LVOT

LVOT stands for the left ventricular outflow tract, the systolic conduit through which blood exits the left ventricle and passes into the aorta. It extends from the left ventricular cavity to the aortic valve and is influenced by the shape of the septum and the mitral valve apparatus.

Obstruction of the LVOT can be fixed or dynamic. Fixed obstruction includes valvular aortic stenosis, discrete subaortic membranes, or fibromuscular subvalvular tunnels that narrow the outflow tract at rest. Dynamic LVOT obstruction commonly occurs in hypertrophic cardiomyopathy, where systolic anterior motion of the mitral valve further narrows the tract during systole, and the gradient can fluctuate with preload, afterload, and contractility.

Diagnosis relies primarily on imaging. Transthoracic echocardiography assesses LVOT anatomy and uses Doppler to estimate blood flow velocity and the corresponding pressure gradient across the tract, often applying the Bernoulli equation. Cardiac MRI or CT may provide detailed anatomic information, especially when surgical planning is needed. Invasive hemodynamic assessment is reserved for complex cases or when noninvasive results are inconclusive.

Clinical significance varies with the underlying cause. LVOT obstruction can reduce cardiac output and cause symptoms such as dyspnea, chest pain, or syncope; in hypertrophic cardiomyopathy, it is associated with adverse outcomes including sudden cardiac death in some patients.

Management depends on etiology and severity. Fixed LVOT lesions may require surgical resection of a subaortic membrane or valve replacement for aortic stenosis. Dynamic LVOT obstruction in hypertrophic cardiomyopathy is often treated with beta-blockers or non-dihydropyridine calcium channel blockers; disopyramide may be used in some cases, and septal reduction therapy (surgical myectomy or alcohol ablation) is considered for refractory symptoms or high gradients. Regular follow-up with imaging guides ongoing care.