Vascular access, technique and materials can vary in accordance with the anatomy.

The aim of the exam is to measure PAP, assess the anatomy of pulmonary arteries and rule out or treat associated anomalies.

Intravenous heparin at a dose of 50–100 UI/kg should be administered.

Arterial access is generally needed to visualise pulmonary arteries in patients with pulmonary atresia and a BT shunt.

Angiography rules out the presence of aortic coarctation and aortopulmonary collaterals.

If the shunt cannot be entered, PAP can be measured via pulmonary veins [2]. We penetrate a pulmonary vein until the catheter is wedged and the shape of the pressure curve changes and a transpulmonary gradient appears.

The same approach is used in patients with inadequate antegrade PBF and a BT shunt.

In our view, it is easier and safer to measure PAP via pulmonary veins rather than via a small BT shunt or a small native pulmonary outflow.

Patients with hypoplastic left heart syndrome are complex patients who need a complete and precise evaluation.

In subjects after a Norwood I operation, venous and arterial access should be obtained. In some cases it is possible to obtain a complete evaluation via venous access alone. The catheter enters the right atrium, and then the left atrial pressure and pulmonary vein wedge pressure are obtained. Then ventricular pressure is measured.

The catheter enters the neoaorta and is guided into the descending aorta. If difficulty is encountered when trying to enter the neoaorta or the child shows instability, this approach should be abandoned and the arterial approach should be adopted.

An angiography should be performed into the BT shunt to visualise pulmonary arteries. It is often difficult to enter the brachiocephalic artery using venous access. Arterial access should be used in those cases. Possible coexisting problems are recoarctation and aortopulmonary collaterals. Both conditions can be treated, if necessary.

Patients with hypoplastic left heart syndrome having received a hybrid treatment are potentially fragile and can display several associated anomalies such as restrictive atrial septal defect, proximal or distal displacement of the ductal stent, stent thrombosis and preductal or postductal coarctation. The treatment of these lesions, including stenting of the atrial septum and of the native aortic arch, will be discussed in the dedicated chapter.

In these patients, the neoaorta provides pulmonary, systemic and coronary circulations. High-volume angiography (2–3 ml/kg) and appropriate views are necessary to obtain an adequate visualisation of the banded pulmonary arteries, the stented arterial duct and the native aortic arch.

I rarely manage to enter a banded pulmonary artery and generally prefer to measure pulmonary pressure via pulmonary vein wedge pressure [2]. If PAP is high, we need to know if this is due to excessive flow, restrictive atrial septal defect, obstructed pulmonary venous return, recoarctation or ventricular dysfunction. The pressure measurement should be repeated once the associated lesions are treated.

Catheterisation is performed, according to the presence of forward flow to the lungs, via the femoral vein or the internal jugular vein [1].

Arterial catheterisation can be needed to rule out or treat aortic recoarctation and aortopulmonary collaterals.

If a pulmonary banding or a BT shunt is left in place, the pulmonary artery can be entered via femoral venous access or femoral arterial access.

However, it is generally easier and rapid to reach pulmonary arteries via the internal jugular vein. PAP and either wedge or left atrial pressure are measured.

Pulmonary angiography is performed in a four-chamber view.

If some washout is found, aortopulmonary collaterals should be suspected and aortography should be performed. If a rapid opacification of pulmonary veins is noticed, pulmonary fistulae should be ruled out. The presence of microfistulae can be confirmed by injecting microbubbles obtained by rapidly mixing 80 % blood with 20 % air in both distal pulmonary arteries. Simultaneously, transthoracic or transoesophageal echocardiography is performed. If pulmonary fistulae are present, generally massive opacification of the left atrium is seen.