Continuous murmur in machinery (Gibson murmur)

Specialty: Cardiovascular.

• continuous murmur of ductus arteriosus
• audible Gibson murmur
• continuous systodiastolic murmur

Why it occurs

• Uncorrected patent ductus arteriosus (PCA)
• Coronary arteriovenous fistula
• Rupture of aneurysm of the sinus of Valsalva in the right atrium or ventricle
• Small aortopulmonary window
• Congenital or acquired systemic or pulmonary arteriovenous fistula

Initial workup

Color Doppler transthoracic echocardiogram to visualize the duct or fistula, evaluate the direction of high-velocity flow (systodiastolic), measure the diameters of the aorta and pulmonary artery and quantify the volume overload of the left ventricle (dilation of the left atrium and ventricle) and estimate the pulmonary artery pressure; Chest x-ray to evaluate prominent pulmonary arch and pulmonary hyperflow; Cardiac catheterization if direct measurement of pulmonary vascular resistance is necessary prior to percutaneous or surgical correction.

Standard management

• Indomethacin — prostaglandin synthesis inhibitor specifically indicated for the pharmacological closure of patent ductus arteriosus in premature newborns; 0.2 mg/kg intravenously followed by doses adjusted according to neonatology and renal function protocol
• Intravenous ibuprofen — alternative in neonates for pharmacological closure of PCA with less nephrotoxicity; 10 mg/kg initial dose, followed by two doses of 5 mg/kg every 24 hours
• Furosemide — diuretic indicated for the control of pulmonary congestive symptoms while surgical or percutaneous closure is planned; 1 mg/kg intravenously in pediatrics or 20 to 40 mg orally in adults
• Enalapril (ACEI to reduce systemic afterload in adults with left ventricular overload due to large-volume PCA; 2.5 to 5 mg once daily orally).