1.06 Systolic Heart Murmurs Cardiovascular system review for the USMLE STEP 1 Exam Heart murmurs are caused by turbulent blood flow in the heart There are 4 different types of systolic murmurs: ventricular septal defect (VSD), patent ductus arteriosus (PDA), aortic stenosis, and mitral or tricuspid regurgitation PDA produces a constant, machine-like murmur VSD produces a harsh holosystolic murmur Aortic stenosis produces a crescendo-decrescendo systolic ejection murmur Mitral and tricuspid regurgitation produce a holosystolic high pitched "blowing" murmur Mitral valve prolapse produces a mid-systolic click followed by a late systolic murmur Aortic regurgitation produces a decrescendo diastolic murmur Mitral stenosis produces a rumbling diastolic murmur