Selected postoperative complications are discussed briefly in this chapter. Problems that occur in the immediate postoperative period, such as low cardiac output state, minor rhythm disorders, blood pressure abnormalities, and renal, metabolic, and hematologic abnormalities, are discussed in Chapter 28. Postoperative complications that occur frequently with certain types of cardiac defects are discussed under those specific conditions.
I. Pleural Effusion
A small amount of fluid is present in the pleural cavity. The reabsorption of this pleural fluid is mainly through the venous system and to some degree through the lymphatic system. Any increase in capillary hydrostatic pressure as a result of disrupted systemic venous hemodynamics (e.g., Fontan surgery, right ventricular failure) may result in accumulation of transudates in the pleural cavity. Trauma to the lymphatic system as is caused by cutting large tributaries of the thoracic duct causes buildup of chyle in the pleural space. Both conditions create a management problem.
Duration of persistent pleural effusion , as a result of increased systemic venous pressure that is common after Fontan operation, may be shortened by intraoperative creation of baffle fenestration. Symptoms may include fever, tachycardia, tachypnea, increased work of breathing, and, in severe cases, respiratory failure. Diagnosis is usually made by chest radiography (frontal, lateral, and decubitus films). Thoracentesis (with ultrasonographic guidance) may be necessary for determination of etiology and/or for treatment. Transudates can be differentiated by amount of protein (<3▒g/100▒mL) and lactate dehydrogenase (LDH) (<200 IU/L) from exudates (protein >3▒g/100▒mL and LDH >200 IU/L), which are caused by increased capillary permeability and may be a sign of infection. In addition, transudates have fewer leukocytes (<10,000/mm3), have more glucose (60▒mg/dL), and have a serous appearance compared with exudates, which are cloudy and have significantly more leukocytes (>50,000/mm 3 ). Furthermore, fluid-to-serum ratios of LDH (>0.6) and protein (>0.5) are further clues to the exudative nature of the fluid.
A small amount of pleural effusion can be tolerated well. It usually responds to medical management with diuresis, afterload reduction, and inotropic support. However, significant and recurrent amounts of pleural effusion will cause cardiorespiratory compromise and will require more aggressive management strategies, including chest tube drainage, now rarely implemented pleurodesis with a sclerosing agent (e.g., talc), and/or Fontan revision. When the drainage is large, appropriate replacement of fluid, electrolytes, and protein is essential.
Chylothorax , an accumulation of chyle in the pleural cavity, may be caused by trauma to peritracheal lymphatics or transmission of increased systemic venous pressure to the thoracic duct, or a combination of both. It may be seen after surgery (up to about 6% of cases) such as COA repair, B-T shunt, or cavopulmonary anastomosis (e.g., Glenn or Fontan operation), or rarely, after ligation of PDA. Occasionally, chylothorax occurs in combination with chylopericardium.
Chyle may or may not have a creamy appearance, depending on the nutritional status of the patient (consumption of fat results in creamy appearance), but a triglyceride level above 110▒mg/dL is highly probable for the diagnosis, whereas a triglyceride concentration of less than 50▒mg/dL makes the diagnosis of chylothorax extremely unlikely. The fluid is usually sterile and is abundant of lymphocytes (2,000 to 20,000/mm 3 ). Presence of chylomicrons (triglyceride-rich lipoprotein particles containing some phospholipids and cholesterol) confirms a diagnosis of chylothorax.
Treatment, apart from medical management (i.e., diuresis, improvement of cardiac output) described previously, is directed at drainage of chylothorax (chest tube placement) and reducing the flow of lymph (by limiting physical activity to reduce lymph flow from the extremities).
In most cases, chest tube drainage is all that is necessary. If chylothorax develops after chest tube removal, needle aspiration every 3 to 4 days usually constitutes adequate treatment. The drainage slows or stops within 7 days in most cases.
Careful attention to the nutrition of the patient is important. Either parenteral hyperalimentation or a diet with medium-chain triglycerides (MCTs) as the fat source is called for. As MCT oil does not contribute in chylomicron formation, it is absorbed by the portal system and not by the lymphatic system. Serum albumin should be followed closely and replaced if necessary.
In persistent cases, continuous intravenous (IV) octreotide (0.5 to 10 μg/kg/hr), a somatostatin analog, has been used effectively.
If the drainage persists, making the patient’s status non per os (NPO) and starting total parenteral nutrition therapy and/or surgical intervention may be considered because continuous loss of chyle results in lymphocyte depletion and subsequent immunocompromise. Indications for the intervention may include (a) average daily loss above 1000▒mL, or, in children, chest tube output more than 2▒mL/kg/day), (b) the chyle flow not slowing after 2 weeks, or (c) imminent nutritional complications.
