Abstract
Background
Children with congenital and acquired heart disease are at high risk for developing anesthesia-related cardiac arrest. Children with single ventricle physiology, left ventricular outflow tract obstruction, including Williams syndrome, cardiomyopathy, and pulmonary hypertension are at the highest risk for developing anesthesia-related cardiac arrest.
Aim of review
The purpose of this article is to review anesthesia in children with cardiovascular diseases, factors associated with anesthesia-related cardiac arrest, and treatment to decrease anesthesia-related mortality.
Key scientific concepts of review
Children with congenital heart disease have fewer complications and lower mortality when the anesthesiologist has specialized training and experience in pediatric cardiac anesthesia. Comprehensive evaluation before anesthesia includes a review of the patient, planned procedure, risks, and interventions for risk reduction. Admission for initiation of intravenous fluids at the start of fasting may be advised, potentially preventing risks associated with decreased preload from fasting. The anesthetic plan includes selection of agents and monitoring for induction, maintenance, emergence, and postanesthesia care. Patients with single ventricle physiology may require adjustments of pulmonary and systemic vascular resistance to optimize pulmonary and systemic blood flow. Left ventricular outflow tract obstruction may be subvalvular, valvular, or supravalvular, static or dynamic, and associated with an increased risk of perioperative cardiac events, including arrhythmias, myocardial ischemia, and heart failure. Patients with Williams syndrome may have supravalvular aortic stenosis, pulmonary artery stenosis, biventricular outflow tract disease, or coronary artery abnormalities; anesthesia typically includes intravenous induction and strategies to minimize blood pressure variation and tachycardia. In patients with pulmonary hypertension crisis under anesthesia, prompt treatment includes mild hyperventilation with 100 % oxygen and initiation of nitric oxide. Multidisciplinary collaboration between specialists, including anesthesiologists, cardiologists, surgeons, radiologists, and interventional specialists, may facilitate the development of the safest possible anesthetic plans.
Graphical abstract
Highlights
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Children with cardiac disease may require specialized anesthesia care.
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Anesthesia-related cardiac arrest occurs most commonly during noncardiac surgery.
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Cardiac anesthesia is safest when potential complications are anticipated.
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Preanesthesia planning includes ensuring the availability of specialized resources.
Abbreviations
LVOT
left ventricular outflow tract
SVAS
supravalvular aortic stenosis
mPAP
mean pulmonary artery pressure
PVR
pulmonary vascular resistance
SVR
systemic vascular resistance
1
Introduction
In the United States, 6 million children undergo general anesthesia for diagnostic and therapeutic procedures annually [ ]. Patient safety with each anesthetic is of utmost importance. Advances in pharmacology, airway management, anesthesia delivery systems, ventilators, monitoring, and training have decreased the incidence of anesthesia-related cardiac arrest and mortality. However, children with underlying heart disease continue to be at high risk and are increasing in number. With advancements in surgery, anesthesia, cardiopulmonary bypass, and intensive care, 85 % of all children born with congenital heart defects are long-term survivors and frequently present for noncardiac surgical procedures, advanced imaging studies, cardiac catheterization, and repeat cardiac surgery. Children with single ventricle physiology left ventricular outflow tract (LVOT) obstruction, including Williams syndrome, cardiomyopathy, and pulmonary hypertension, are at highest risk for having an anesthesia-related cardiac arrest.
The purpose of this article is to review anesthesia in children with cardiovascular diseases such as single ventricle lesions, LVOT obstruction, Williams syndrome, and pulmonary hypertension. Decreased cardiovascular reserve and increased susceptibility to cardiac ischemia may cause children with these conditions to have an increased risk of developing anesthesia-related cardiac arrest. We review strategies that enable pediatric cardiac anesthesiologists to evaluate children who have severe underlying heart disease and develop the safest possible anesthetic plan. A complete review of anesthesia for children with varied types of cardiomyopathy is beyond the scope of this article [ ].
2
Anesthesia-related cardiac arrest
In 1994, the American Society of Anesthesiologists and American Academy of Pediatrics established the Pediatric Perioperative Cardiac Arrest registry. There were 80 centers in the United States and Canada that enrolled in this voluntary registry and anonymously reported cases of anesthesia-related cardiac arrest in patients aged <18 years. The creation of the registry was important because anesthesia-related cardiac arrest is rare, and no single center had sufficient data to study the causes and outcomes of cardiac arrest in anesthetized children and develop preventive strategies. The initial study of the registry data showed that anesthesia-related cardiac arrest had an overall incidence of 1.4 per 10,000 anesthetic exposures and mortality rate of 26 % [ ]. Major risk factors for anesthesia-related cardiac arrest included age <12 months, emergency surgery, and American Society of Anesthesiologists physical status 3 or greater [ ], and underlying heart disease was present in 34 % of children who had cardiac arrest.
