The last 60 years have seen significant changes in the care of congenital heart disease for both pediatric and adult patients. Increasing patient survival rates have widened the number and scope of potential patients seen by congenital cardiologists.1 These patients often undergo multiple surgeries, particularly since few lesions are truly ‘repaired.’ The majority of patients will have residua or sequelae of surgery, requiring long-term follow-up or further operations. A thorough understanding of the post-operative patient with congenital heart disease is essential for all physicians who are involved in any aspect of their care.
Residua versus Sequelae
Surgeries for congenital heart disease are typically reparative, palliative, or revisionary. Full knowledge of the scope and variety of presentation of lesions is necessary for clinicians caring for post-operative patients. In general, potential post-operative complications can be classified as being associated with intraoperative management (surgical technique, cardiopulmonary bypass, and perfusion), anatomical substrate, or intensive care management.2
Perloff has divided post-operative conditions into categories: ‘residua’ and ‘sequelae.’ Residua refers to conditions that are ‘left-over,’ i.e. that are obligatory to or consequences of the pre-operative diagnosis and state. They are separate from the operative design and are not the result of surgery having fallen short of its objective.3 Examples of this include a systemic right ventricle in congenitally corrected transposition and an unrepaired anomalous coronary artery in tetralogy of Fallot. Sequelae meanwhile consist of incurred conditions that arise as a result of the operation and that are considered necessary consequences of the operation. They are specifically ‘intrinsic to the operative design.’3 Examples include ventricular tachyarrhythmias after ventriculotomy and pulmonary regurgitation after tetralogy repair.
Complications in the Immediate Post-operative Period Related to Intraoperative Management
Any intrathoracic procedure portends a risk for pneumothorax or hemothorax. The risks of clinical compromise from pneumothorax are largely negligible with routine chest tube placement. Continued air leak from chest or mediastinal tubes should raise the possibility of a bronchial air leak.4 Persistent blood drainage from chest tubes may indicate a continued bleeding source, and chest exploration may be performed to identify the source. Fresh frozen plasma infusions can be used to replenish coagulation factors. Platelet infusions can be used to assist in obtaining hemostasis.
Pleural effusions occur commonly post-operatively, especially in the first days following surgery as fluid shifts occur after cardiopulmonary bypass. These effusions should be treated with aggressive diuresis and continued chest tube drainage, as they can delay and complicate recovery from cardiac surgery. Supplemental procedures including pleurodesis can be performed if the pleural effusions are persistent and hemodynamically significant.5
New-onset pericardial effusion (see Figure 1) presenting weeks after surgery can be a sign of the immune-mediated post-pericardiotomy syndrome. White blood cell counts and other markers of inflammation (erythrocyte sedimentation rate, C-reactive protein) will be elevated.6 Any patient for whom the pericardial sac is opened is at risk for post-pericardiotomy syndrome, but it appears to occur more frequently in older children and adolescents rather than in neonates.7 Treatment includes diuretics and anti-inflammatory medications including salicylates, non-steroidal anti-inflammatory drugs (NSAIDs), or steroids in extreme cases.2 If pericardiocentesis is needed to drain a large pericardial effusion, a pericardial drain should remain in place for at least two to three days. If drainage is persistent, the effusion may need to be addressed surgically, particularly in the case of pericardial hemorrhage.8 If the fluid is not free-flowing, an extensive decortication procedure may be needed.
Chylothorax refers to a collection of chyle in the pleural cavity. This is most commonly caused by damage to the thoracic duct or other major lymphatic vessels in the chest during surgery, and is most common in the neonatal–infantile age group.9 Chylous effusions can be particularly frequent following the Glenn and Fontan procedures. The effusion seen in chest tube drainage is often milky-colored in appearance (if the patient has received enteric feedings) due to the high triglyceride content. Treatment consists of removal of free fatty acids from the diet, either by using parenteral nutrition or by providing oral nutrition with a low free fatty acid formula.10 Potential treatments for persistent effusions can include intravenous infusion of octreotide or surgical pleurodesis.9
Diaphragmatic paralysis can occur with any manipulation of the phrenic nerve, but is a particular risk after manipulation of the branch pulmonary arteries, superior vena cava, or aorta reconstruction.2 Diagnosis is often made several days post-operatively by an elevated hemidiaphragm noted on chest radiography (see Figure 2), as well as by difficulty with ventilation (or inability to tolerate extubation) in the absence of other pulmonary disease.
