Syndrome	Typical genetic defect	Typical cardiac defects
Down syndrome	Trisomy 21	Atrioventricular septal defect, VSD, ASD, PDA
Holt–Oram syndrome	12q2	ASD, VSD
Turner syndrome	XO	Aortic coarctation, bicuspid aortic valve
Noonan syndrome	12q	Pulmonary stenosis, hypertrophic cardiomyopathy
Di George syndrome	22q11 deletion	Truncus arteriosus, tetralogy of Fallot, interrupted aortic arch
Williams syndrome	7q11 deletion	Supravalvular aortic stenosis, peripheral pulmonary artery stenosis

Non-genetic

Table 8.2 Non-genetic associations with congenital heart disease (known or suspected maternal factors)

Infective	Rubella, toxoplasmosis, Coxsackie B virus
Environmental	Trichloroethylene, dichloroethylene, chromium
Iatrogenic	Antiepileptics, lithium, thalidomide, warfarin, isotretinoin
Lifestyle	Alcohol and illicit drug use, low folate intake
Medical	Diabetes mellitus, phenylketonuria

Atrial septal defect (ASD)

Communication between the atrial chambers allowing mixing of blood.

Types of ASD (Figure 8.1)

Figure 8.1 Schematic demonstrating anatomical locations of inferior sinus venosus ASD. TV, Tricuspid valve.

Ostium secundum defect

May present in adulthood with first occurrence of symptoms.

Defect in the area of fossa ovalis. May be amenable to transcatheter closure.

Ostium primum defect

This is part of a spectrum of atrioventricular septal defects, resulting from defective fusion of the inferior and superior endocardial cushions, leading to a common atrioventricular junction. Associated atrioventricular valve, atrial septal and ventricular septal anomalies can occur within this spectrum.

Associated with Down syndrome.

Definitive management is surgical. Repaired patients may present later with left atrioventricular valve regurgitation or, less commonly, left ventricular outflow tract obstruction.

Sinus venosus defect

The defect lies in the majority of cases at the mouth of the superior vena cava (superior sinus venosus) and is frequently associated with anomalous drainage of the right upper pulmonary vein into the right atrium. Rarely the defect lies next to the inferior vena cava (inferior sinus venosus).

Definitive management is surgical.

Coronary sinus ASD

At least part of the wall between the coronary sinus and LA is absent. Often associated with a persistent left superior vena cava. Similar clinical course to secundum ASD, also dependent on size of defect and shunt.

Definitive management is surgical.

Clinical features

May be asymptomatic and discovered incidentally, but symptoms appear increasingly with age. Presentation includes:

Atrial fibrillation, atrial flutter, sick sinus syndrome

Right heart volume overload/right heart failure

Exertional dyspnoea

Recurrent chest infection

Paradoxical emboli

Pulmonary hypertension (ASD is associated with pulmonary hypertension though there is not thought to be a direct causal relationship)

Cyanosis.

Indications for closure

Right heart volume overload

ASD minimum diameter 10 mm

Left to right shunt > 1.5:1

Paradoxical emboli.

Before closure need to assess for: presence of significant pulmonary hypertension (precludes closure), presence of significant mitral valve disease (severity may be underestimated and may cause decompensation following closure).

The prognostic benefit of closure is reduced with increased age, though this does not preclude intervention. Delayed closure is associated with an increased risk of long term complications including atrial arrhythmias and reduced survival.

Ventricular septal defect (VSD)

Types of VSD

Membranous (perimembranous/infracristal)

Most common.

Beneath crista supraventricularis, posterior to papillary muscle of conus, beneath aortic valve

Associated tricuspid valve abnormalities.

Outlet (supracristal/infundibular/doubly committed subarterial)

Located between crista supraventricularis and pulmonary valve. Right coronary cusp of aortic valve may prolapse into VSD leading to aortic regurgitation/subpulmonary stenosis.

Inlet

Defect in central fibrous body between tricuspid and mitral valves.

Often associated defects.

Muscular

Often multiple; in muscular septum.

Clinical features

Clinical features depend upon the anatomy and haemodynamic severity of the VSD and presence of associated anomalies.

VSDs can be classified according to haemodynamic effect. The measured variables are the pulmonary artery: aortic systolic pressure ratio and pulmonary blood flow: systemic blood flow ratio.

