Introduction

The commonly reported incidence of congenital heart disease (CHD) in the United States is between 4 and 10 per 1,000 live births. The most common defects are ventricular septal defect, atrial septal defect, valvular pulmonary stenosis, tetralogy of Fallot, coarctation of the aorta, atrioventricular (AV) septal defect and transposition of the great arteries. The National Birth Defects Prevention Network data estimate that there are more than 6,100 cases annually of five defects in the US: truncus arteriosus, transposition of the great arteries, tetralogy of Fallot, AV septal defect, and hypoplastic left heart syndrome (HLHS). Annually, there are an estimated 9,200 patients requiring an invasive procedure related to CHD in the first year of life [1].

With improving survival, the number of unrepaired, repaired, and palliated patients of all ages is increasing. With this increase in the number of patients living with CHD, there is a concomitant increase in the number of patients of all ages presenting for noncardiac procedures requiring anesthetic care. Using data from the Pediatric Health Information System (PHIS), an administrative database that includes the surgical data from 52 freestanding children’s hospitals, Nasr et al. report a significant increase in noncardiac surgical encounters from 38,272 in 2015 to 45,993 in 2019 (p < 0.001) [2]. In fact, also according to PHIS data, 41% of pediatric patients with CHD requiring surgical management of their CHD in the first year of life also have at least one noncardiac procedure before the age of 5 years, most commonly gastrointestinal or otolaryngologic procedures [3]. Adult patients with CHD are also accounting for an increasing percentage of patients presenting for noncardiac surgical procedures and represent a challenge in perioperative management [4].

Data from the Pediatric Perioperative Cardiac Arrest (POCA) Registry report a higher risk of perioperative cardiac arrest in children with CHD undergoing anesthesia compared with the rest of the pediatric population, and 54% of arrests occurred during noncardiac procedures. Mortality after cardiac arrest is also substantially higher for patients with cardiac disease, being 33% among those with heart disease, compared with 23% among those without. It is critical to recognize the patients at highest risk of anesthesia‐related mortality: infants with single‐ventricle lesions and patients with left ventricular outflow tract obstruction (LVOTO), cardiomyopathy or pulmonary hypertension [5, 6]. Risk assessment and stratification has become increasingly important for perioperative planning.

The recognition of high‐risk patient groups has led to improved multidisciplinary discussion, selection of appropriate operative venue and recovery area, selection of anesthesia care provider, conduct of anesthesia and surgery, and level of monitoring with the goal of reducing morbidity and mortality. In fact, over the last several years, there has been a reduction in the incidence of mortality in patients undergoing noncardiac surgery at children’s hospitals. This is attributed to improved patient selection, medical optimization, and expertise found at dedicated children’s hospitals [2].

Over the last several years, the literature suggests that an optimized milieu for the perioperative planning and discussion, acquired and shared expertise in caring for these patients, and multidisciplinary collaboration in care has allowed for improved outcomes in this fragile population undergoing noncardiac procedures. It is possible that shared decision‐making allows the group to attempt and be successful in performing procedures on patients that were once deemed too risky.

Preoperative preparation for noncardiac surgery

Nil per os

Fasting times of 6 hours for solids or formula, 4 hours for breast milk, and 2 hours for clear liquids are the recommended guidelines from the American Society of Anesthesiologists.[11]. For patients with CHD, these fasting times are recommended as well. However, there are some important considerations in this patient population. Patients with LVOTO including hypertrophic obstructive cardiomyopathy, subaortic stenosis, aortic stenosis, and supravalvular aortic stenosis (Williams syndrome or non‐Williams syndrome); systemic‐to‐pulmonary artery shunts (e.g. modified Blalock–Taussig shunt, ductal stent, central shunt); and polycythemic, cyanotic patients have an increased risk of perioperative morbidity and mortality when hypovolemic. Hypovolemic patients with LVOTO may develop significant hypotension during an inhalation induction with a resultant decrease in coronary perfusion pressure that results in unresuscitatable cardiac arrest. Shunted patients with pulmonary blood flow that is completely dependent on systemic blood pressure may become profoundly hypotensive and hypoxemic on induction of anesthesia. Also, when there is decreased blood flow through the shunt, the likelihood of shunt thrombosis increases, as does an unfortunate cycle of hypotension and hypoxemia (Figure 35.1). Other polycythemic, cyanotic patients are at risk for thrombosis and stroke due to increased blood viscosity, which can be due to prolonged fasting. Hypovolemia due to fasting has been reported as a cause of periprocedural morbidity and mortality [12, 13].

