Navigating the perioperative maze: Challenges in neurosurgical patients with pacemakers

Sir, Patients with pacemakers in situ may require surgical interventions for various indications and perioperative management of such patients is challenging. The authors shed light on the intricate management required for patients with pacemakers undergoing neurosurgical procedures, emphasizing the complexity of perioperative care in this specific patient population. We encountered a middle-aged male with a history of a syncopal attack 5 years prior, leading to the insertion of a cardiac pacemaker. The patient presented with symptoms indicative of high-grade glioma in the right parietal-temporal-occipital lobe, necessitating craniotomy, and tumor excision. The unique aspects of perioperative management of neurosurgical patients with a pacemaker include unreliability of heart rate as a sign to detect raised intracranial pressure (ICP). Hence, other signs of Cushing’s triad, i.e. hypertension and respiratory pattern along with Glasgow Coma Scale and pupils must be meticulously monitored for detecting changes in ICP. Unlike patients without pacemakers, those undergoing neurosurgical procedures with pacemakers do not exhibit reflex responses such as trigeminocardiac reflex (TGR). TGR, a protective physiological reflex, has an important role in undergoing neurosurgical procedures such as cerebellopontine angle tumors, transsphenoidal surgeries, microvascular depression, aneurysmal clipping, and neurointerventional procedures.[1] In addition, during the management of posterior fossa surgeries, the surgeon relies on cardiovascular responses such as tachycardia, bradycardia, arrhythmias, hypotension, or hypertension, as a sign for their proximity to vital structures (lower pons, upper medulla, floor of fourth ventricle, and cranial nerve nuclei) during surgical stimulation, which might be missed in the patients with pacemakers undergoing such procedures.[2] Other concerns for neurosurgical patients on asynchronous pacemaker mode such as inadequate analgesia, hypotension, and hypovolemia are not accompanied by reflex tachycardia, hence titrated dose of induction agents must be administered to avoid induction dose hypotension and adequate intraoperative analgesia should be administered. Furthermore, hypovolemia due to blood loss must be promptly replaced with fluids and blood while keeping an eye on ongoing losses. However, dynamic measures of fluid responsiveness such as systolic pressure variation and pulse pressure variation could also be employed to guide the fluid status. We can also explore bedside measurement of inferior vena cava size and collapsibility using ultrasonography to assess the response to fluid challenge or use advanced hemodynamic monitors for evaluation of cardiac output and systemic vascular resistance in such patients.[3] Patients with pacemakers should undergo pacemaker-compatible magnetic resonance imaging (MRI) or computed tomography (routine MRI is not possible as placement of a magnet over a permanent pacemaker temporarily reprograms the “pacer” in an asynchronous pacing mode) for the diagnosis. Hyperventilation which has a role in the management of acute changes in ICP as well as brain bulge, may lead to a sudden fall in serum potassium levels and needs to be avoided in patients with pacemakers.[4] The Heart Rhythm Society recommends preoperative interrogation of cardiac implantable electronic devices within specific timeframes: within 6 months for automated implantable cardioverter-defibrillator, 12 months for conventional permanent pacemaker (PPMs), and 3–6 months for cardiac resynchronization therapy devices.[5] Patients with a pacing burden ≥40% or predominantly paced electrocardiogram rhythms are pacing-dependent. During preoperative assessment, pacing dependence and the risk of electromagnetic interference (EMI) should be evaluated. If pacing dependence is confirmed and EMI interaction is likely, the pacemaker mode should be changed to asynchronous pacing mode using a programming machine or magnet. Efforts must be made to minimize EMI due to cautery devices as a high energy electromagnetic field while passing through the pacemaker filters can lead to oversensing resulting in pacemaker inhibition and cardiac arrest. This life-threatening complication is avoided by preemptively programming the pacemaker into an asynchronous pacing mode or using magnet, converting pacemaker to fixed-rate asynchronous mode. Mostly, pacemakers and implantable cardioverter-defibrillator (ICD) have magnetic REED switches that are designed to “ON” and “OFF” circuitry that changes in response to the placement of magnet over the pulse generator leading to nonsensing asynchronous mode. Magnet application disables antitachycardia function in the ICD system. However, not all pacemakers switch to asynchronous mode on the application of magnet, so their use should be judicious, as it can affect the REED switch and lead to unintended consequences. The response varies with model and manufacturer. Another implication of this is the behavior of the REED switch as it does not necessarily remain closed and is unpredictable in MRI units, especially with strong magnetic fields (0.5, 1.5, or 3 T).[6] Further, the use of monopolar cautery is contraindicated. Bipolar cautery use must also be minimized to <15 s in one go which might pose a problem during surgical hemostasis resulting in increased bleeding. The cautery plate must be placed as far as possible from the pacemaker and cutting mode should be preferentially used over coagulation mode.[5] Other issues include the theoretical possibility of displacement of the pacemaker while insertion of a central venous line, making its placement difficult. Nitrous oxide should also be avoided as its use can result in pacemaker dysfunction due to the formation of air pockets. The authors present a thorough and thoughtful exploration of perioperative management, offering a roadmap for anesthetic teams facing similar neurosurgical patients with pacemakers. By adhering to these protocols, health-care teams can ensure safe perioperative care and optimize patient outcomes. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.