Small: Pressure ratio < 0.3 and flow ratio < 1.4

Moderate: Pressure ratio > 0.3 and flow ratio 1.4 to 2.2

Large: Pressure ratio > 0.3 and flow ratio > 2.2

Eisenmenger: Pressure ratio > 0.9 and flow ratio < 1.5

Where the right ventricular systolic pressure is lower than left ventricular systolic pressure, in the absence of right ventricular outflow tract obstruction, the VSD is termed “restrictive”

Adults may have a small unrepaired VSD, a repaired VSD or Eisenmenger syndrome. Moderate or large VSDs are likely to have been repaired in childhood. Haemodynamically significant VSDs can lead to left heart pressure loading, right heart volume loading, pulmonary vascular disease and Eisenmenger syndrome.

Other complications include:

Infective endocarditis.

Aortic regurgitation due to aortic cusp prolapse (outlet VSD and membranous VSD).

Arrhythmia: Atrial fibrillation may occur with left atrial dilatation secondary to left heart volume overload. Ventricular arrhythmia and late sudden death are reported.

Right ventricular outflow obstruction. It may take the form of a ‘double chamber right ventricle’ in which muscular bands divide the right ventricle into a high-pressure proximal chamber and lower pressure distal chamber.

Indications for adult intervention include:

Significant left to right shunt (Qp/Qs > 2)

Pulmonary artery systolic pressure > 50 mmHg. If the pulmonary artery pressure (or arteriolar resistance) is greater than 2/3 systemic arterial pressure (or arteriolar resistance), there must be evidence of a net left to right shunt of ≥ 1.5 or evidence of reactivity or potential reversibility (assessment with pulmonary vasodilator or lung biopsy).

Ventricular dysfunction (left ventricular volume overload or right ventricular pressure overload)

Aortic cusp prolapse with greater than mild aortic incompetence

Significant right ventricular outflow tract obstruction (mean gradient > 50 mmHg).

Patent ductus arteriosus (PDA)

The ductus arteriosus allows oxygenated blood to pass from the placenta to the aorta, bypassing the lungs in utero. The pulmonary end is situated just left of the bifurcation of the main pulmonary artery and connects to the descending aorta, distal to the left subclavian artery. It normally closes shortly after birth. Persistence of the ductus is associated with congenital rubella and is more common after premature birth. It may be present with other cardiac anomalies and in some cases is essential for survival.

Figure 8.2 Schematic demonstrating anatomical locations of ventricular septal defects. RA = right atrium, TV = tricuspid valve leaflets, PA = pulmonary artery.

Clinical features

After birth the shunt direction reverses with changes in systemic and pulmonary pressures.

Large isolated PDAs are characterized by heart failure in infancy.

A PDA may be clinically silent throughout life or may not present till adulthood.

If the PDA is very small or operated early in childhood, normal survival can be expected.

Complications in unoperated or late operation of a significant PDA can include left atrial dilatation and atrial arrhythmia, left heart failure, pulmonary hypertension and Eisenmenger syndrome. If Eisenmenger syndrome occurs, deoxygenated blood via the PDA supplies lower extremities whilst the oxygenated aortic blood supplies the upper body (differential cyanosis).

Management

Selected adult cases for surgical or transcatheter closure.

Irreversible pulmonary hypertension should be excluded before closure of sizeable ducts. Closure is not always performed in clinically silent PDAs.

Coarctation of the aorta

A narrowing in the aorta, usually just distal to the left subclavian artery and at the level of the ductus arteriosus (or ligamentum arteriosum).

Associations include:

Bicuspid aortic valve, VSD, subvalvular aortic stenosis, mitral valve abnormalities

Circle of Willis aneurysm

Turner syndrome.

Clinical features

Presentation is dependent on the degree and site of obstruction, presence of associated congenital heart defects and collaterals which may mask the severity of the obstruction.

Figure 8.3 Patent ductus arteriosus: AO: Aorta; PA: Pulmonary artery.

Most adults with aortic coarctation have been previously operated. Untreated adults typically present with systemic arterial hypertension or less commonly with a murmur or symptoms such as headache or exertional leg discomfort. Occasionally angina or left ventricular failure will occur. Repair of the lesion should not be considered curative as late complications are common and include recoarctation, aneurysm formation (especially following Dacron patch aortoplasty), persistent systemic arterial hypertension (even in the absence of residual significant coarctation) and premature atherosclerosis with associated increased risk of cardiovascular events. Additional complications can arise from associated lesions.

Management

A pullback gradient of > 20 mmHg at catheterization is usually considered significant (in the absence of well-developed collaterals).

