PMC5420013_01
The upper image shows the pre-coronary artery bypass graft (CABG) chest radiograph demonstrating the position of the subcutaneous implantable cardioverter-defibrillator sternal lead and generator. The upper red arrowhead points to the distal tip of the subcutaneously tunneled sensing electrode of the sternal lead, the middle red arrowhead points to the shock coil of the lead, and the lower red arrowhead points to the subxiphoid proximal sensing electrode and anchoring sleeve position of the lead. The long red arrow points to the transthoracic portion of the subcutaneously tunneled lead and the blue triangle points to the implanted position of the generator of the subcutaneous defibrillator. The lower pictured electrocardiogram shows a pre-CABG tracing from the lead II vector configuration of the subcutaneous recording from the distal electrodes to the can, demonstrating adequate QRS/T-wave ratio of 5:1, demonstrated by the superimposed orange discrimination template.
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A chest radiograph revealed normal S-ICD lead and generator positions and the electrogram recording from the S-ICD lead demonstrated normal sensing function (Figure 1). Pre- and post-vector analysis of the QRS and T-wave amplitudes was measured from the S-ICD lead and the results met acceptable criteria along all measured vectors for effective QRS and T-wave discrimination (Figure 1, Figure 2).
The upper image shows the post-coronary artery bypass graft (CABG) chest radiograph demonstrating the position of the subcutaneous implantable cardioverter-defibrillator lead and generator. The upper red arrowhead points to the distal tip of the subcutaneously tunneled sensing electrode of the sternal lead carefully placed to avoid any possible contact with the sternal wires that could contribute to noise sensing, the middle red arrowhead points to the shock coil of the lead, and the lower red arrowhead points to the subxiphoid proximal sensing electrode and anchoring sleeve of the lead, which was exposed but not released during the surgery, therefore retaining the exact same position post-CABG. The transthoracic portion of the subcutaneously tunneled lead and implanted position of the generator of the subcutaneous defibrillator remain unaltered by the surgery. The lower pictured electrocardiogram shows a post-CABG tracing from the lead II vector configuration of the subcutaneous recording from the distal electrodes to the can, demonstrating a slightly diminished but still adequate QRS/T-wave ratio of 3:1, demonstrated by the superimposed orange discrimination template. At repeated outpatient testing post-discharge the QRS/T-wave ratio was back to the 5:1 baseline.
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S-ICD lead that was lying in the field of a standard median sternotomy incision. S-ICD lead positioning was undertaken to assure that the distal or proximal sensing electrode was not in contact with any sternal wires (Figure 2). Pre- and post-vector analysis of the QRS and T-wave amplitudes was measured from the S-ICD lead and the results met acceptable criteria along all measured vectors for effective QRS and T-wave discrimination (Figure 1, Figure 2).
Intraoperative photograph demonstrating the post-coronary artery bypass graft replacement of the sternal lead, after sternal wiring and thoracic cavity closure had been completed, but before subcutaneous and skin layers had been closed.
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The lead was nested into a central position (Figure 3) above which the subcutaneous and skin layers were closed in the standard fashion.