Noninvasive Transthoracic Temporary Cardiac Pacing in Dogs

Abstract

Temporary cardiac pacing is used in the emergency treatment of life-threatening bradyarrhythmias and for the support of heart rate and blood pressure of patients with sick sinus syndrome or high-grade atrioventricular (AV) block undergoing general anesthesia, typically for permanent pacemaker implantation. We retrospectively evaluated the safety and efficacy of a noninvasive transthoracic external cardiac pacing system in 42 dogs treated for bradyarrhythmias. Optimal placement of the patch electrodes on the skin of the thorax was initially established on 2 anesthetized normal dogs. The optimal electrode placement was determined to be on the right and left hemithoraces, directly over the heart. Afterward, by means of this electrode placement, all 42 dogs treated for bradyarrhythmias in this study were successfully paced with the noninvasive transthoracic system. Dogs ranged in age from 1 to 15 years and weighed between 3.2 and 40 kg. Miniature Schnauzers, German Shepherds, and mixed breeds were most common in the study population. Indications for noninvasive transthoracic pacing included emergency treatment of hemodynamically unstable 3rd-degree AV block (2 dogs); support of heart rate during general anesthesia for permanent pacemaker implantation or lead-wire adjustment (38 dogs); and support of heart rate during general anesthesia for ophthalmologic surgery in dogs with sick sinus syndrome (2 dogs). Complications included pain and skeletal muscle stimulation, which required general anesthesia. We conclude that the noninvasive transthoracic pacing system evaluated is satisfactory for clinical veterinary use.Key words: Advanced atrioventricular block; Bradyarrhythmias; Pacemaker; Sinus node dysfunction.T emporary cardiac pacing is a potentially lifesaving intervention used primarily to correct profound medically refractory bradycardia in hemodynamically unstable patients. Temporary cardiac pacing is also useful prophylactically (or therapeutically) to support heart rate and blood pressure in patients with sick sinus syndrome or high-grade atrioventricular (AV) block undergoing general anesthesia, typically for permanent pacemaker implantation. Transvenous temporary pacing is the only temporary pacing system described in the clinical veterinary literature.1-7 Although transvenous pacing is generally well tolerated by the patient, it is an invasive procedure that requires considerable skill to accomplish, and its use has been associated with potentially serious complications including infection, leadwire displacement, arrhythmias, cardiac chamber perforation, hemorrhage, and thromboembolism. [8][9][10] A noninvasive alternative to transvenous temporary pacing was introduced in human patients in the 1950s.11 After some modifications of the original design, these noninvasive external transthoracic pacing systems have been used for the acute care of humans for nearly 20 years.12-22 Transthoracic pacing is desirable because it is a safe, easy, and noninvasive system for temporary cardiac pacing. After performing an ini...

Use of transcutaneous external pacing during transvenous pacemaker implantation in dogs

“…Local skeletal muscle contraction is occasional a reason for termination of TEP in human beings; modification of the electrodes and reduction of the stimulation threshold reduced its occurrence (Zoll and others 1981). DeFrancesco and others (2003) reported signs of pain and skeletal muscle contraction in all dogs studied, and found that stimulation of skeletal muscles occurred even when TEP was initiated during general anaesthesia. As reported by Lee and others (2008), placement of the pacing electrodes over the left and right fifth to seventh costochondral joint resulted in only minimal twitching of the deep pectoral muscles.…”

“…The use of TEP in clinical veterinary medicine was previously described by DeFrancesco and others (2003) in 42 dogs that underwent PMI, ophthalmic surgery, or emergency treatment for haemodynamically unstable bradyarrhythmias. In the present study, third-degree AVB was the most common indication for, in agreement with previously published data (Sisson and others 1991, Oyama and others 2001, Wess and others 2006, Johnson and others 2007).…”

“…DeFrancesco and others (2003) previously reported the optimal electrode placement in two dogs. Lee and others (2008) evaluated different sizes of electrodes and their placement in 10 beagles; they concluded that electrodes with a surface area of 20 cm 2 , placed over the fifth to seventh left and right costochondral joints, minimised the pacing current, and resulted in the most efficient pacing compared with other placements.…”

“…The use of TEP during surgical procedures, as reported elsewhere (DeFrancesco and others 2003), can be challenging.…”

A fatal complication arising during pulmonic balloon valvuloplasty in a seven‐month‐old female bulldog

“…Defrancesco and others (2003) reported that non-invasive transthoracic temporary pacing was a successful and safe method in the management of clinically relevant bradyarrhythmias in dogs.…”