What is the effect of the Valsalva (Valsalva maneuver) on venous return to the right atrium?

From the Guidelines

The Valsalva maneuver decreases venous return to the right atrium. During this maneuver, a person forcefully exhales against a closed glottis, which increases intrathoracic pressure. This elevated pressure compresses the great veins in the thorax, particularly the superior and inferior vena cavae, creating resistance to blood flow returning to the heart. As a result, venous return to the right atrium is temporarily reduced. This hemodynamic effect occurs in four phases: initially, there's a brief increase in venous return and blood pressure as the maneuver begins; then during sustained strain, venous return drops significantly and cardiac output decreases; when the strain is released, intrathoracic pressure suddenly drops, allowing increased venous return; finally, blood pressure and heart rate normalize.

The Valsalva maneuver is used clinically to terminate certain supraventricular tachycardias, as the reduced venous return and subsequent changes in autonomic tone can reset abnormal heart rhythms, as recommended by the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1. The maneuver also explains why people may feel lightheaded during forceful straining, as the reduced venous return leads to temporarily decreased cardiac output and cerebral perfusion.

Some key points to consider when performing the Valsalva maneuver include:

• The patient should be in the supine position 1
• The maneuver should be performed by bearing down against a closed glottis for 10 to 30 seconds, equivalent to at least 30 mm Hg to 40 mm Hg 1
• The practice of applying pressure to the eyeball is potentially dangerous and has been abandoned 1
• Vagal maneuvers, including the Valsalva maneuver, are recommended for acute treatment in patients with regular SVT, as they can be performed quickly and are a first-line intervention to terminate SVT 1

From the Research

Effect of Valsalva Maneuver on Venous Return

• The Valsalva maneuver decreases venous return to the heart during the strain phase 2
• This decrease in venous return is due to the increase in intrathoracic pressure, which impedes pulmonary venous return 2, 3
• The decrease in venous return leads to a decrease in cardiac output, which is counterbalanced by an increase in heart rate and cardiac contractility 2, 4
• After the release of the Valsalva maneuver, there is an increase in venous return to the right atrium, leading to an increase in diastolic filling and stroke volume output 2

Comparison with Other Maneuvers

• The party balloon inflation maneuver has been shown to be more effective in enhancing venous return to the right atrium after release compared to the conventional Valsalva maneuver 5
• This suggests that the party balloon inflation maneuver may be a useful alternative for detecting right-to-left shunts in patients with a patent foramen ovale 5

Hemodynamic Changes

• The Valsalva maneuver leads to changes in cardiac hemodynamics, including decreases in mitral valve diastolic velocity and left ventricular end-diastolic volume 3
• The maneuver also leads to an increase in right-to-left shunt through a patent foramen ovale due to the increased pressure in the chest and decreased left ventricular filling 3