Description:
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<jats:title>Background:</jats:title>
<jats:p>A completely extracardiac pacing system provides the potential for clinical advantages over existing device alternatives that require intravascular, endocardial, or epicardial contact. Preliminary studies evaluating the feasibility of cardiac pacing with a lead in the anterior mediastinum, outside the pericardium and circulatory system have been completed. These studies examined (1) the anatomic access route, (2) the usability of a delivery tool to facilitate lead placement, and (3) the pacing performance of the extracardiac lead.</jats:p>
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<jats:title>Methods:</jats:title>
<jats:p>Feasibility evaluations included (1) a retrospective computed tomography analysis to characterize anatomic variations related to lead access, (2) accessing the anterior mediastinum in cadavers and human subjects using a custom delivery tool, and (3) acute clinical pacing performance.</jats:p>
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<jats:title>Results:</jats:title>
<jats:p>Major findings: (1) A total of 166 (95%) out of 174 patients had a viable lead access path through the fourth, fifth, or sixth intercostal space. (2) Access to the targeted implant location using a delivery tool was successful in all 5 cadavers and 3 humans without use of fluoroscopy and with an average lead delivery time of 121±52 s. No damage to the lung, pericardium, heart, or internal thoracic vessels occurred. (3) Pacing performance was tested in 6 human subjects showing a threshold voltage of 4.7 V (2.7–6.7), threshold pulse width of 1.8 ms (1.0–2.5), and an impedance of 1205 Ω (894–1786). R-wave amplitudes measured 9.6 mV (5.6–12.0).</jats:p>
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<jats:title>Conclusions:</jats:title>
<jats:p>Results support the feasibility for this completely extracardiac pacing method in a heterogeneous patient population, using a minimally invasive, parasternal, delivery approach and with adequate sensing and thresholds suited for temporary pacing.</jats:p>
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