M-mode echocardiography in cardiac tamponade

The M-mode sweep in panel A is from the left ventricular (LV) cavity to the aortic root (Ao) in a patient with a large pericardial effusion (EFF) and cardiac tamponade. Right ventricular (RV) narrowing is seen in the minor axis; only minimal cavitary expansion occurs with inspiration (IN), although it becomes more marked toward the right ventricular outflow tract (RVOT). With inspiration there is a reduction in the dimension of the LV cavity, seen by the more posterior position of the interventricular septum (IVS) (black arrow); there is also a reduction in the E to F slope of mitral valve (MV) movement during inspiration, a result of reduced volume and flow from left atrium to ventricle (red arrows). After pericardiotomy (panel B), the pericardial effusion has disappeared, the RV is decompressed, and there are no changes in LV or RV volume with respiration. Note that the M-mode sweep after pericardiectomy goes from Ao to LV cavity.