What is a normal left ventricular (LV) intracavity pressure gradient?

From the Guidelines

A normal intracavity LV gradient is typically less than 30 mmHg at rest. This threshold is based on the latest guidelines from the American Heart Association, as outlined in the 2024 AHA/ACC/AMSSM/HRS/PACES/SCMR guideline for the management of hypertrophic cardiomyopathy 1. According to this guideline, obstruction is considered present if the peak LVOT gradient is $30 mm Hg, and resting or provoked gradients $50 mm Hg are generally considered capable of causing symptoms.

Key Points to Consider

• The measurement of intracavitary LV gradients is crucial for diagnosing and managing conditions such as hypertrophic cardiomyopathy.
• Gradients can be dynamic and sensitive to ventricular preload, afterload, and contractility, varying with heart rate, blood pressure, volume status, activity, medications, food, and alcohol intake 1.
• Provocative maneuvers, such as standing, Valsalva strain, or exercise with simultaneous auscultation or echocardiography, are recommended if minimal gradients (ie, <30 mm Hg) are observed at rest to assess for latent LVOTO.
• The site and characteristics of obstruction should be identified, as management will change depending on whether the obstruction is deemed to be valvular, dynamic LVOTO, fixed subvalvular, or midcavitary due to hypertrophied/anomalous papillary muscles and/or hyperdynamic LV function with systolic cavity obliteration 1.

Clinical Implications

• Small gradients (less than 30 mmHg) can be physiological and may occur in healthy individuals, especially during conditions that increase cardiac contractility such as exercise, anxiety, or dehydration.
• Gradients exceeding 30 mmHg at rest are generally considered abnormal and may suggest pathological conditions such as hypertrophic cardiomyopathy, particularly if the gradient occurs in the outflow tract.
• Understanding these normal values is important for correctly interpreting cardiac function studies and distinguishing between normal physiological variants and pathological conditions requiring intervention.

From the Research

Normal Intracavity LV Gradient

• A normal intracavity LV gradient is generally considered to be less than 36 mm Hg, as stated in the study by 2.
• This value is associated with patients who have left ventricular cavity obliteration (LVCO) without hypertrophic obstructive cardiomyopathy (HOCM) or severe left ventricular hypertrophy (LVH).
• The magnitude of the intracavity gradient is quantitatively associated with the extent and duration of LVCO, as found in the study by 2.

Comparison with Other Conditions

• In patients with hypertrophic obstructive cardiomyopathy (HOCM), the intracavity gradient can be higher, with a peak/mean gradient ratio of 2-3, as reported in the study by 2.
• In contrast, patients with severe aortic stenosis (AS) have a peak/mean gradient ratio of 2 or less, as stated in the study by 2.
• The study by 3 found that the causes of left ventricular outflow tract obstruction (LVOTO) are diverse, and the occurrence of LVOTO might depend on the coexistence of primary morphological LV characteristics and hemodynamic LV status.

Dynamic Intracavity Gradients

• Dynamic intracavity gradients can be induced or accentuated by provocative situations, such as the Valsalva maneuver, as reported in the study by 4.
• The Valsalva maneuver can be used to decrease preload and provoke left ventricular outflow tract (LVOT) gradient in dynamic LVOT obstruction, as stated in the study by 5.
• The study by 6 found that a small estimated neo-LVOT area was significantly associated with LVOT obstruction after transcatheter mitral valve replacement (TMVR), and may help identify patients at high risk for LVOT obstruction.