Anesthetic Considerations for Cardiac and Noncardiac Surgery in the Child With Congenital Cardiac Disease

Introduction

The complexity of congenital cardiac lesions and increased requirements for imaging studies and interventions in this growing patient population necessitate the specialized skills of the pediatric cardiac anesthesiologist. The great majority of these practitioners undergo primary training in anesthesiology, followed by a fellowship in pediatric anesthesia and additional training in pediatric cardiac anesthesia, most recently as a 1-year subspecialty fellowship. Moreover, specifically trained certified registered nurse anesthetists may take part in the care of children with congenital cardiac disease. These members of the pediatric cardiac anesthesia care team treat patients in a wide variety of settings, such as the echocardiography laboratory, cardiac catheterization lab, magnetic resonance imaging suites, cardiac operating rooms, general operating rooms (OR), and cardiac intensive care units. Young children with congenital cardiac disease undergo repeated diagnostic, curative, or palliative procedures in these settings, which frequently require deep sedation or general anesthesia to provide the required immobility.

Preoperative Assessment

Since the spectrum of congenital and acquired cardiac lesions is extremely varied and patient histories often complex, performing a focused physical examination and obtaining pertinent information regarding the specific cardiac anatomy, previous cardiac evaluations and catheterizations, history of surgical procedures and comorbidities, are critical to devising a safe anesthetic plan. Particular attention is given to factors impacting airway management, cardiopulmonary function and reserve, and neurologic status. For neonates, details of prenatal and perinatal events are obtained. Complications during labor and delivery, such as need for postnatal mechanical ventilator support, should be elicited. Preparation includes the appreciation for genetic syndromes that can be associated with congenital heart disease (CHD) and may significantly impact anesthetic management ( Table 90.1 ). For example, certain syndromes complicate airway management (e.g., Pierre Robin, choanal atresia), while others may affect management of blood products and electrolyte management, for example DiGeorge syndrome.

Failure to thrive, difficulty feeding, tachypnea or sweating with feeding, decreased activity level, and easy fatigability are markers for impaired cardiopulmonary reserve that are taken into consideration when choosing anesthetic drugs, airway management, and postoperative ventilator strategy. Degree of cyanosis (via pulse oximetry, visual inspection, or polycythemia) and the incidence of hypoxemic spells (e.g., in tetralogy of Fallot), or syncope (e.g., in left-sided obstructive lesions) are critical for risk stratification.

Obtaining a cardiovascular medication history is part of any preoperative assessment, as many anesthetic agents interact with a variety of medications and can result in potentially severe adverse reactions. Children on medications for congestive heart failure, such as diuretics and inotropic agents (e.g., digitalis), should have preoperative electrolytes and appropriate drug serum levels checked. Patients who are on anticoagulants may need to have their medications either held (e.g., enoxaparin) or transitioned (e.g., Coumadin) prior to their planned procedure. Aspirin therapy to prevent shunt thrombosis should usually be continued; many recommend a 5- to 10-day period. Although some institutions may prefer to continue all medications through the day of surgery, other practitioners may request holding angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers and diuretics the day of the procedure due to the potential for severe arterial hypotension. This practice is based on studies of adults with ischemic heart disease and hypertension in which hypotension on induction of anesthesia was reported. However, other adult data dismisses these claims and data in children are lacking.

Details of recent illnesses, particularly upper respiratory infections, should be elicited as children with ongoing upper respiratory infections (URIs) have been shown to have a higher incidence of respiratory and postoperative complications after cardiac surgery. There is evidence that patients with an active URI have a higher incidence of bronchospasm, laryngospasm, hypoxemia, atelectasis, and extubation failures. In addition, postoperative length of stay is prolonged in patients with URIs, while overall morbidity and mortality may not be increased. However, respiratory tract infections may have a greater impact on pulmonary vascular resistance in children with pulmonary hypertension or cavopulmonary anastomosis. It is therefore generally recommended that elective surgery be delayed for 6 to 8 weeks in patients with an active URI; however, the severity of symptoms and potential risks of postponing the procedure need to be considered.

Physical examination should include a detailed evaluation of the airway, chest, and heart. Vital sign assessment should include four extremity noninvasive blood pressure measurements to identify any discrepancy in circulation, such as with coarctation of the aorta, aberrant subclavian artery, or impact of surgical shunts. Determining the patient's baseline oxygen saturation and range will allow tailoring periprocedural care. Critical review of laboratory data, preoperative imaging studies, and electrocardiogram complete a thorough preoperative cardiac anesthesia assessment.

Current practice guidelines for preoperative fasting have been developed by the American Society of Anesthesiologists Task Force on Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration. These guidelines allow clear liquids to be ingested for up to 2 hours before procedures requiring general anesthesia, regional anesthesia, or procedural sedation and analgesia. Fasting periods of 4 hours or longer for breast milk, 6 hours or longer for infant formula, and 6 hours or longer for light meals or nonhuman milk are recommended. Additional fasting times of 8 hours or longer will be needed for intake of fried or fatty foods and large volumes of nonhuman milk. Infants on prostaglandin infusions have delayed gastric emptying times and longer fasting times may be warranted. It is important to note that encouraging parents to administer clear fluids up until 2 hours before the procedure not only improves patient and parental satisfaction, but may also reduce the risk of perianesthetic hypotension and potential shunt thrombosis. Ideally, high-risk patients, especially shunted single ventricle patients and patients with left ventricular outflow tract obstruction, should be anesthetized early in the day to minimize fasting time. This will also allow for longer postanesthetic observational period in outpatients.

Two final circumstances should be considered as part of the preoperative evaluation. First, many children with congenital cardiac disease may suffer from adrenal insufficiency, whether part of their disease process or secondary to prolonged steroid therapy. It is important to review their endocrinologist's recommendations prior to their procedure. Finally, the 2017 Prevention of Infective Endocarditis Guidelines from the American Heart Association should be familiar to and followed by the provider caring for the patient with congenital cardiac disease undergoing surgical and interventional procedures.

Preparation and Preprocedural Sedation

One of the important components of an anesthetic, particularly in the pediatric cardiac patient, is the psychologic preparation of the patient and family to facilitate a smooth anesthetic induction. A thorough preoperative discussion, allaying anxiety related to prior experiences, and pharmacologic premedication are helpful in easing the child's separation from the family and facilitating hemodynamic and respiratory stability during induction of general anesthesia or sedation. Older children and teenagers may have developed strong personal preferences regarding premedication and the method of induction of anesthesia that should be respected, if feasible. Some of the agents currently utilized for pharmacologic preparation include midazolam (0.5 to 1 mg/kg by mouth [PO] or intranasally [IN], ketamine [5 to 10 mg/kg IN], dexmedetomidine [1 to 3 µg/kg IN], or pentobarbital [4 to 5 mg/kg PO]). However, pharmaceuticals need to be used carefully, as they can cause myocardial depression, especially in the failing heart, and may cause hypoventilation which can result in hypercarbia, acidosis, hypoxemia, and increased pulmonary vascular resistance. Furthermore, patients who are prone to airway obstruction (obstructive sleep apnea or trisomy 21) may develop airway compromise once sedated. In children deemed inappropriate for an inhalational induction and therefore requiring intravenous (IV) access prior to induction, excellent anxiolysis can be achieved by titrating midazolam intravenously to patient comfort prior to parental separation and entry into the procedure room.