Thoracic duct ligation with or without chemical pleurodesis has been used successfully. During pleurodesis, the introduced chemicals cause inflammation between the parietal and visceral pleura. This reaction causes adhesions between the layers and prevents further fluid accumulation. The procedure may be painful and cause fever and nausea so that this procedure has become out of favor at most centers.
II. Paralysis of the Diaphragm
Paralysis or paresis of a hemidiaphragm occurs in about 0.5% to 2% of patients after thoracic surgery, though the incidence may be as high as 10% in young children. It is the result of damage to the phrenic nerve. It may occur after COA repair, PDA ligation, B-T shunt, or open heart surgery and may be due to nerve transection, blunt trauma, stretching during retraction, electrocautery, or hypothermic injury. Infants are more vulnerable to respiratory distress owing to their greater dependence on the diaphragm for respiration.
The diagnosis should be suspected if there is persistent unexplained tachypnea, respiratory distress, hypoxia and/or hypercapnia, atelectasis, inability to wean from the ventilator, or persistent elevation of a hemidiaphragm on serial chest radiographs. Fluoroscopy or sonogram that reveals paradoxical motion of the hemidiaphragms is diagnostic if it is done during spontaneous breathing. When paralysis is not caused by transection, return of function usually occurs in 2 weeks to 6 months. In 20% of the cases the paralysis is permanent.
Management ranges from conservative to surgical intervention.
Some investigators recommend ventilator support only for the initial 2 to 6 weeks.
Continuous positive airway pressure (CPAP) may be useful in management as well as in identifying patients who may benefit from plication.
If respiratory insufficiency persists, surgical plication should be considered. Plication of the diaphragm usually is not necessary as long as the patient can be extubated without developing respiratory insufficiency.
III. Postpericardiotomy Syndrome
Postpericardiotomy syndrome (PPS), a febrile illness with pericardial and pleural inflammatory reactions, develops after surgery involving pericardiotomy. This occurs in about 25% to 30% of patients who undergo pericardiotomy. The etiology remains speculative. Though questioned in more recent studies, an autoimmune response to cardiac antibodies in association with a recent or remote viral infection was postulated in the 1970s. Studied patients who developed PPS had a high titer of antiheart antibodies along with high antibody titers against adenovirus, coxsackievirus B1-6, and cytomegalovirus.
Onset is a few weeks to a few months (median 4 weeks) after pericardiotomy. PPS is characterized by fever, chest pain, irritability, malaise, joint pain, decreased appetite, nausea, and vomiting. Chest pain, which may be severe, is caused by both pericarditis and pleuritis. It may be worse in supine position or with deep inspiration. It is rare in infants younger than 2 years. Physical examination may reveal pericardial and pleural friction rubs and hepatomegaly. Tachycardia, tachypnea, rising venous pressure, falling arterial pressure, and narrow pulse pressure with a paradoxical pulse are signs of cardiac tamponade. Blood laboratory findings include leukocytosis with left shift. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are usually elevated. Chest radiography shows enlarged cardiac silhouette and pleural effusion. Electrocardiogram (ECG) shows persistent ST-segment elevation and flat or inverted T waves in the limb and left precordial leads. Echo is a reliable test in confirming the presence and amount of pericardial effusion and in evaluating evidence of cardiac tamponade. Although the disease is self-limited, its duration is highly variable; the median duration is 2 to 3 weeks. About 20% of patients have recurrences.
Bed rest is all that is needed for a mild case. A nonsteroidal antiinflammatory agent such as oral aspirin (80 to 100▒mg/kg/day divided in 3 or 4 doses) or ibuprofen (20 to 40▒mg/kg/day divided in 3 or 4 doses) is effective in most cases. In severe cases, corticosteroids (prednisone, 2▒mg/kg/day up to 60▒mg/day) tapered over 3 to 4 weeks may be indicated if the diagnosis is secure and infection has been ruled out. Emergency pericardiocentesis or creation of pericardial window may be required if signs of cardiac tamponade are present. Diuretics may be used for pleural effusion.
IV. Postcoarctectomy Hypertension
Paradoxical hypertension following repair of COA is quite common, particularly in older children. This condition is usually biphasic with mostly systolic hypertension developing within 24 to 48▒hours of the procedure, followed by a more delayed phase. The mechanism is believed to be multifactorial, including intraoperative stimulation of sympathetic nerve fibers, postoperative altered baroreceptor activity, and derangement of the renin-angiotensin system. The first phase of hypertension is believed to be the result of increased catecholamine levels and altered baroreceptor response. Elevated levels of renin and angiotensin are believed to be responsible for the later phase hypertension, which is more pronounced in diastole.
