Chapter

Congenital heart disease in the adult

S.A. Thorne

in Oxford Textbook of Medicine

Fifth edition

Published on behalf of Oxford University Press

Published in print May 2010 | ISBN: 9780199204854
Published online May 2011 | e-ISBN: 9780199570973 | DOI: http://dx.doi.org/10.1093/med/9780199204854.003.1612_update_001

Series: Oxford Textbooks

Congenital heart disease in the adult

Show Summary Details

Preview

Adults with congenital heart disease are a growing population, and now outnumber children with congenital heart disease in the UK. Many adult survivors have complex, surgically-altered hearts and circulations that reflect the surgical and interventional practices of the preceding two decades. For some, their long term outlook is unknown and they remain at lifelong risk of complications that may require further intervention. The organization of services to provide specialist care is key to their long term survival.

Classification of congenital heart disease

The classification and description of complex congenital heart disease can appear intimidating, but should be easily understood by using a simple physiological approach that takes into account whether a condition is cyanotic or acyanotic, whether there is a shunt, and the implications of the morphology for pulmonary blood flow.

The description of the congenitally malformed heart is aided by a sequential segmental analysis of the relationship of the three cardiac segments, which makes it possible to understand and describe how a complex heart is connected. The three segments to be considered are: (1) The atria; (2) The ventricles; (3) The great vessels. The next step is to describe each segment and its relation to the next segment: (1) Atria: ◆ Situs solitus is the usual arrangement of the atria (and other asymmetrical structures) ◆ Atrial situs inversus is the mirror-image arrangement of the atria ◆ Isomerism describes abnormal symmetry of paired structures that usually show laterality – eg bilateral morphological left atria in left atrial isomerism. (2) How the atria connect to the ventricles, ie the atrioventricular connections, and the morphology of the atrioventricular valves: ◆ Atrioventricular concordance, which is the normal arrangement, with the right atrium connecting to the right ventricle via a tricuspid valve, and the left atrium connecting to the left ventricle via a mitral valve ◆ Atrioventricular discordance, which is abnormal: the right atrium connects to the left ventricle via a mitral valve, and the left atrium connects to the right ventricle via a tricuspid valve (3) How the ventricles connect to the great vessels, ie the ventriculo-arterial connections, and the morphology of the great arteries: ◆ Ventriculo-arterial concordance, which is the normal arrangement, with the right ventricle connecting to the pulmonary artery via a pulmonary valve, and the left ventricle connecting to the aorta via an aortic valve ◆ Ventriculo-arterial discordance, which is abnormal: the right ventricle connects to the aorta via an aortic valve, and the left ventricle connects to the pulmonary artery via a pulmonary valve.

Important general aspects

Cyanosis

Cyanosis occurs as a result of a right to left shunt, with its natural history determined by the pulmonary blood flow. If pulmonary blood flow is limited (e.g. by pulmonary stenosis in the presence of a large VSD), then pulmonary blood flow and arterial oxygen will be low, as will pulmonary artery pressure. Cyanotic patients with low or normal pulmonary artery pressure are usually amenable to surgical repair that abolishes the cyanosis. By contrast, if the pulmonary circulation is unprotected (e.g. if the defect includes a large ventricular septal defect and no pulmonary stenosis), then pulmonary blood flow will be high and at high pressure, pulmonary vascular remodelling will occur, and - without intervention - pulmonary vascular disease will eventually develop (pulmonary arterial hypertension; the Eisenmenger syndrome). Once pulmonary vascular disease is established, it is not possible to repair the defect and abolish the right to left shunt.