Percutaneous and surgical options are available for repair.

Surgical techniques include: resection with end-to-end anastomosis, subclavian flap aortoplasty (not recommended in adults), patch aortoplasty, interposition tube grafting and bypass (jump) grafting.

Usually infants and children undergo surgical repair.

Adults with previously unoperated native coarctation or with recoarctation may be suitable for transcatheter stenting.

Bicuspid aortic valve

1–2% of the population have a bicuspid aortic valve.

This is the most common cause of congenital aortic stenosis and results from commissural fusion of two valve leaflets. Associated anomalies include aortic coarctation, PDA and VSD. The natural history includes development of aortic stenosis or regurgitation (sometimes following infective endocarditis). There is also an associated abnormality of aortic root tissue, which increases risk of aortic aneurysm formation and aortic dissection.

Treatment options include: balloon valvuloplasty (children), open aortotomy (children), prosthetic valve replacement, Ross procedure.

Figure 8.4 Schematic demonstrating anatomical location of coarctation of the aorta.

Subvalvular aortic stenosis

Typically a thin membrane or fibromuscular ridge in the left ventricular outflow tract. Occasionally takes the form of a fibromuscular tunnel or ring.

Associated lesions include VSD, bicuspid aortic valve and aortic coarctation.

Clinical features include secondary left ventricular hypertrophy and aortic regurgitation (due to damage from turbulent flow).

Subvalvular stenosis is often progressive and not uncommonly recurs after surgical repair.

Intervention may be considered if:

symptomatic

catheter or mean echo gradient > 50 mmHg (the gradient may be underestimated in the presence of a VSD).

evidence of progressive, greater than mild aortic regurgitation.

Supravalvular aortic stenosis

Rare.

Associated with Williams syndrome.

It can take various forms and may be focal or diffuse. It is usually localized at the level of the sinotubular junction.

Other major vessels may be stenosed, including branch pulmonary arteries, carotid arteries and other systemic arterial vessels. The coronary arteries may be dilated and are also prone to accelerated atherosclerosis as they are exposed to high pressure proximal to the stenosis.

Intervention may be considered if the catheter or mean echo gradient > 50 mmHg.

Pulmonary stenosis

Pulmonary valve stenosis is the most common form of right ventricular outflow tract obstruction. It usually occurs in isolation and in most cases the valve is dome shaped with fused commissures.

Subvalvular pulmonary stenosis typically occurs in tetralogy of Fallot and in association with VSD. Double chambered right ventricle is a form of subinfundibular right ventricular outflow tract obstruction resulting from prominent right ventricular muscle bands.

Supravalvular pulmonary stenosis is associated with tetralogy of Fallot, Williams syndrome, Noonans syndrome and maternal rubella. It can also occur iatrogenically following pulmonary artery banding or arterial switch for transposition of the great arteries.

Haemodynamic severity is graded according to the peak systolic pressure gradient on cardiac catheterization. It provides an important guide for management decisions.

Trivial: < 25 mmHg

Mild: 25–49 mmHg

Moderate: 50–79 mmHg

Severe or Critical: > 80 mmHg

Indications for intervention include:

Pullback gradient at catheterization of > 50 mmHg

Symptomatic

Significant arrhythmia

Presence of right to left shunt (e.g. associated ASD)

Double chambered right ventricle with mid cavity gradient at catheterization > 50 mmHg

Pulmonary valve stenosis is often amenable to transcatheter balloon valvuloplasty. If pulmonary valve replacement is required, a human homograft is often used.

Ebstein anomaly

Describes apical displacement of the septal and posterior tricuspid valve leaflets with variable displacement and dysplasia of the anterior leaflet. There are varying degrees of tricuspid regurgitation.

Associated lesions include ASD, pulmonary stenosis and accessory conduction pathways. It is also seen in corrected transposition of the great arteries.

There is a spectrum of severity, which largely depends on the degree of leaflet displacement and tricuspid regurgitation and presence of associated lesions. In infancy it may present with heart failure and cyanosis with poor prognosis. Milder forms can be asymptomatic throughout life. Adults may develop exercise intolerance or symptomatic arrhythmia. Sudden death is also reported and thought to be arrhythmic. In the presence of an atrial septal defect there may be cyanosis or paradoxical embolic events.

In severe cases a bidirectional Glenn shunt or modified Fontan may be performed and the patient managed as for univentricular circulation. Less severe cases may be suitable for tricuspid valve replacement or repair.

