LVOT Obstruction

LVOT (left ventricular outflow tract) obstruction is a physical obstacle that restricts blood flow that your heart’s left ventricle pumps out as it attempts to deliver blood to your entire body.

With LVOT obstruction, this blockage creates a sudden pressure difference (gradient). This means your heart has to push harder than usual against the obstacle to move blood past it.

Causes include problems you have at birth or acquire later. This condition is common in people with hypertrophic cardiomyopathy (HCM).

Healthcare providers classify LVOTO by location. For example:

• Valvular: Happens in a valve, like with aortic valve narrowing
• Supravalvular: Occurs above a valve, like narrowing of your aorta
• Subvalvular: Happens below a nearby valve, like subaortic stenosis

Symptoms of LVOT obstruction

If the obstruction isn’t severe, you may not have symptoms. If you do have LVOT obstruction symptoms, these may include:

• Chest pain (angina)
• Fainting
• Shortness of breath when you exert yourself
• Fatigue when you exert yourself
• Dizziness
• Heart palpitations

Often, LVOT obstruction symptoms are dynamic. This means things like physical activity and changes in your body’s “fight or flight” response (vagal and sympathetic tone) can provoke them.

LVOT obstruction causes

Hypertrophic cardiomyopathy is a common cause of LVOT obstruction. Many people with HCM have a thickened interventricular septum (the muscle barrier between the two ventricles) and long mitral valve leaflets. These can cause obstructions.

Systolic anterior motion (SAM) of an anterior leaflet (the one closest to the wall, or septum) causes dynamic LVOT obstruction. Dynamic means the pressure can go up and down, depending on what you’re doing.

Systolic means the leaflet moves when your heart muscles contract. At that time, the anterior leaflet can touch the thickened wall between the lower heart chambers. When the leaflet and wall touch, they obstruct blood flow.

Other causes of LVOT obstruction include:

• Aortic valve narrowing (stenosis)
• Narrowing below your aortic valve (subaortic stenosis)
• Narrowing (coarctation) of the aorta
• Missing valve flap (bicuspid aortic valve)
• Reversed main arteries (L-transposition of the great arteries, or L-TGA)
• Williams syndrome
• Mitral and aortic valve replacement using a catheter
• Low fluid levels (hypovolemia)
• Excessive movement (hyperkinesia)
• Heart attack

Risk factors

LVOT obstruction can happen to children and adults. In many cases, it develops because of an inherited condition. Lowering your risk of other causes, like a heart attack, can lower your risk of LVOTO, as well.

Sometimes, a surgeon sees something in your anatomy that puts you at risk of an LVOT obstruction from a mitral valve procedure. If this is the case, there are things they can do during surgery to limit your risk.

Complications of this condition

Without treatment, LVOT obstruction can make your heart’s left ventricle thick, stretched out or unable to work. This condition can also lead to kidney or liver injury.

How doctors diagnose this condition

Your healthcare provider may hear a heart murmur when they listen to your heartbeat.

To diagnose LVOT obstruction, they may request these tests:

• Electrocardiogram (EKG)
• Echocardiogram (echo)
• MRI
• Angiogram
• Stress test

How is it treated?

LVOT obstruction treatment consists of medicines, procedures or surgery. These address the cause of the condition. You may need surgery if you have a severe case or other issues, like a hole between ventricles or a leaky aortic valve.

Treatments may include:

• Beta-blockers
• Calcium channel blockers
• Mavacamten
• Biventricular pacemaker
• Balloon valvuloplasty
• Septal myectomy
• Aortic valve repair
• Alcohol septal ablation
• Implantable cardioverter defibrillator (ICD)

When should I see my healthcare provider?

Contact your provider if you’re having symptoms of this condition or if symptoms don’t improve after treatment. You may get relief from medicines. If you don’t, ask your provider about procedures that could help.

Questions you may want to ask your provider include:

• What caused LVOT obstruction in my case?
• What’s the best treatment for me?
• In your experience, do most people need a procedure?

What can I expect if I have this condition?

Sometimes, LVOTO can be a short-term condition. For example, it can happen with hypovolemia. Reducing certain medicines or starting others and adding fluids can fix LVOTO in these cases. But for many other people, this is a long-term problem.

A gradient or pressure difference of 50 millimeters of mercury or more in your left ventricular outflow tract is severe. Without treatment, this can give you a poor prognosis.

Surgery can relieve symptoms from LVOT obstruction. People tend to have better results when their surgical team does a higher volume of myectomies (removing thickened heart tissue). Your outcome also depends on what other conditions you have and their severity, as well as your age.

Having LVOT obstruction may increase your risk of endocarditis. Your healthcare provider may suggest taking antibiotics before some dental work. This medicine can help you avoid getting inflammation in your heart.