If suspected but not evident on chest radiography, chest fluoroscopy, or ultrasound scanning can be used to examine diaphragm mobility.11 Paralysis is usually transient, but if a patient is continually unable to be extubated due to persistent diaphragmatic paralysis, a surgical plication of the diaphragm can be performed.12
Injury to the recurrent laryngeal nerve is common during aortic arch surgery, including repair of coarctation, interrupted arch, the Norwood procedure, and patent ductus arteriosus ligation. Recurrent laryngeal nerve injury can cause transient vocal cord paralysis.13 This can cause stridor and difficulty in extubation and changes in voice post-operatively, and can increase the risk of aspiration. Rarely, but dangerously, if both vocal cords are paralyzed significant airway obstruction can occur.14 The diagnosis can be made by laryngoscopy. Treatment ranges from simple observation to surgery, depending on presentation and effect on respiration.
Post-operative cyanosis despite adequate ventilation is a dilemma in the ‘repaired’ patient with congenital heart disease. In all patients a healthy index of suspicion needs to be maintained regarding the surgical procedure and accuracy of preoperative diagnosis, particularly when post-operative clinical status and hemodynamics are not improving in the expected manner.2 One potential cause of post-operative cyanosis or desaturation is a residual right-to-left shunt, particularly after repair of ventricular septal defects, tetralogy of Fallot, and transposition of the great arteries. In these lesions, cyanosis occurs only if there is right-to-left shunting due to elevated right ventricular pressures. In these patients, right ventricular outflow tract obstruction, branch pulmonary artery obstruction, and causes of elevated pulmonary vascular resistance should be investigated.
Cyanosis following Glenn or Fontan operations largely occurs due to abnormal right-to-left shunts that allow blood to unexpectedly bypass the pulmonary arterial bed and thus avoid oxygenation. Examples of this include veno-venous fistulae, pulmonary arteriovenous malformations, or an anomalous source of systemic venous return. After a Glenn operation, if the azygous vein is not ligated the superior vena cava can decompress through the azygous to the inferior vena cava circulation, with resulting cyanosis. Cyanosis can similarly occur after a fenestrated Fontan operation if the fenestration from the inferior vena cava pathway to the right atrium is too large.2
In lesions where myocardial resection has been performed (hypertrophic cardiomyopathy or tetralogy of Fallot), coronary fistulae can occur that do not cause cyanosis. These are typically left-to-right shunts. Coronary steal phenomenon rarely occurs. These problems are easily identified during post-operative echocardiography.15 When a residual defect or unexpected cyanosis is present post-operatively, further imaging including echocardiography and/or cardiac catheterization is indicated, with subsequent interventions performed depending on imaging results.16
Thrombosis/Perfusion
The risk of cerebral embolism or cerebral ischemia during repair or palliation of congenital heart disease is low. Nearly 20% of neonatal patients may experience seizures17 post-operatively, either clinical or subclinical. Risk factors for seizure activity include young age at surgery, prolonged period of circulatory arrest, and concurrent cerebral structural abnormalities.18 Use of cerebral oxygen saturation monitoring has become increasingly valuable in predicting those patients at risk for poor outcomes.19,20 Prompt referral to neurology as well as rehabilitation services on suspicion of cerebrovascular insult can be crucial for long-term outcome.
