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CARDIAC pacing is an intervention that provides effective ventricular beats when intrinsic ventricular activity is not able to maintain haemodynamic stability. Cardiac pacing is used in both human and veterinary medicine for the treatment of symptomatic bradycardia ( ACC/AHA/HRS Writing Committee and ACC/AHA Task Force 2008 , Oyama and Sisson 2009 ). The technique has been studied since the late 1800s ( McWilliam 1889 ). Both temporary invasive and non-invasive transcutaneous external pacing (TEP) have been in use since the 1950s ( Callahan and Bigelow 1951 , Zoll 1952 ), and permanent pacing was introduced soon afterwards ( Elmqvist and Senning 1960 ). TEP has been successfully used for the treatment of Morgagni-Adams-Stokes disease (a sudden loss of consciousness due to complete atrioventricular block [AVB]) in human beings ( Zoll and others 1954 ). During TEP, an electrical current passes from an external pulse generator via a conducting cable and self-adhesive electrodes through the thorax, and stimulates the heart to depolarise and contract. A modified transcutaneous external pacemaker with a large electrode surface area and longer pulse duration has been shown to increase patient comfort by reducing the current required for capture of the ventricle ( Zoll and others 1981 ). TEP can be used in the emergency setting for transient conduction disturbances, prophylactically for anticipated dysrhythmias, or as a therapeutic bridge until permanent pacing can be provided. The technique is occasionally used for non-invasive overdrive pacing to terminate supraventricular or ventricular tachycardias ( Grubb and others 1993 ). Temporary pacing may result in increased survival in human beings with symptomatic bradyarrhythmias ( O'Toole and others 1987 ).
Temporary transvenous pacing (TTP) is widely used in clinical veterinary medicine ( Gelzer and Kraus 2009 ). In contrast, there is little published material ( DeFrancesco and others 2003 ) on the use of TEP in clinical practice, in dogs that underwent pacemaker implantation (PMI), ophthalmic surgery, and as an emergency treatment for haemodynamically unstable third-degree AVB. Lee and others ( 2008 ) have described the optimal size and placement of transdermal electrodes in dogs.
The aim of this retrospective study was to evaluate the utility of TEP during PMI in dogs referred to the authors' electrophysiology laboratory because of symptomatic bradycardia.
Materials and methods
Case series