Congenital Heart Disease in Adults

Published on 13/02/2015 by admin

Filed under Cardiothoracic Surgery

Last modified 13/02/2015

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 2025 times

Chapter 15 Congenital Heart Disease in Adults

Since the first surgical ligation of a patent ductus arteriosus by Gross in 1938, enormous advances have been made in the repair and palliation of congenital heart disease. Excluding bicuspid aortic valve, approximately 0.9% of infants are born with congenital heart disease; the incidences of the major types of defect are listed in Table 15-1. As a result of improvements in medical and surgical treatment, the population of adults with congenital heart disease has grown such that it now exceeds the population of children with congenital heart disease in many parts of the developed world.1,2

Table 15-1 Incidence of Congenital Heart Disease

Lesion Incidence/1000 Live Births
Ventricular septal defect 3.57±2.9
Patent ductus arteriosus 0.80±1.4
Atrial septal defect 0.94±1.0
Atrioventricular septal defects 0.35±0.16
Pulmonary stenosis 0.73±0.73
Aortic stenosis 0.40±0.54
Coarctation of the aorta 0.41±0.25
Tetralogy of Fallot 0.42±0.19
d-Transposition of the heart arteries 0.32±0.12
Hypoplastic right heart 0.22±0.20
Tricuspid atresia 0.08±0.05
Ebstein anomaly 0.11±0.14
Pulmonary atresia 0.13±0.12
Hypoplastic left heart 0.27±0.22
Truncus arteriosus 0.11±0.07
Double-outlet right ventricle 0.16±0.10
Bicuspid aortic valve 13.56±13.05
All congenital heart disease (excluding bicuspid aortic valve) 9.60±7.40

Adapted from Hoffman JI, Kaplan S: The incidence of congenital heart disease. J Am Coll Cardiol 39:1890-1900, 2002.

Adults with congenital heart disease usually present to the intensive care unit (ICU) following a reoperation of a previously corrected or palliated heart defect. Occasionally, ICU care is required for acute hemodynamic decompensation, usually due to arrhythmias or congestive heart failure. Thus, it is important to have a working knowledge of the types of lesions that occur in adulthood and of their medical and surgical management.

CLASSIFICATION OF CONGENITAL HEART DISEASE

Surgically corrected or palliated congenital heart disease may be classified on the basis of whether there is a two-ventricle or a single-ventricle circulation (Table 15-2). With a two-ventricle circulation, the right ventricle is usually the pulmonary pump and the left ventricle the systemic pump, but in certain situations (e.g., atrial baffle repairs for transposition of the great arteries), the right ventricle is the systemic pump. For some defects a two-ventricle repair is not possible, and a staged palliation is performed; it results in a functionally single-ventricle circulation. The final stage of palliation is a Fontan-type operation, as explained later.

Table 15-2 Congenital Cardiac Defects in Which a Functionally Normal Circulation May Be Obtained vs. Defects Managed by Fontan-type Palliation

Biventricular Repair
Ventricular septal defect
Atrial septal defect
Atrioventricular canal defect
Tetralogy of Fallot
Transposition of the great arteries
Truncus arteriosis
Anomalous pulmonary venous drainage
Valvular/subvalvular/supravalvular aortic stenosis
Interrupted aortic arch
Coarctation of the aorta
Ebstein anomaly of the tricuspid valve
Fontan Operation
Tricuspid atresia
Hypoplastic left heart
Pulmonary atresia with intact ventricular septum
Double-outlet left ventricle
Heterotaxy syndromes

Patients may also be classified on the basis of whether cyanosis occurs at rest. Cyanosis occurs in the settings of uncorrected cyanotic heart disease, Eisenmenger syndrome, and after repairs involving fenestrations or residual shunts. The majority of corrective or palliative procedures do not result in persistent right-to-left shunting, so patients who have undergone these procedures are “pink.”

Multisystem Disease

Congenital heart disease does not involve only the cardiovascular system; it also causes multisystem disease. It is common for patients to undergo repeated thoracic surgeries, and they are at risk for developing scoliosis, which can lead to pulmonary restriction. Renal impairment is common because of the effects of previous cardiac surgery, nephrotoxic drugs (particularly radiographic contrast agents used during cardiac catheter studies), and associated congenital kidney abnormalities, such as renal dysplasia and hydronephrosis. High systemic venous pressure, such as that which occurs after Fontan-type operations and with right ventricular dysfunction, can lead to pleural effusions, ascites, hepatic congestion, and even cirrhosis. Hepatic dysfunction can also occur due to hepatitis C infection acquired from exposure to infected blood products.

