From the Guidelines
The Valsalva maneuver decreases left ventricular (LV) afterload during the strain phase. When a person performs the Valsalva maneuver by forcefully exhaling against a closed glottis, intrathoracic pressure increases significantly. This elevated intrathoracic pressure is transmitted to the aorta and arterial system, creating a pressure gradient that facilitates blood flow out of the heart. As a result, the resistance against which the left ventricle must pump (afterload) temporarily decreases, making it easier for the heart to eject blood.
Key Points to Consider
- The effect of the Valsalva maneuver on LV afterload is complex and varies across its four phases.
- The reduced afterload during Valsalva is one reason this maneuver is sometimes used clinically to assess cardiovascular function or to terminate certain supraventricular tachycardias, as noted in the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia 1.
- However, it's essential to consider the overall clinical context and the specific patient's condition, as the Valsalva maneuver can have varying effects on different individuals.
- The 2014 AHA/ACC guideline for the management of patients with valvular heart disease suggests that vasodilator therapy may be reasonable in certain cases to reduce afterload, but this is not directly related to the Valsalva maneuver 2.
- An older guideline from 2008 also discusses the importance of afterload in the management of patients with valvular heart disease, particularly aortic stenosis, but does not specifically address the Valsalva maneuver 3.
Clinical Implications
- The Valsalva maneuver can be a useful tool in certain clinical situations, such as terminating supraventricular tachycardias.
- However, its effects on LV afterload must be carefully considered, particularly in patients with underlying cardiovascular disease.
- Clinicians should be aware of the complex hemodynamic changes that occur during the Valsalva maneuver and use this knowledge to inform their clinical decision-making.
From the Research
Effect of Valsalva Maneuver on Left Ventricular Afterload
- The Valsalva maneuver increases intrathoracic pressure, which affects left ventricular function by increasing left ventricular transmural pressures and thus afterload 4.
- During the Valsalva maneuver, the increase in intrathoracic pressure incites a sequence of rapid changes in preload and afterload stress, with increases in total peripheral resistance producing further increases in afterload 5.
- The Valsalva maneuver can be used to aid accurate echocardiographic diagnosis, with its hemodynamic effect consisting of four basic phases that can be used to yield an accurate diagnosis, including decreasing preload and provoking left ventricular outflow tract gradient in dynamic left ventricular outflow tract obstruction 6.
- In patients with cardiomyopathy, the Valsalva maneuver has an altered effect on left ventricular volume, with left ventricular end-diastolic volume not significantly different from control in either the four-chamber or two-chamber views 7.
- A noninvasive device using finger photoplethysmography during a Valsalva maneuver has been shown to be useful in identifying elevated left ventricular filling pressure, with a calculated left ventricular end-diastolic pressure >20 mm Hg having a 70% sensitivity and 86% specificity for identifying measured left ventricular end-diastolic pressure >20 mm Hg 8.
Key Findings
- Increased intrathoracic pressure during the Valsalva maneuver increases left ventricular transmural pressures and afterload 4, 5.
- The Valsalva maneuver can be used to assess left ventricular function and diagnose various cardiac conditions 6, 7, 8.
- The maneuver has different effects on left ventricular volume in patients with cardiomyopathy compared to normal subjects 7.