Irregularities of heart rhythm may impact on peak performance. Conditions such as atrial fibrillation, with uncoordinated muscle contractions, result in reduced cardiovascular efficiency.
Traditionally, treatment for atrial fibrillation was based on medication with quinidine sulphate. Although often effective, it may be associated with a high risk of side effects.
A promising new treatment for atrial fibrillation, transvenous electric cardioversion, is now available at the University of Veterinary Medicine in Vienna. Targeted electric shocks are used to return the heart to its normal rhythm.
The new therapy, which is among the routine treatment options in humans, is now offered by the Department for Equine Internal Medicine to their animal patients.
Jessica Cavalleri, head of the Department of Equine Internal Medicine explains that electric shocks are administered directly to the heart to reorient the muscle’s electrical activity.
Special catheters, which can measure blood pressure, are used to introduce the electrodes to the heart. Pressure differences between the pulmonary artery, right atrium and right ventricle help confirm the electrodes are correctly placed.
An ultrasound scan is also used to visualize the catheter in the heart.
Before the horse is finally placed under general anaesthesia, the position of the electrodes is once again checked by means of an X-ray image.
The many control measures are an important safeguard, adds Dr. Hannah Junge, veterinarian of the clinical department.
The horse is then given a first shock under general anaesthesia. Further pulses are given, as necessary. With each shock the current is gradually increased. Values of up to 360 Joules may be required.
The exact timing is important so that no dangerous cardiac arrhythmias are triggered.
Once the heart rhythm reverts to normal, the horse is kept under anaesthesia for a short period of time and then allowed to wake up.
The animal then remains in the clinic for three more days for monitoring. After a rest period of four weeks, a further inspection is carried out. Training can then usually resume.
In contrast to drug treatment, Cavalleri reports that the success rate is slightly higher and the risk of side effects is lower.
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