They are used to determine:

Large left atrium: the test can help to determine if the left atrium is enlarged to a large blood flow then unusually
Large right atrium and ventricle: the test will help to determine if the right atrium and ventricle are enlarged due to a greater blood flow
ASD: the test will help to determine if there is a hole between the two atria and if blood is flowing through both
Stenotic mital valve: the test will help to determine if the blood flow through the mitral valve is normal or if the mitral valve is stiff, has a reduced opening, and constricting blood flow through it. Color flow mapping and Doppler imaging
A color flow and doppler imaging is used to help confirm the presence as well as evaluate the severity of ASD and MS. Chest X-ray
A chest x-ray will be given to determine the size of the heart and the blood vessels supplying blood to the lungs. Cardiac catheterization
Cardiac catheterization is done to confirm a diagnosis; it is not routinely done prior. It can also be used to evaluate the severity of ASD and measure the mitral valve area. To determine the presence ASD, a catheter is passed through the suspected hole between the atrium into the left atrium. Treatments
To treat Lutembachers syndrome, the underlying causes of the disorder must first be treated: mitral stenosis and atrial septal defect.
No patient was found to have died from either interventional or surgical treatments and only 7.2% of patients
who received a device and 24.0% of patients who had surgery had complications. The hospital stay for each group also varied, the surgical group was 3.4 ± 1.2 days and device group 1.0 ± 0.3 days. As seen by this study, prognosis was good and quality of life could be excellent. Side effects
Side effects with interventional device closure have not been extensively supported as yet.Possible side effects from the ASD device closure procedure could be:
fever
Chest pain
Swelling
Swelling, bleeding, change in skin color at site of initial catheterization in groin, or pain in the groinWith surgically closure, the normal risk of infection, fevers, and blood clots are among the risks. If any signs of infection such as swelling, pain, or fever are present, the patient should seek medical attention. Patients who have ASD repaired later in life are also at a higher risk of developing atrial fibrillation especially if the device is not stable.