McConnell’s Sign Still Holds Its Value: A Lesson Learned from Two Cases

Acute pulmonary embolism (PE) can be potentially fatal if not diagnosed and treated early. Mortality in untreated cases can be as high as 30%. Atypical presentation and submassive PE can be missed due to subtle clinical features. Computerized tomography pulmonary angiogram is expensive, exposes to radiation and carries the risk of contrast nephropathy or anaphylactic reactions. On the contrary, McConnell's sign, which is a highly specific sign of PE, can be demonstrated at the bedside with a transthoracic echocardiogram (TTE). Here we discuss two cases where bedside TTE demonstrating McConnell's sign helped in the diagnosis and treatment of PE.


Introduction
The diagnosis of submassive to massive pulmonary embolism (PE) is critical to prevent mortality. In an emergent situation, computerized tomography (CT) pulmonary angiogram is the diagnostic modality of choice. In conditions like renal impairment or contrast allergy, the test cannot be performed. Ventilation-perfusion scan results may not be readily available. In pregnant patients with low pretest probability, these tests are not recommended. McConnell's sign is a regional right ventricular (RV) wall motion abnormality with hypokinesia of mid and basal walls sparing the RV apex [1]. A meta-analysis of the use of transthoracic echocardiogram (TTE) in diagnosing PE showed the sensitivity of McConnell's sign to be only 22% but high specificity of 97% [2]. In questionable cases, an inexpensive test like bedside echocardiogram demonstrating McConnell's sign can guide further investigations and treatment.

Case I
A 48-year-old man was brought to the emergency department (ED) for syncope. He also complained of shortness of breath on exertion for three days. On examination, he had tachycardia 177/min, tachypnea 24/min, normal blood pressure and oxygen saturation. Distended neck veins were noted on examination. The electrocardiogram (ECG) showed atrial fibrillation with a rapid ventricular response of 174/min ( Figure 1). D-dimer was equivocal. The Pulmonary Embolism Rule-out Criteria (PERC) rule score was 1 (cannot rule out PE) and the Wells score was 1.5 (low-risk group; 1.3% of PE). Even though the Wells score was low, CT pulmonary angiogram was planned because of McConnell's sign on echocardiography. CT pulmonary angiogram was suggestive of a saddle pulmonary embolus within the main pulmonary artery ( Figure 2) extending into the right and left pulmonary arteries ( Figure 3). There was near-complete occlusion of the right and left secondary branches of pulmonary arteries.

Case II
An 80-year-old woman was evaluated in ED for syncope that occurred while she was trying to stand up from sitting position. She denied chest pain, palpitation, headache, convulsion or incontinence. Her medical history was suggestive of hypertension, diabetes mellitus type 2, asthma and obesity grade 3. On examination, she had tachycardia 140/min, tachypnea 22/min and a normal blood pressure of 134/78 mmHg. Physical examination showed mildly tender and swollen left leg compared to the right. Duplex ultrasound of bilateral lower extremities showed acute deep vein thrombosis in common femoral vein, bilateral femoral and popliteal veins.
Laboratory investigations were significant for elevated creatinine of 2.4 mg/dl (patient's baseline creatinine 1.1 mg/dl) and elevated troponin I 0.92 ng/ml. ECG was suggestive of sinus tachycardia with a new-onset right bundle branch block ( Figure 6). The patient was advised urgent coronary angiogram but she refused and declined any other invasive intervention. The Wells score was 7.5 (high-risk group; 40.6% chance of PE), the PERC rule score was 3 (cannot rule out PE). CT pulmonary angiogram was deferred in lieu of the elevated creatinine. Instead, a bedside TTE was done. It showed normal ejection fraction (EF > 55%), mildly dilated RV with reduced RVEF, elevated RV systolic pressure (>60 mmHg) and moderate tricuspid regurgitation. Hyperkinesis of the RV apex and hypokinesis of the RV free wall were also noted (McConnell's sign) (Video 2).

VIDEO 2: Video showing hyperkinesis of right ventricular apex and hypokinesis of the right ventricular free wall (McConnell sign)
View video here: https://youtu.be/jJSSaoeMcxc With a high suspicion of PE and McConnell's sign on echocardiogram, she was started on heparin infusion and later shifted to oral anticoagulation. After a week, the patient was stable to be discharged. Repeat ECG before discharge was normal (Figure 7). McConnell's sign along with the high Wells score justified starting and continuing anticoagulation to complete six months of therapy.

Discussion
The above-mentioned cases demonstrate the importance of McConnell's sign in PE. In normotensive patients, like the above two cases, TTE is not recommended for diagnosis but can be used for risk stratification [3]. In the situation where CT pulmonary angiogram is not feasible, a demonstration of RV dysfunction can justify the need for thrombolysis. Demonstrating McConnell's sign [1] can strongly suggest PE even if the clinical findings are non-specific.
McConnell et al. [1] in their original study found this distinct pattern of RV dysfunction at midfree wall vs normal to be highly specific for acute PE (p = 0.0001). The study showed the positive predictive value of 77% and the negative predictive value of 96%. Over time, other studies have validated the results and came to a similar conclusion.
Bedside TTE is not just limited to the McConnell sign in PE. There are studies showing the importance of quantitative parameters of RV function, such as tricuspid annular plane systolic excursion, RV/left ventricular ratio and RV global and free wall longitudinal strain [4] in diagnosing PE. A study by Kearon et al. [5] showed that about 50% of diagnosed PEs are associated with RV dysfunction, which is associated with approximately fivefold greater inhospital mortality.