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

From the Guidelines

The Valsalva maneuver decreases preload to the right atrium. During Valsalva, forced exhalation against a closed glottis increases intrathoracic pressure, which compresses the great veins in the thorax and impedes venous return to the heart 1. This reduction in venous return directly decreases the volume of blood entering the right atrium, thereby reducing right atrial preload. The effect occurs in four phases: initially, there's a brief increase in venous return as blood is squeezed from the pulmonary circulation (phase 1), followed by the main effect of decreased venous return during strain (phase 2), then a further transient decrease immediately after release (phase 3), and finally an overshoot with increased venous return as blood that pooled peripherally returns to the heart (phase 4) 1.

Mechanism of Action

The mechanism of the Valsalva maneuver is well-described in the context of its use for terminating supraventricular tachycardias. By reducing preload and subsequently triggering a baroreceptor-mediated vagal response, the Valsalva maneuver can effectively break the reentry circuit causing the arrhythmia 1. This is particularly relevant for conditions like orthodromic AVRT, where vagal maneuvers, including the Valsalva maneuver, are recommended as first-line interventions due to their effectiveness and safety 1.

Clinical Implications

In clinical practice, understanding the effect of the Valsalva maneuver on preload to the right atrium is crucial for managing patients with supraventricular tachycardias. The ability to decrease preload and induce a vagal response makes the Valsalva maneuver a valuable tool in the acute treatment of these conditions, potentially avoiding the need for more invasive procedures or pharmacological interventions 1.

Key Points

• The Valsalva maneuver decreases preload to the right atrium by increasing intrathoracic pressure and impeding venous return.
• This effect is utilized clinically to terminate supraventricular tachycardias through a baroreceptor-mediated vagal response.
• The maneuver is recommended as a first-line intervention for acute treatment in patients with orthodromic AVRT and other supraventricular tachycardias, due to its efficacy and safety profile 1.

From the Research

Effect of Valsalva Maneuver on Preload to the Right Atrium

• The Valsalva maneuver decreases venous return to the heart during the strain phase, which in turn decreases preload to the right atrium 2.
• This decrease in venous return is due to the increase in intrathoracic pressure, which compresses the veins and reduces blood flow back to the heart 2.
• However, after the termination of the Valsalva strain, there is an increase in venous return to the right atrium, leading to an increase in diastolic filling and stroke volume output 2.
• The Valsalva maneuver can be used as a bedside test to evaluate filling pressures in patients with heart failure, and studies have shown a significant correlation between the cardiovascular response to the Valsalva maneuver and invasively measured ventricular filling pressures 3.
• Respiratory variations, including the Valsalva maneuver, can change right ventricular preload and afterload, affecting the right ventricular ejection fraction 4.
• In contrast to the Valsalva maneuver, the party balloon inflation maneuver can increase venous return blood flow to the right atrium more effectively after release 5.