Encountering a child with congenital heart disease after surgical palliation in the emergency department, specifically the single-ventricle or ventricular assist device, without a basic familiarity of these surgeries can be extremely anxiety provoking. Knowing what common conditions or complications may cause these children to visit the emergency department and how to stabilize will improve the chance for survival and is the premise for this article, regardless of practice setting.
Key points
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Hypovolemia and hypoxemia, associated with a routine childhood viral illness, require prompt stabilization without overshooting the mark for a child with a ventricular assist device or single-ventricle physiology.
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The highest mortality for children with complex congenital heart disease is related to respiratory tract infections.
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Ask the caregiver of a child with single-ventricle physiology for the child’s baseline oxygen saturation and target that number.
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Depending on the ventricular assist device, a blood pressure or pulse obtained in the conventional way might not be accurate. Obtain a Doppler mean arterial pressure.
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The newer ventricular assist devices have magnets within, so MRI is absolutely contraindicated.
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Ventricular assist device physiology and single-ventricle physiology palliation are both preload dependent and afterload sensitive. Cardiac arrest sends their physiology into a vicious cycle, nearly unrecoverable, so resuscitate promptly, carefully, and decisively. Never has the adage, “an ounce of prevention is worth a pound of cure,” ever been truer.
Introduction to children with surgical palliation of cardiac disease in the emergency department
This article addresses children following surgical intervention for cardiac disease; the approach to the undiagnosed critical congenital cardiac child in the emergency department (ED) can be found elsewhere and will not be covered. There are a few common surgical interventions for congenital heart disease with various names. A quick pictorial review of surgical interventions can be found at COVE Point CHD ( www.pted.org ). Although the most common indication for surgical repair is a ventricular septal defect, the more common complex surgical repair is for the single-ventricle physiology heart, and this will be the focus of the article. Single-ventricle physiology refers to several anatomic variants: tricuspid atresia, double-outlet right ventricle, hypoplastic left heart syndrome (HLHS), hypoplastic right heart syndrome, pulmonary atresia, and pulmonary stenosis, among others. Rather than discussing the individual defects that create a single-ventricle physiology, focusing on knowledge of associated surgical procedures encourages providers to consider the possible complications and physiology of both the single-ventricle physiology and the palliation or repair. To survive, neonates with HLHS require both atrial and ventricular level communications and a patent ductus arteriosus (PDA). A few decades ago, children with a functional single ventricle providing both systemic and pulmonary blood flow in parallel using persistent fetal circulation conduits (patent foramen ovale, PDA, and such) were managed palliatively until these connections naturally but fatally closed around 1 to 2 weeks of life. Children with HLHS suffered from pulmonary overcirculation and pulmonary hypertension and inadequate systemic circulation, leading to metabolic acidosis, ischemia, and eventually, cardiogenic shock and death. Children with single-ventricle physiology had a less than 30% survival to adulthood before modern surgical and perioperative management strategies. Because of advances in surgical techniques in the 1970s to 1980s and preoperative and postoperative cardiac care, children are living longer, with associated “growing pains.” Now, more than 70% of children born with single-ventricle physiology who undergo staged palliation live to reach adulthood. , The 5-year risk of death for a 40-year-old after the complete staged surgical palliation is similar to that of a 75-year-old without congenital heart disease. Despite close monitoring of a multidisciplinary team, complications do occur. These children are discharged to home between stages, these complications can prompt presentation to any ED.
A 3-staged surgical palliation strategy is used, and details of each stage are outlined in Table 1 . Children with a known acquired or congenital heart disease, whether preoperative or postoperative, are at increased risk for cardiac arrest. Children with congenital heart disease have a cardiac arrest at a rate greater than 10-fold higher than children hospitalized without cardiovascular disease. Children with single-ventricle disease have a lower survival rate than children with other forms of cardiovascular disease. Most children are discharged home after their stage I Norwood-equivalent procedure; while they grow before the stage II Glenn procedure; this timeframe is known as the tenuous “interstage” period. Cashen and colleagues found that nearly 80% of these children required an ED visit, and mortality was as high as 8% to 12%. Death for these children is often sudden and unexpected, and in this study, half of the children died close to home in a community ED away from their tertiary cardiothoracic center. , , It is imperative that all emergency physicians in all practice settings have familiarity to stabilize these high-risk patients. There is a paucity of literature to guide physicians about emergency presentations for children after congenital heart surgery; however, it is hoped this brief review will provide a systematic approach to children with surgical palliation or ventricular assist device (VAD) and allow improved outcomes and reduced provider emotional stress.