Patient nutrition is extremely important following cardiac surgery. It can be stunted by complications including chylothorax, infection, and respiratory issues that interfere with enteric feeding.21 Total parenteral nutrition should be used whenever possible to augment the slow advancement of oral feedings in post-operative patients. Liver enzyme abnormalities following cardiopulmonary bypass are not uncommon but rarely progress to fulminant liver failure.22 Necrotizing enterocolitis can occur in infants with congenital heart disease, particularly those lesions with compromised aortic outflow or wide pulse pressure due to diastolic run-off (truncus arteriosus, hypoplastic left heart syndrome, aortopulmonary window).23
Renal failure following cardiopulmonary bypass is more common in patients who have had prolonged bypass times, low cardiac output, left-sided obstructive lesions, or pre-operative renal dysfunction.2 Electrolyte abnormalities secondary to renal failure can make post-operative management difficult. Dialysis should be considered in any patient for whom renal compromise is affecting cardiac output, respiratory status, caloric intake, or fluid balance.2,24 Peritoneal dialysis is most often used in neonatal patients, whereas hemodialysis or continuous arteriovenous ultrafiltration can be used in older patients.
Cardiac Arrhythmia
Overall, arrhythmias occur in more than 25% of patients following cardiopulmonary bypass. They typically occur within 48 hours after surgery.2 Intra- or post-operative electrolyte abnormalities can increase the risk of arrhythmia presentation. Additionally, any history of ventriculotomy, ischemia, or ventricular hypertrophy can increase arrhythmia risk.
Complete heart block most commonly occurs when there is significant manipulation of the area near or around the atrioventricular (AV) node. This may occur during repair of AV septal defects or ventricular septal defects (VSD), during the Rastelli procedure for transposition of the great arteries and in patients with congenitally corrected transposition of the great arteries.25,26 Heart block can also occur after cardiac catheterization in susceptible patients, typically on manipulation of catheters around the ventricular septum and in those with underlying bundle branch block. While usually transient in nature, pacing may be required if the heart block is persistent.27 A permanent pacemaker is typically placed for patients in whom complete heart block persists beyond one week after surgery.
Supraventricular tachycardia (SVT) is common in many different types of intracardiac surgery and is typically responsive to anti-arrhythmic medications, including amiodarone. Surgeries involving significant suturing of atrial tissue (Ebstein’s anomaly, atrial switch, anomalous pulmonary veins) are at increased risk for developing SVT.28 These risks can be minimized by concurrent surgical Maze procedures29 if indicated. Development of atrial flutter or atrial fibrillation occurs in a similar fashion and is usually responsive to medication or cardioversion. The majority of older patients undergoing valve replacement surgery may experience transient post-operative atrial arrhythmias. Adolescent or adult patients who have had a classic Fontan procedure (atriopulmonary connections) are at particular risk for atrial arrhythmias in short-term and long-term follow-up due to severely enlarged right atria.30
Post-operative ventricular tachycardia is rare in congenital heart disease. Most commonly this occurs in patients with a history of ventricular dysfunction and systemic or pulmonary hypertension and after prolonged cardiopulmonary bypass.31 Additionally, patients with a history of myocardial ischemia and ventricular hypertrophy and those who have had a ventriculotomy or ventricular plication may be at increased risk.32 Differentiation between ventricular tachycardia and SVT with aberrant conduction can be difficult. Treatment may include cardioversion, ablation, and anti-arrhythmic medications, including amiodarone or lidocaine.
Junctional ectopic tachycardia (JET) is a common post-operative tachyarrhythmia thought to arise from tissue damage adjacent to the AV junction of the conduction system.33 It occurs particularly after surgery that involves suturing on the ventricular septum, including ventricular septal defects, tetralogy of Fallot, and AV septal defects.34,35 Hyperthermia has also been implicated as a risk factor for postoperative JET, although the exact causative etiology behind this is unknown. As such, surface cooling of the patient with JET is a necessary treatment adjunct.36 Post-operative JET is usually transient.37 Overall, use of medications such as amiodarone is successful in treating 60–80% of cases of JET.38,39 Use of catecholaminergic pressors, including epinephrine, can exacerbate JET and should be avoided if possible.
Post-operative patients with congenital heart disease may eventually require pacemaker placement. According to the American College of Cardiology (ACC)/American Heart Association (AHA)/North American Society of Pacing and Electrophysiology (NASPE) 2002 guidelines, Class I indications for pacemaker placement post-operatively include persistent second- or third-degree AV block (for seven days or not expected to resolve) and complete AV block with ventricular ectopy or dysfunction or wide QRS escape rhythm. Class IIa and IIb indications include bradycardia–tachycardia syndrome and bradycardia with concurrent loss of AV synchrony and impaired hemodynamics.27 By contrast, post-surgical AV block with return of normal conduction is not an indication for pacemaker placement.
