Preimplantation Orders

Although outpatient pacemaker implantation can be performed, the usual practice is to admit the patient to the hospital. This may be done on the day of the procedure if the patient's medical condition does not in itself mandate prior hospitalization. Routine pre-implant laboratory tests include a 12-lead ECG, a complete blood cell count (including platelet count), and measures of the prothrombin and activated partial thromboplastin times (aPTT), serum electrolytes, blood urea nitrogen (BUN), and creatinine. It may be valuable to have a recent posteroante-rior and lateral chest radiograph to compare to the post-procedure radiographs.

Food is withheld for 6 to 8 hours before the procedure. Hydration is maintained by the establishment of an intravenous line, preferably with a large-bore cannula in a vein of the upper extremity ipsilateral to the intended implant site. This will facilitate the injection of contrast should difficulty be encountered in achieving venous access. In general, the patient is allowed to continue whatever medication he or she has been taking, with the obvious exception of anticoagulants, which are stopped prior to the procedure (see subsequent section). The dosage of insulin or oral hypoglycemic drugs may require temporary alteration.

As many as 45% of patients requiring a pacemaker implant may be on oral anticoagulation.9 Their peri-implant management is often complicated and related to their indication for anticoagulation. There are three general options. The traditional approach has been to convert the patient on oral anticoagulation to intravenous unfractionated heparin. The latter can be stopped 4 to 6 hours before implant if there is concern about the duration of time during which the patient is not effectively anticoagulated (as for example, the presence of a mechanical mitral valve). Implantation is usually performed when the International Normalized Ratio (INR) is 1.2 or less. If necessary, heparin may be restarted 8 to 12 hours after the procedure and warfarin may be reinitiated the day of the procedure or even the night before. It should be understood that intravenous heparin administered within 24 hours after pacer or defibrillator implantation presents a significant risk (up to 20%) of pocket hematoma formation; this risk is five times that encountered in an unanticoagulated patient.10 Resumption of intravenous anticoagulation should thus be deferred for as long as possible after implant and then only with careful attention to the PTT. Many operators now have abandoned intravenous heparin in favor of transitioning patients on oral anticoagulation to subcutaneously administered low-molecular-weight heparin (LMWH), which may be given up to 12 to 18 hours before planned implantation. This obviates pre-procedural hospitalization and is generally well tolerated. Resumption of warfarin at its maintenance dose post procedure with simultaneous LMWH for 3 to 5 days allows for the outpatient transition back to oral anticoagulation.The risk of post-procedure bleeding with LMWH is thought to be similar to that experienced with unfractionated heparin. There are, however, no randomized controlled trials demonstrating the safety and efficacy of LMWH compared to standard unfractionated heparin for this indication. The third option for managing the patient on warfarin is to perform the procedure without reversal of the anticoagulant. Recently Giudici and colleagues reported excellent results with this strategy in a series of 470 patients having a mean INR of 2.6.9 The authors used meticulous implantation technique and suggest that the risk of pocket bleeding is not prohibitive because hemostasis in these procedures is primarily a function of capillary vasoconstriction and platelet activity. It should be emphasized, however, that this approach is associated with potential risk and is not, at this time, standard practice.

Antibiotic prophylaxis is controversial, but there has been a suggestion that its use, either systemic or local, decreases the incidence of infection.11 A meta-analysis of randomized trials that used a systemic antibiotic supports the use of prophylactic antibiotic to prevent infection associated with permanent pacemaker implantation.12 In an accompanying report, the same investigators suggested that contamination by local flora cultured at the site of implant can result in pacemaker-related infections presenting months later.13 We routinely give a drug active against Staphylococcus (nafcillin, cephalosporin, vancomycin, etc.) before the procedure and for 24 hours after the procedure. Procedures that are prolonged, complicated by potential breaches in sterility, or are "redo" in nature are empirically given slightly longer courses of therapy (3 to 5 days).

The implant site (typically the area from above the nipple line to the angle of the jaw bilaterally) should be cleaned just before the patient's arrival in the pacemaker laboratory. Although shaving the surgical site is controversial, I continue to have this done. A reliable intravenous line is established in the prep area and intravenous fluids administered for hydration. Mild pre-procedural sedation (e.g., 5—10mg of diazepam [Valium] and 25—50mg of diphenhydramine [Benadryl], orally) is given in the prep area. This will be augmented by intravenous sedatives/analgesics during the procedure (e.g., 0.5—1 mg of midazolam, 25—50 mg fentanyl) as needed.

Care should be taken not to oversedate patients, especially the elderly. Drugs to reverse sedation should be readily available: intravenous flumazenil in 0.2-mg increments reverses midazolam; intravenous naloxone in 0.2-mg increments reverses fentanyl. On rare occasions for particular patients (such as children or emotionally disturbed patients), light general anesthesia may be needed. If such a situation is anticipated, appropriate arrangements with an anesthesiologist should be made in advance.

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Responses

  • fiammetta trevisano
    When to give vancomycin prior to planned pacemaker insertion?
    6 years ago

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