| Surgical Stages of Palliation | Target Age for Surgical Stage | Goal of Surgical Intervention | Surgical Components |
|---|---|---|---|
| Stage I: Norwood B-T, Sano, or PDA stent | Birth |
| Norwood (see Fig. 1 ) B-T shunt: subclavian artery to the pulmonary artery connection OR Sano shunt: nonvalved connection from right ventricle to right pulmonary artery AND Ligate ductus arteriosus, create atrial septectomy if the atrial communication is restricted, patch pulmonary arteries If HLHS: neoaorta creation with the main pulmonary artery trunk and hypoplastic aorta Hybrid Norwood does not require cardiac bypass and includes selective bilateral branch pulmonary artery banding (restricting pulmonary over circulation) and aortopulmonary artery conduit creation, often by ductus arteriosus stent |
| Stage II: Bidirectional Glenn | 4–6 mo | Partial cavopulmonary anastomosis: create passive, in-series blood flow from SVC to pulmonary arterial circulation, allowing the single ventricle to support systemic circulation | Connect the SVC to the pulmonary arteries Remove the B-T shunt (see Fig. 2 ) |
| Stage III: Fontan | 18–36 mo | Total cavopulmonary anastomosis | Connect the IVC to the pulmonary arteries Create a septum, which is sometimes fenestrated to allow some pop-off desaturated systemic blood flow for children with elevated PVR or single-lung physiology (see Fig. 3 ) |
Staged surgical management of a single-ventricle physiology
Since the most tenuous surgical physiology is the single-ventricle patient, a review of the named 3-staged surgical corrections ( Figs. 1–3 , see Table 1 ) is a good place to start. The important 3-staged palliation surgery for patients with a single ventricle has provided longer life expectancy. Initially, following the first stage, the pulmonary circulation is supported by a small shunt (Sano or Blalock-Taussig [B-T]) that functionally replaces the PDA. The pulmonary and systemic physiology remain in parallel until the neonatal PVR drops and a surgical cavopulmonary anastomosis is performed to create a circulation in series. Typically, the interstage period oxygen saturation (Sp o 2 ) is 75% to 85%. Maintaining a Qp (pulmonary blood flow):Qs (systemic blood flow) ratio of 1:1 is a delicate balance or “teeter-totter” during the “interstage period,” as small shifts in PVR or SVR will dramatically change the Qp:Qs balance. The “interstage” period is well recognized as a time of fragility. , ,
After completion, rather than a single ventricle tasked with pumping systemic blood flow (Qs) and pulmonary blood flow (Qp) in parallel through fetal conduits ( Fig. 4 ), a circulation in series (see Fig. 3 ) is created, and systemic blood flow (Qs) is accomplished with the single ventricle, whereas pulmonary blood flow (Qp) is accomplished through passive venous return. The key to completion of the staged surgeries is that the pulmonary blood flow (Qp) is dependent on the pulmonary vascular resistance (PVR), being low enough to permit “passive” pulmonary blood flow from the systemic venous return in the absence of a right ventricle by using a cavopulmonary anastomosis and that preload is sufficient to allow filling of the pulmonary vasculature.