Prevention of hypovolemia is the key to minimizing this risk. Careful planning and communication will minimize the time these patients are without fluids. Families should be advised to give clear fluids liberally until 2 hours prior to the procedure, and if the procedure is delayed, clear fluids can be administered by mouth at the hospital until 2 hours prior to the procedure. In addition, intravenous fluids can be started upon arrival in the hospital to replace losses before induction of anesthesia. Patients may also be admitted the night before surgery to receive intravenous fluids while fasting. These strategies may decrease perioperative risk.

Implementation of more liberal guidelines such as allowing clear fluids until one hour prior to the procedure have been shown to be associated with similar aspiration risks as classic NPO guidelines. Liberal guidelines for clears have been adopted in Sweden, Australia, and the United Kingdom with no increase in aspiration. The European Society of Anaesthesiology updated its guidelines as well [14–16]. With this in mind, it may be beneficial to allow patients with a higher hemodynamic risk profile to drink clear fluids until one hour prior to induction to maintain intravascular volume [15, 16].

Pacemakers and defibrillators

The number of pediatric patients with cardiovascular implantable electronic devices (CIEDs), pacemakers and defibrillators, has increased as technology has advanced [27]. An increasing number of pediatric patients with these devices will likely present for noncardiac as well as cardiac surgery. It is crucial to manage these devices properly to avoid injury, inappropriate shocking, and hemodynamic instability. A more extensive discussion of pacemaker and defibrillator therapy is presented in Chapters 22 and 34.

Preoperatively, it is important to understand the type of device in place, generator location, associated cardiac disease, indications for placement, and the remaining battery life. The underlying cardiac rhythm and degree of pacemaker dependence for cardiac output (none, partial, or complete) are key points of information. This information is best gleaned from a combination of history, physical exam, review of chest radiograph, discussion with or previous note from the cardiologist, and an interrogation of the device in the holding area by a CIED programmer (cardiologist, specialized nurse, or certified company representative from the device manufacturer).

Electromagnetic interference (EMI) in the OR is most commonly caused by monopolar electrocautery. EMI can result in inappropriate triggering or inhibition of pacing, reversion to asynchronous mode, inappropriate shock or anti‐tachycardia therapy, and induction of current in the leads, resulting in myocardial damage. Strategies for reducing EMI include the use of bipolar instead of monopolar electrocautery, using short bursts of cutting rather than coagulation current when monopolar is required, and placing the grounding pad for the electrocautery far from the device site.

If EMI is likely during a procedure, the CIED programmer should reprogram the pacemaker to an asynchronous mode with a rate greater than the patient’s intrinsic rate. Similarly, the anti‐tachycardia function of a defibrillator should be disabled until the risk of EMI is low. It is critical to monitor the patient for a perfusing rhythm with either a plethysmographic or arterial line waveform, as well as electrocardiogram (ECG), after reprogramming. In addition, temporary pacing/defibrillation equipment must be available at all times, and the availability of appropriately sized equipment must be confirmed.

After the procedure when the risk of EMI is low, the device should be interrogated and reprogrammed back to its original baseline settings. It is critical to monitor for a perfusing rhythm and to have pacing/defibrillation equipment present until the device is reprogrammed [28–30].

A magnet can be used in an emergency situation to reprogram a CIED. It is not a substitute for interrogation/reprogramming by a CIED programmer, and it can have unpredictable consequences, particularly with modern multifunction pacemaker/defibrillator devices. For pacemakers, application of the magnet will usually change the pacemaker mode to an asynchronous mode (AOO, VOO or DOO – see Chapter 22) at a fixed rate, usually between 65 and 100 beats/minute (bpm). This fixed rate is device‐specific and dependent on remaining battery life [31]. Untoward effects of magnet application include pacing at a rate or in a rhythm that does not meet the patient’s metabolic or hemodynamic needs. For defibrillators, application of the magnet usually suspends the anti‐tachycardia function, but does not change the pacemaker to an asynchronous mode. If the patient experiences ventricular tachycardia or ventricular fibrillation while the magnet is applied, the magnet should be quickly removed so that the anti‐tachycardia function is restored and the device can deliver a shock [29]. This restoration does not occur with all systems, however; some are disabled until interrogation/reprogramming occurs [32]. There is no substitute for consultation with an expert, assessing the function of the device and converting the functions to an appropriate intraoperative mode. Obviously, there may be emergency situations where this will not be possible. The critical importance of monitoring the patient for a perfusing rhythm throughout the procedure, having backup pacing/defibrillation equipment present, and interrogating and reprogramming the device postoperatively cannot be overemphasized. There is a discussion of MRI‐compatible pacemakers later in the chapter.