Considerations After Valve Replacement
Replacement of cardiac valves with either tissue or mechanical prostheses has become routine in the modern age of cardiothoracic surgical care. Rarely, unexplained hemodynamic compromise in a patient after valve replacement can signify dysfunction of the valve prosthesis. This can occur due to thrombus formation on the valve despite routine post-operative anticoagulation, or immobility of one or more of the valve leaflets.40 When echocardiography shows evidence of an unexpectedly significant gradient or severely regurgitant valve soon after valve replacement, valve fluoroscopy can be performed to assess leaflet mobility41 (see Figure 3). Fluoroscopic examination of a mechanical valve is usually performed without sedation or the need for invasive vascular access.
Special mention should be made of valve reparative procedures, including extensive remodeling of tricuspid valve tissue that occurs in surgery for Ebstein anomaly. Rarely, dehiscence of the Ebstein repair can occur post-operatively.42 This may or may not be associated with symptoms. but can be diagnosed by clinical exam (change in the regurgitant systolic murmur) and by the right atrial waveform (elevated v-waves). Similar dehiscence of a valve repair has been reported after mitral valve annuloplasty.43
Anatomical Substrate
In addition to the above-mentioned rhythm, thrombosis, and surgical complications noted in the post-operative period, each specific congenital heart lesion portends its own set of potential intra- or extra-cardiac complications. These lesions are discussed below. Regardless of lesion, all patients should receive a post-operative electrocardiogram, echocardiogram, and chest radiography prior to hospital discharge.
Ventricular Septal Defect
Post-operative evaluation of patients after ventricular septal defect (VSD) repair is dependent on the type of VSD repaired, but complications are uncommon. All patients should have the usual radiographic and clinical auscultatory follow-up. In addition, a post-operative echocardiogram is usually sufficient to rule out recurrent defects in the ventricular septum. Rarely, an undiagnosed defect may be apparent post-operatively that was not found pre-operatively or during surgery. Membranous VSDs are often in close proximity to the AV node and patients should be monitored for intra- and post-operative dysrhythmia.44 Supracristal VSDs are associated with aortic regurgitation and the amount of regurgitant flow should be assessed on clinical exam and echocardiography.45,46
Atrial Septal Defect
Similar to VSDs, complications after atrial septal defect (ASD) surgery are uncommon and are related to the type of ASD. Echocardiography can be performed to rule out recurrent or residual defects of the atrial septum. Secundum ASDs are rarely associated with transient atrial dysrhythmias, which should be monitored and treated if symptomatic.47 After repair of a coronary sinus ASD or isolated primum ASD there is a low risk of atrial dysrhythmia.2
Sinus venosus ASDs are associated with anomalous pulmonary drainage, particularly of the right-sided veins. The Warden technique has become a popular method of repairing these defects. This technique involves an anastomosis of the superior vena cava to the right atrial appendage and baffling of the anomalous veins to the left atrium. Pulmonary venous obstruction, superior vena cava obstruction, and sinus node dysfunction are potential complications of this procedure.48
Atrioventricular Septal Defects
Partial atrioventricular septal defect (AVSD), or partial atrioventricular (AV) canal, includes a primum ASD and a cleft mitral valve. Post-operatively, these patients have a risk for transient atrial or AV nodal dysrhythmia, as well as a risk for recurrent/residual mitral valve regurgitation.49,50 This can be monitored via clinical exam and echocardiography.
Complete AVSD is associated with subaortic obstruction (due to elongation of the left ventricular outflow tract) and this should be monitored periodically with echocardiography.51,52 Similar to ASD and VSD, the repaired septum should be examined for residual shunts.
