McConnell's sign is an echocardiographic finding characterized by regional right ventricular (RV) dysfunction with akinesia of the mid-free wall but preserved contractility of the apex. This pattern is highly specific for acute pulmonary embolism (PE).

In acute PE, sudden obstruction of the pulmonary artery leads to acute right ventricular pressure overload, causing regional wall motion abnormalities. The sparing of the apex differentiates it from other causes of RV dysfunction such as myocardial infarction.

This sign is considered a useful bedside clue in the echocardiographic diagnosis of PE, especially when combined with clinical findings and Doppler evidence of elevated pulmonary pressures.

The sign is described in the "Textbook of Clinical Echocardiography, 6e", Chapter on Acute Right Heart Dysfunction, with reference to McConnell's original description and its clinical significance in acute pulmonary embolism diagnosis【20:340-345†Textbook of Clinical Echocardiography】.