What is the effect of the Valsalva maneuver on preload to the left atrium?

From the Guidelines

The Valsalva maneuver decreases preload to the left atrium. During the strain phase of Valsalva, increased intrathoracic pressure compresses the pulmonary veins and impedes venous return to the heart, reducing blood flow into the left atrium 1. This decreased preload results in reduced left atrial filling and subsequently diminished left ventricular stroke volume. The effect occurs because the elevated intrathoracic pressure creates a pressure gradient that opposes venous return from the pulmonary circulation to the left atrium.

Physiological Response

The changes in mitral inflow with the Valsalva maneuver can help distinguish normal from pseudonormal (PN) filling patterns 1. A decrease of E/A ratio of ≥50% or an increase in A-wave velocity during the maneuver, not caused by E and A fusion, are highly specific for increased LV filling pressures. This is because the Valsalva maneuver reduces preload, which in turn affects the mitral inflow velocities.

Clinical Implications

The Valsalva maneuver is used in certain clinical scenarios, such as terminating supraventricular tachycardias, where the changes in preload and subsequent alterations in autonomic tone can help restore normal cardiac rhythm. The magnitude of preload reduction depends on the force and duration of the Valsalva effort, with stronger and longer strains causing more significant decreases in left atrial filling 1.

Key Points

• The Valsalva maneuver decreases preload to the left atrium
• The decrease in preload results in reduced left atrial filling and subsequently diminished left ventricular stroke volume
• The Valsalva maneuver can be used to distinguish normal from PN filling patterns
• The maneuver is used in certain clinical scenarios, such as terminating supraventricular tachycardias
• The magnitude of preload reduction depends on the force and duration of the Valsalva effort 1.

From the Research

Effect of Valsalva Maneuver on Preload to the Left Atrium

• The Valsalva maneuver decreases preload to the left atrium by reducing venous return to the heart 2.
• This decrease in preload is caused by the increase in intrathoracic pressure, which impedes pulmonary venous return and results in left ventricular limited filling 3.
• The reduction in preload leads to a decrease in left atrial diameter, with studies showing a significant decrease in LA diameter during the Valsalva maneuver in both healthy controls and patients with hiatal hernia 4.
• The Valsalva maneuver can exacerbate left atrial compression in patients with large hiatal hernia, leading to a greater decrease in LA diameter compared to controls 4.
• The decrease in preload also affects left ventricular function, with studies showing a decrease in left ventricular end-diastolic volume and area during the Valsalva maneuver 3, 5.
• The Valsalva maneuver can be used to assess cardiac function and diagnose conditions such as diastolic dysfunction, with a decrease in E/A ratio in mitral inflow >50% with Valsalva correlating with increased LV filling pressure and diastolic dysfunction 6.