The patient on ventricular assist device support

Heart failure most commonly resulting from CHD, cardiomyopathy, and myocarditis is the diagnosis associated with more than 12,000 annual pediatric hospital admissions in the United States [33]. Most of these patients can be managed medically or surgically, but there are a growing number of pediatric patients that require extracorporeal membrane oxygenation (ECMO) or ventricular assist device (VAD) placement. There are now devices that are appropriate for all sizes of pediatric patients for long‐term support (see Table 35.4) [34, 35]. These devices are discussed in detail in Chapter 37.

After placement, cardiac output can be maintained for these patients until cardiac function recovers or a suitable organ becomes available for transplant. In some cases, the patient can remain on VAD support indefinitely, as destination therapy. Destination therapy has been described in patients with end‐stage heart disease due to muscular dystrophy [36]. These patients on long‐term VAD support will likely require anesthesia or sedation for multiple imaging procedures and noncardiac interventions and procedures. In order to provide care for this population of patients, one should become familiar with the different types of devices and the management of hypotension, hypertension, and a decrease in output. A perfusionist or VAD‐trained nurse should be present for all noncardiac procedures to assist with management and transport of the device. In addition, bacterial endocarditis prophylaxis is warranted in all VAD‐supported patients.

The Berlin EXCOR (EXCOR Pediatric Ventricular Assist Device, Berlin Heart, GmbH, The Woodlands, Texas, USA) is a pneumatically driven pump that generates a pulsatile pressure with a rate between 30 and 150 bpm depending on the size of the pump chamber and the size and needs of the patient. The transparent pump chamber allows for visual evaluation of filling, emptying, and thrombus formation. Because of the range of pump sizes, it can be used in neonates, infants, and children, and it is the device that is used most commonly for long‐term support in pediatric patients at the present time [35].

Anesthetic management of the patients with a Berlin EXCOR device requires familiarity with the pump and how to troubleshoot hypotension, hypertension, and reduced output. Cave et al. describe a 69% incidence of hypotension in a case series of 29 noncardiac procedures on 11 patients with a Berlin EXCOR device. This group found that hypotension on induction was most associated with the use of remifentanil and was least associated with the use of ketamine as an induction agent. Care should be taken with the administration of anesthetic agents associated with a decrease in systemic vascular resistance (SVR), and intravascular volume and vasoactive agents that increase SVR should be on hand [37].

When caring for a patient with a Berlin EXCOR device, it is critical to maintain the ability to visually inspect the pump. This may require clear drapes, a mirror, and a flashlight. The membrane should be inspected regularly to check for fibrin deposition and for membrane wrinkling. Membrane wrinkling is a sign of incomplete filling of the chamber. Device inspection is a key component of determining the cause of hypotension and the appropriate treatment [34].

Intraoperative emergencies in a patient with a Berlin EXCOR include malignant dysrhythmias, sudden loss of cardiac output, the appearance of air or clot in the pump chamber, and sudden cyanosis. If the patient develops a dysrhythmia, the pump should be examined for filling and output. The right ventricle (RV) can act like a conduit in the short term, and VAD output can be maintained. The patient may require external cardioversion. Loss of cardiac output is most commonly associated with an alarm from the Berlin EXCOR driver unit. It is most commonly caused by a kink in the external tubing of the device. The device should be examined and the tubing unkinked. Appearance of air or clot in the pump chamber can signal an impending embolism. A cardiac surgeon and a perfusionist should be called to the bedside for an urgent pump exchange. Sudden cyanosis in a patient with a Berlin EXCOR device may be a sign of pulmonary embolism with right‐to‐left shunting through an interatrial communication. Transthoracic echocardiography can aid in diagnosis [38].

Most left ventricular assist devices (LVADs) are preload dependent and afterload sensitive. Preload dependence means that, in the case of an LVAD, the left side of the heart must receive enough blood to fill the pump. Lack of left ventricular filling can be due to hypovolemia or right ventricular dysfunction. Treatment can include volume administration and support of the RV either with the administration of inotropic agents or decreasing PVR. Increased afterload can lead to inadequate ejection in the Berlin EXCOR or a decrease in VAD flow in a continuous flow device. The troubleshooting of the Berlin EXCOR and continuous flow devices can be found in Figures 35.2 and 35.3, respectively [39, 40]. In the patient with a right ventricular assist device, the afterload is the PVR which must be managed to facilitate flow.

