Transcutaneous Pacing

Chapter 52 Transcutaneous Pacing



Teresa DeFrancesco, DVM, DACVIM (Cardiology), DACVECC



KEY POINTS



• Transcutaneous pacing (TCP) is a noninvasive modality of cardiac pacing in which patch electrodes are placed on the skin of the right and left hemithorax at the cardiac precordium. A current passed between these electrodes causes both electrical and mechanical capture of the heart.

• Indications for TCP are similar to those for temporary transvenous cardiac pacing—that is, emergency management of medically refractory and hemodynamically significant bradyarrhythmias, and support of heart rate and blood pressure of patients with sick sinus syndrome or high-grade atrioventricular block undergoing general anesthesia, typically for permanent pacemaker implantation.

• TCP is preferred over transvenous pacing in life-threatening situations because of the shorter time to implementation.

• The most common complications of TCP in dogs are discomfort and musculoskeletal stimulation associated with the pacing stimulus, which requires heavy sedation or general anesthesia. These limit its use for short-term temporary cardiac pacing.


INTRODUCTION


Transcutaneous pacing (TCP) is a noninvasive mode of temporary pacing used in patients with life-threatening, medically refractory bradyarrhythmias. TCP is also used to support cardiac output in patients with medically refractory bradyarrhythmias that are undergoing general anesthesia, typically but not exclusively for permanent pacemaker implantation. TCP is an attractive alternative to transvenous cardiac pacing for short-term pacing. Although transvenous cardiac pacing is well tolerated by most patients, it is an invasive procedure requiring considerable operator skill, and its use has been associated with serious complications in humans such as arrhythmias, infection, lead dislodgement, cardiac perforation, hemorrhage, and thromboembolism.1,2


TCP is preferred in emergency situations because of the shorter time to cardiac pacing.3 TCP does not require vascular access. Vascular access, even with an experienced operator, can cause unacceptable delays in initiation of cardiac pacing. TCP was introduced in human patients during the 1950s and has been used routinely in acute care settings for approximately 20 years.4,5 It was first described for use in client-owned dogs with medically refractory bradyarrhythmias in 2003.6 Because of the cost of the equipment needed to implement TCP, the procedure usually is available only at selected university and private specialty veterinary hospitals.



INDICATIONS FOR TRANSCUTANEOUS PACING


Indications for TCP include emergency treatment of medically refractory and life-threatening bradyarrhythmias. Typical case scenarios include dogs with hemodynamically unstable complete AV block. In the author’s experience, the dogs in this category are those with erratic ventricular escape rhythms in which many seconds can elapse with no ventricular contraction. TCP is also useful for an in-hospital cardiac arrest due to complete AV block or other medically refractory bradycardias in which a meaningful recovery can be expected.


A second indication for TCP is support of heart rate and blood pressure in dogs undergoing general anesthesia for permanent pacemaker implantation. Candidates are generally dogs with high-grade AV block or symptomatic sick sinus syndrome. TCP can also be used for permanent pacemaker replacement or readjustment of a dislodged lead wire. These dogs generally are hemodynamically stable at rest but have the potential for low cardiac output and even cardiac arrest while under general anesthesia. The TCP system typically is placed just before induction of general anesthesia and is in a ready state to implement for asystole, or simply for support of cardiac output if hypotension or extreme bradycardia occurs during the anesthetic period.


A third indication for TCP is support of heart rate and blood pressure in dogs with clinically silent sinus node dysfunction that have experienced an episode of profound and medically refractory bradycardia while undergoing general anesthesia. Typically these dogs were undergoing anesthesia for surgery unrelated to the heart, such as cataract extraction or cystotomy for urolithiasis removal, which was aborted because of the medically refractory and life-threatening bradycardia. If the owner or the dog’s clinical status dictates that the surgery be reattempted, these dogs usually require temporary cardiac pacing to tolerate the anesthesia. The author generally does not recommend permanent pacemakers in dogs with asymptomatic sinus node dysfunction. The author believes TCP is a better option than transvenous cardiac pacing in these surgical cases because of its noninvasive nature and lower risk for infection.

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  4. Allergic Airway Disease in Dogs and Cats and Feline Bronchopulmonary Disease

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Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Transcutaneous Pacing

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