As the repair of AVSD directly involves both mitral and tricuspid reconstruction, both valves should be checked for degree of regurgitation. Finally, the AV node is displaced inferiorly and posteriorly in patients with AVSD, and complete repair carries a risk of dysrhythmia, including complete heart block, in both short-term and long-term follow-up.53,54
Total Anomalous Pulmonary Venous Return
Infants undergoing repair of total anomalous pulmonary venous return (particularly the infradiaphragmatic form) may be quite ill pre-operatively due to severe pulmonary venous obstruction. Paroxysmal pulmonary hypertensive crises can develop post-operatively. Treatment for this is nitric oxide or anesthetic paralysis.2 Residual pulmonary venous obstruction can occur in 10% of patients and if suspected can be investigated with echocardiography.55
Tetralogy of Fallot
Typical ‘reparative’ surgery for patients with teralogy of Fallot includes closure of the VSD and relief of the right ventricular outflow tract obstruction. This right ventricular outflow tract relief is accomplished by performing a pulmonary valvotomy, resecting excess muscle in the right ventricular outflow tract and sometimes placing a transannular patch across the pulmonary valve annulus.
The transannular patch results in a patent right ventricular outflow tract but leaves the patient with severe regurgitation. A subannular patch leaves the patient with less valvular regurgitation. The surgeon will therefore usually attempt to use a subannular patch if possible, but a transannular patch is required if the pulmonary annulus is restrictive.56
Post-operatively, electrocardiographic anomalies (most commonly right bundle branch block) are very common.57 In addition, any residual shunt across the ventricular septum or residual right ventricular outflow tract obstruction can result in hemodynamic instability. Children typically tolerate the severe pulmonary regurgitation post-transannular patch, but this is often poorly tolerated in neonates and it becomes a progressive problem in older patients.58 Not infrequently, a patient with tetralogy of Fallot may have a non-compliant right ventricle prior to any surgery. When the right ventricular outflow tract obstruction is eventually relieved, the ventricle cannot undergo the necessary contraction to provide sufficient pulmonary flow.2 These patients present with shock and cyanosis and are difficult to ventilate postoperatively. For these reasons, monocusp valves are utilized in infants who require early ‘repair’ of tetralogy of Fallot.
Coarctation of the Aorta
Severe systemic hypertension is common following coarctation repair and should be treated aggressively to prevent unnecessary stress on the coarctation repair sutures.59,60 Post-operative arrhythmias in this lesion are uncommon. Due to the location of the surgery, injury to the recurrent laryngeal nerve or phrenic nerve is possible, which could result in difficulty with weaning from ventilation.13 Residual obstruction across the arch repair can be diagnosed using clinical exam (four-limb blood pressures and pulses) and echocardiography. A computed tomography (CT) scan may be useful in patients with particularly extensive repairs to ensure the geometry of the arch remains intact. ‘Post-coarctectomy syndrome’ is a post-operative mesenteric arteritis that occurs due to the sudden increase in visceral perfusion of the gut after coarctation surgery.61 Symptoms may include abdominal pain, nausea, and vomiting. The incidence of post-coarctectomy syndrome can be reduced with aggressive control of post-operative hypertension and by delaying the resumption of enteral feeding. In the modern era, patients usually have meticulous control of systemic blood pressure and this syndrome is rarely encountered.
d-Transposition of the Great Arteries
The most common repair performed in the last 20 years has been the arterial switch.62 Left ventricular dysfunction can be problematic post-arterial switch and can be due to acute dysfunction of the ‘unprepared’ ventricle or due to coronary ischemia.63 Residual shunts through a VSD (if one was present pre-operatively) can be assessed by echocardiography. Most repairs of d-transposition of the great arteries (d-TGA) prior to 1985 were performed using the atrial switch technique (Mustard or Senning repairs).64,65 Due to the large amount of atrial manipulation, atrial arrhythmias are the most common complication.66,67 Obstruction of both the systemic and the pulmonary venous pathways is possible, both of which can be evaluated using echocardiography, CT, or magnetic resonance imaging (MRI) post-operatively.68
Truncus Arteriosus
Repair of truncus arteriosus often involves resection of the pulmonary artery from the aorta, repair of the aorta, closure of the VSD, and placement of a conduit for flow from the right ventricular outflow tract to the pulmonary artery. There is potential for a residual ventricular shunt post-operatively. The truncal valve now functions as the aortic valve and it should be assessed clinically and echocardiographically. Similar to tetralogy of Fallot, right bundle branch block is common in these patients after surgical closure of the VSD.