VAD use in the failed single ventricle population is increasing, although it is fairly uncommon [41, 42]. In the case of the Fontan, there is no “right heart” that must be supported. In this case, preload is maintained through volume administration and the reduction of PVR using standard measures and pulmonary vasodilators such as nitric oxide or sildenafil.

Preoperative evaluation for the patient with a VAD starts with an investigation into the patient’s anatomy and indications for VAD placement. An understanding of renal, hepatic, neurologic function should be sought. The patient may be on a variety of medications including diuretics, ACE inhibitors (or other afterload reducing agents), antiarrhythmics, pulmonary vasodilators, and inotropic agents for right heart dysfunction. The patient will also likely be on antiplatelet agents and anticoagulants. The ECG should be reviewed and the rhythm noted. Many patients on VAD support have CIEDs, which should be managed similarly to other patients in the perioperative period. The cardiologist managing the VAD should be contacted, and the VAD should be interrogated for alarm history including low flow, power elevations, malfunction, and backup battery. A recent echocardiogram should also be reviewed. Information about RV function, PVR, and aortic insufficiency should be sought out [39, 40, 43].

Monitoring should include standard ASA monitors: ECG, temperature, capnography, blood pressure monitoring, and pulse oximetry. Unfortunately, with continuous flow devices, pulse oximetry and noninvasive blood pressure (NIBP) monitoring can be unreliable. Invasive arterial blood pressure monitoring should be considered for all cases and is necessary for major noncardiac operations. NIRS monitoring can also yield important information about perfusion and cardiac output. Intraoperative transesophageal echocardiography can be used to optimize right heart function and filling [39, 40, 43].

Intraoperatively, the VAD console for a continuous flow device should be in plain sight and monitored. For the Berlin EXCOR, the chamber should be visually inspected to look for thrombus or membrane wrinkles. The management of systemic vascular resistance is critical for optimal VAD functioning. An age‐appropriate MAP should be selected, and optimization of the MAP may include the manipulation of anesthetic depth and the administration of vasopressors and vasodilators. For teenagers and adults, a MAP of 70–80 mmHg should be adequate to maintain good VAD flow and provide an adequate perfusion pressure to end organs. In adults, a MAP greater than 90 mmHg has been shown to be associated with low VAD flow, pump stasis, and embolic stroke [40, 43]. Right heart function may require augmentation with inotropic agents, and PVR may be manipulated to optimize cardiac output.

Data from an adult cohort of 246 VAD patients undergoing 702 noncardiac procedures provide some useful information about perioperative complications and monitoring. The most common perioperative complications were intraoperative hypotension (27%) and acute kidney injury (18%). Interestingly, invasive arterial blood pressure monitoring was only used in 20% of the cases. There were also gaps in blood pressure monitoring of greater than 20 minutes in 55% of cases. There were no recorded blood pressures in 5.5% of cases. During these gaps in monitoring, there is potential for unrecognized hypotension [44].

Postoperatively, the patient should be monitored in a special care or ICU to monitor cardiac, respiratory, and neurologic status. Increases in PaCO₂ associated with hypoventilation can lead to increases in PVR and suboptimal filling of the pump, as can hypovolemia associated with fluid shifts. Pain can increase both PVR and SVR and should be managed carefully.

Patients with VAD support may need to undergo noncardiac surgeries where the intraoperative management for the procedure is not aligned with optimal VAD management. For example, during one‐lung ventilation for a video‐assisted thoracic surgery (VATS), the patient may become hypercarbic and hypoxemia resulting in an increase in PVR, a decrease in right ventricular function, and a decrease device filling. The anesthesiologist should be prepared to take steps to decrease PVR and augment right ventricular function. Transesophageal echocardiography assessing septal configuration, and central venous pressure (CVP) monitoring can facilitate the diagnosis and treatment [45]. Likewise, during neurosurgical procedures, it is important to balance the provision of brain relaxation with the goals for optimal VAD function. In a report of an adult patient undergoing craniotomy for tumor resection, some of the management goals were similar such as the maintenance of a MAP of 70–80 mmHg and hyperventilation. However, mannitol was held due to the effect on preload and the potential for suboptimal VAD function [46].

Of note, the AHA has issued a new statement on resuscitation for the patient with a ventricular assist device. Defibrillation and medication administration per Pediatric Advanced Life Support or Adult Cardiac Life Support Algorithms are indicated, and at this time, external compressions are advised [39, 47]. See Chapter 25 for an extensive discussion of management of cardiac arrest in patients on mechanical support.