AMYL NITRITE INDUCED CHANGES IN CARDIAC SHUNTS

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Abstract
Hemodynamic changes following amyl nitrite inhalation have been assessed in patients with congenital heart disease by means of indicator dilution curves. All left-to-right shunts are diminished and most right-to-left shunts are increased by amyl nitrite. However, the greatest changes occur in patients with pulmonary stenosis. In some patients with pulmonary stenosis and ventricular septal defect with left-to-right shunts at rest, amyl nitrite causes a reversal of the shunt to one that is entirely right to left. In the patient with pulmonary stenosis and a ventricular septal defect with balanced ventricular pressures, and no demonstrable shunt by conventional techniques, a dye dilution curve after nitrite inhalation will show a right-to-left shunt and reveal the presence of the defect. Large increases in the magnitude of right-to-left shunts were only observed in the presence of pulmonary stenosis.