Tetralogy of Fallot

The most common congenital cyanotic heart disease in adults.

The four components of the tetralogy are: infundibular right ventricular outflow tract obstruction ± valvular and supravalvular pulmonary stenosis, right ventricular hypertrophy, perimembranous VSD, aorta overriding interventricular septum (Figure 8.5).

There is a spectrum of severity. The majority of cases present early with cyanosis. With mild right ventricular outflow tract obstruction, the occasional patient will present in adulthood (‘pink tetralogy’). An extreme variant is pulmonary atresia with VSD in which the right ventricular outflow tract is atretic and pulmonary blood flow is obtained from major aortopulmonary collaterals (MAPCAs), patent ductus arteriosus or other acquired collaterals.

Figure 8.5 Schematic demonstrating the cardiac abnormalities associated with tetralogy of Fallot.

Today, most adults have been surgically repaired or, less commonly, shunt-palliated. Rarely, adults are previously unoperated.

Associated anomalies include:

Right side aortic arch

Coronary artery anomalies

ASD (pentalogy of Fallot)

Second VSD

Palliative procedures

Anastomosis of systemic to pulmonary circulation to increase pulmonary blood flow and include:

Blalock-Taussig shunt: subclavian artery to pulmonary artery (now modified)

Waterston anastomosis: right PA to ascending aorta (historical)

Potts anastomosis: left PA to descending aorta (historical)

Brock procedure: resection of right ventricular infundibular obstructive tissue (historical).

Corrective surgery

Now performed in infancy.

VSD closed.

Right ventricular outflow tract reconstruction: this may involve resection of infundibular obstructive tissue and patch placement to augment outflow. A transannular patch (crossing the pulmonary valve annulus) may need to be placed but is avoided where possible. In some cases, such as in pulmonary atresia, a right ventricular to pulmonary artery extracardiac conduit may be formed.

Outcome

In adults who are unoperated or previously palliated, morbidity and mortality is high. Late repair should be considered to improve outcome.

Late complications in repaired patients include:

Pulmonary regurgitation: (especially if previously placed transannular patch). This can lead to right ventricular dilatation and systolic dysfunction. It is a major clinical concern, particularly with regard to timing of reintervention.

Right ventricular outflow tract aneurysmal dilatation.

Tricuspid regurgitation: secondary to right ventricle dilatation.

Aortic regurgitation +/– aortic root dilatation is described.

Residual right ventricular outflow tract obstruction.

Residual VSD.

Endocarditis.

Tendency to atrial arrhythmias.

Ventricular arrhythmia: the usual focus is the RVOT. Increased QRS duration > 180 ms is a marker for sustained VT and sudden cardiac death.

Late sudden death, presumably arrhythmic, is recognized.

Transposition of the great arteries (D-transposition of the great arteries)

There is ventriculoarterial discordance and atrioventricular concordance: the aorta arises discordantly from the morphological right ventricle and the pulmonary artery arises discordantly from the morphological left ventricle. The atria connect concordantly to the ventricles (right atrium to right ventricle and left atrium to left ventricle). The aorta sits to the right and anterior to the pulmonary trunk (dextro-transposition or D-transposition).

Survival depends upon a connection allowing mixing which may be provided by a patent ductus arteriosus and patent foramen ovale or associated ventricular septal defect.

Presentation

Usually born at term with the clinical course largely determined by associated anomalies and degree of mixing between systemic and pulmonary circulations. Approximately 1/3 of patients have associated anomalies, which typically include VSD and pulmonary stenosis (left ventricular outflow tract obstruction).

Initial management in neonates may involve prostaglandin E1 infusion to maintain patency of the ductus arteriosus and balloon atrial septostomy (Rashkind procedure), which can be performed percutaneously under echocardiographic/angiographic guidance.

Subsequent surgical strategies

1. Atrial switch. Mustard and Senning procedures. Largely replaced by the arterial switch procedure. A conduit or ‘baffle’ is formed following excision of the interatrial septum to divert systemic venous return to the left ventricle via the mitral valve and pulmonary venous return to the right ventricle via the tricuspid valve. The right ventricle functions as the systemic ventricle.

2. Arterial switch. The aorta and pulmonary artery are repositioned correctly. The coronary arteries are re-anastomosed. Can be performed in the first two weeks of life. The left ventricle functions as the systemic ventricle.

