General Principles of Treatment of Congenital Heart Disease

Published on 27/03/2015 by admin

Filed under Pediatrics

Last modified 27/03/2015

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 2388 times

Chapter 428 General Principles of Treatment of Congenital Heart Disease

Daniel Bernstein

Most patients who have mild congenital heart disease require no treatment. The parents and child should be made aware that a normal life is expected and that no restriction of the child’s activities is necessary. Overprotective parents may use the presence of a mild congenital heart lesion or even a functional heart murmur as a means to exert excessive control over their child’s activities. Although fears may not be expressed overtly, the child may become anxious regarding early death or debilitation, especially when an adult member of the family acquires unrelated symptomatic heart disease. The family may have an unexpressed fear of sudden death, and the rarity of this manifestation should be emphasized in discussions directed at improving their understanding of the child’s congenital heart defect. The difference between congenital heart disease and degenerative coronary disease in adults should be emphasized. General health maintenance, including a well-balanced, “heart-healthy” diet; aerobic exercise; and avoidance of smoking, should be encouraged.

Even patients with moderate to severe heart disease need not be markedly restricted in physical activity. Physical education should be modified appropriately to the child’s capacity to participate. The extent of such modification can generally be determined best by formal exercise testing. Competitive sports for many of these patients is discouraged, but decisions are usually made on an individual basis. Patients with severe heart disease and decreased exercise tolerance usually tend to limit their own activities. Dyspnea, headache, and fatigability in cyanotic patients may be a sign of increasing hypoxemia and may require limitation of activity in those for whom specific medical or surgical treatment is not available. Routine immunizations should be given, with the inclusion of influenza vaccine during the appropriate season; patients who might be considered candidates for heart or heart-lung transplantation should not receive live-virus vaccinations just before transplantation.

Bacterial infections should be treated vigorously, but the presence of congenital heart disease is not an appropriate reason to use antibiotics indiscriminately. Prophylaxis against infective endocarditis should be carried out during dental procedures for appropriate patients. The American Heart Association has recently significantly revised these recommendations, with most patients no longer requiring routine prophylaxis (Chapter 431).

Cyanotic patients need to be monitored for a multitude of noncardiac manifestations of oxygen deficiency (Table 428-1). Treatment of iron deficiency anemia is important in cyanotic patients, who will show improved exercise tolerance and general well-being with adequate hemoglobin levels. These patients should also be carefully observed for excessive polycythemia. Cyanotic patients should avoid situations in which dehydration may occur, which leads to increased viscosity and increases the risk of stroke. Diuretics may need to be decreased or temporarily discontinued during episodes of acute gastroenteritis. High altitudes and sudden changes in the thermal environment should also be avoided. Phlebotomy with partial exchange transfusion is carried out only in symptomatic patients with severe polycythemia (usually those hematocrit >65%). Patients with moderate to severe forms of congenital heart disease or a history of rhythm disturbance should be carefully monitored during anesthesia for even routine surgical procedures. Consultation with an anesthesiologist experienced in the care of children with congenital heart disease is encouraged. Women with nonrepaired severe congenital heart disease should be counseled on the risks associated with childbearing and on the use of contraceptives and tubal ligation. Pregnancy may be dangerous for patients with chronic cyanosis or pulmonary arterial hypertension. Women with mild to moderate heart disease and many of those who have had corrective surgery can have normal pregnancies, although those with residual hemodynamic derangements or with systemic right ventricles should optimally be followed by a high-risk perinatologist and a cardiologist with expertise in caring for adults with congenital heart disease.

