Annex A > Chapter 3 - Developments in the UK, in the Diagnosis and Treatment of Congenital Heart Abnormalities in Children, 1984-1995 > The specific heart abnormalities and procedures referred to in the Inquiry > Total Anomalous Pulmonary Venous Drainage (TAPVD)

Total Anomalous Pulmonary Venous Drainage (TAPVD)

Figure 9: Total Anomalous Pulmonary Venous Drainage

The problem

79 TAPVD is rare, comprising around 1% of all congenital heart abnormalities. A successful operation can usually ensure uncomplicated survival, whereas 80% to 90% of babies with TAPVD die before their first birthday if they are not treated surgically. All of the pulmonary veins draining blood from the lungs should normally be connected to the left atrium. In TAPVD they drain instead into the right atrium, or more commonly into one of the veins from the body which eventually drains into the right atrium. The diagram (Figure 9) demonstrates the different possible sites to which the pulmonary veins commonly drain. It is essential that the hole in the wall between the atriums, normally present in the fetus, remains open in the newborn baby so that blood returning from the lungs can flow from the right to the left atrium and then to the body. Much of the blood returning from the lungs to the right heart is again pumped to the lungs together with blood returning from the body. The increased flow causes the right ventricle to become volume loaded and also causes lung congestion. If the inter-atrial hole is too small, then the flow to the right ventricle and the lungs is even greater, with consequently worsening congestion. It is more usual for right to left atrial flow to be adequate in which case there is still volume-overload of the right ventricle together with lung congestion, but there is sufficient oxygenated blood flowing to the body. The pulmonary veins most commonly connect to one of the veins from the upper part of the body and this is usually associated with the fewest severe emergency problems. When the pulmonary veins connect to one of the veins draining the lower part of the body, the blood often has to flow through the liver before it reaches the main lower vein joining the right atrium. The passage of blood, by going through the liver, or even through a more tortuous route, is considerably slowed down, and the pulmonary venous drainage is essentially obstructed, causing severe congestion of the lungs. Babies will then often present within hours after birth with severe breathlessness and cyanosis, and resuscitation may be difficult.

Diagnosis

80 Newborn babies with TAPVD present with severe breathlessness and cyanosis and are often confused with those who more commonly have a primary lung problem, known as `respiratory distress syndrome'. The diagnosis of TAPVD by echocardiography can be extremely difficult, and was even more so in the mid-1980s when colour-flow mapping was not available. The diagnosis depends on showing that the pulmonary veins are not connected to the left atrium, and also being able to visualise their connection to an abnormal site. Even when colour-flow mapping is used, it may be difficult to identify the flow in the pulmonary veins. Cardiologists, despite being meticulous in searching for the confirmation or rejection of the diagnosis of TAPVD, may remain uncertain of its presence. The baby with either TAPVD or with respiratory distress syndrome is usually so ill that there is reluctance to undertake cardiac catheterisation because of the considerable risk.

Management

81 Most babies with TAPVD are very ill when the diagnosis is made. Normal pre-operative supporting measures are undertaken while arrangements are being made for corrective surgery. Pre-operative measures might include the admission to the ICU and support on a ventilator. The operation is a major procedure using an open-heart technique but the majority of the operation takes place outside the heart, the only intra-cardiac element being the connection of the pulmonary veins to the left atrium. In the mid-1980s the operative risk was significantly higher than it became in the early and mid-1990s. The better results were due largely to improvements in early diagnosis as well as in pre-operative intensive care, surgical techniques and post-operative management. The most difficult cases have always been those in whom the pulmonary veins tended to be obstructed in some part of their course.

82 After successful repair it is unusual to have significant longer-term problems. Occasionally the pulmonary veins become obstructed at or near the surgical connection to the left atrium and re-operation becomes necessary. Most babies proceed to lead trouble-free, uncomplicated and normal lives.

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