Left ventricular outflow tract obstruction

Left Ventricular Outflow Tract Obstruction

Left ventricular outflow tract obstruction (LVOTO) is a condition characterized by the narrowing of the outflow tract from the left ventricle of the heart to the aorta. This obstruction can impede the normal flow of blood, leading to various clinical symptoms and complications. LVOTO can be congenital or acquired and is associated with several cardiac conditions.

Pathophysiology

The left ventricular outflow tract (LVOT) is the passage through which blood exits the left ventricle and enters the aorta. Obstruction in this area can occur at different levels:

• Subvalvular: Below the aortic valve, often due to hypertrophic cardiomyopathy or a discrete fibromuscular ridge.
• Valvular: At the level of the aortic valve, commonly due to aortic stenosis.
• Supravalvular: Above the aortic valve, which can be due to conditions like supravalvular aortic stenosis.

The obstruction increases the workload on the left ventricle, leading to hypertrophy and potentially heart failure if untreated.

Causes

LVOTO can be caused by a variety of conditions, including:

• Hypertrophic Cardiomyopathy (HCM): A genetic disorder characterized by thickened heart muscle, particularly affecting the septum, which can obstruct the LVOT.
• Aortic Stenosis: Narrowing of the aortic valve, which can be congenital or acquired, often due to calcification in older adults.
• Congenital Heart Defects: Such as subaortic stenosis or supravalvular aortic stenosis.

Symptoms

Symptoms of LVOTO can vary depending on the severity of the obstruction and may include:

• Shortness of breath
• Chest pain
• Syncope (fainting)
• Fatigue
• Palpitations

Diagnosis

Diagnosis of LVOTO typically involves:

• Echocardiography: The primary tool for assessing the structure and function of the heart, including the degree of obstruction.
• Cardiac MRI: Provides detailed images of the heart's anatomy and can help in assessing myocardial fibrosis.
• Cardiac Catheterization: May be used to measure pressures within the heart and assess the severity of the obstruction.

Treatment

Treatment options for LVOTO depend on the underlying cause and severity of the obstruction:

• Medications: Beta-blockers or calcium channel blockers to reduce heart rate and improve symptoms.
• Surgical Intervention: Such as septal myectomy for hypertrophic cardiomyopathy or valve replacement for aortic stenosis.
• Percutaneous Procedures: Such as alcohol septal ablation for hypertrophic cardiomyopathy.

Prognosis

The prognosis for individuals with LVOTO varies based on the cause and treatment. Early diagnosis and appropriate management are crucial for improving outcomes.

Also see

• Hypertrophic Cardiomyopathy
• Aortic Stenosis
• Congenital Heart Defects
• Echocardiography

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