Table 428-1 EXTRACARDIAC COMPLICATIONS OF CYANOTIC CONGENITAL HEART DISEASE AND EISENMENGER PHYSIOLOGY

PROBLEM ETIOLOGY THERAPY
Polycythemia Persistent hypoxia Phlebotomy
Relative anemia Nutritional deficiency Iron replacement
CNS abscess Right-to-left shunting Antibiotics, drainage
CNS thromboembolic stroke Right-to-left shunting or polycythemia Phlebotomy
Low-grade DIC, thrombocytopenia Polycythemia None for DIC unless bleeding, then phlebotomy
Hemoptysis Pulmonary infarct, thrombosis, or rupture of pulmonary artery plexiform lesion Embolization
Gum disease Polycythemia, gingivitis, bleeding Dental hygiene
Gout Polycythemia, diuretic agent Allopurinol
Arthritis, clubbing Hypoxic arthropathy None
Pregnancy complications: abortion, fetal growth retardation, prematurity increase, maternal illness Poor placental perfusion, poor ability to increase cardiac output Bed rest, pregnancy prevention counseling
Infections Associated asplenia, DiGeorge syndrome, endocarditis Antibiotics
Fatal RSV pneumonia with pulmonary hypertension Ribavirin; RSV immunoglobulin (prevention)
Failure to thrive Increased oxygen consumption, decreased nutrient intake Treat heart failure; correct defect early; increase caloric intake
Psychosocial adjustment Limited activity, cyanotic appearance, chronic disease, multiple hospitalizations Counseling

CNS, central nervous system; DIC, disseminated intravascular coagulation; RSV, respiratory syncytial virus.

Postoperative Management

After successful open heart surgery, the severity of the congenital heart defect, the age and condition (nutritional status) of the patient before surgery, the events in the operating room, and the quality of the postoperative care influence the patient’s course. Intraoperative factors that influence survival and that should be noted when a patient returns from the operating room include the duration of cardiopulmonary bypass, the duration of aortic cross-clamping (the time during which the heart is not being perfused), and the duration of profound hypothermia (used in some newborns: the period during which the entire body is not being perfused).

Immediate postoperative care should be provided in an intensive care unit staffed by a team of physicians, nurses, and technicians experienced with the unique problems encountered after open heart surgery in childhood. In most major centers, this occurs in a dedicated pediatric cardiovascular intensive care unit. Preparation for postoperative monitoring begins in the operating room, where the anesthesiologist or surgeon places an arterial catheter to allow direct arterial pressure measurements and arterial sampling for blood gas determination. A central venous catheter is also placed for measuring central venous pressure and for infusions of cardioactive medications. In more complex cases, right or left atrial or pulmonary artery catheters may be inserted directly into these cardiac structures and used for pressure monitoring purposes. Flow-directed thermodilution monitoring (Swan-Ganz) catheters are sometimes used for monitoring pulmonary capillary wedge pressure and the cardiac index, although this modality is not commonly used in children. Temporary pacing wires are placed on the atrium or ventricle, or both, in case temporary postoperative heart block occurs. Transcutaneous oximetry provides for continuous monitoring of arterial oxygen saturation.

Functional failure of one organ system may cause profound physiologic and biochemical changes in another. Respiratory insufficiency, for example, leads to hypoxia, hypercapnia and acidosis, which, in turn, compromise cardiac, vascular, and renal function. The latter problems cannot be managed successfully until adequate ventilation is re-established. Thus, it is essential that the primary source of each postoperative problem be identified and treated.

Respiratory failure is a serious postoperative complication encountered after open heart surgery. Cardiopulmonary bypass carried out in the presence of pulmonary congestion results in decreased lung compliance, copious tracheal and bronchial secretions, atelectasis, and increased breathing effort. Because fatigue and, subsequently, hypoventilation and acidosis may rapidly ensue, mechanical positive pressure endotracheal ventilation may be continued after open heart surgery for a minimum of several hours in relatively stable patients and for up to 2-3 days or longer in severely ill patients, especially infants. Patients with certain congenital heart lesions, particularly those with DiGeorge syndrome, may also have airway abnormalities (micrognathia, tracheomalacia, bronchomalacia) that can make extubation more difficult.

The electrocardiogram should be monitored continuously during the postoperative period. A change in heart rate, even without arrhythmia, may be the first indication of a serious complication such as hemorrhage, hypothermia, hypoventilation, or heart failure. Cardiac rhythm disorders must be diagnosed quickly because a prolonged untreated arrhythmia may add a severe hemodynamic burden to the heart in the critical early postoperative period (Chapter 429). Injury to the heart’s conduction system during surgery can result in postoperative complete heart block. This complication is usually temporary and is treated with surgically placed pacing wires that can later be removed. Occasionally, complete heart block is permanent. If heart block persists beyond 10-14 days postoperatively, insertion of a permanent pacemaker is required. Tachyarrhythmias are a common problem in postoperative patients. Junctional ectopic tachycardia (JET) can be a particularly troublesome rhythm to manage (Chapter 429), although it usually responds to intravenous amiodarone.

