Grade IV Loud with palpable thrill
Grade V Loud with thrill, audible with stethoscope at 45° angle
Grade VI Loud with thrill, audible with stethoscope off chest 1 cm septal defects (ASDs), and coarctation of the aorta. Holosystolic murmurs have their onset with S1. The murmur has a plateau quality and may be heard with ventricular septal defects (VSDs) and mitral or tricuspid regurgitation. A late regurgitant murmur may be heard after a midsystolic click in mitral valve prolapse.
Murmurs are often heard along the path of blood flow. Ejection murmurs usually are best heard at the base of the heart, whereas holosystolic murmurs are louder at the LLSB and apex. Pulmonary ejection murmurs radiate to the back and axilla. Aortic ejection murmurs radiate to the neck. The intensity or loudness of a heart murmur is assessed as grade I through VI (Table 139-4). The frequency or pitch of a murmur provides information regarding the pressure gradient. The higher the pressure gradient across a narrowed area (valve, vessel, or defect), the faster the flow and higher the frequency of the murmur. Low-frequency murmurs imply low pressure gradients and mild obstruction or less restriction to flow.
vibratory murmur LLSB or between LLSB and apex Grades I-III/VI Vibratory, musical quality Intensity decreases in upright position
Venous hum Continuous murmur 3–6 yr Infraclavicular region (right > left) Grades I-III/VI Louder with patient in upright position Changes with compression of jugular vein or turning head
Carotid bruit Systolic ejection murmur Any age Neck, over carotid artery Grade I-III/VI ejection murmur LUSB Grade I-III/VI Usually softer in upright position Does not radiate to back
Peripheral Systolic ejection murmur Newborn to 6 mo pulmonary Axilla and back, LUSB/ stenosis RUSB
Grade I-III/VI Harsh, short, high-frequency
LLSB, Left lower scapular border; LUSB, left upper scapular border; RUSB, right upper scapular border.
Diastolic murmurs are much less common than systolic murmurs, and should be considered abnormal. Early diastolic murmurs occur when there is regurgitation through the aortic or pulmonary valve. Mid-diastolic murmurs are caused by increased flow (ASD, VSD) or anatomic stenosis across the mitral or tricuspid valves.
Continuous murmurs are heard when there is flow through the entire cardiac cycle and are abnormal with one common exception, the venous hum. A PDA is the most common abnormal continuous murmur. Continuous murmurs can also be heard with coarctation of the aorta when collateral vessels are present.
Normal physiologic or innocent murmurs are common, occurring in at least 80% of normal infants and children, heard most often during the first 6 months of life, from 3 to 6 years of age, and in early adolescence. They have also been called benign, functional, vibratory, and flow murmurs. Characteristic findings of innocent murmurs include the quality of the sound, lack of significant radiation, and significant alteration in the intensity of the murmur with positional changes (Table 139-5). Most important, the cardiovascular history and examination are otherwise normal. The presence of symptoms, including failure to thrive or dysmorphic features, should make one more cautious about diagnosing a normal murmur. Diastolic, holosystolic, late systolic, and continuous (except for the venous hum) murmurs and the presence of a thrill are not normal.