Transthoracic cardiac pacing is a historic technique of pacing the heart with an electrode introduced percutaneously into the ventricular cavity using a needle trocar introducer. There is sparse literature on transthoracic cardiac pacing, and the benefits and complications are not well defined. Before the advent of effective and efficient transcutaneous pacing, transthoracic pacing was a faster alternative to transvenous pacing in the patient with an acutely unstable dysrhythmia. Presently, the indications for transthoracic pacing are extremely rare. The technique of transthoracic pacing is included in this text as it is occasionally performed in situations where transcutaneous pacing is unavailable or ineffective.1–3
The history of electrical stimulation of the heart dates back to 1862 when Walsh discussed the possibility of causing the heart to contract through stimulation of the sympathetic nervous trunk by an induced current.4 By 1910, it was largely understood that the neuromuscular mechanism of the heart was electrically dependant. In 1932, Hyman used a needle electrode to carry stimulating current directly to heart muscle.5 Zoll accomplished the first successful clinical application of external cardiac pacing in 1952 by resuscitating two patients in asystole following bradycardia from a high-degree AV block.6 He concluded that external cardiac pacing was a safe and effective means of resuscitating ventricular standstill. Unfortunately, Zoll's devices caused significant chest pain, skeletal muscle spasm, superficial skin burns, and disrupted electrocardiographic patient monitoring.6 The quest for alternative pacing modalities continued with the refinement of the transesophageal technique, initially suggested by Zoll in 1952, and clinically demonstrated by Shafiroff and Linder in 1957.7 In 1958, Thevenet et al. reported the emergency use of a lumbar puncture needle introduced 5 mm into the myocardium, through which a conducting wire was introduced, to produce transthoracic cardiac pacing.8 In 1959, Furman and Robinson passed a transvenous wire catheter and successfully applied an electrical current to the endocardial surface of the right atrium.9 Transvenous pacing subsequently became the most widely accepted method of emergency cardiac pacing until the reemergence of Zoll with a modified external pacing system in 1981.10
The heart is the only muscle of the body that generates its own electrical impulses. 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. The blood supply to the conduction system of the heart originates from the right coronary artery. Arrhythmias and conduction delays are often the result of inadequate blood flow to the heart due to ventricular infarction and coronary artery occlusion.
Considering the proven ...