Continuous murmurs begin in systole and continue through the second sound into diastole. A continuous murmur occurs only in a vascular channel, because only there can turbulent blood flow continue throughout the cardiac cycle. Other than the innocent venous hum, such murmurs represent some type of acquired congenital vascular malformation. Let us listen to and observe the murmur at the upper left sternal edge in a patient with patent ductus arteriosus. Note that the murmur continues through the second heart sound and, in this instance, it is literally continuous.