HCM: Mitral Valve SAM and Dynamic LVOT Obstruction, Provocative Tests
Provocation of Dynamic LVOT Obstruction in HCM
According to the updated ASE guidelines on multimodality imaging of patients with hypertrophic cardiomyopathy (Nagueh S.F. et al., 2022), it is mandatory to conduct various provocative maneuvers in patients who do not reach the gradient thresholds for considering septal reduction therapy (SRT). Postprandial imaging can also reveal latent obstruction.
Valsalva Maneuver
One of the described maneuvers for assessing the provoked LVOT gradient is the strain phase of the Valsalva maneuver. During forced expiration against a closed airway, intrathoracic pressure increases and venous return decreases, which can provoke LVOT obstruction (LVOTO).
The limitation of the Valsalva maneuver is the subjective nature of the effort applied and, consequently, the variability of the response.
Assessment of the Gradient Across the Aortic Valve
Normally, the systolic gradient across the AoV between the left ventricle and the aorta is <120 mmHg (Blagodir B.V., 2024). This minor gradient facilitates the free passage of blood from the ventricles into the main arteries.
Detailed threshold values of the provoked LVOT gradient specific to indications for SRT are not provided in the source fragments — [clarify].
Additional Methods for Assessing LV Function
The assessment of global longitudinal strain (GLS) using 2D speckle-tracking echocardiography (2D STE) plays a role in identifying subclinical LV dysfunction and should be performed according to previously described general standards (Pandian N.G. et al., 2023).
Frequently asked questions
When are provocative tests mandatory in HCM?
In patients who do not reach the gradient thresholds for considering septal reduction therapy (SRT), provocative maneuvers are mandatory (ASE, 2022).
How does the Valsalva maneuver provoke LVOT obstruction?
During the strain phase of forced expiration against a closed airway, intrathoracic pressure increases and venous return decreases, which can provoke LVOTO.
What is the limitation of the Valsalva maneuver?
The subjective nature of the effort applied and, consequently, the variability of the response.
Can the postprandial state help reveal obstruction?
Yes, postprandial imaging can reveal latent obstruction (ASE, 2022).
What is the normal systolic gradient between the LV and the aorta?
The systolic gradient across the AoV between the left ventricle and the aorta is <120 mmHg (Blagodir B.V., 2024).