Peripheral pulmonary artery murmur of atrial septal defect.

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Abstract
Left-to-right shunts at atrial level are typically associated with intracardiac systolic murmurs that originate at the pulmonary orifice. The notion that additional systolic murmurs may originate in the peripheral pulmonary arteries of subjects with uncomplicated atrial septal defects has not been entertained so far. The purpose of this report is to call attention to "peripheral pulmonary artery murmurs" in 6 patients in whom left-to-right interatrial shunts were the sole hemodynamic faults. A number of points support the argument that such murmurs exist the precordial bruits were of insufficient intensity to justify distributions to right chest, axillae, and back on the basis of transmission alone; in the majority of instances, transmission appeared to be an unlikely mechanism, because the peripheral murmurs occurred with little or no attenuation when compared to precordial amplitudes; systolic murmurs resembling atrial septal defect bruits, both in location and intensity, typically occurred without thoracic radiation; the onset of the peripheral murmurs tended to follow the onset of the precordial murmurs at slight but discrete intervals, a temporal sequence in accord with peripheral origin; operation resulted in obliteration of the peripheral murmurs despite retention of soft praecordial bruits. The occurrence of peripheral pulmonary artery murmurs in uncomplicated atrial septal defects is understandable in view of the increased velocity of pulmonary blood flow characteristic of this malformation. In subjects with left-to-right shunts at either aortopulmonary or interventricular levels, flow rates through the lungs are less rapid than flow rates with interatrial shunts, but should peripheral systolic murmurs nevertheless occur, they are apt to be overshadowed by transmission of the loud precordial bruits. In patients with atrial septal defects, it may be difficult to distinguish peripheral murmurs, due to flow alone from those due to coexisting pulmonary branch stenosis. However, observations described support the idea that peripheral pulmonary artery murmurs can occur in uncomplicated large shunt atrial septal defects with hyperkinetic pulmonary flow. In addition, observations also serve to re-emphasize the importance of careful thoracic auscultation at non-precordial sites.