Authors: Van Steenkiste Glenn, Delhaas Tammo, Hermans Ben, Vera Lisse, Decloedt Annelies, van Loon Gunther
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Ventricular premature depolarisations (VPDs) occur regularly in horses, yet identifying their anatomical origin remains clinically challenging because equine cardiac conduction differs substantially from humans, limiting the applicability of standard human electrocardiographic criteria. Van Steenkiste and colleagues used vectorcardiography (VCG)—a three-dimensional analysis of electrical activity derived from standard 12-lead ECG data—to determine whether pacing-induced VPDs from different ventricular sites (apex, mid and high septum, mid and high free wall, and right ventricular outflow tract) produced distinct electrical signatures in seven anaesthetised horses, with catheter placement confirmed by electro-anatomical mapping and echocardiography. The researchers found that both the initial and maximum electrical axes of the QRS complex differed significantly (p < 0.05) between pacing locations and between induced VPDs and sinus rhythm, suggesting distinct spatial patterns based on origin point. These findings indicate that VCG analysis could provide equine practitioners with a non-invasive, ECG-based method to localise the source of ectopic activity in clinical cases, potentially guiding targeted management strategies or identifying underlying structural pathology; however, further validation in conscious horses with spontaneous VPDs will be necessary to confirm clinical utility.
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Practical Takeaways
- •Vectorcardiography may provide equine practitioners with a more reliable diagnostic tool than standard 12-lead ECG for identifying the specific site of origin of ventricular arrhythmias, potentially enabling more targeted therapeutic interventions
- •This technique could improve the diagnostic workup and prognosis assessment of horses presenting with clinically significant ventricular ectopy by pinpointing anatomical origin
- •Results suggest the equine heart's conduction system requires species-specific diagnostic approaches; VCG characteristics cannot be directly extrapolated from human cardiology protocols
Key Findings
- •Vectorcardiography (VCG) successfully differentiated pacing-induced ventricular premature depolarizations from seven anatomically distinct locations in equine ventricles based on initial and maximum electrical axes
- •Pacing at different ventricular sites (apex, mid/high septum, mid/high free wall, right ventricular outflow tract) produced significantly different VCG characteristics (p < 0.05)
- •VCG-derived electrical axes differed significantly between paced rhythms and sinus rhythm in all horses studied
- •VCG is proposed as a useful diagnostic technique for identifying the anatomical origin of ventricular ectopy in horses, addressing limitations of 12-lead ECG alone in this species