Single Ventricles—Palliative Shunts
In patients for whom a single ventricle pathway has been selected, the first operation is often to place an arterial to pulmonary artery shunt. This is most commonly either a Blalock-Taussig subclavian-PA (BT) shunt or a Sano-type RV-PA shunt. Complications are uncommon following BT-shunt placement but can include chylothorax and injury to the recurrent laryngeal or phrenic nerves.2,9,13 This shunt is the only supply of pulmonary blood flow, therefore any hemodynamic instability with cyanosis should raise concern that the shunt has become compromised.2,69 Echocardiography or angiography can evaluate shunt patency.
Single Ventricles—Norwood Operation
The Norwood procedure is undertaken for patients with hypoplastic left heart syndrome and typically includes arch reconstruction, atrial septectomy, and BT or Sano shunt placement.70,71 These patients can be extremely labile post-operatively, and particular attention should be paid to balancing the Qp:Qs (pulmonary:systemic blood flow ratio). Low cardiac output is a common postoperative concern and can be due to AV valve regurgitation, ventricular dysfunction, or unbalanced Qp:Qs.72 Manifestations of low cardiac output include necrotizing enterocolitis and liver or kidney ischemia.23
Glenn Operation
The second-stage surgery for most patients with single ventricle physiology (including hypoplastic left heart syndrome) is the Glenn or bidirectional cavopulmonary anastomosis. This operation diverts all superior vena cava return to the pulmonary arteries.73 Common surgical complications can include phrenic nerve injury, superior vena cava pathway obstruction (with resultant superior vena cava syndrome), and transient sinus node dysfunction.74,75
Fontan Operation
The final stage for patients with single ventricle physiology involves creation of a pathway for inferior vena cava venous return to the pulmonary arteries, bypassing the right ventricle. This is most commonly performed using a tunneled pathway of material, either through the right atrium (lateral tunnel pathway) or via an extra-cardiac conduit pathway.73,76 Arrhythmias are common, including atrial flutter and JET.77,78 Since ventricular contraction does not assist in propelling pulmonary flow, post-Fontan patients are extremely sensitive to volume depletion, anemia, and arrhythmia. They are highly preload-dependent and often develop hemodynamic compromise in response to these stressors.79
Intensive Care Management
The role of post-operative pain control and sedation is often underappreciated, especially in neonates. Prevention of hemodynamic changes in shunting, particularly right-to-left shunts, can in turn prevent hypercyanotic episodes and hypoxemia in susceptible patients.72 Ventricular tachycardia or SVT can be induced by tachycardia responses to painful stimuli. Cardiac output is often at its lowest point the first night following surgery and any interventions that can be undertaken to prevent further uncontrolled and unexpected drops in cardiac output are crucial, particularly in patients with single ventricle physiology.2 After repair of coarctation of the aorta, patients need aggressive control of hypertension to prevent further stress on sutures and development of postcoarctectomy syndrome.59,60 Routine use of vasoactive medications and positive inotropes via continuous intravenous infusion is essential. This care should include appropriate doses of analgesics and sedative medications in the immediate post-operative period. Finally, post-operative pulmonary toilet is vital to prevent atelectasis and pneumonia.80
When to Obtain Further Imaging
Chest radiography should be obtained routinely for any change in respiratory status post-operatively. Most symptomatic effusions, pleural or pericardial, should be visible on radiography. Follow-up echocardiography can be obtained for questions of valve function, or conduit gradients, pericardial effusions, or to assess residual shunts. Cardiac catheterization is not routinely performed unless coronary insufficiency, residual shunts, or fistulous connections require evaluation. CT or MRI can be performed if needed to assess aortic arch repairs, aortic grafts, pulmonary artery architecture, or right ventricular function.
Conclusions
With recent advances in intra- and post-operative care for patients with congenital heart disease, survival rates continue to improve. Today more children and adults have successful surgical procedures. Post-operative monitoring and follow-up is essential for the prevention of serious morbidity and mortality. Physicians caring for post-operative patients with congenital heart disease require a unique understanding of lesion-specific complications, as well as the baseline physiology and surgical techniques involved.