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
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 ...