The clinical presentation varies from the blowing, holosystolic murmur of variable intensity in an asymptomatic patient, to a similar murmur in a patient with signs of heart failure, to essentially no murmur with a loud pulmonary closure sound in a cyanotic patient. The ECG is useful in evaluating ventricular volume overload and hypertrophy. The CXR is useful in evaluating heart size and pulmonary blood flow . An echocardiogram helps to evaluate defect size and location. Right ventricular pressure and the magnitude of the shunt can be determined also.
Cardiac catheterization is the best method for evaluating pulmonary vascular resistance.
The size of the shunt controls flow. Right ventricular pressures and pulmonary vascular resistance are low. The patient should be asymptomatic, ECG and CXR are normal. These defects do not require therapy. The amount of shunting is greater than with a small defect but the defect size still offers some restriction to shunt flow.