09.02 Defects of Increased Pulmonary Blood Flow

Hey guys, in this lesson we are going to go over heart defects that cause an increase in pulmonary blood flow. This information will build on what is discussed in the congenital heart defects lesson so check that one out if you haven’t already!

The defects that cause an increase in pulmonary blood flow are Atrial Septal Defect, Ventricular Septal Defect, Atrioventricular Canal Defect and Patent Ductus Arteriosus. These are all abnormal openings in the heart, we’ll talk more specifically about their locations in just a second. Remember that pressure on the left side of the heart is greater than on the right side of the heart, so these openings allow blood that has already been oxygenated to flow back to the right side of the heart. This is called a left to right shunt. Blood is being circulated through the lungs again, increasing pulmonary blood flow and the right side of the heart is having to work extra hard.

The blood leaving the heart is going to be oxygenated so for the most part these patients will not be cyanotic at first.

We are going to talk through each defect and highlight the things that are unique to each one.

Atrial Septal Defect or ASD is a hole in the septum connecting the right and left atria. Oxygenated blood shunts from the left back to the right and is recirculated. A lot of times patients with ASD are asymptomatic for a long time. Some even present well into adulthood with heart palpitations and shortness of breath.

For our peds patients they may have a murmur and they may present with dyspnea and frequent respiratory infections.

When they go undiagnosed patients are at risk for atrial dysrhythmias, clot formation and stroke.

Ventricular Septal Defect is a hole between the right ventricle and the left ventricle. Again, the blood is shunted from left to right recirculated the oxygenated blood.

How symptomatic the kid is will depend on large the defect is. If it’s small they may be asymptomatic, but larger defects will often present in the first few months of life. Usually it presents as feeding difficulties so babies struggle to eat, sweating while feeding and tiring easily and they may not meet growth milestones.

Over time, if untreated the right side of the heart will hypertrophy and heart failure can occur.

Atrioventricular Canal Defect is an opening between all four chambers. This is a much larger defect than the previous two. Again, blood moves left to right, increasing pulmonary blood flow. This is the most common heart defect seen in patients with Down Syndrome.

This defect usually presents in the first few months of life and if severe enough the patient can be cyanosed. Most of the time though, and you’ll be seeing a pattern by now, it presents as respiratory distress, frequent infections and feeding difficulty. They may also have a murmur and again, if untreated it can lead to moderate to severe heart failure.

Patent Ductus Arteriosus is a little different than the other three we’ve talked about. It’s not located in the septum. It’s an opening between the aorta and the pulmonary artery. This opening is called the ductus arteriosus and in a fetus it’s totally normal, but it should close after the baby is born. If it doesn’t it’s called Patent Ductus Arteriosus.

Blood still moves from the higher pressure (aorta) to the lower pressure (pulmonary artery) so there is still going to be increased pulmonary pulmonary blood flow.

Probably the most classic symptom of a PDA is a machine-like murmur. As with the others symptoms it will be worse with larger holes. And you’ve probably guessed it, presentation is often respiratory distress, frequent respiratory infections and feeding difficulties. Over time, heart failure can occur but is rare in childhood.

Management of these vary but sometimes watchful waiting is appropriate. VSD and PDA will sometimes close on their own, so we keep an eye on the kid and wait to see if this happens.

Cardiac catheterization can be used to repair ASD and VSD.

Surgery is needed to repair the atrioventricular defect because it is much larger and has to be patched rather than just closed.

Medications can be used to close the PDA. If it doesn’t close on it’s own NSAIDS will actually close it. Prostaglandins keep the PDA open and NSAIDS inhibit prostaglandin synthesis so this can cause it to close. This is why pregnant women shouldn’t take NSAIDS. We need the DA to stay open!

Your priority nursing concepts for a peds patient with a congenital heart defect that causes increased pulmonary blood flow are perfusion, oxygenation, and gas exchange.

Okay, let’s recap the key points for this lesson. We talked through, Atrial Septal Defects, Ventricular Septal Defects, Atrioventricular Canal Defects and Patent Ductus arteriosus. These are all abnormal openings in the heart. They cause oxygenated blood to shunt from the left side back into the right side to be recirculated through the lungs. This results in increased pulmonary blood flow that can cause pulmonary congestion and makes the right side of the heart work harder.

Because these don’t immediately cause cyanosis a lot of babies are asymptomatic for a while and presentation is usually respiratory distress and feeding difficulty.

Treatment varies and can be watchful waiting, Cardiac Catheterization and Surgery. NSAIDS can be used to help trigger the close of the PDA.

That's it for our lesson on heart defects that cause an increase in pulmonary blood flow.

Make sure you check out all the resources attached to this lesson. Now, go out and be your best self today. Happy Nursing!