Your pulmonary veins collect oxygen-rich blood from your lungs and carry it to your heart. Many different conditions can affect your pulmonary veins, including ones that you’re born with and others that develop later in life. Pulmonary veins are also the place where atrial fibrillation begins. So, they’re often the target of A-Fib treatment.
Pulmonary veins are blood vessels that carry oxygen-rich blood from your lungs to your heart.
Your pulmonary veins are part of your body’s pulmonary circuit. This is a system of blood vessels that moves blood between your heart and your lungs. This circuit also includes your pulmonary arteries.
Your pulmonary veins and pulmonary arteries have two main differences:
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Your pulmonary veins are the only veins in your body that carry oxygen-rich blood. All your other veins carry oxygen-poor blood.
Similarly, your pulmonary arteries are the only arteries that carry oxygen-poor blood. All the rest of your arteries carry oxygen-rich blood.
As you can see, the pulmonary circuit is a unique part of your body! Your blood vessels in this circuit are the exceptions to the rules about the type of blood each vessel carries.
But one aspect remains the same. That’s the direction of travel. Your pulmonary veins, like all your other veins, carry blood toward your heart. And your pulmonary arteries, like all your other arteries, carry blood away from your heart.
Most people (60% to 70%) have four pulmonary veins. Everyone else has either three or five pulmonary veins. These changes in number don’t cause any health problems. They’re simply anatomical variations (differences from what scientists consider “normal”) that some people are born with.
Your pulmonary veins collect oxygen-rich blood from your lungs and carry it to your heart. From there, your heart sends the blood to all your other organs and tissues.
Your heart gets a lot of credit for being your body’s pumping powerhouse. And it should. But it can be easy to forget about the blood vessels that enable your heart to pump that blood. If your pulmonary veins suddenly stopped doing their job, your heart wouldn’t receive freshly oxygenated blood to send out to the rest of your body.
So, your pulmonary veins play an essential role in helping your heart do its job. In turn, your pulmonary veins help keep your entire body working.
Your pulmonary veins are located between your lungs and your heart. Many smaller blood vessels converge in each of your lungs (right and left) to form a pair of pulmonary veins. Each pair leaves its respective lung through a spot known as the hilum, or root. From there, your pulmonary veins travel to your heart and connect with your left atrium. This is the top left chamber of your heart.
Most people have four pulmonary veins, with two connected to each lung (right and left):
“Superior” means above, and “inferior” means below. So, the name of each vein describes which lung it drains and how it’s positioned.
Normally, each pulmonary vein connects directly with your left atrium. In that case, there are four ostia (openings) in your left atrium, one for each of your pulmonary veins. Oxygen-rich blood travels through these openings and into your left atrium. From there, your blood moves into your left ventricle, which pumps it out to your body through your aorta.
There are several possible variations of the normal pulmonary vein structure. Some variations affect the number of pulmonary veins you have and how they enter your left atrium. These are healthy and harmless variations.
Other variations prevent your pulmonary veins from draining properly into your left atrium. These variations interfere with your heart’s normal functioning and can be life-threatening.
About 38% of people have harmless anatomical variations in pulmonary vein structure. These variations affect how many pulmonary veins they have and how those veins connect with their left atrium. These variations include:
These variations are still healthy, and your veins work as they should. That’s because these variations still allow for oxygen-rich blood to enter your left atrium. From there, it can follow the normal path into your left ventricle and then out to the rest of your body.
Some variations prevent your pulmonary veins from bringing oxygen-rich blood to your left atrium. As a result, your heart can’t function as it should.
These variations arise as congenital heart defects. They’re usually diagnosed soon after birth but diagnosis can occur into adulthood as well. They include:
In the U.S., about 1 in 7,809 babies are diagnosed with TAPVR. It’s not clear exactly how many babies are born with PAPVR. But estimates show PAPVR may affect 1 in 143 people, and it occasionally goes unnoticed until adulthood.
Babies with TAPVR or PAPVR usually have a hole between their top two heart chambers (atrial septal defect). This defect is actually life-saving because it allows blood to travel from the baby’s right atrium to their left atrium, and then out to their body. This blood doesn’t contain as much oxygen as it should, but it’s still enough to keep the baby alive until treatment.
The diameter of a healthy pulmonary vein ranges from 9 to 13 millimeters. Your pulmonary veins vary in diameter as they travel from your lungs to your heart. In general, veins gets wider as it approaches your heart. Your left inferior pulmonary vein is the exception to this rule. It starts out wider as it leaves your left lung and gets narrower as it reaches your heart.
Three layers of tissues and fibers make up all your veins, including your pulmonary veins. These layers include:
Unlike other veins in your body, your pulmonary veins are partly covered by a thin myocardial layer. This is a “sleeve” of heart muscle tissue that covers a portion of each pulmonary vein near its connection with your left atrium. The average length of this sleeve is 9 millimeters. Your superior pulmonary veins have longer sleeves than your inferior pulmonary veins.
Conditions that can affect your pulmonary veins include:
Atrial fibrillation (A-Fib) is an abnormal heart rhythm that begins in your pulmonary veins. It may also begin at their junction with your left atrium. Any of your pulmonary veins may trigger A-Fib, but your left superior pulmonary vein is most often involved.
Healthcare providers use a catheter-based procedure called pulmonary vein isolation to treat A-Fib.
Providers use several different imaging tests to check your pulmonary veins. These include:
If you’ve been diagnosed with a pulmonary vein condition, it’s important to follow your healthcare provider’s guidance. Many pulmonary vein problems stem from other medical conditions. These need careful treatment and monitoring. Ask your provider what you can do at home to manage your condition and reduce any symptoms.
A note from Cleveland Clinic
Your pulmonary veins carry oxygen-rich blood from your lungs to your heart. They’re essential workers that help keep your body going strong. If you have a heart or lung condition that affects your pulmonary veins, talk with your provider about your prognosis.
Last reviewed by a Cleveland Clinic medical professional on 06/02/2022.
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