[Single-lead bipolar electrocardiography in the diagnosis of heart diseases].

The research article focuses on using single-lead bipolar electrocardiography to diagnose heart diseases in race horses. The study involved 67 thoroughbred horses of varying ages and training lengths, with the evaluation of various time and voltage measurements linked to heart rhythms. These measurements were then correlated to the presence of heart blocks and other heart conditions to understand the effect of training on heart health in these animals.

Study Participants and Examination Method

• The study utilized 67 thoroughbred race horses as the subjects. These animals represented various age categories, and their respective training lengths matched these categories.
• The horses were examined using bipolar lead-apex of the heart — withers electrocardiography.

Electrocardiographic Evaluation

• The research team conducted a statistical evaluation of basic time and voltage criteria of EKG, interpreting them according to the recorded electrocardiographic curves.
• Measurements included: TF (heart rate) = 35.1 +/- 6.82 pulses per min, time P (atrial systole) = 0.16 +/- 0.03 sec, PQ (the time the electrical impulse takes to travel from the sinus node through the AV node) = 0.03 +/- 0.04 sec, QRS (reflecting the spread of a signal through the heart’s ventricles) = 0.12 +/- +/- 0.01 sec, TQc (isoelectric line between T and Q waves in ECG) = 0.50 sec, R (a positive deflection in the QRS complex) = 2.83 +/- 0.63 mV, and Q (a negative deflection preceding the R wave) = 0.38 +/- 0.31 mV.

Detected Heart Conditions

• Among the horse population studied, 14.93% displayed AV block I (a delay or blockage in the conduction system between the atria and ventricles), 2.98% had AV block II (an intermittent failure of some atrial action potentials to reach the ventricles), 1.49% showed sinoauricular block II (a delay or disconnection between the sinus node and the atrial myocardium), and another 1.49% had auricular fibrillation (an irregular and often rapid heart rate).

Key Findings and Discussion Points

• A major finding of the study was that the repolarization phase of the chamber complex, particularly the T wave, was the most variable component of the whole EKG.
• The researchers also attempted to associate the basic EKG values and the occurrence of arrhythmia with the rate of the training of the horses.
• This study might lay groundwork for further investigation into the effect of training on the cardiac health of race horses, and how electrocardiography can aid in early detection of heart diseases in these animals.