Heart failure with poor cardiac output after cardiac surgery may be secondary to respiratory failure, serious arrhythmias, myocardial injury, blood loss, hypovolemia, a significant residual hemodynamic abnormality, or any combination of these factors. Treatment specific to the cause should be instituted. Catecholamines, phosphodiesterase inhibitors, nitroprusside and other afterload-reducing agents, and diuretics are the cardioactive agents most often used in patients with myocardial dysfunction in the early postoperative period (Chapter 436). Postoperative pulmonary hypertension can be managed with hyperventilation and inhaled nitric oxide. In patients who are unresponsive to standard pharmacologic treatment, various ventricular assist devices are available, depending on the patient’s size. If pulmonary function is adequate, a left ventricular assist device (LVAD) may be used. If pulmonary function is inadequate, extracorporeal membrane oxygenation (ECMO) may be used. These extraordinary measures are helpful in maintaining the circulation until cardiac function improves, usually within 2-3 days. They have also been used with moderate success as a bridge to transplantation in patients with severe nonremitting postoperative cardiac failure.

Acidosis secondary to low cardiac output, renal failure, or hypovolemia must be prevented or if present, promptly corrected. Serial monitoring of arterial blood gases and lactate concentrations is performed. An arterial pH <7.3 may result in a decrease in cardiac output with an increase in lactic acid production and may be the forerunner of arrhythmias or cardiac arrest.

Renal function may be compromised by congestive heart failure and further impaired by prolonged cardiopulmonary bypass. Blood and fluid replacement, cardiac inotropic agents, and vasodilators will usually re-establish normal urine flow in patients with hypovolemia or cardiac failure. Renal failure secondary to tubular injury may require temporary peritoneal or hemodialysis or hemofiltration.

Neurologic abnormalities can develop after cardiopulmonary bypass, especially in the neonatal period. Seizures may occur when the patient awakens from sedation and can usually be controlled with anticonvulsant medications. In the absence of other neurologic signs, self-limited isolated seizures in the immediate postoperative period usually carry a good long-term prognosis. Thromboembolism and stroke are rarer but serious complications of open heart surgery. In the long term, both subtle and more substantial learning disabilities may develop. Patients who have undergone surgery entailing the use of cardiopulmonary bypass, especially in the newborn period, should be watched carefully during their early school years for signs of mild to moderate learning disabilities, which are often amenable to early remedial intervention. The risk is higher in patients who have undergone repair using hypothermic total circulatory arrest than in those where systemic blood flow is maintained using cardiopulmonary bypass.

The postpericardiotomy syndrome may occur toward the end of the 1st postoperative week or may sometimes be delayed until weeks or months after surgery. This febrile illness is characterized by fever, decreased appetite, listlessness, nausea, and vomiting. Chest pain is not always present, so a high index of suspicion should be maintained in any recently postoperative patient. Echocardiography is diagnostic. In most instances, the postpericardiotomy syndrome is self-limited; however, when pericardial fluid accumulates rapidly, the potential danger of cardiac tamponade should be recognized (Chapter 434). Rarely, arrhythmias may also occur. Symptomatic patients usually respond to salicylates or indomethacin and bed rest. Occasionally, steroid therapy or pericardiocentesis is required. Late recurrences can occur but are less usual.

Hemolysis of mechanical origin is seen, although rarely, after repair of certain cardiac defects, for example, atrioventricular septal defects (AVSDs), or after the insertion of a mechanical prosthetic valve. It is due to unusual turbulence of blood at increased pressure. Reoperation may be necessary in rare patients with severe and progressive hemolysis who require frequent blood transfusions, but in most instances the problem slowly regresses.

Infection is another potentially serious postoperative problem. Patients usually receive a broad-spectrum antibiotic for the initial postoperative period. Potential sites of infection include the lungs (generally related to postoperative atelectasis), the subcutaneous tissues at the incision site, the sternum, and the urinary tract (especially after an indwelling catheter has been in place). Sepsis with infective endocarditis is an infrequent complication, and can be difficult to manage, especially if prosthetic material was placed at the time of surgery (Chapter 431).