Children who have undergone repair or palliation for congenital heart disease have, on average, lower IQs than their peers and are more likely to have developmental disabilities.3,4 Many adults with congenital heart disease were cyanotic for long periods of time during their childhoods; they may have experienced periods of circulatory compromise and may have undergone cardiopulmonary bypass during the formative years of that technology. In addition, some patients have syndromes in which congenital heart disease and mental disability are associated (e.g., Down syndrome). Anxiety and depression are also relatively common and may be exacerbated by admission to the ICU.

General Perioperative Considerations

In addition to a thorough cardiac assessment, preoperative evaluation must include consideration of other organ systems (see earlier discussion, Multisystem Disease). Respiratory function tests may be indicated for patients who have undergone multiple previous cardiac operations. Patients who are older than 40 or have risk factors for coronary artery disease should undergo coronary angiography. For patients who have cyanosis with thrombocytopenia, careful preoperative phlebotomy can promote hemostasis by initiating a temporary increase in platelet numbers. When the hematocrit exceeds 55%, increased citrate must be added to the tubes that are used for coagulation testing.

Patients have usually undergone multiple arterial and venous catheterizations. Thus, vascular access may be difficult, and there may be thrombosis and occlusion of central veins and arteries. Prior exposure to blood products may have led to antibody formation, creating difficulties in cross-matching blood for transfusion. For patients with right-to-left shunts it is essential to avoid all air bubbles in venous lines because they can embolize systemically.

Most surgeries performed for congenital heart disease in adults are reoperations, and in many cases cardiopulmonary bypass times are long. Conduits from previous operations may be located directly behind the sternum and can be damaged during sternotomy. Postoperative problems involving excessive bleeding, coagulopathy, myocardial stunning, and pulmonary hypertension are not uncommon. Chronic volume and pressure overload of the cardiac chambers, along with scarring from previous surgeries, predispose to the development of ventricular dysfunction and arrhythmias. Poor nutritional state, chronic hypoxemia, and low cardiac output contribute to poor wound healing and the occurrence of nosocomial infection. Adults with congenital heart disease are at increased risk for developing endocarditis (see Table 10-7) and require antibiotic prophylaxis prior to certain invasive procedures (see Endocarditis Prophylaxis in Chapter 10). If these patients become febrile it is essential to draw blood cultures prior to commencing antibiotic treatment.

SPECIFIC CONGENITAL HEART DISEASES

Tetralogy of Fallot

The essence of the tetralogy of Fallot (Fig. 15-1) is anterior displacement of the conal septum. This results in obstruction of the right ventricular outflow tract (RVOT) and a ventricular septal defect (VSD) and causes the aorta to override the crest of the ventricular septum. RVOT obstruction and right ventricular volume loading cause right ventricular hypertrophy, which is the fourth feature of the tetralogy. RVOT obstruction in the presence of a VSD causes a variable degree of right-to-left shunting and hypoxemia. Patients usually present in infancy with a murmur. If right ventricular outflow obstruction is severe, patients become cyanotic and may experience hypercyanotic “spells.”

A tetralogy of Fallot was first palliated in 1944 by the classical Blalock-Taussig shunt. In this procedure, the subclavian artery is transected and anastomosed directly onto the pulmonary artery. Additional palliative strategies have included the Waterston and Potts shunts, in which the aorta (ascending or descending, respectively) is anastomosed side-to-side to a branch pulmonary artery. A modified version of the Blalock-Taussig shunt, in which a tube graft is used to connect the right subclavian artery to the right pulmonary artery (Fig. 15-2), is still performed to palliate lesions in which pulmonary blood flow is inadequate.

In the 1950s a more complete repair of the tetralogy of Fallot was developed. Repair involves patch closure of the VSD and reconstruction of the obstructed RVOT (Fig. 15-3); the latter is commonly achieved by placing a patch across the annulus of the pulmonary valve, rendering it incompetent. Patients usually undergo surgical correction in early childhood; depending on institutional practice and the presence and severity of cyanosis, it may have been preceded by a Blalock-Taussig shunt in infancy. Long-term survival rates are excellent. However, free pulmonary regurgitation causes right ventricular overload, which can eventually lead to right ventricular failure and ventricular arrhythmias. Patients who have undergone repair of a tetralogy of Fallot are at increased risk for sudden death, and those with ventricular tachyarrhythmias should be considered for internal cardiac defibrillators. Pulmonary valve replacement can prevent these problems, although there is disagreement about the optimal timing of surgery. Most centers use a combination of symptoms, measured exercise tolerance, and quantitative assessment of right ventricular function (usually by means of a magnetic resonance imaging scan) to establish the need for pulmonary valve replacement.

Preoperative Assessment for Pulmonary Valve Replacement

Buy Membership for Cardiothoracic Surgery Category to continue reading. Learn more here