Treatment of a Paroxysmal Atrioventricular Block by Implantation of a Bipolar, Single-Chamber Cardiac Pacemaker in a Donkey

SIMPLE SUMMARY: A two-year-old donkey showed repeated signs of collapse. Detailed examinations identified an arrhythmia as the cause. This special form of arrhythmia is called paroxysmal atrioventricular block in human medicine. In this type of arrhythmia, the contraction of the heart chambers is missing in certain phases. The paroxysmal AV-block episodes were terminated by ventricular escape beats. This type of arrhythmia has not yet been described in donkeys or horses. For therapy, a cardiac pacemaker was implanted to prevent the donkey from collapsing again. Detailed information on the implantation procedure, the anesthesia protocol, and the follow-up is presented. The donkey was in good health over 17 months of follow-up and has not collapsed since. ABSTRACT: Case Summary: A two-year-old donkey presented with recurrent syncope. Electrocardiography revealed periods without any atrioventricular conduction and without any ventricular escape rhythm with a duration of up to one minute. Finally, atrioventricular conduction resumed spontaneously with a preceding ventricular escape beat. Laboratory tests and echocardiography identified no reversible cause. The diagnosis of a paroxysmal atrioventricular block (PAVB) was made. Therefore, a single-chamber cardiac pacemaker was implanted under general anesthesia. The device was programmed in the VVI mode to prevent further syncope. The therapy was considered successful as the donkey revealed no further syncope during the follow-up period of 17 months. Clinical relevance: Clinically relevant bradycardia is rare in equids. This is the first report to our knowledge to describe a PAVB, a term commonly used in human medicine, in a donkey. Detailed information about the diagnosis and the successful therapy is included, with a special focus on the implantation and programming of the permanent pacemaker.