Basic Physiology Principles of the Single-Ventricle Repair
It is important for clinicians to comprehend the tenuous hemodynamics of the functionally single-ventricle physiology, as its management is distinct from typical dual-ventricle cardiac physiology. Hemodynamic management in children with congenital cardiac disease is a balance of pulmonary and systemic circulation. It is best to think of management in terms of manipulating the PVR and systemic vascular resistance (SVR) to obtain the optimal pulmonary blood flow (Qp) and systemic blood flow (Qs). Rather than discuss each of the many possible repaired lesions or combination thereof, the understanding of basic principles that can be applied to each unique patient is a more appropriate approach ( Table 2 ).
| The “Teeter-Totter” Balance | Qp (Pulmonary Blood Flow to the Lungs) | Qs (Blood Flow to the Body) |
|---|---|---|
| Determinants of flow | PVR | SVR |
| Surrogate clinical measures to assess flow | Sp o 2 | Blood pressure Capillary refill time |
| Increase Qp or Qs |
|
|
| Decrease Qp or Qs |
|
|
Understanding how oxygen, intrathoracic pressure, and fluid bolus affect SVR and PVR is paramount to understanding the resuscitative management of all children with congenital cardiac lesions, whether repaired or newly diagnosed. Oxygen is a potent pulmonary vasodilator; thus, PVR will decrease and Qp will increase. PVR can be manipulated with supplemental oxygen. For example, increasing oxygen saturation from 80% (Qp:Qs 25:20) to 100% will increase pulmonary vascular flow by 25 times (Qp:Qs 25:0). Providing supplemental oxygen vasodilates the pulmonary vascular bed, thereby PVR is decreased, so Qp is increased, which improves oxygenation and further reduces PVR and increases Qp.
If the patient has pulmonary edema or systemic hypoperfusion, removing supplemental oxygen, or hyperventilating the child and decreasing pulmonary carbon dioxide (P co 2 ), will increase PVR. With this increase in PVR, Qp will decrease, thus shunting blood to the systemic circulation and increasing Qs for the hypotensive patient. Hypoventilation can precipitate pulmonary hypertensive crises as well, so cautious hyperventilation is advised, and this should be a last resort.
Box 1 provides a discussion of complications related to single-ventricle physiology and resultant surgeries.
- 1.
Arrhythmia
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Most common: supraventricular tachydysrhythmias like atrial flutter or atrial fibrillation
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Decreased capacity to tolerate arrhythmias compared to dual ventricle patients
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- 2.
Anastomotic incompetency or leak may cause:
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Cardiac tamponade, AV valve regurgitation, or AV valve rupture, aneurysmal dilation, and congestive heart failure
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- 3.
Thrombosis
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Most commonly due to low-flow, stagnant state (exacerbated by dehydration and hypovolemia)
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Risk factor: Lack of post-Fontan antiplatelet therapy
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Presents as cyanosis or hypoxemia with shock, metabolic acidosis, and a tell-tale loss of the B-T or Sano shunt murmur
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Heparin bolus and gtt, or tPA if periarrest or cardiac arrest
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- 4.
Anastomosis stenosis
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Presents similarly to their presurgical presentation
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May occur as children outgrow their B-T or Sano shunt
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- 5.
Reduced Qp from reduced preload (dehydration) or decreased FRC causing increased PVR (respiratory illness) , , , , , ,
- 6.
Infection
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Endocarditis is rare (incidence of 0.4%).
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Febrile diagnoses similar to the general pediatric ED population.
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Lesions with increased Qp have increased risk for pneumonia
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- 7.
Congestive heart failure
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Because of stress on the heart from repair failure, in-stent or anastomotic stenosis, thrombosis, infection, or protein-losing enteropathy (50% 5-year mortality)
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- 8.
Pleural effusions, pericardial effusions, chylothorax
- 9.
Anemia
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Goal Hematocrit (HCT) is >45%
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- 10.
Protein Losing Enteropathy
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50% mortality within five years of diagnosis.
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Protein:Albumin ratio and consider Albumin 25% repletion
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- 11.
Dehydration
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predisposes to thrombosis, decreases preload thereby decreasing Qp and Qs causing hypoxemia and hypotension
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5-10 mL/kg aliquots pre-Fontan, 20 mL/kg post-Fontan
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Kids will be kids, even if they have cardiac disease: other illnesses
Approach to Altering Common Pediatric Emergency Algorithms
The leading cause of morbidity and mortality for children over 1 year of age is trauma. The decision to pursue imaging for children postoperatively from congenital cardiac surgery who require antiplatelet agents or anticoagulation must be considered. There is little guiding pediatric-specific literature on this topic, so clinicians should be familiar with adult literature and extrapolate accordingly.