Systemic hypertension needs to be treated promptly, as this could increase the risk of postoperative hemorrhage. In addition to pain management and sedation, short-acting IV β-receptor blocker administration (e.g., esmolol, loading dose of 100 to 500 μg/kg IV over 1▒minute followed by 50 to 500 μg/kg/min continuous drip) can be used to control the first phase of postcoarctectomy hypertension. Other medications that have been used successfully include longer-acting β-receptor blockers (e.g., propranolol, nadolol), combined α- and β-receptor blockers (e.g., labetalol), and vasodilators (nitroprusside, hydralazine). Long-term management of paradoxical hypertension is achieved with angiotensin-converting enzyme (ACE) inhibitors (e.g., enalapril, captopril) or angiotensin II receptor antagonists (e.g., losartan).
Postcoarctectomy syndrome is a well-described but rare complication of repair of COA. Occurring in up to 5% to 10% of older children, it is characterized by severe, intermittent abdominal pain beginning 2 to 4 days after surgery with accompanying fever, leukocytosis, and vomiting. In severe cases ascites, ileus, melena, ischemic bowel, and even death were reported. Persistent paradoxical hypertension may be present. Abdominal findings are believed to be caused by acute inflammatory changes in mesenteric arteries resulting from sudden increase in pulsatile pressures in arteries distal to the coarctation.
Because of mesenteric arteritis, feeding of solid foods is delayed; some centers advocate NPO status for the first 48▒hours following the repair. Treatment includes bowel decompression and treatment of the accompanying hypertension.
V. Protein-Losing Enteropathy
Protein-losing enteropathy (PLE) is a condition characterized by excessive loss of plasma protein through the intestinal mucosa. Although it can be a primary gastrointestinal disorder with intestinal lymphangiectasia and associated peripheral edema, PLE occurs most frequently as a complication of Fontan procedure. It is believed to be caused by chronically elevated central venous pressure secondary to unfavorable PA anatomy, increased PVR, decreased cardiac output, or loss of electrical AV synchrony. Patients with PLE have been shown to have loss of heparin sulfate and syndecan-1 proteoglycans necessary for maintenance of intestinal epithelial barrier function, thus promoting intestinal protein loss. Additionally, inflammatory mediator release and individual genetic predisposition are postulated in the mechanism of PLE after Fontan operation. PLE in association with Fontan-type surgery has a cumulative 10-year occurrence risk of 13% and a poor 5-year survival rate of about 50%.
Children may present a few weeks, months, or even years after the surgery with symptoms of anasarca, abdominal pain and distention, diarrhea, emesis, and poor weight gain. Patients may be tachycardic if sinus node function is preserved. Tachypnea may be a clue to concurrent pleural effusion. Hepatomegaly is seen frequently. Signs of fluid retention including ascites and anasarca may be found on examination.
Serum albumin, immunoglobulins, and total protein are decreased. In addition, α 1 -antitrypsin 24-hour fecal clearance and α 1 -antitrypsin random fecal concentration are increased. Electrolyte imbalance is seen, which may be iatrogenic secondary to diuretic therapy. ECG and Holter monitoring need to be obtained to rule out any arrhythmia such as sinus node dysfunction. Chest radiography may reveal cardiomegaly and/or pleural effusion. Echo is performed to evaluate ventricular function or Fontan baffle obstruction. Cardiac catheterization may be needed as a diagnostic but also as a therapeutic tool.
Treatment includes the following:
High-protein, low-fat, high-MCT, low-sodium, high-calcium diet
Consider vitamin D supplement
Diuretics (furosemide, spironolactone)
ACE inhibitors (enalapril)
Phosphodiesterase type 5 inhibitors (sildenafil, tadalafil)
Endothelin receptor antagonists (bosentan)
Subcutaneous unfractionated (100 units/kg, maximum 5000 units daily) or low-molecular-weight heparin (enoxaparin, 0.5 to 1.5▒mg/kg/dose SC every 12 to 24▒hours) to achieve target anti-factor Xa levels of 0.5 to 1 units/mL in a sample taken 4 to 6▒hours after SC injection)
Corticosteroids (budesonide, 6▒mg for children <4 years, 9▒mg for children >4 years; dose should be weaned after normalization of albumin [3▒mg/dL] to lifelong 3▒mg every other day)
Trial of octreotide (continuous IV drip 0.5 to 10 μg/kg/hr or subcutaneous injection of 1 to 10 μg/kg/day divided 3 times daily to a maximum of 150 μg per dose)
More invasive management apart from interventional cardiac catheterization may include selective lymphatic embolization of pathologic regional lymphatic network, pacemaker insertion, repair of residual defects (e.g., repair of AV valve, repair of residual COA), Fontan revision, or cardiac transplantation.
