From the Guidelines
McConnell's sign is a specific heart movement pattern seen on an ultrasound of the heart that suggests a blood clot in the lungs, also known as pulmonary embolism, characterized by the base of the right ventricle not moving well, while the tip continues to contract normally. This unusual movement happens because the blood clot in the lungs creates high pressure that strains the right side of the heart, affecting how certain parts of the heart muscle function. In simple terms, it shows the right side of the heart not working properly, with the middle and outer parts of the heart wall moving differently. Doctors look for this sign during emergency evaluations when they suspect a patient might have a dangerous blood clot in their lungs, as it is considered fairly reliable evidence that a pulmonary embolism might be present and helps guide further testing and treatment decisions 1. Some key points to note about McConnell's sign include:
- It is characterized by normokinesia and/or hyperkinesia of the apical segment of the RV free wall despite hypokinesia and/or akinesia of the remaining parts of the RV free wall 1
- Concomitant echocardiographic signs of pressure overload are required to prevent false diagnosis of acute PE in patients with RV free wall hypo/akinesis due to RV infarction 1
- The sign has a high positive predictive value, especially in patients without known previous cardiorespiratory diseases 1
- It is not present in all cases of pulmonary embolism, but when observed, it is a significant indicator of the condition 1.
From the Research
Definition of McConnell's Sign
- McConnell's sign is a medical term that refers to a specific finding on an echocardiogram, which is an ultrasound test that uses sound waves to create images of the heart [ 2 ].
- In layman's terms, McConnell's sign is characterized by a condition where the right ventricular free wall of the heart is not moving properly, but the apex (or tip) of the heart is moving normally [ 2 ].
Association with Pulmonary Embolism
- McConnell's sign is often associated with pulmonary embolism (PE), which is a blockage of an artery in the lungs [ 3 ].
- However, studies have shown that McConnell's sign is not exclusive to PE and can be found in other conditions, such as pulmonary hypertension [ 2 ].
- The positive predictive value of McConnell's sign for diagnosing acute pulmonary embolism is relatively poor, ranging from 40% to 57% [ 3 ].
Other Conditions Associated with McConnell's Sign
- McConnell's sign can also be found in patients with chronic obstructive pulmonary disease (COPD) and systemic lupus erythematosus [ 2 ].
- Reverse McConnell's sign, which is a rare echocardiographic finding, has been associated with acute respiratory distress syndrome and septic shock [ 4 ].
- McConnell's sign can be an indicator of increased right ventricular afterload, rather than a specific diagnosis [ 4 ].
Clinical Significance
- McConnell's sign can be a useful tool in the diagnosis and management of acute pulmonary embolism, particularly when used in conjunction with other diagnostic tests [ 5 ].
- Echocardiographic parameters, such as pulmonary artery systolic pressure and tricuspid regurgitation, can help differentiate between patients with and without pulmonary embolism [ 6 ].