Chapter 21

The survival rates for all types of cardiac arrest with standard Advanced Cardiac Life Support (ACLS) regimens ranges from 8.5 to 28.5 percent.1–3 Survival rates for patients with asystolic or pulseless idioventricular rhythm are quite low, with mortality rates close to 100 percent.4–6 Obviously, any technique or therapy that improves these statistics would be highly desirable and expected to be associated with poor results.

Transthoracic cardiac pacing is the technique of pacing the heart with an electrode introduced percutaneously into the ventricular cavity using a needle trocar introducer. Bipolar pacing wires are commonly used today. The transthoracic cardiac pacing technique is faster and simpler to implement than transvenous cardiac pacing. It requires no venous access, blood flow, fluoroscopy, or electrocardiograph for guidance.

Although the history of electrical stimulation of the heart dates back to the mid-eighteenth century, Zoll accomplished the first successful clinical application of external cardiac pacing in 1952, utilizing externally applied closed chest pacing for a Stoke-Adams attack.7 Transthoracic cardiac pacing was introduced in 1957 and became popular in the 1960s. With the development of sophisticated transvenous pacemaker electrodes, the technique of transthoracic cardiac pacing fell out of vogue. Recent improvements in the design of the transcutaneous cardiac pacing unit will allow this noninvasive device to be well tolerated by patients. The capture rates for transcutaneous pacing is over 80 percent and hence preferred as the initial mode of cardiac pacing. There is limited literature on transthoracic cardiac pacing; it comprises mostly anecdotal data and retrospective analysis rather than prospective randomized trials. The benefits and complications of transthoracic pacing are not well defined.

The heart is the only muscle of the body that generates its own electrical impulses. 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 system controls the rate of impulse generation at the SA node. Once the electrical stimulus is generated, it 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 originates from the right coronary artery. Occlusion of the right coronary artery can result in arrhythmias and conduction delays.

The indications for transthoracic cardiac pacing are not well described. General guidelines suggest that when the time and clinical situation permits, cardiac pacing should be done using the transvenous route, employing fluoroscopy or a flow-directed pacemaker catheter.9When time is a factor, transthoracic cardiac pacing may be performed if a transcutaneous pacemaker is ...

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