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INTRODUCTION

Emergency cardiac pacing can be accomplished by several methods. These include epicardial, esophageal, transcutaneous, transthoracic, and transvenous pacing. Emergency cardiac pacing can be a temporizing and lifesaving technique that should be familiar to Emergency Physicians.1-3 It will allow the patient to maintain a cardiac rhythm while providing oxygen and nutrients to the vital organs.

The earliest use of electricity to stimulate the heart can be found in an essay written in the late 1700s.4 It discusses the use of electric current and artificial ventilation to revive victims of drowning. Transvenous pacing was first attempted on dogs in 1905. The transvenous approach in humans was developed in 1959 using a stiff pacing wire. Semiflexible pacing wires were developed in 1964 and were placed using fluoroscopic guidance. The demand pacemaker was developed in 1966. Catheter technology improved with the semi-floating catheter in 1969 and the balloon tip catheter in 1973. The technology and technique have since been developed to allow successful transvenous cardiac pacing in humans. It involves the placement of a pacing wire through the central venous circulation and into direct contact with the myocardium of the right ventricle.

ANATOMY AND PATHOPHYSIOLOGY

The heart is the only muscle of the body that generates its own electric impulses (Figure 43-1). Its automaticity and subsequent rhythmic contractions propel blood to the tissues of the body. The initial cardiac impulse starts in the right atrium of the heart at the sinoatrial (SA) node. The sympathetic and parasympathetic nervous systems control the rate of impulse generation at the SA node. The electric stimulus is conducted along the internal conduction pathways of the heart to the muscular atrial and ventricular walls. A delicate balance between electrolyte flux to create action potentials, myocardial integrity to allow impulses to become contractions, and an intact conduction system must be maintained. Conduction system problems are often the result of inadequate blood flow to the heart due to ventricular infarction and coronary artery occlusion. The blood supply to the conduction system of the heart usually originates from the right coronary artery. Occlusion of the right coronary artery can result in arrhythmias and conduction delays.

FIGURE 43-1.

Conduction system of the heart. (Used from Madhero88, www.commons.wikimedia.org.)

A transvenous pacing catheter may be introduced through the femoral, internal jugular, or subclavian veins.5 The right internal jugular vein and left subclavian vein are the recommended sites (Figure 43-2). These routes allow a more direct and easy access for the pacing catheter to enter the right ventricle. The right internal jugular vein is preferred. It allows a relatively straight line of access through the superior vena cava and right atrium into the right ventricle.6 The left subclavian vein is a good second choice if access to the ...

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