VI. Fontan-Associated Liver Disease
With improvement in technical aspects of congenital cardiac surgery as well as medical management, more patients with single ventricular physiology survive to adulthood. The number of the patients who have successfully undergone Fontan procedure has increased. This, however, means increased prevalence of medium-term and long-term Fontan-associated complications. One entity that has been of significant concerns is Fontan-associated liver disease (FALD). Derangement in perinatal circulation as well as lifetime hepatic insults by means of medications, frequent cardiac catheterization, and surgical interventions all contribute to an abnormal hepatic physiology. Not surprisingly, nearly all Fontan patients have abnormal liver histology. A detailed FALD pathophysiology and management is beyond the scope of this handbook. However, a short list of studies for FALD evaluation, which should be performed every 1 to 2 years, is provided:
Complete blood cell count
Prothrombin time (PT), international normalized ratio (INR)
Aspartate aminotransferase (AST), alanine aminotransferase (ALT), albumin, total protein, alkaline phosphatase, creatinine
Total and direct bilirubin
Ultrasound of liver with Doppler and elastography
Ultrasound of spleen
In the case of abnormal findings with thrombocytopenia, abnormal liver enzymes, prolonged PT, INR, elevated direct bilirubin, hypoalbuminemia, splenomegaly, or hepatic mass, consider referral to hepatology.
VII. Junctional Ectopic Tachycardia
Postoperative junctional ectopic tachycardia (JET) occurs in 5% to 10% of pediatric postoperative patients, most frequently following surgeries adjacent to the AV node (e.g., VSD, TOF, ECD repair, Fontan procedure), as well as in patients with prolonged aortic cross-clamp and CPB times. Postoperative JET usually occurs within hours after cardiac surgery and may last for several days. Though it is self-limited, it is a serious and life-threatening arrhythmia owing to its occurrence in a very vulnerable phase of a patient’s postoperative course. It is characterized by tachycardia with a ventricular rate usually in excess of 180 beats/min (faster than atrial rate), AV dissociation (unlike re-entrant SVT), and capture beats (occasional antegrade conduction of a normal sinus beat).
Driven by an automatic focus within the proximity of the AV node or bundle of His, JET does not respond to strategies such as electrical or pharmacologic cardioversion. Tachycardia and loss of AV synchrony are responsible for a decrease in cardiac output, especially in an already hemodynamically compromised patient. Treatment is aimed at correcting tachycardia and restoring AV synchrony as well as optimizing cardiac output.
Measures to maximize cardiac output include the following:
Treatment of anemia.
Treatment of acidosis.
Inotropic, lusitropic, and vasodilatory support with milrinone without the undesired arrhythmogenic effect.
Measures to decrease oxygen consumption (e.g., pain control, sedation, and, if necessary, paralysis).
Attempts to restore AV synchrony include:
Correction of electrolyte imbalance (magnesium 2+ , calcium 2+ , and potassium + ).
Attempting atrial pacing at a rate higher than the JET rate to achieve AV synchrony, once the ventricular rate is less than 200 beats/min.
Attempts to control the ventricular rate, though challenging, may include the following strategies and/or antiarrhythmic medications:
Lowering the infusion rate of catecholamines (proarrhythmogenic).
IV amiodarone (loading dose: 5▒mg/kg over 30 to 60▒minutes, followed by IV drip at a rate of 5 to 15 μg/kg/min or IV boluses of 2.5▒mg/kg every 6▒hours).
Combination of IV procainamide (loading dose: 2 to 6▒mg/kg, maximum dose 100▒mg/dose, followed by IV drip at 20 to 80 μg/kg/min, maximum 2▒g/day) and hypothermia.
IV esmolol (loading dose: 100 to 500 μg/kg IV over 1▒minute, followed by IV drip at 50 to 500 μg/kg/min).
Induced hypothermia (34° to 36°C) using cooling blanket or IV cold saline infusions.
If the above efforts to control JET fail and the patient continues to deteriorate, extracorporeal life support (ECLS) may need to be initiated.