Case of the week #9
Circumferential pericardial effusion with early evidence of tamponade in patient with new diagnosis of JAK2+ myoproliferative syndrome
This patient’s presentation highlights the importance of early cardiac pocus imaging when a patient presents with significant tachycardia. This patient in 2:1 atrial flutter without any improvement in rate despite maximum diltiazem drip certainly warrants a focused cardiac ultrasound.
Starting in parasternal long axis, we see a circumferential pericardial effusion. We know it is a pericardial effusion (as opposed to pleural) because the anechoic fluid stays above the descending aorta (difficult to see in this image). You can see hypoechoic space between the liver and the RV as well as between the LV and posterior pericardium.
Anterior pericardial effusion
Posterior pericardial effusion
When considering if there is evidence of tamponade the size of the effusion is less relevant, as slowly accumulating effusion can become massive without signs of tamponade. At the same time, small effusions that occur quickly may compress the heart and cause tamponade.
To understand the early signs of tamponade, it is important to recap the basic pathophysiology of tamponade. Since the heart sits in a sac made of tough connective tissue, if fluid builds up inside the pericardium, it will move to the path of least resistance. Therefore the earliest sign that the heart is under stress will be the time and place with the lowest pressure, which is the right atrium during systole and the right ventricle during diastole.
Detect RV collapse with point of care ultrasound using M-mode
While a formal ultrasound can more accurately characterize cardiac pathology, it is often not available at 2am. Also not accessible to the clinician using pocus is realtime ekg tracing that corresponds to the echo images. Enter M-mode.
Placing M-mode across the anterior leaflet of the mitral valve and the RV free wall can help differentiate collapse during systole vs diastole.
Based on the anterior leaflet of the mitral valve motion, diastole occurs from when the mitral valve opens to when it closes, seen here on the tracing with label A (opening) and B (closing). And abnormal RV motion seen M-mode between these points would be diastolic collapse.
Each layer corresponds to a different portion of the heart. First we look at the mitral valve excursion to define diastole (A and B), then we look at the RV wall portion (white arrow) to see if it collapses during diastole as seen here. Via.
The specificity of RV collapse in tamponade has been reported at between 72-100%, and anywhere from 48% to 100% sensitive. Right atrial collapse is also reported variably. These are difficult to measure since it depends on the severity of the tamponade when the study is done.
If IVC is 2cm or greater with minimal respiratory variation, this is highly sensitive for tamponade (97%), so can be very helpful to rule out tamponade. In the clip below, you can see the right atrium beating quickly and the IVC dumping its blood into the right atrium. If the pressure in the right atrium and right ventricle is high due to compression from pericardial effusion, the blood in the IVC will not be able to flow forward, and will dilate the IVC. Of note, in this image the IVC slides in and out of view which gives the appearance it is varying but in fact it remains plethoric with inspiration and expiration.
Don't forget your physical exam
Surprisingly, pulsus paradoxus has pretty good accuracy to detect tamponade. If greater than 10, one review article with the pooled sensitivities of multiple studis is about 82%. Diminished heart sounds, on the other hand, is only 28% sensitive. If you forget how to perform a pulsus paradoxus, watch this video.
With this knowledge in hand, M-mode was placed on the anterior leaflet of the mitral valve and the free RV wall and there was evidence of RV diastolic collapse. Cardiology was urgently consulted and a formal limited echo was performed to confirm the findings and he was urgently taken to the cath lab for pericardiocentesis.
After the procedure his heart rate returned to normal in 24 hours and he was started on chemotherapy with much improvement in his symptoms.
For more on cardiac ultrasound, go here.