Ventricular Septal Defect

Amara H. Estrada, DVM, DACVIM (Cardiology), University of Florida

ArticleSeptember 20141 min read

A grade 4/6 high-frequency systolic murmur (best heard on the right cranial thorax) is auscultated in this heart sound, resulting from a ventricular septal defect (VSD).

VSD murmurs vary tremendously in shape and quality; however, they are often harsh, mid- to high-frequency systolic murmurs best heard on the right cranial thorax. Murmur intensity may be reduced with large VSD murmurs. 

Patients with large VSD murmurs can develop severe pulmonary hypertension, causing the murmur to be absent. Splitting of the second heart sound may also be appreciated.