Long-Term Management

Patients who have undergone surgery for congenital heart disease can be divided into several major categories: (1) lesions for which total repair has been achieved; (2) lesions for which both anatomic and physiologic correction has been achieved; and (3) lesions for which only palliation, albeit potentially long-term, has been achieved. There is some disagreement among cardiologists as to exactly which categories a particular congenital heart lesion might fall, and to some degree every case should be considered individually. Many argue that only for isolated patent ductus arteriosus is total repair really achieved, with no requirement for long-term follow-up. Patients who are able to undergo anatomic and physiologic correction include many of the left-to-right shunt lesions (atrial and ventricular septal defects) and milder forms of obstructive lesions (e.g., valvar pulmonic stenosis, some forms of valvar aortic stenosis, and coarctation of the aorta), and some forms of cyanotic heart disease, for example, uncomplicated tetralogy of Fallot and simple transposition of the great arteries. These patients usually have achieved total or near-total physiologic correction of their lesion; however, they are still at some risk of long-term sequelae, including late heart failure or arrhythmia, or recurrence of a significant physiologic abnormality (e.g., recoarctation of the aorta, worsening mitral regurgitation in patients with AVSDs, or long-standing pulmonary regurgitation in patients with tetralogy of Fallot repaired with a transannular patch). These patients require regular follow-up with a pediatric cardiologist (and when old enough, with an adult congenital heart disease specialist [Chapter 428.1]), however, their long-term prognosis is generally very good. Patients with more complex lesions, such as those with single ventricle physiology, are at much higher risk of long-term sequelae and require even closer follow-up. These patients, particularly those who have undergone the Fontan procedure, are at risk long-term for arrhythmia, thrombosis, protein losing enteropathy, end-organ (especially hepatic) dysfunction, and heart failure. Some may eventually require cardiac transplantation.

Physical limitations are variable, ranging from minimal to none in patients with physiologic correction, to mild to moderate in patients with palliative procedures. The extent to which a patient should be allowed to participate in athletics, both recreational and competitive, can best be determined by the cardiologist, often with the assistance of the data that can be derived from cardiopulmonary exercise testing (Chapter 417.5).

Long-term morbidities affecting neurologic function and behavior are influenced by many factors, including the effects of any genetic alterations on the developing central nervous system. Data suggest a greater role for prenatal central nervous system abnormalities (anatomic or secondary to alterations in cerebral blood flow or oxygenation) than previously suspected; these include microcephaly, cerebral atrophy, altered cerebral biochemistry (lactate, choline, N-acetylaspartate) average diffusivity, and fractional anisotropy of white matter tracts. Chronic hypoxemia and failure to thrive also may influence the developing brain, and there is evidence that the type of intervention required (cardiopulmonary bypass, hypothermic total circulatory arrest, catheter-based therapy) plays a substantial role. In general, in the absence of a significant genetic syndrome or major perioperative complication, most children function at a fairly high level after repair of congenital heart defects and are able to attend regular school. Group mean scores on standard cognitive tests are not different from the general population; however, some areas appear to be more at risk than others, including certain aspects of motor function, speech, visual-motor tracking, and phonological awareness. Awareness of these potential issues is critical to obtaining prompt remedial assistance if a child is found to be struggling in school.

Bibliography

Barbu D, Mert I, Kruger M, et al. Evidence of fetal central nervous system injury in isolated congenital heart defects: microcephaly at birth. Am J Obstet Gynecol. 2009;201:43.e1-43.e7.

Bellinger DC, Newburger JW, Wypij D, et al. Behaviour at eight years in children with surgically corrected transposition: The Boston Circulatory Arrest Trial. Cardiol Young. 2009;19:86-97.

Bjarnason-Wehrens B, Dordel S, Schickendantz S, et al. Motor development in children with congenital cardiac diseases compared to their healthy peers. Cardiol Young. 2007;17:487-498.

Hoffman TM, Bush DM, Wernovsky G, et al. Postoperative junctional ectopic tachycardia in children: incidence, risk factors, and treatment. Ann Thorac Surg. 2002;74:1607-1611.

Buy Membership for Pediatrics Category to continue reading. Learn more here

Related posts:

Disorders of the Complement System Default ThumbnailFlukes (Liver, Lung, and Intestinal) Default ThumbnailDiseases of the Salivary Glands and Jaws Default ThumbnailSplenomegaly Treatment of Rheumatic Diseases Default ThumbnailEsophageal Perforation