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Emergency Ultrasound

Cases That Count (Cardiac Tamponade)

Marsia Vermeulen, DO, Di Coneybeare, MD & Meghan Herbst, MD

Questions:
1. What key features are shown in the ultrasound clips to suggest cardiac tamponade?
2. What additional sonographic findings would be consistent with tamponade physiology?
3. How can ultrasound help guide the treatment of cardiac tamponade?

Case 1:
A 52-year-old male with history of hepatitis C, hypertension, diabetes and polysubstance abuse (alcohol and cocaine) presented with altered mental status. On arrival, the patient was febrile, tachycardic, and hypotensive. He was intubated for airway protection, given broad-spectrum antibiotics, placed on vasopressors and transferred to the medical ICU.

In the ICU, the patient remained in critical condition with septic shock, intubated on double pressors. Diagnostic testing revealed MRSA bacteremia, bacterial meningitis and septic intracranial infarcts secondary to presumed endocarditis. On hospital day 5, the patient acutely decompensated and required significantly more vasopressor support over a two-hour period. A point-of-care ultrasound for hypotension was performed by an emergency physician, which revealed a new pericardial effusion with tamponade physiology.

Cardiology was consulted and pericardiocentesis was performed at bedside with placement of a pericardial drain. Initial drainage produced 70cc of bloody fluid with immediate improvement in hemodynamics.

Case 2:
A 37-year-old male with no significant past medical history presented with increasing chest pain for the past month associated with increasing exertional dyspnea, intermittent fevers (Tmax 102), night sweats and reflux. The patient travels frequently for work and has been experiencing diarrhea for the last several months. Within the past 3 months, he has been to Mexico, Canada and Scotland. Patient additionally endorsed unintentional weight loss of 20lbs over the last 2 months.

Initial vital signs were significant for fever and tachycardia, but the patient remained normotensive. Patient’s bedside echo in the ED showed pericardial effusion consistent with early tamponade physiology. He was given 2L NS bolus and admitted to the ICU for further care. A repeat echo in the ICU showed agreement with bedside echo and a pericardiocentesis was performed with drainage of 500cc of fluid.

Role of emergency physicians in assessment of cardiac tamponade:
Point-of-care ultrasonography has become an integral tool for emergency physicians to assess patients in extremis, particularly when classic physical exam findings such as Beck’s triad of elevation in JVD, muffled heart sounds and hypotension are rarely present.1-3 Point-of-care echocardiography for the evaluation of pericardial effusion is well within the scope of practice for emergency physicians and supported by the American College of Emergency Physicians and American Society of Echocardiography.1,3 Emergency physicians detect pericardial effusions on bedside ultrasound with a sensitivity of 96%, specificity of 98%, and overall accuracy of 97.5%.4 Furthermore, emergency physicians identify tamponade physiology in the evaluation of the hypotensive patient with high sensitivity and negative predictive value.5

Answers to questions:

1. What key features in the ultrasound clips suggest cardiac tamponade?

The clips (Clip 1 & Clip 2) show a subcostal view and an apical-four-chamber view of the heart surrounded by moderate pericardial effusion. The right atrium and ventricle are moving in a serpentine like pattern with collapse of the right ventricle in early diastole supporting tamponade physiology. 

2. What additional sonographic findings would be consistent with tamponade physiology?

Increased pressure in the pericardial sac from accumulation of fluid deters the lower pressure system of the heart to fill during diastole causing right atrial and ventricular collapse. The earliest and most sensitive sign of cardiac tamponade is right atrial collapse.6 Right ventricular collapse is very specific for tamponade physiology, but less sensitive.3 A plethoric IVC with no respiratory variation can also be found in tamponade though this is non-specific and can occur in other conditions with elevated right heart pressure. Importantly, if a patient has chronic pulmonary hypertension with chronically elevated right heart pressures, right atrial or ventricular collapse may be very late manifestations.3

To differentiate between diastolic collapse and systole, view the heart in a parasternal long view using M mode with the axis through both the right ventricular free wall and the mitral valve.3,7,8 In tamponade, the right ventricular free wall paradoxically moves inwards toward the septum as the mitral valve opens.

Sonographic pulsus paradoxus can be documented in the apical-four chamber view with pulsed-wave Doppler. Paradoxical decrease in velocity of blood flow through the mitral valve greater than 25% during inspiration will be seen in tamponade physiology.7 There is great variability in the degree of velocity change with respiration in tricuspid, pulmonic, and aortic valves.3,6-8 

3. How can ultrasound help guide the treatment of cardiac tamponade? 

Pericardiocentesis has been performed to relieve tamponade since the 18th century, but without visualization of the effusion, blind pericardiocentesis has historically had an unacceptable rate of morbidity of up to 50% and mortality of 6%.9 Since the advent of ultrasound in the 1970s, ultrasound-guided pericardiocentesis has become the standard-of-care, significantly reducing the complication rate to 4.7% and increasing its success rate to 97%.9-10

A recommended approach is to locate the largest accumulation of fluid closest to the skin with no intervening vital organs as an ideal puncture site (usually the left chest wall).10 Then, use a low frequency convex probe to visualize the needle in-plane as it approaches the pericardial fluid.11

 

References:   

  1. Labovitz AJ, Noble VE, Bierig M, et al. Focused cardiac ultrasound in the emergent setting: a consensus statement of the American Society of Echocardiography and American College of Emergency Physicians. J Am Soc Echocardiogr. 2010;23(12):1225-30.
  2. Tang A, Euerle B. Emergency department ultrasound and echocardiography. Emerg Med Clin North Am. 2005;23(4):1179-94.
  3. Weekes AJ, Quirke DP, Emergency echocardiography. Emerg Med Clin North Am. 2011;29(4):759-87.
  4. Mandavia DP, Hoffner RJ, Mahaney K, et al. Bedside echocardiography by Emergency Physicians. Ann Emerg Med. 2001;38(4):377-82.
  5. Ghane MR, Gharib M, Ebrahimi A, et al. Accuracy of early rapid ultrasound in shock (RUSH) examination performed by emergency physician for diagnosis of shock etiology in critically ill patients. J Emerg Trauma Shock. 2015;8(1):5-10.
  6. Materazzo C, Piotti P, Meazza R, et al. Respiratory changes in transvalvular flow velocities versus two-dimensional echocardiographic findings in the diagnosis of cardiac tamponade. Ital Heart J. 2003;4(3):186-92.
  7. Chandraratna PA, Mohar DS, Sidarous PF. Role of echocardiography in the treatment of cardiac tamponade. Echocardiography. 2014;31(7):899-910.
  8. Perera P, Lobo V, Williams SR, et al. Cardiac echocardiography. Crit Care Clin. 2014;30(1):47-92.
  9. Tsang TS, Freeman WK, Sinak LJ, et al. Echocardiographically guided pericardiocentesis: evolution and state-of-the-art technique. Mayo Clin Proc. 1998;73(7):647-52.
  10. Tsang TS, Enriquez-Sarano M, Freeman WK, et al. Consecutive 1127 therapeutic echocardiographically guided pericardiocenteses: clinical profile, practice patterns, and outcomes spanning 21 years. Mayo Clin Proc. 2002;77(5):429-36.
  11. Nagdev A, Mantuani D. A novel in-plane technique for ultrasound-guided pericardiocentesis. Am J Emerg Med. 2013;31(9):1424.e5-9.11. 



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