Your Child Needs A Bubble Study--What's That?

If a pediatrician or cardiologist has just ordered a bubble study for your child, you may be wondering what it's all about. Here's an overview of this very clever and minimally invasive way to diagnose certain heart problems.

What is a Bubble Study?

A bubble study (AKA agitated saline echo testing) is a special type of echocardiogram or ultrasound of the heart. While a technician takes Doppler images of the heart muscle in action, a tiny cloud of bubbles is infused through an IV line. When the bubbles enter the heart in the bloodstream, the technician and cardiologist "reading" the echo can see exactly where they go, getting a precise visual pathway of how blood moves through the heart.

Why Did the Doctor Order This Test?

This test is usually ordered to see if there is a hole between the upper chambers of the heart (the atria). This hole is present in everyone in the womb, but should close automatically when a baby takes their first breath after being born. In some instances, however, the flap doesn't close over this hole or it doesn't close completely, allowing blood to travel between the two atrial chambers instead of emptying into the ventricles (the lower chambers that send blood to the body).

When blood moves in one direction from one atrium to the other, it's known as a patent foramen ovale. When it travels back and forth between the two chambers, it's called an atrial septal defect (ASD).

Your child's doctor probably ordered this test because they heard a heart murmur when listening to your child's heart with a stethoscope. It could also be ordered if your child has symptoms of a patent foramen or ASD, such as becoming lightheaded, dizzy, easily fatigued, or even blue in the hands and face (from lack of sufficient oxygen). In extreme cases, your child may also retain water easily or have some swelling in the extremities.

What Should Your Child Expect During the Procedure?

Before the echocardiogram, your child will be given an IV, so the bubble cloud can be infused intravenously. The IV runs a saline solution, and the bubble cloud is simply a vial of saline that is shaken vigorously to produce the bubbles.

The nurse or technician who starts the IV will clean the area and apply a tourniquet, which will feel very tight just for a moment. The IV puncture may hurt for a second, much like getting a vaccination shot. Once the saline starts running in via the IV, your child may feel a little chill, as the saline is colder than body temperature.

During the test, your child will be monitored with an EKG (also called an ECG or electrocardiogram) to watch the heart rhythm during the test. For this part of the procedure several electrodes are stuck to the chest with a sticky gel and hooked to wires that go to the monitor. The electrodes can feel a bit cold.

The gel that is used to improve the Doppler transmission for the echo can feel cold as well. The technician moves a conducting wand over the chest where it covers the heart. It usually helps to distract a child by showing them the images of their heart on the monitor screen and enjoying this rare glimpse of a miraculous organ as it works.

Your child will be in a hospital gown for the test, and their chest will be exposed during the echo. If they are modest about being bare chested for the procedure, assure them that the staff doing the test are used to seeing patients this way. They will make every effort to only expose areas of the body that they need to access for the procedure.

Sometimes a cardiologist is present during the study and can read the images on the spot. Other times the test is recorded for the physician to interpret later. The technician has been through rigorous training and can identify anything needing a doctor's immediate attention during the test.

Are Bubble Studies Safe?

Bubble studies are a wonderful way to diagnose "holes in the heart," because they are so minimally invasive. The biggest risk is from infection at the IV site, which is quite small, as the IV doesn't remain in place for more than an hour or two.

The quantity of air bubbles infused during the procedure has been checked to be safe enough not to cause an embolism. The rest of the test is completely non-invasive and poses no risk to your child.

Once the test has been performed, your physician will have a better idea of where to proceed from there. If no patent foramen or ASD is detected, your child's symptoms can be studied for other causes. If there is an opening between the atria, your cardiologist will discuss with you how best to manage it, depending on its size and your child's symptoms. Management possibilities include:

  • doing nothing and taking a wait-and-see attitude
  • medication
  • transcatheter patch in the cardiac catheterization lab
  • heart surgery

Even if the results of the test are positive, you can move forward and take the best action for your child's health. Work with a health care clinic, like Idaho Arthritis Center, to more fully understand the how and why of a bubble study.