From the Guidelines
A Cabot-Locke murmur is a continuous murmur heard in patients with patent ductus arteriosus (PDA), characterized by a continuous sound throughout systole and diastole, typically best heard at the left upper sternal border [ 1 ]. This murmur is a result of the abnormal communication between the aorta and pulmonary artery, leading to continuous blood flow from the higher-pressure aorta to the lower-pressure pulmonary artery. The clinical and physiological manifestations of PDA, including the Cabot-Locke murmur, depend on the size of the vessel and the relative systemic and pulmonary vascular resistances [ 1 ].
Key Characteristics of Cabot-Locke Murmur
- Continuous sound throughout systole and diastole
- Typically best heard at the left upper sternal border
- Result of abnormal communication between the aorta and pulmonary artery
- Clinical and physiological manifestations depend on the size of the vessel and relative systemic and pulmonary vascular resistances
Management of PDA with Cabot-Locke Murmur
The management of PDA with a Cabot-Locke murmur depends on the symptoms and physiological expression of the lesion. According to the 2018 AHA/ACC guideline for the management of adults with congenital heart disease, PDA should be closed in patients with signs of left ventricular volume overload or pulmonary arterial hypertension with a pulmonary artery pressure less than two-thirds of systemic pressure or pulmonary vascular resistance less than two-thirds of systemic vascular resistance [ 1 ]. Device closure is the method of choice where technically suitable [ 1 ].
Recommendations for Intervention
- PDA should be closed in patients with signs of left ventricular volume overload or pulmonary arterial hypertension with a pulmonary artery pressure less than two-thirds of systemic pressure or pulmonary vascular resistance less than two-thirds of systemic vascular resistance [ 1 ]
- Device closure is the method of choice where technically suitable [ 1 ]
- PDA closure should be considered in patients with pulmonary arterial hypertension and a pulmonary artery pressure greater than two-thirds of systemic pressure or pulmonary vascular resistance greater than two-thirds of systemic vascular resistance but still a net left-to-right shunt [ 1 ]
From the Research
Definition and Characteristics
- A Cabot-Locke murmur, also known as a Continuous Murmur of Patent Ductus Arteriosus, is associated with patent ductus arteriosus (PDA), a congenital heart defect where the ductus arteriosus fails to close after birth 2, 3, 4, 5, 6.
- This murmur is continuous, meaning it occurs throughout the cardiac cycle, and is typically heard at the left upper sternal border 5, 6.
Clinical Significance
- The presence of a Cabot-Locke murmur can indicate a significant left-to-right shunt through the PDA, which can lead to heart failure, pulmonary hypertension, and other complications 2, 3, 4.
- Clinical signs of PDA include murmur, tachycardia, bounding peripheral pulses, and congestive heart failure, although symptoms may not always be present 2.
Diagnosis and Treatment
- Diagnostic imaging, such as echocardiography and cardiac catheterization, is critical for confirming the diagnosis of PDA and assessing its severity 2, 5.
- Treatment options for PDA include medical intervention, surgical ligation, and transcatheter closure, with the choice of treatment depending on the size and severity of the PDA, as well as the patient's age and overall health 2, 3, 4, 5.