When using an echocardiograph (echo) to visualize the heart,[a] strain can appear with the RV being enlarged and more round than typical. When normal, the RV is about half the size of the left ventricle (LV). When strained, it can be as large as or larger than the LV.[5] An important potential finding with echo is McConnell's sign, where only the RV apex wall contracts;[7] it is specific for right heart strain and typically indicates a large PE.[8]
On an electrocardiogram (ECG), there are multiple ways RV strain can be demonstrated. A finding of S1Q3T3[b] is an insensitive[10] sign of right heart strain.[11] It is non-specific (as it does not indicate a cause) and is present in a minority of PE cases.[12] It can also result from acute changes associated with bronchospasm and pneumothorax.[6] Other EKG signs include a right bundle branch block[13] as well as T wave inversions in the anterior leads, which are "thought to be the consequence of an ischemic phenomenon due to low cardiac output in the context of RV dilation and strain."[13] Aside from echo and ECG, RV strain is visible with a CT scan of the chest and via cardiac magnetic resonance.[14]
^The apical-four-chamber (A4C) view is best to visualize right heart strain by echo.[5]
^Indicative of a prominent S wave in lead I, a Q wave in lead III, and an inverted T wave in lead III,[9] which is also known as the McGinn–White sign[6]
^Walsh, Brooks M.; Moore, Christopher L. (2015-09-01). "McConnell's Sign Is Not Specific for Pulmonary Embolism: Case Report and Review of the Literature". The Journal of Emergency Medicine. 49 (3): 301–304. doi:10.1016/j.jemermed.2014.12.089. PMID25986329.