Why do Right Sided Heart Murmurs Increase with Inspiration?
A heart “murmur” is the sound of blood flowing (i.e through a valve).
RIGHT SIDED MURMURS (i.e Tricuspid regurgitation or Pulmonary stenosis) will INCREASE WITH INspiration.
WHY? When inhaling, a more negative intra-thoracic pressure is created. This increases venous return to the right ventricle. More venous return means more blood flow over the valve and an increase in the intensity of the right sided murmur.
Likewise during EXpiration, LEFT SIDED MURMURS (i.e mitral regurgitation) INCREASE. This is due to the expanded lung parenchyma collapsing and the pooled volume of blood in it being squeezed into the left side of the heart.
Exception : MVP and HOCM murmurs DO NOT increase on expiration.
Chapter 267: Physical Examination of the Cardiovascular System. Patrick T. O’Gara; Joseph Loscalzo. Harrison’s Principles of Internal Medicine, 19e
Chapter 14. The History, Physical Examination, and Cardiac Auscultation. Richard A. Walsh; Robert A. O’Rourke; James A. Shaver. Hurst’s The Heart, 13e