Children with underlying heart disease may be at a higher risk of having anesthesia-related cardiac arrest. In one report, the 30-day mortality of children with congenital heart disease undergoing noncardiac surgery was 6.0 %, which was 3.5-fold greater than in children without underlying heart disease [ ]. In another study of 92,881 consecutive patients aged <18 years who received a general anesthetic, the incidence of perioperative cardiac arrest with noncardiac surgery was 2.9 per 10,000 anesthetics, and 87.5 % of these patients had underlying heart disease [ ].
A reexamination of cardiac arrest data from the registry, focusing on the characteristics (age, diagnosis, stage of repair) and outcomes of anesthesia-related cardiac arrest in children with congenital or acquired heart disease, showed that age was a significant factor, with 47 % of anesthesia-related cardiac arrests in children with underlying heart disease occurring in children aged less than six months and 70 % in children aged less than two years [ ]. The four diagnoses that accounted for 75 % of the anesthesia-related cardiac arrests in the registry were single ventricle physiology, LVOT obstruction, cardiomyopathy, and pulmonary hypertension. At the time of the anesthesia-related cardiac arrest, 59 % of patients had defects that were unrepaired, 26 % of patients had undergone palliation, and only 13 % of patients were fully repaired.
Anesthesia-related cardiac arrest occurred during noncardiac surgery (54 %), cardiac surgery (26 %), cardiac catheterization (17 %), and diagnostic imaging procedures (3 %). Children with underlying heart disease were more likely to have a cardiac arrest during elective surgery and less likely to survive than other children. The surgical procedures associated with cardiac arrest, in decreasing order or frequency, were gastrointestinal procedures (such as gastrostomy tube placement, fundoplication, esophagogastroduodenoscopy, and colostomy), otolaryngology procedures (bronchoscopy, tracheostomy, repair of choanal atresia, myringotomy), and central line placement [ ].
The outcome of an anesthesia-related cardiac arrest documented in the registry depended on the type of underlying cardiac disease [ ]. Patients with single ventricle physiology had the highest frequency of cardiac arrest (19 % of reported cardiac arrests) but lowest mortality (25 %). Patients with LVOT obstruction had the next highest frequency of cardiac arrests (16 %) but higher mortality (45 %), and mortality after cardiac arrest was greatest in patients with aortic stenosis (62 %). Mortality was more frequent in children with underlying heart disease (33 %) than those without heart defects (23 %). In a propensity-matched review of the pediatric database of the American College of Surgeons National Surgical Quality Improvement Program, overall mortality was 2.8 % in patients with congenital heart disease and 1.2 % without congenital heart disease [ ]. Therefore, children with underlying heart disease are more likely to have an anesthesia-related cardiac arrest and less likely to survive the event.
3
Pediatric anesthesiology training
In 2020, there were 3541 members of the Society of Pediatric Anesthesiology in the United States [ ]. The Congenital Cardiac Anesthesia Society, a subsection dedicated to promoting excellence in the care of children with congenital and acquired heart disease and continued development of the subspecialty, had 1191 members in 2020, including residents and fellows and practitioners in other countries [ , ]. In response to the limited number of providers with additional fellowship training or extensive experience in pediatric cardiac anesthesia and the need to allocate resources to optimize outcomes, a risk classification tool was developed that was based on cardiac arrest and mortality data and expert opinion from pediatric cardiac anesthesia providers [ ]. After high-risk patients were assigned to a pediatric cardiac anesthesiologist, 100 consecutive encounters were associated with a complication rate of 9 % in the high-risk group but no mortalities, suggesting that additional training and experience in pediatric cardiac anesthesia may be important for optimal outcomes.
4
Effects of anesthesia on the cardiovascular system
General anesthesia typically decreases preload, contractility, and afterload, causing an imbalance in myocardial oxygen supply and demand. In addition, anesthesia causes changes in heart rate and rhythm that may have harmful effects. The optimal level of anesthesia should be adequate to prevent sympathetic stimulation and tachycardia from painful and stressful procedures. However, the rapidity and frequency of change in surgical stimulation makes this impossible at all moments. Tachycardia may be especially dangerous because myocardial oxygen demand is increased and supply is decreased, with decreased time for coronary artery perfusion during diastole. Furthermore, too much anesthesia for the level of stimulation may cause hypotension, bradycardia, decreased cardiac output, and tissue hypoxia. Abnormal cardiac pathophysiology associated with pediatric cardiac disorders may heighten the imbalances between myocardial oxygen supply and demand during anesthesia, leading to cardiac arrest.