The right ventricle

The right ventricle is a key factor in the long term outcome of many congenital cardiac conditions. It may fail as a result of either longstanding pressure or volume overload. (1) Pressure loading – this occurs in patients in whom the right ventricle supports the systemic circulation, such as those with congenitally corrected transposition of the great arteries, and in those who underwent interatrial repair (Mustard or Senning operation) of simple transposition of the great arteries. The right ventricle is hypertrophied, and ultimately fails, with tricuspid regurgitation secondary to annular dilatation hastening the decline. (2) Volume loading – this commonly occurs as a result of pulmonary regurgitation secondary to pulmonary valvotomy or repair of tetralogy of Fallot in early life. There may be no audible murmur because there are often only remnants of pulmonary valve tissue, such that the regurgitant flow is laminar. Partly because of the lack of physical signs, and partly because pulmonary regurgitation is usually tolerated for many years before the right ventricle begins to fail, patients may present very late with a very dilated and impaired ventricle. Longstanding large atrial septal defects produce similar right ventricular volume loading effects. The right ventricle may be inherently abnormal, as in Ebstein anomaly where a combination of a functionally small ventricle and volume loading from tricuspid regurgitation may cause the right ventricle to fail.

The Fontan circulation

Hearts which have only one functional ventricle present a particularly difficult challenge. Patients are cyanosed, and only a few will reach adulthood if left unoperated. The ultimate aim for patients with only one functional ventricle is a Fontan circulation: a palliative approach that reduces ventricular volume loading and abolishes cyanosis. It is critically dependent on a low pulmonary vascular resistance, hence early control of pulmonary blood flow is paramount. If pulmonary blood flow is too high, it is controlled by placing a pulmonary artery band: i.e. by the creation of iatrogenic, protective pulmonary stenosis. If pulmonary blood flow is too low, the infant will not thrive, and pulmonary blood supply is augmented by means of a systemic to pulmonary artery shunt. There are many variations of the Fontan operation, but all involve the separation of pulmonary and systemic circulations by using the single ventricle to support the systemic circulation and by connecting the systemic veins directly (or via the right atrium) to the pulmonary artery. There is thus no ‘pump’ in the pulmonary circulation, so although cyanosis is abolished, the Fontan circulation is one of a chronic low output state. Thus, although the Fontan approach enables most patients with a single ventricle to reach adulthood, they have a fragile circulation and will develop a range of complications. They are particularly at risk if they have a tachyarrhythmia or acute non-cardiac illness, since they tolerate such insults poorly and are dependent on their medical teams’ understanding of their circulation to ensure good hydration, avoidance of vasodilatation and rapid restoration of sinus rhythm.

Tachyarrhythmia

Tachyarrhythmias are a major cause of sudden death in patients with congenital heart disease, with scar-related atrial tachyarrythmias being common in those who have had previous cardiac surgery, and probably a commoner cause of death than ventricular arrhythmias. Atrial tachyarrhymias are the reason that patients who underwent interatrial repair (Mustard or Senning operations) of transposition of the great arteries are the congenital cardiac group with the highest incidence of sudden death. Their surgically created atrial ‘baffles’ mean that atrial function is abnormal, and ventricular filling is impaired, particularly at high heart rates. Atrial flutter is common post Mustard or Senning, and patients are usually able to conduct 1:1 at a rate of 300bpm, resulting in cardiovascular collapse. Correct management is rapid restoration of sinus rhythm, followed by flutter ablation. Patients with a Fontan circulation are similarly vulnerable to interatrial re-entry tachyarrythmias. Ventricular and atrial tachycardias may both occur in most survivors of complex congenital heart disease, particularly post repair of tetralogy of Fallot. If ablation is not successful, consideration should be given to an internal cardiovertor defibrillator.

Pregnancy and contraception

Most women with congenital heart disease wish to consider pregnancy. For most this can be undertaken with only a small increased risk, but for some pregnancy carries a significant risk of complication, long term morbidity and death. Outcomes can be optimised by pre-conception counseling and specialist joint cardiac and obstetric care. Access to safe and effective contraception is important to allow patients to avoid potentially high risk pregnancies. Estrogen containing preparations are not suitable for those at risk of intracardiac thrombus or who have a right to left shunt; long acting progestogen-only methods offer safe and effective alternatives.

Acknowledgement: Dr P J Oldershaw wrote with Dr S Thorne on this subject in the fourth edition of the Oxford Textbook of Medicine. Some of that material has been retained in this edition, and we acknowledge Dr Oldershaw’s contribution.

Chapter.  23078 words.  Illustrated.

Subjects: Cardiovascular Medicine

Full text: subscription required

How to subscribe Recommend to my Librarian

Buy this work at Oxford University Press »

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.