Hybrid Long-Term Temporary Pacing

Temporary pacemakers are associated with high complication rates, and if pacing is required for more than 24 hours, the need for repeat intervention to reposition the lead or re-site the venous access is relatively commonplace.^1-4 We describe a case where an alternative approach was taken to anticipated prolonged temporary pacing. Case Report A 79-year-old man presented to hospital with a history of weight loss and fever. He had undergone aortic valve replacement with a porcine prosthesis two years prior for infective endocarditis. On examination he appeared anemic, cachectic and was febrile. There was a soft murmur in the aortic area. ECG showed left bundle branch block (LBBB), left axis deviation and borderline first degree atrioventricular block (PR 200 ms). Transthoracic and trans-esophageal echocardiography showed evidence of an aortic root abscess and prosthetic aortic valve endocarditis. Methicillin resistant Staphylococcus Aureus (MRSA) was subsequently isolated in blood cultures, and appropriate antibiotic therapy was commenced. On serial ECGs over a period of 10 days, the PR interval gradually increased to 280 ms. In view of this and the pre-existing left bundle branch block, prophylactic temporary pacing was felt appropriate due to the theoretical risk of the development of high-grade AV block. As a tunnelled central venous line had already been placed via the right subclavian vein, access was attempted via the left internal jugular vein. This provided adequate pacing thresholds, but the temporary pacing lead repeatedly dislodged requiring re-manipulation, and a stable position could not be achieved. As a prolonged period of prophylactic pacing was anticipated but implantation of a permanent system was not possible due to sepsis, we elected to implant a hybrid pacing system. Under local anaesthesia the right subclavian vein was directly punctured, and using the Seldinger technique, a standard 7 French introducer sheath was used to pass an active fixation permanent pacemaker lead (Medtronic CapSureFix Novus) to the right ventricle. The acute pacing threshold was 0.2V with a sensed R wave of 9 mv.The distal end of the lead was then tunnelled subcutaneously approximately 6 cm below the clavicle. The lead was sutured to the subcutaneous tissues at the subclavian puncture site with the lead cuff, and this small incision closed with a single suture (Figures 1 and 2). A single-chamber pulse generator (Medtronic Sigma) programmed to bipolar pacing and bipolar sensing was connected to the external end of the pacing lead. Acute implantation parameters were: R wave 10mV, threshold 0.3V at a pulse duration of 0.5 ms. Following implantation of the pacing lead, the device continued to display excellent threshold (0.6V and 0.5V at 1.0ms pulse duration) and sensing values (R wave 10mV, 9mV) at 1 and 3 months respectively, and there was no sign of local infection. The patient responded slowly to parenteral antibiotics, with gradual reduction in the inflammatory markers, and blood cultures became sterile. He subsequently underwent cardiac surgery four months after diagnosis of endocarditis. As the PR interval had shortened in response to medical treatment, and no episodes of high-grade AV block occurred, the pacing lead was ultimately removed two weeks after surgery by freeing the subcutaneous retainer cuff, retracting the fixation helix at the tip of the electrode and by applying gentle traction. The duration of the implant was four months in total. Discussion This approach to expected long-term temporary pacing proved highly successful in our patient. The procedure was well tolerated and provided long-term pacing support with a lower risk of line infection compared to the use of traditional trans-venous temporary pacing wires and venous sheaths. In addition, the significant risk of complications from temporary pacing is reduced due to avoidance of repeat procedures for repositioning and rotation of venous access sites, particularly in cases such as this where lead stability has been poor. One should always consider this method as an option where temporary pacing is likely to be required for protracted periods. It is of interest that the clinical course was complicated by infection of the tunnelled venous cannula, but the pacing system remained free of infection. As the pacemaker generator is not internalized, it is possible to clean and re-use the device in future cases. An important point to emphasize is that the pulse generator must be programmed to bipolar sensing, as the generator is external and the default setting would normally be unipolar sensing from lead-tip to can. There are little published data on this technique, although a report on a series of patients described low complication rates.⁵ This technique could be used more often, and this article will hopefully increase clinicians awareness and highlight the relative simplicity of the procedure.