Right heart strain
Right heart strain is a medical finding of right ventricular dysfunction where the heart muscle of the right ventricle is deformed. Right heart strain can be caused by pulmonary hypertension, pulmonary embolism, RV infarction, chronic lung disease, pulmonic stenosis, bronchospasm, and pneumothorax.
When using an echocardiograph to visualize the heart, 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. When strained, it can be as large as or larger than the LV. An important potential finding with echo is McConnell's sign, where only the RV apex wall contracts; it is specific for right heart strain and typically indicates a large PE.
On an electrocardiogram, there are multiple ways RV strain can be demonstrated. A finding of S1Q3T3 is an insensitive sign of right heart strain. It is non-specific and is present in a minority of PE cases. It can also result from acute changes associated with bronchospasm and pneumothorax. Other EKG signs include a right bundle branch block 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." Aside from echo and ECG, RV strain is visible with a CT scan of the chest and via cardiac magnetic resonance.
