What is McConnell’s sign

McConnell’s sign is a classic echocardiographic finding described in acute pulmonary embolism (PE), characterized by a distinctive pattern of right ventricular (RV) regional wall motion abnormality.

Definition

McConnell’s sign refers to akinesia or severe hypokinesia of the mid-free wall of the right ventricle with preserved or hyperdynamic apical contraction on transthoracic echocardiography.

Historical Background

First described in 1996 by McConnell et al., the sign was proposed as a specific echocardiographic marker of acute massive pulmonary embolism, helping differentiate acute from chronic RV pressure overload.

Echocardiographic Description

The hallmark components include:

Marked hypokinesia or akinesia of the RV mid-free wall

Normal or hyperdynamic contraction of the RV apex (apical sparing)

Often accompanied by RV dilatation

Reduced tricuspid annular plane systolic excursion (TAPSE)

Elevated pulmonary artery pressures (may be underestimated early)

This peculiar pattern gives the appearance of a “tethered” or paradoxically preserved apex despite global RV dysfunction.

Pathophysiology

The exact mechanism is multifactorial and includes:

Sudden increase in RV afterload due to acute pulmonary arterial obstruction

Ischemia of the RV free wall caused by increased wall stress and reduced coronary perfusion

Mechanical tethering of the RV apex to a normally contracting left ventricle

Geometric distortion of the RV in acute pressure overload

Why the apex is spared remains debated, but ventricular interdependence plays a major role.

Clinical Significance

Suggests acute rather than chronic RV pressure overload

Supports the diagnosis of massive or submassive pulmonary embolism in unstable patients

Useful when CT pulmonary angiography is not immediately available or contraindicated

Associated with worse hemodynamics and higher short-term mortality

Sensitivity and Specificity

Original studies reported high specificity (~94%) but moderate sensitivity. Later data showed that:

Sensitivity is limited

Specificity is lower than initially believed

The sign is supportive but not diagnostic of acute PE

Therefore, McConnell’s sign should always be interpreted in clinical context.

Conditions Other Than Pulmonary Embolism

McConnell’s sign is not exclusive to PE and may be seen in:

Right ventricular myocardial infarction

Acute respiratory distress syndrome (ARDS)

Severe pulmonary hypertension (rarely)

Acute RV strain due to other causes

Hence, false positives can occur.

Differentiation from Chronic Pulmonary Hypertension

Acute PE:

Regional RV dysfunction with apical sparing

Relatively thin RV free wall

Sudden RV dilatation

Chronic pulmonary hypertension:

Global RV hypokinesia

RV hypertrophy

No apical sparing pattern

Associated Echocardiographic Findings in Acute PE

RV/LV ratio > 1

D-shaped left ventricle (septal flattening)

Elevated tricuspid regurgitation velocity

Dilated inferior vena cava with reduced collapse

Reduced RV strain on speckle-tracking echo

Role in Emergency and Critical Care

In hypotensive or shocked patients, bedside echocardiography showing McConnell’s sign can:

Rapidly raise suspicion of massive PE

Prompt immediate anticoagulation or thrombolysis (when appropriate)

Guide urgent decision-making before confirmatory imaging

Limitations

Operator dependent

Not pathognomonic

Can be missed in poor acoustic windows

Should not delay definitive imaging when patient is stable

Key Takeaway

McConnell’s sign is a classic but imperfect echocardiographic marker of acute pulmonary embolism, reflecting acute right ventricular pressure overload with regional wall motion abnormality. It is most valuable as a supportive bedside clue in critically ill patients and must always be integrated with clinical findings, ECG, biomarkers, and definitive imaging.

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