Congenital heart disease

Chapter 10 Congenital heart disease

Chest X-ray

Echocardiography

Transoesophageal echocardiography

Cardiac magnetic resonance

Cardiac CT

Cardiac catheterization

Atrial and ventricular septal defects

Aortic coarctation

Transposition of the great arteries

Tetralogy of Fallot

Aberrant coronary anatomy

Patent ductus arteriosus

Major aorto-pulmonary collateral arteries (MAPCAs)

Pulmonary arterial hypertension including Eisenmenger’s syndrome

Congenital heart disease

The phrase ‘congenital heart disease’ encompasses a range of cardiovascular problems from simple patent foramen ovale (PFO) to complex conditions such as tetralogy of Fallot. Cardiovascular imaging is essential in the diagnosis and understanding of congenital heart disease. Many specialists who train in congenital heart disease include a dedicated imaging component in their training.

Cardiovascular imaging

CMR and transthoracic echocardiography (TTE) are the modalities of choice for the routine assessment and follow-up of patients with congenital heart disease.

TTE is fundamental to the assessment of congenital heart disease, particularly in the acute setting and at initial diagnosis, but requires a high level of expertise.

All major centres for congenital heart disease will have access to CMR although studies are time-consuming (30–60min) and any patient with a pacemaker or an implantable cardioverter defibrillator (ICD) is currently excluded from CMR examination.

CT has been used in the assessment of congenital heart disease for many years, but predominantly for non-cardiac indications such as CT pulmonary angiography. Any patient who is unable or unwilling to undergo CMR can be assessed by multi-detector CT (MDCT). Although flow data will not be available, most other aspects of a CMR study are available within the MDCT dataset.

Chest X-ray

Advantages of chest X-ray

Widely available

Allows serial comparison

Disadvantages of chest X-ray

Limited data on intracardiac anatomy

Two-dimensional with compression of 3D data

What can chest X-ray tell us?

An important point to check in congenital heart disease is the left and right labels on the CXR! In a normal chest X-ray there will be a left fundal bubble, a left cardiac apex, long left and short right bronchi, and a rightsided liver. Some key signs of congenital heart disease to be aware of are the following.

Situs: fundal bubble (usually left); cardiac apex (usually left), bronchial tree (normally long left, short right), position of liver (Fig. 10.1).

Extracardiac: trachea, cervical ribs, thoracotomy/sternotomy scars, kyphoscoliosis, diaphragms? Raised post-op, clips, prosthetic devices, sternal wires (not always used in paediatric cardiac surgery), pacemaker/ICDs and position of leads, rib notching in aortic coarctation (Fig. 10.2).

Cardiothoracic ratio:?enlarged,?dilated right-side.

Cardiac silhouette: certain typical patterns.

Aortic arch:?collaterals, right-sided arch.

Calcification of conduits.

Pulmonary arteries: dilatation or absence.

Lung markings: vascular and parenchyma.

Pleural effusions.

Fig. 10.1 30-year-old female patient with an unoperated secundum atrial septal defect showing dilated right heart, enlarged pulmonary arteries, and pulmonary plethora.

Fig. 10.2 29-year-old female patient with transposition of the great arteries with a stent in the superior baffle and a ventricular pacing lead through the stent into the subpulmonary left ventricle.

Echocardiography

Advantages of echocardiography

Portable and widely used non-invasive imaging tool

Non-invasive detailed anatomical information with serial assessment

Flow assessment.

Disadvantages of echocardiography

Anatomical knowledge and understanding of congenital heart disease essential when performing echoes

Studies are operator dependent

May be difficult to see some aspects of the cardiac system or vascular connection.

What can echocardiography tell us?

All the basic principles of TTE (assessment of ventricular function, valvular function, and presence of a pericardial effusion) are usually possible in all patients and a full dataset is acquired, including suprasternal, subcostal, and right parasternal views (Figs. 10.3 and 10.4). Some key aspects that are of importance when performing echocardiography in congenital heart disease patients are as follows.

It is useful to start imaging after you have tried to visualize the anatomy.

A sequential segmental approach must be used in all patients.

Patients may have more than one lesion.

Doppler assessment of valves, aortic arch (coarctation), shunt calculation (rarely used), and baffle obstruction (patients who have had arterial switch transposition of the great arteries (TGA)) is possible.

Contrast bubble echo can be used for the identification of shunts (e.g. PFO).

Dobutamine stress echo can be used in patients who have had arterial switch TGA to assess for ischaemia.

Advanced techniques can all be used to derive further information, including tissue Doppler for ventricular function and 3D for detailed anatomical information (e.g. Ebstein’s anomaly, atrioventricular septal defect), speckle tracking, and dyssynchrony assessment.

Fig. 10.3 Parasternal long-axis view with TTE demonstrating a perimembranous ventricular septal defect (VSD). Colour flow mapping shows the jet between the left ventricular outflow tract and the right ventricle. In this situation it is important to assess the aortic valve and identify any aortic regurgitation.

Fig. 10.4 Parasternal long-axis view with TTE and colour flow mapping demonstrating a muscular VSD. There may be multiple defects and therefore the colour Doppler must be placed along the whole length of the ventricular septum during the study.

Transoesophageal echocardiography

What can TOE tell us?

Experience is essential for interpreting TOE in complex CHD and therefore should be undertaken in specialist centres and/or by specialists in congenital heart disease. TOE is usually used perioperatively to assess patients before and during the procedure. This is the case for both surgical and percutaneous procedures (ASD/PFO/VSD closure, valve surgery) (Fig. 10.5). Increasingly 3D TOE is being used to allow better visualization of variation in the 3D cardiac anatomy.

Two things to be aware of in patients with congenital heart disease are as follows:

care should be taken with sedation as this may result in cardiovascular collapse

always check for previous oesophageal surgery or abnormalities.

A sequential analysis is used and some of the particular areas of the cardiovascular system that lend themselves to evaluation by TOE are:

pulmonary veins

pathways/baffles/communications/intracardiac thrombus (prior to cardioversion)

contrast/bubble echo to identify shunts/PFO

assessment of endocarditis

assessments of aorta such as patent ductus arteriosus (PDA), coarctation, outflow tract obstruction

patients with difficult transthoracic views (e.g. chest deformity)

ventricular function from transgastric views in patients with difficult views.

Fig. 10.5 Transoesophageal bicaval view demonstrating a secundum atrial septal defect. A Chiari network with multiple stands of the network extending across the right atrium is also evident.

Cardiac magnetic resonance

Advantages of CMR

Any imaging plane is possible.

Independent of body habitus.

Accurate quantification of cardiac chambers.

Can assess vasculature and aorta as well as heart.

Can study chest and other areas of body during the same study.

Disadvantages of CMR

Specialist experience in both congenital heart disease and CMR are essential during acquisition (to ensure that the correct sequences are recorded) and interpretation scan. Therefore congenital CMRs are usually only undertaken in specialist centres.