Although mortality is higher for children with congenital heart disease, the highest mortality for children with complex congenital heart disease is related to respiratory tract infections. , , What we often think of as “just a virus” can be a life-threatening illness to a child with congenital cardiac disease. Admission for at least 24 hours is prudent, even when transport to a higher level of care away from home is required. Hypovolemia, hypoxemia, and fever are common in children suffering from routine childhood viral illnesses, but for a child with a VAD or single-ventricle physiology, they require prompt stabilization.
Common Pediatric Emergency Department Medications: Are They Safe in the Single-Ventricle Child?
For children who have had surgery for a single ventricle, administering medications used routinely for common childhood illnesses may require additional consideration. Acetaminophen and ibuprofen improve hemodynamics by reducing the tachycardia associated with fever and pain. Steroids for croup or asthma should be given to optimize respiratory mechanics. β2-agonists can precipitate an unstable arrhythmia, so ensure the wheezing is likely asthma (not pulmonary edema or bronchiolitis) before administration by using ultrasound, chest radiograph, and B-type Natriuretic peptide (BNP) or N-terminal (NT)-pro hormone BNP (NT-proBNP) if diagnostic equipoise exists. Ondansetron helps improve dehydration for children with gastroenteritis and is safe provided the QTc is not prolonged. Ill children with single-ventricle physiology or VAD are American Society of Anesthesiologists level 3 or greater, and procedural sedation should be done in an operative setting with anesthesia specialists. Implied in this anesthesia risk is the fact that medical management of semi-stable arrhythmias rather than sedated cardioversion may be a prudent choice in the ED. Once hemodynamics are optimized, diuretics may be given to improve subacute pulmonary edema and Qp. Both intravenous (IV) fluids and oxygen are important medications and deserve separate discussion.
Approach to the resuscitation and stabilization for admission or transfer of children with postoperative congenital cardiac disease
The initial resuscitative approach for the emergency physician caring for a child with a palliated single ventricle is described in Box 2 .
- 1.
Ask the parents:
- a.
What surgery the child has had?
- b.
What is the child’s baseline oxygen saturation (Sp o 2 )?
- a.
- 2.
Call cardiologist and/or intensivist to arrange early transfer (if indicated) and consultation.
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Obtain preductal oxygen saturation in the right arm (pearl: p R e = R ight).
- 4.
Assess balance of circulation (Qp:Qs ratio), simplified as Qp:Qs = (25):(100 − Sp o 2 ). The goal is to have equal flow Qp:Qs of 1:1 to the lung and heart. Qp > Qs is indicative of pulmonary overcirculation and hypotension, while Qs > Qp is indicative of cyanosis due to hypoxemia
- 5.
Address for shock or heart failure
- a.
Tachycardia without hypotension may be compensated shock
- b.
Capillary refill time greater than 2 seconds can point to shock or heart failure
- c.
Hepatomegaly can indicate heart failure
- a.
- 6.
Use bedside tools like electrocardiogram (ECG), chest radiograph (CXR), and bedside ultrasound.
- a.
ECG can diagnose arrhythmia.
- c.
CXR can assess for pulmonary overcirculation (Qp > Qs)
- d.
Bedside ultrasound can assess for the cause of shock using the RUSH protocol, global cardiac contractility, tamponade, inferior vena cava distensibility, and pulmonary B lines indicative of edema with serial reassessments after IV fluid boluses to guide resuscitation. Without baseline knowledge of the child’s venous return, assessments for inferior vena cava filling will be hard to interpret. Assessment for right ventricular dilation suggesting a pulmonary embolism will be confounded by whether the child has elevated PVR or a single ventricle with large right atrium.
- a.
- 7.
Evaluate for metabolic acidosis, anemia, hypoxemia, dehydration secondary to fluid loss, or infection.
- 8.
Consider oxygen, fluid bolus, or vasopressors.
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