5
Evaluation for anesthesia in high-risk patients
The anesthesiologist performs a comprehensive evaluation and creates an anesthesia plan before an elective procedure. A thorough understanding of the underlying heart disease is necessary to develop the safest possible plan. In addition to the choice of anesthetic agent, preparation and careful planning include the assignment of the necessary anesthetic team in the appropriate setting, such as a dedicated pediatric cardiac anesthesiologist at a tertiary care hospital versus general anesthesiologist at an outpatient center. Availability of additional staffing support may be greater during weekdays, with fewer staff typically available at night or on weekends. Planning includes ensuring availability of specialized resources that may be needed, such as nitric oxide and extracorporeal membrane oxygenation.
It is important to ensure open communication and discussion with the patient’s primary cardiologist, the provider performing the procedure, and other subspecialists involved in the patient’s care. Preoperative discussion includes a review of the patient, planned procedure, risks, and interventions for risk reduction. Open communication is based on mutual respect, listening to all viewpoints, and valuing the importance of divergent perspectives. The anesthesiologist may question whether the procedure may be medically necessary to justify the associated risks.
6
Principles of anesthesia planning in high-risk patients
After careful evaluation of the patient and planned procedure, hemodynamic goals are set. The risks and benefits are examined for each step in the anesthesia plan to achieve these goals, from fasting to postoperative care [ ]. A fasting period without solid food and liquids may prevent aspiration before the induction of anesthesia but may place high-risk patients at greater risk for myocardial ischemia from decreased preload and cardiac output [ ]. Admission for placement of an intravenous catheter and initiation of intravenous fluids at the start of fasting may be advised, potentially preventing risks associated with a decrease in preload from fasting.
After determining whether preadmission is advised, the next step is planning the type of induction of anesthesia. Anesthesia induction may be achieved by using an anesthesia mask with an inhalational agent or an intravenous medication. An inhalational agent is typically used for healthy children aged <10 years but not for patients with high-risk underlying heart disease because the dose of the inhalational agent may have major adverse inotropic effects.
Infective endocarditis prevention is planned. The most recent American Heart Association guidelines are helpful to determine the antibiotic recommendation before a procedure including antibiotic selection, timing, and dose [ , ].
Monitoring is initiated before the induction of anesthesia and typically includes continuous pulse oximetry, noninvasive or invasive blood pressure monitoring, end-tidal carbon dioxide monitoring, and continuous ST segment analysis of leads II and V with a 5‑lead electrocardiogram instead of the 3‑lead monitoring used for children without heart disease. Near-infrared spectroscopy cerebral monitoring also may be recommended.
Induction of anesthesia is planned, and if extracorporeal membrane oxygenation backup is a consideration, arrangements are made to have the cardiac surgical team readily available. Some high-risk patients may benefit from standby extracorporeal membrane oxygenation because cardiopulmonary resuscitation alone may be insufficient for rescue. Induction is recommended in an area suitable for resuscitation, with avoidance of small procedure rooms, remote locations, or ambulatory centers. Emergency medications are prepared and ready for administration. The goal at induction is to ensure adequate preload, avoid myocardial depression by using agents such as etomidate or ketamine that have minimal negative inotropic effects, maintain sinus rhythm at an age-appropriate rate, preserve systemic vascular resistance (SVR), and carefully control the airway to prevent hypercarbia and hypoxemia. Hypotension is treated quickly and aggressively.
There previously was a belief that anesthesia induction and emergence may be the periods of highest risk, similar to the analogy of an airplane pilot during takeoff and landing. However, registry data show that the surgical period has the highest prevalence of cardiac arrest (48 %) [ ]. Therefore, heightened vigilance is sustained during surgery, and minor changes in hemodynamics are evaluated and corrected rapidly. In contrast, fewer cardiac arrests may occur during the presurgical (36 % during induction, positioning, preparing the surgical site, or draping the patient) and emergence phases (16 % including postoperative recovery stay) because of heightened awareness of the perceived risks and more rapid treatment of changes in vital signs. Nonetheless, it is important to maintain careful attention to detail and planning at all stages.
Planning for emergence from anesthesia includes the avoidance of tachycardia with medications such as dexmedetomidine and multimodal pain management. In the recovery period, it is important to monitor the 5‑lead electrocardiogram, blood pressure, and pulse oximetry continuously. The location of recovery is important, and many centers will admit high-risk patients to an intensive care unit that has a team with greater familiarity of cardiac pathophysiology than a typical postanesthesia care unit. The duration of observation is important, and the American Heart Association has recommended postanesthesia observation after routine outpatient procedures for a minimum of 4 to 6 h in high-risk cardiac patients, in contrast with 30 to 60 min for healthy children [ ].
