Cardiology
The Valsalva maneuver may be used to arrest episodes of supraventricular tachycardia. The maneuver can sometimes be used to diagnose heart abnormalities, especially when used in conjunction with echocardiogram. For example, the Valsalva maneuver classically increases the intensity of hypertrophic cardiomyopathy murmurs, viz. those of dynamic subvalvular left ventricular outflow obstruction; whereas it decreases the intensity of most other murmurs, including aortic stenosis and atrial septal defect.
| Effect of Valsalva | Cardiac Finding |
|---|---|
| Decreased | |
| Aortic Stenosis | |
| Pulmonic Stenosis | |
| Tricuspid Regurgitation | |
| Increased | |
| Hypertrophic cardiomyopathy, mitral valve prolapse |
The Valsalva maneuver works by decreasing preload to the heart. A complementary maneuver for differentiating disorders is the Handgrip maneuver, which increases afterload.
The Valsalva maneuver alters heart rate through sympathetic stimulation (i.e. the accelerator nerve). Neuro-muscular junctions at the sinoatrial node (SAN) release the neurotransmitter norepinephrine(noradrenaline), which increases the SAN's depolarisation rate.
These effects decrease the time between pacemaker action potentials, which results in a faster heartbeat. In later phases of the Valsalva maneuver (phases II and III), heart rate is reduced due to parasympathetic interplay.
Read more about this topic: Valsalva Maneuver