McConnell sign in Pulmonary Embolism: Mechanism

McConnell sign in Pulmonary Embolism: Mechanism

McConnell sign is hypokinesia of right ventricular free wall noted on echocardiography with sparing of the apex, seen in acute pulmonary embolism [1].

Three mechanisms proposed for the McConnell sign are [2]:

1. Tethering of the right ventricular apex to the left ventricle which is hyperdynamic
2. Abrupt increase in afterload causing the right ventricle to assume a more spherical shape to equalize regional wall stress
3. Localized ischemia of right ventricular free wall due to elevated wall stress

Echocardiography has low sensitivity for the diagnosis of pulmonary embolism. But accuracy is higher for the diagnosis of massive pulmonary embolism, especially when decision regarding early thrombolysis has to be taken at the bedside. Of course, the gold standard now for the diagnosis of pulmonary embolism is computed tomographic pulmonary angiography. But since it is not available at the bedside, it may be difficult to obtain in person who is very sick and hypotensive due to massive pulmonary embolism. In such situations, if McConnell sign is present, it may add more value for the presumptive diagnosis of pulmonary embolism prior to thrombolytic therapy which has potential bleeding risks.

Though McConnell sign is useful in the bedside diagnosis of pulmonary embolism, it is not pathognomonic. It can occur in right ventricular infarction as well. A study compared 107 cases with pulmonary embolism (group 1) and 54 cases with right ventricular infarction (group 2). McConnell sign was noted in 70% group 1 and 67% in group 2 [3]. The sign was absent in 32 cases of pulmonary embolism and 18 cases of right ventricular infarction. Though the sensitivity was 70%, the specificity was only 33% in this study.

Reverse McConnell Sign

A “Reverse McConnell’s Sign” has been described in Takotsubo cardiomyopathy [4]. Basilar and middle segments of the right ventricular free fall were hyperkinetic and apex hypokinetic in the same manner as in the left ventricle. This discordant motion opposite to that of McConnell’s sign in pulmonary embolism has been called “reverse McConnell” phenomenon. It is associated with worse right ventricular failure symptoms in Takotsubo cardiomyopathy. Authors mentioned that this phenomenon may also be found in some patients with severe and acute cardiogenic shock without Takotsubo cardiomyopathy.

References

1. McConnell MV, Solomon SD, Rayan ME, Come PC, Goldhaber SZ, Lee RT. Regional right ventricular dysfunction detected by echocardiography in acute pulmonary embolism. Am J Cardiol. 1996; 78: 469-473.
2. Sosland RP, Gupta K. Images in cardiovascular medicine: McConnell’s Sign. Circulation. 2008 Oct 7;118(15):e517-8.
3. Casazza F, Bongarzoni A, Capozi A, Agostoni O. Regional right ventricular dysfunction in acute pulmonary embolism and right ventricular infarction. Eur J Echocardiogr. 2005 Jan;6(1):11-4.
4. Liu K, Sun Z, Wei T. “Reverse McConnell’s Sign”: Interpreting Interventricular Hemodynamic Dependency and Guiding the Management of Acute Heart Failure during Takotsubo Cardiomyopathy. Clin Med Insights Cardiol. 2015 Mar 23;9(Suppl 1):33-40.