7
Single ventricle congenital heart defects
7.1
Definition and clinical findings
Cardiac formation occurs during days 30 to 56 of gestation [ ]. The prevalence of congenital heart disease is 10 in 1000 live births [ , ]. Single ventricle congenital heart defects include various cardiac abnormalities in which one ventricle is hypoplastic, or the interventricular septum is not formed. The most common single ventricle congenital heart defects are hypoplastic left heart syndrome, which occurs in 3 of 10,000 live births ( Fig. 1 ), unbalanced atrioventricular septal defect, double-inlet left ventricle, and tricuspid atresia [ ]. The developmental process causing these defects is not fully understood. Although single ventricle defects are rare, most patients survive into adulthood because of advances in surgical care. It is important to understand the physiology associated with single ventricle congenital heart defects and how to evaluate and treat the pulmonary and systemic circulation during an anesthetic to improve patient outcomes [ ].
Survival after birth of patients with single ventricle congenital heart defects is possible only when there is an unobstructed mixing of pulmonary and systemic venous return and a way to provide arterial flow to both pulmonary and systemic circulation. Unrestricted mixing may require atrial septostomy and stent placement to enable blood to reach the functional ventricle [ ]. The arterial oxygen saturation may be 75 % to 85 % with optimal mixing. As the single ventricle is the source of perfusion for both pulmonary and systemic circulation, flow is determined by relative resistance. During the transition from fetal to adult circulation at 48 to 72 h after birth, there is a decrease in pulmonary vascular resistance (PVR) and an increase in pulmonary blood flow, which may cause increased oxygen saturation, decreased systemic oxygen delivery and perfusion, and cardiogenic shock. Medical treatment is complex but seldom sufficient and includes endotracheal intubation, hypoventilation, or inhaled nitrogen to increase PVR and improve systemic perfusion [ ]. The ductus arteriosus must remain patent because it may be the source of blood flow into the pulmonary circulation in patients with hypoplastic right heart syndrome with pulmonary atresia or the systemic circulation in patients with hypoplastic left heart syndrome with aortic atresia. An infusion of prostaglandin E1 is started immediately after birth to prevent the ductus arteriosus from closing and continues until placement of a ductus arteriosus stent in the catheterization laboratory or shunt at surgery [ ]. The blood flow ratio between pulmonary and systemic circulations ideally should be balanced at 1:1, providing a systemic oxygen saturation of 75 % to 85 % [ ]. Higher oxygen saturation levels occur when there is greater pulmonary than systemic circulation, and decreased oxygen saturation levels occur with lower pulmonary than systemic circulation [ ]. Control of the balance between pulmonary and systemic circulation may be affected by physiological conditions and medications ( Table 1 ).
| Goal | Mechanism of action | Effects | |
|---|---|---|---|
| Physiological | Pharmacologic a | ||
| Improve pulmonary blood flow; decrease PVR/SVR ratio | |||
| Decrease PVR | Higher fraction of inspired oxygen | Nitric oxide | |
| Hypocarbia | Sildenafil | ||
| Alkalosis | Fentanyl | ||
| Controlled ventilation | Milrinone | ||
| Positive end-expiratory pressure | Isoproterenol | ||
| Increase SVR | Pain Valsalva maneuvers Hypothermia Hypovolemia | Vasoconstrictors (epinephrine, phenylephrine, norepinephrine) | |
| Improve systemic blood flow; increase PVR/SVR ratio | |||
| Increase PVR | Lower fraction of inspired oxygen | Epinephrine | |
| Hypercapnia | Norepinephrine | ||
| Acidosis | Nitrous oxide | ||
| Pain | |||
| Valsalva maneuvers Atelectasis Hypothermia b | |||
| Decrease SVR | Adequate analgesia | Milrinone | |
| Propofol | |||
| Systemic vasodilators | |||
| Volatile anesthetics | |||
a Etomidate and ketamine have minimal effect on SVR and PVR.
b Hypothermia increases both PVR and SVR, greater effect on PVR.
Single ventricle lesions are treated with neonatal transcatheter or surgical palliation, then further staged palliative surgery. At age 3 to 6 months, a superior vena cava to pulmonary artery anastomosis (also known as bidirectional Glenn procedure) is performed. At age 2 to 5 years, an inferior vein cava to pulmonary artery anastomosis (also known as Fontan procedure) is constructed, the last of the staged palliative procedures. After these procedures, the pulmonary circulation remains without a dedicated ventricle, and the systemic circulation is no longer controlled by the balance between PVR and SVR. Systemic venous blood returns to the pulmonary artery without an intervening pumping chamber.
