From the Guidelines
The Valsalva maneuver significantly reduces left ventricular output through a series of hemodynamic changes, with cardiac output potentially decreasing by 25-40% during the strain phase. During the strain phase of Valsalva, increased intrathoracic pressure compresses the heart and great vessels, reducing venous return to the right side of the heart, as seen in the study by 1. This decreased preload subsequently diminishes left ventricular filling and stroke volume. Additionally, the increased intrathoracic pressure impedes left ventricular ejection by increasing afterload, further compromising cardiac output.
Key Hemodynamic Changes
- Decreased venous return to the right side of the heart
- Decreased left ventricular filling and stroke volume
- Increased afterload, impeding left ventricular ejection
These effects are most pronounced during the strain phase (Phase 2) of the Valsalva maneuver. Upon release of the strain (Phase 3), there is a transient further drop in blood pressure before a compensatory overshoot occurs in Phase 4, as venous return suddenly increases while peripheral vascular resistance remains elevated from sympathetic activation, as discussed in 1. This mechanism explains why Valsalva is used clinically to terminate supraventricular tachycardias, as the hemodynamic changes affect cardiac conduction. In patients with heart failure, the Valsalva response may be blunted, reflecting impaired autonomic function and reduced cardiovascular reserve.
Clinical Implications
- Valsalva maneuver can be used to terminate supraventricular tachycardias
- Blunted Valsalva response in heart failure patients may indicate impaired autonomic function and reduced cardiovascular reserve
- Hemodynamic changes during Valsalva maneuver can affect cardiac conduction and output, as seen in the study by 1.
From the Research
Effect of Valsalva Maneuver on Left Ventricular Output
- The Valsalva maneuver has a significant effect on the output of the left ventricle, with studies showing a decrease in left ventricular end-diastolic volume in normal subjects 2.
- In patients with cardiomyopathy, the left ventricular end-diastolic volume was not significantly different from control during the Valsalva maneuver 2.
- The Valsalva maneuver decreases preload and can provoke left ventricular outflow tract (LVOT) gradient in dynamic LVOT obstruction 3.
- The maneuver also momentarily increases right atrial pressure, which can help unmask a patent foramen ovale with the use of saline contrast 3.
- During the strain phase of the Valsalva maneuver, mitral valve diastolic velocity E and A peaks significantly decrease, and left ventricular end-diastolic volume and area decrease significantly 4.
- The Valsalva maneuver increases pressure in the chest, impedes pulmonary venous return, and results in left ventricular limited filling, leading to a decrease in E and A peaks 4.
- The pressure of the left ventricle and atrium is lower than that of the right side during the Valsalva maneuver, resulting in right-to-left shunt through a patent foramen ovale 4.
- The Valsalva maneuver can be used to differentiate between normal and pseudonormal left ventricular filling patterns, with an abnormal response to the maneuver indicating elevated filling pressures and pseudonormal filling patterns 5.