3. Rastelli procedure (TGA + large VSD + pulmonary stenosis). Closure of VSD and formation of conduit from the right ventricle to pulmonary artery. Patch placed obstructing flow from the right ventricle to aorta. The left ventricle functions as the systemic ventricle. May be performed after an early palliation, e.g. modified Blalock-Taussig shunt.

Long term complications

1. Atrial switch: (the previous intervention in most current adults with TGA), failure of morphologic right ventricle (supporting systemic circulation), systemic AV valve regurgitation, arrhythmia (including sinus node dysfunction and intra-atrial re-entrant tachycardia), sudden cardiac death (likely arrhythmic), baffle leak or obstruction.

2. Arterial switch: right ventricular outflow tract obstruction, neoaortic valve regurgitation, neoaortic root dilatation, coronary obstruction.

3. Rastelli: conduit obstruction, subaortic stenosis (LV–aorta tunnel), arrhythmia, sudden cardiac death (likely arrhythmic), left ventricular dysfunction.

Congenitally corrected transposition of the great arteries (L-transposition of the great arteries)

Characterized by both ventriculoarterial and atrioventricular discordance, or `double discordance’. As a result, the morphologic right ventricle supports the systemic circulation. The aorta sits anteriorly and to the left of the pulmonary artery (levo-transposition or L-transposition).

Usually has associated lesions which contribute to the presentation, typically: VSD, pulmonary stenosis and systemic AV valve abnormalities.

Clinical features

Right heart failure (systemic ventricle)

Tricuspid regurgitation (systemic AV valve)

Cyanosis can occur if associated lesions present (VSD and significant pulmonary stenosis)

Conduction abnormalities: congenital and acquired complete heart block

May not be diagnosed until older adulthood, particularly in the absence of associated anomalies.

Management

Early palliation may be indicated (e.g. PA banding for large VSD, modified BT shunt for severe pulmonary stenosis).

Medical surveillance in some cases is the chosen strategy. Surgical repair, where indicated, may include the following:

Conventional or ‘classic’ repair is treatment of associated anomalies, typically: closure of the VSD, replacement of the systemic AV valve and relief of pulmonary stenosis. The latter may require formation of a valved conduit between the morphologic left ventricle and pulmonary artery.

Figure 8.6 Schematic demonstrating variations in the anatomical origin of the great arteries. (A) Normal. (B) Congenitally corrected transposition of the great arteries (CCTGA). (C) Transposition of the great arteries (TGA).

The double-switch procedure, in which the morphologic left ventricle becomes the systemic ventricle, involves an atrial switch plus arterial switch or atrial switch with Rastelli procedure. The prerequisite is a morphologic left ventricle capable of supporting the systemic circulation and it may need to be ‘trained’ first with a pulmonary artery band. This is usually performed in childhood.

A Fontan-type repair may be considered if there is severe hypoplasia of either ventricle.

Heart transplantation may be offered in selected cases.

Figure 8.7 Schematic demonstrating anatomical changes following complex congenital cardiac surgery for transposition of the great arteries (TGA). (A) The Mustard/Senning operation for TGA. (B) The Rastelli operation for TGA and associated ventricular septal defect.

Cyanotic congenital heart disease

Cyanosis occurs in the presence of right to left shunting, with or without pulmonary hypertension.

Cyanotic conditions include transposition of the great arteries, tetralogy of Fallot, tricuspid atresia and Ebstein anomaly with ASD.

Eisenmenger syndrome describes a cyanotic condition of pulmonary vascular obstructive disease arising in the context of a pre-existing systemic-pulmonary vascular connection. Pulmonary hypertension results from progressive remodelling of the pulmonary vascular bed, with subsequent reversal of the left to right shunt or bidirectional shunting. Underlying conditions include VSD (Eisenmenger complex), PDA, ASD and atrioventricular septal defect. Iatrogenic causes include historically performed surgical procedures such as the Potts and Waterston shunts. Management of Eisenmenger syndrome is predominantly conservative. There is a potential role for selective pulmonary vasodilators and some cases may be suitable for lung or heart–lung transplant.

Complications of cyanotic congenital heart disease include the following:

1. Secondary erythrocytosis: Due to chronic hypoxaemia. Hyperviscosity symptoms may be absent, even with very high haematocrit level. Venesection is generally contraindicated due to the increased stroke risk, particularly with concomitant iron deficiency. In emergencies it may be considered if Hb > 20 g/dl and Hct > 65% with iron and equal volume replacement.

