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The modified Valsalva maneuver is an effective technique used to cardiovert, or revert, a supraventricular tachycardia (SVT) back to a normal heart rhythm. SVT is a condition where the heart suddenly beats much faster than normal due to abnormal electrical signals in the heart's upper chambers.
The modified Valsalva works by using a combination of pressure and positional changes to stimulate the vagus nerve, which can slow down the heart rate. Here’s how it works:
Initial Strain Phase: The patient is asked to blow into a syringe or similar device with moderate force for about 15 seconds. This creates increased pressure in the chest, which momentarily decreases the return of blood to the heart, leading to a temporary drop in blood pressure.
Release Phase: After the strain, the patient quickly lies back while the legs are elevated at a 45-degree angle. This sudden change in position causes blood to rush back to the heart, increasing the blood pressure and stimulating the vagus nerve.
Reflex Response: The vagus nerve, when stimulated, triggers a reflex that slows the heart rate. In some cases, this is enough to disrupt the abnormal electrical circuit causing the SVT and restore the heart to a normal rhythm.
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