Author: Dr. Vanessa Petrak
Background
- Cardiac tamponade occurs when fluid accumulates in the pericardial space that impairs the filling of the right sided chambers which eventually leads to decreased cardiac output and hemodynamic compromise. This is a CANNOT MISS diagnosis and should always be on our mind when a patient walks in complaining of chest pain and/or shortness of breath. There are multiple causes of cardiac tamponade, however most cases are idiopathic. Other possible causes include, but are not limited to:
- Blunt trauma rupture of the right atrium or right atrial appendage blood filling the pericardial sac
- Deceleration injuries cardiac or pericardial rupture, herniation, or a myocardial contusion intrapericardial hemorrhage
- Blast injuries
- Malignancy
- Acute infection (viral, bacterial, mycoplasma, fungal, parasitic, or endocarditis)
- Radiation exposure
- Chronic conditions: Tb, renal failure, autoimmune disease drugs that induce a lupus-like syndrome, hypothyroidism, or ovarian hyperstimulation syndrome.
Pathophysiology
- The pericardium is a fibro-collagenous sac that covers the heart like a cozy blanket and has a small amount (<50mL) of physiologic lubricating serous fluid. Consider it a very stretchy blanket, as it is able to expand due to its elastic properties in response to increased intrapericardial fluid. In the setting of too much fluid accumulation that exceeds this stretch capacity of the pericardium, it can lead to pericardial tamponade and hemodynamic instability. A moderate pericardial effusion is when there is 100-500mL in the pericardial sac and a large (scary) pericardial effusion is when there is > 500mL of fluid in the pericardial sac.
Presentation
- The classic board question when thinking of cardiac tamponade is going to center around Beck’s Triad which is the trio of hypotension, jugular vein distension, and muffled heart sounds. Your patient is typically going to walk into the ED complaining of chest pain and shortness of breath. Other symptoms may include nausea, esophageal pain, or abdominal pain from hepatic and visceral congestion. Nonspecific symptoms that many of our patients will also have include fever, lethargy, weakness, anorexia, and palpitations. One of the key physical exam findings that often shows up on board exams is Pulsus Paradoxus which is defined as an abnormal decrease in systolic blood pressure (more than 10mmHg) which results in cardiac contraction that does not result in a normal pulse. This causes a paradoxical pulse.
- The sensitivity of exam findings for cardiac tamponade are pulses paradoxus is 82%, tachycardia is 77%, JVD is 76%, diminished heart sounds is 28% and hypotension 26%.
- If your patient has Becks triad AND pulses paradoxus, grab that bedside ultrasound and evaluate for cardiac tamponade!
Diagnostic Evaluation
- Ultrasound is going to be your best friend in diagnosing cardiac tamponade. What are you looking for on beside ultrasound?
- Pericardial effusion
- Right sided chamber collapse
- Plethoric IVC
- EKG may show electrical alternans which is alternating high and low amplitude QRS complexes as the heart swings toward and then away from the EKG leads on the chest wall with each contraction.
Treatment
- Emergency pericardiocentesis is indicated when there is hemodynamic instability in the setting of cardiac tamponade. Contraindications for pericardiocentesis includes aortic dissection. Relative contraindications include uncorrected coagulopathy, anticoagulant therapy, thrombocytopenia, and small posterior loculated effusions.
Let’s summarize with an amazing infographic created by Dr. Walid Malki, PGY2
Sources:
- Tintinalli’s Emergency Medicine: A comprehensive Study Guide, 9th edition. Tintinalli, Ma, Yealy, Meckler, Stapczynski, Cline, and Thomas. Chapter 34, Pages 223-229
- http://www.emdocs.net/us-probe-when-does-an-effusion-become-pericardial-tamponade/
- Infographic by Dr. Walid Malki