James Day BA, RDCS
The left ventricle (LV) usually receives the most attention regarding point-of-care ultrasound (POCUS). With that being the case, let’s take a moment to focus on the right ventricle (RV).
The Anatomy:
The RV can be anatomically divided into an inflow area, an outflow area, and the apex area. Contraction of the right heart occurs longitudinally, while circumferential and radial thickening is less important than in the left ventricle. The right ventricular free wall is the source of RV contractile power.
A normal RV is two-thirds the size of the left ventricle, as measured in diastole. Think of the RV as a sort of sail attached to the LV. Near the apex is a band of muscles known as the Moderator band, which can be mistaken for a thrombus. The Moderator band is a prominent trabeculation of the RV extending from the base of the anterior papillary muscle to the interventricular septum. The Moderator band is present in most normal adults, but there are tremendous individual variations, such as the thickness and shape in the patient population.
The right ventricular free wall (RVFW) is best evaluated in a subcostal view to assess for thickening or collapsing as a patient approaches tamponade. The interventricular septum (IVS) makes up the opposite wall where it is ‘shared’ with the LV and RV. One can note the classic “D” sign in a SAX. As the RV is overloaded one will see septal flattening.
3 Common Right Heart Pathologies and the Associated Sonographic Findings:
In addition, there are three precipitants to the three common right heart pathologies:
1. Pressure overload
2. Volume overload
3. Ischemia
4. Or a combination of all three
Right Heart Pathologies:
Right Ventricular Myocardial Infarction
The regional wall motion of the RV must be examined within a four-chamber view as well as apical views because these demonstrate the anterior and posterior walls. Generally, most right ventricular infarctions are in the posterior wall. Right ventricular infarction occurs in 30-50% of patients with inferior myocardial infarction. Fortunately, the right ventricular function returns to normal in most cases. Patients with a dilated right ventricle and inferior infarctions should be suspected of having RV infarction. The presence of tricuspid regurgitation (as a plausible reason for RV dilatation) could be part of the right heart dilatation because TR could be a secondary phenomenon.
Sonographic findings of pericardial tamponade on ultrasound include large anechoic pericardial effusion. Systolic right atrial collapse will be the earliest sign.
Diastolic right ventricular collapse is a very specific sign. The RV free wall will be seen collapsing and appearing to touch or “wobble” along the length of the inferior vena cava (IVC).
POCUS can help guide the diagnosis of pulmonary embolism(PE). Sonographic findings include:
- Visualization of a right heart thrombus
- RV dilatation
- Acute Cor pulmonale
- McConnell sign (The most definitive sonographic finding)
The McConnell Sign
The McConnell sign is found in patients with acute PE. It’s an echocardiographic finding, creating a regional pattern of right ventricular dysfunction. The apex of the RV gives off the appearance of a flailing sail constantly bouncing while all other portions of the RV are still. Other causes of acute right ventricular strain are likely to produce a similar pattern, but to date, this has not been extensively studied.
McConnell’s sign has long been established as an echocardiographic sign with high specificity for acute PE. A recent meta-analysis in patients with suspected PE confirmed that McConnell’s sign had a sensitivity of 22% and a specificity of 97% for the detection of acute Pulmonary embolism.
Overall, echocardiography has a low sensitivity for diagnosing PE; however, the accuracy is much higher in the diagnosis of massive PE. POCUS may be useful in cases of massive PE where a speedy diagnosis is required before the use of thrombolytics. Regional wall motion abnormalities sparing the right ventricular apex (McConnell’s sign) are particularly suggestive of PE.
Who is Dr. McConnell?
Dr. McConnell is a native of Brooklyn, NY, and attended MIT, obtaining his BS and MS in Electrical Engineering/Biomedical Engineering, followed by his MD at Stanford University. He returned to Boston and specialized in Cardiovascular Medicine and Cardiovascular Imaging at Brigham and Women’s and Beth Israel Hospitals and then joined the faculty at Harvard Medical School, where he also obtained a MS in Clinical Investigation. His early research discovery in echocardiography has become known as “McConnell’s sign.” He joined the faculty at Stanford in 1998 and went on to become their Professor of Medicine and Electrical Engineering and Molecular & Cellular Physiology. He has published over 130 peer-reviewed articles.