2. Relative iron deficiency: The resulting microcytosis is associated with cerebrovascular events.

3. Bleeding and thrombosis: Coagulation and platelet abnormalities increase bleeding risks, such as pulmonary haemorrhage and perioperative bleeding. Thrombotic events may be associated with microcytosis, blood stasis, presence of prostheses and atrial arrhythmias. High risk of in situ pulmonary thrombus.

4. Cerebral abscess.

5. Paradoxical emboli

6. Hyperuricaemia.

7. Cholelithiasis.

8. Hypertrophic osteoarthropathy and scoliosis.

Univentricular physiology

The univentricular heart describes a functionally single ventricle which is not amenable to two-ventricle repair. Conditions with univentricular physiology include tricuspid atresia, hypoplastic left heart syndrome and double inlet left ventricle.

Tricuspid atresia (see Figure 8.8)

The tricuspid valve is not formed and there is an obligatory right to left shunt at atrial level.

Figure 8.8 Schematic demonstrating the cardiac abnormalities in tricuspid atresia.

Hypoplastic left heart

Spectrum of congenital cardiac anomalies characterized by underdevelopment of the left heart/ascending aorta. It is a prenatal/neonatal diagnosis and fatal without intervention.

Double inlet left ventricle

Usually the great vessels are transposed. The aortic arch is left-sided. Both atria are connected to the left ventricle. The right ventricle is rudimentary. A VSD is present.

The initial presentation and management of the functionally univentricular heart depend in part upon degree of pulmonary blood flow:

1. Associated pulmonary stenosis/atresia → reduced pulmonary blood flow and severe cyanosis.

Requires a systemic to PA shunt.

2. No anatomic restriction to pulmonary flow → left to right shunting with features of congestive heart failure.

Requires pulmonary artery banding.

Figure 8.9 Schematic demonstrating the cardiac abnormalities in univentricular left heart physiology.

3. Rarely may be ‘balanced’ with a degree of pulmonary stenosis → mild cyanosis without congestive heart failure.

No early intervention necessary.

Further surgical palliation, usually in infancy when the PA pressure is low, is provided by the cavopulmonary shunt (Glenn procedure).

Some of these patients will undergo a Fontan operation in which caval blood is directed to the pulmonary arteries without circulating through a subpulmonary ventricle. Systemic to pulmonary flow is passive and driven by venous pressure. The circulation relies on good single ventricular function, lack of atrioventricular valve regurgitation and low pulmonary vascular resistance. Not all so-called Fontan circulations are identical as the term may be used to describe modifications of the original with different connections and materials.

Figure 8.10 Schematic demonstrating cardiac abnormalities in hypoplastic left heart syndrome.

In the original (atriopulmonary) Fontan procedure (first described for palliation of tricuspid atresia) the right atrium is directly anastomosed to the pulmonary artery. This leads in the long term to dilatation of the right atrium. This in turn can predispose to atrial arrhythmias, thrombus formation and pulmonary venous compression.

In the current era patients with univentricular physiology undergo total cavopulmonary connection (TCPC) surgery, usually in two stages: with a bidirectional Glenn followed by TCPC completion with either a lateral tunnel in the right atrium or more recently an extracardiac conduit. The TCPC may be fenestrated to create a small left-right shunt, intended to improve cardiac output and reduce excessive venous pressure. It is hoped that the modifications of the classic Fontan will reduce the problems associated with right atrial dilatation, though complications remain.

Complications of the Fontan/TCPC circulation

Characterized by low cardiac output, poor effort tolerance and chronic venous hypertension.

Issues:

Protein-losing enteropathy

Hepatic congestion

Progressive systemic ventricular dysfunction

Progressive AV valve incompetence

Right atrial enlargement (atriopulmonary Fontan)

Atrial arrhythmias common, poorly tolerated and increase in frequency over time

Sinus/AV node dysfunction common

Obstruction in circuit

Thromboembolism (sluggish flow, atrial arrhythmia, thrombophilic state). Can be pulmonary or systemic.

Figure 8.11 Schematic demonstrating variants of the Fontan operation. RPA: right pulmonary artery, LPA: left pulmonary artery, RA: right atrium, IVC: inferior vena cava, PA: pulmonary artery, RSVC: right superior vena cava, LSVC: left superior vena cava, TCPC: total cavopulmonary connection.

Source: Adult congenital heart disease: a practical guide. Michael A. Gatzoulis, Lorna Swan, Judith Therrien, George Pantely, Eugene Braunwald. Blackwell Publishing, 2005.