BIOMED - Pathophysiology

🫀 𝘛𝘰𝘵𝘢𝘭 𝘈𝘯𝘰𝘮𝘢𝘭𝘰𝘶𝘴 𝘗𝘶𝘭𝘮𝘰𝘯𝘢𝘳𝘺 𝘝𝘦𝘯𝘰𝘶𝘴 𝘙𝘦𝘵𝘶𝘳𝘯 (𝘛𝘈𝘗𝘝𝘙)

©️ Cincinnati Children's

A video to get started (2:34mins)

Total Anomalous Pulmonary Venous Return (TAPVR)

There are three classifications of TAPVR. These are:

1 | Supracardiac Total Total Anomalous Pulmonary Venous Return
Where the pulmonary veins drain into the R) atrium by the superior vena cava. The pulmonary veins come together behind the heart and drain upwards to an abnormal vertical vein, that joins the innominate vein that connects to the R) superior vena cava and drains to the R) atrium.

2 | Cardiac Total Total Anomalous Pulmonary Venous Return
Where the pulmonary veins come together behind the heart and drain into the R) atrium via the coronary sinus.

3 | Infracardiac Total Total Anomalous Pulmonary Venous Return
Where the pulmonary veins drain into the R) atrium by the hepatic veins and inferior venacava. The pulmonary veins join together behind the heart and drain downwards through the vascular bed of the liber and enter the R) atrium from the hepatic veins.

All types of TAPVR
All types must have an atrial septal defect (see ASD chap for more info) to allow some oxygenated blood entering the R) atrium to shunt across into the L) atrium and out to the body.

Due to the left side of the heart only receiving mixed blood, the overall oxygen saturations in the body are decreased. If the ASD is small or limits blood shunting from R) to L) atrium, then the volume of the L) atrium & ventricle is reduced, which can lead to low blood supply to the body, and therefore shock.

In some instances, the route that the blood takes to make it back to the R) atrium may have stenosis or obstruction, restricting blood passage and increasing the pressure in the veins, leading to pulmonary hypertension and congestion (i.e., pulmonary oedema, or excessive fluid).

These obstructive TAPVR patients are critically ill with severe cyanosis and unstable blood pressure, and urgent surgery may be required.

Obstructive pulmonary veins are more common in infracardiac TAPVR, however can occur with an atomic types as well.

Signs & Symptoms
The first sign detected is often a typical heart murmur, and there may be evidence of overload on the R) side of the heart.

Due to the above discussed, there will be low oxygenation in babies without pulmonary venous obstruction.

Diagnosis
Electrocardiogram (ECG) will show problems with enlargement of the heart.

Chest X-Ray shoes R) sided heart enlargement, and in newborns with TAPVR & obstructed pulmonary vein return, chest X-ray can show signs of pulmonary oedema.

Echocardiogram shoes if the R) atrium and ventricle are larger than normal, as well as the size and flow across the ASD.

And sometimes, cardiac catheterisation is necessary to diagnose TAPVR, by defining the abnormal connection of all pulmonary veins, and whether there is an obstruction present. If the ASD is shown to be too small, balloon dilation may be done to enlarge the defect.

Treatment
Surgical management is necessary in TAPVR, however timing depends on the type of TAPVR the child has.

With obstructive TAPVR, surgery is undertaken right away. Some of these babies will need ECMO—extracorporeal life support—prior to surgery due to their blood flow instability.

Without obstructive TAPVR, babies have surgery days to weeks after diagnosis.

Surgical repair involves connecting the veins to the back of the left ventricle, and tying off all other routed of pulmonary venous drainage, as well as closure of the ASD.

Management & Long-Term Outlook
With surgical mortality less than 5% in elective surgical cases, mortality is higher in emergency situations in obstructive TAPVR. Recovery of these babies can be extended, on a ventilator until their lungs recover.

Long-term, babies recover well with normal circulation, developing and growing as normal. Regular follow up is required however to detect problems should these occur, such as developing pulmonary obstruction or abnormal cardiac rhythms (late complications of TAPVR).

In saying that, adults who have successful surgical repair often do well, and most do not need follow-up care in adulthood.

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