7.2
Anesthesia
Untreated single ventricle congenital heart defects are fatal, but survival is 90 % in patients who have surgical correction and achieve age one year [ ]. Therefore, surgical correction and proper preoperative and intraoperative anesthesia are necessary for patient survival.
The degree of cardiopulmonary reserve is variable between patients who have the same single ventricle congenital heart defect. Therefore, a detailed assessment of each patient, with attention to cardiac and hemodynamic function, is important before administering an anesthetic. The results of the most recent cardiac catheterization and serial echocardiograms are used to assess ventricular function, shunt patency, and effects of the Glenn and Fontan procedures.
In addition to the assessment of cardiac function, it is important to prevent tissue hypoxemia and end-organ dysfunction by maintaining systemic perfusion. Oxygen saturation is monitored carefully and maintained at 75 % to 85 % to perfuse organs and avoid ischemia. Signs of excessive pulmonary circulation, such as pulmonary edema, are treated with diuretics. In addition to maintaining adequate oxygenation, an optimal hematocrit of 40 % may maintain sufficient oxygen delivery to tissues [ ].
Preoxygenation with 100 % oxygen is a standard anesthesia technique prior to the period of apnea that occurs during intubation. Supplemental oxygen prevents a steep drop in oxygen saturation until oxygenation and ventilation are resumed via the endotracheal tube. The use of preoxygenation must be managed thoughtfully in patients with single ventricle congenital heart defects. Some practitioners avoid preoxygenation with 100 % oxygen during anesthetic induction in patients to prevent increasing the pulmonary blood flow at the expense of the systemic cardiac output. After induction and endotracheal intubation, supplemental oxygen is quickly tapered to room air.
Anesthesia induction typically is safest with intravenous medications [ ]. Ultrasound-guided intravenous line placement may be necessary. It is important to consider the induction options before administration to prevent hemodynamic instability because induction medications have varied effects on circulatory stability ( Table 1 ). Induction is typically achieved with etomidate, which has minimal effects on hemodynamics, or ketamine.
Patients with single ventricle physiology are monitored carefully during surgery because hemodynamic changes may occur rapidly and cause anesthesia-related cardiac arrest [ ]. After induction, it is important to maintain a balanced circulation in shunt-dependent patients. In patients with a previous Glenn or Fontan procedure, pulmonary blood flow determines the systemic ventricle preload and cardiac output. Treatment is directed to avoid an increase in SVR that may occur with decreased intravascular volume from fasting and rapid blood loss and to avoid an increase in PVR, which may occur with acidosis, atelectasis, hypoxia, hypercapnia, or hypothermia. As patients with single ventricle physiology may not tolerate the reduced cardiac output from persistent arrhythmias, arrhythmias are treated as quickly as possible with intravenous antiarrhythmic medications or electrical cardioversion.
After extubation, analgesics are given, starting with low doses to prevent hypoventilation. Dexmedetomidine is an adjunct to the treatment of pain and does not cause the respiratory depression observed with opioids.
8
Left ventricular outflow tract obstruction
8.1
Definition and clinical findings
LVOT obstructions are stenotic lesions that decrease blood flow from the left ventricle ( Table 2 ) [ ]. These lesions may be congenital or acquired and may occur anywhere along the LVOT into the descending aorta, including subvalvular, valvular, or supravalvular lesions. There may be a single lesion, but multiple levels of obstruction may occur, such as Shone complex, which is a rare congenital heart defect characterized by multiple left-sided obstructive lesions that include a supravalvular mitral ring, parachute mitral valve, subaortic membrane, valvular aortic stenosis, and coarctation of the aorta ( Fig. 2 ).
| Level of obstruction | Subtype | Prevalence |
|---|---|---|
| Subvalvular | Discrete membranous rings or ridges | 8 % to 10 % of congenital LVOT obstructions |
| Hypertrophic cardiomyopathy | 0.2% a | |
| Leading cause of sudden cardiac death in young athletes | ||
| Complex LVOT abnormalities | 10 % of LVOT obstructions | |
| Valvular | Bicuspid aortic valve | 1 % to 2% a |
| 50 % to 70 % of congenital aortic stenosis in children | ||
| Aortic stenosis | 3 % to 6 % of congenital heart defects | |
| Supravalvular | Supravalvular aortic stenosis | 1 in 10,000 a |
| 50 % to 75 % of cases occur in Williams syndrome | ||
| Coarctation of the aorta | 4 % to 6 % of congenital heart defects |
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