Left ventricular outflow tract obstruction (LVOTO)

What is LVOTO?

Left ventricular outflow tract obstruction (LVOTO) is a recognised feature of hypertrophic cardiomyopathy.

It is caused by the thickened heart muscle and the abnormal movement of the mitral valve. This is the main mechanism of debilitating symptoms in hypertrophic cardiomyopathy patients.

It is also one of the risk factors for sudden cardiac death, especially in young patients.


Causes of LVOTO

Hypertrophic cardiomyopathy is the single most common form of inherited heart disease.

Left ventricular outflow tract obstruction (LVOTO) is a recognised feature of this condition which arises when blood leaving the outflow tract is impeded by systolic anterior motion of the mitral valve. In an important minority of patients, breathlessness, chest pain and loss of consciousness may occur despite the use of medication.


Symptoms of LVOTO

Left ventricular outflow tract obstruction (LVOTO) can present any of the following symptoms:

  • breathlessness with activity
  • light-headedness, especially with or after activity or exercise
  • fainting or near fainting
  • palpitations
  • chest pain with activity.

Diagnosis

The diagnosis of LVOTO rests upon detecting an increase in thickness of the left ventricular wall,  that is not explained solely by any loading conditions of the heart.

The thickness of the left ventricular wall can be measured by imaging techniques including:


Treatment for LVOTO

The left ventricular outflow tract obstruction management programme at Royal Brompton and Harefield hospitals offers a holistic approach to the treatment and management of LVOTO.

The programme offers the highest level of diagnostic expertise and all internationally available management options for LVOTO.

There are currently two techniques available if medication does not deliver the desire results: alcohol septal ablation and surgical myectomy.

Surgical myectomy

In suitable candidates, surgery may relieve obstruction and its associated symptoms. This procedure entails surgical muscle resection after specialist imaging to access the obstruction and the anatomy of the left ventricle and the mitral valve.

During the procedure, the surgeon will reach the inside of the heart through the aorta and aortic valve to resect the inner surface of the heart muscle to relieve blockage in the areas which are thickened. Occasionally, the resection of the muscle is not sufficient and then a repair or replacement of the mitral valve may become necessary.

Alcohol septal ablation

Alcohol septal ablation (ASA) is a nonsurgical reduction of the thickness of the ventricular muscle in the area of the outflow tract, and is a clinically efficient therapeutic option in selected cases.

The procedure involves the tip of a catheter being wedged into a small artery that supplies blood to the thick muscle. Then the area of blood supply is carefully checked with specialised imaging. If appropriate, an infarction is generated in the area by injecting a small amount of ethanol through the catheter. This results in scarring and shrinking of the wall thickness reducing or even eliminating the obstruction. The improvement may not manifest itself immediately after the procedure.


Benefits of successful LVOTO treatment

Patients who have had successful LVOTO treatment will experience relief from symptoms such as fainting, fatigue and breathlessness as well as reduced risk of sudden cardiac arrest (particularly in young patients).

This results in a dramatic improvement in patients’ quality of life, and a lowered risk of other complications related to LVOTO.

 

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