Cardiac tamponade is a condition in which there is life threatening compression of the heart as a result of external pressure from the presence of fluid, gas, pus, clots, or blood in the pericardial space.
Cardiac output in tamponade decreases as a result of decreased venous return as well as from compression of the right ventricle into the left ventricle on inspiration. This then causes decreased filling of the LV and therefore decreased stroke volume. As we recall, CO = SV x HR where CO is cardiac output, SV is stroke volume, and HR is heart rate. This causes the classic finding of pulsus paradoxus which is a decrease in SBP > 10 mmHg on inspiration.
True diagnosis of cardiac tamponade can only be made by assessing patient’s improvement after pericardiocentesis. In one study involving 29 postoperative cardiothoracic surgical patients with confirmed cardiac tamponade, the following clinical features were noted:
|Finding||% Patients with Tamponade|
|Right atrial collapse||34%|
|Right ventricular diastolic collapse||27%|
|Left ventricular diastolic collapse||65%|
|Left atrial collapse||13%|
Note that only 24% patients were hypotensive and only 27% had RV collapse.
Treatment of tamponade involved decompression of the pericardial sac via pericardiocentesis or pericardial window. The first emergent blind “needle” pericardiocentesis was performed by Franz Schuh in Vienna in 1840 in a 24-year-old woman with symptoms consistent with cardiac tamponade. Schuh inserted a trochar into the 3rd intercostal space at the left sternal border without return of fluid. He then repeated the procedure in the 4th intercostal space with return of a large amount of fluid with resolution of patient’s extremis. The subxiphoid approach was then developed in 1911 by a pediatrician named Antoinne Marfan (yes, that Marfan) as a safer alternative.
Today in the emergency department, we utilize a subxiphoid needle approach as it has been shown to decrease morbidity and mortality in contrast to the anterior sternal approach. Anterior sternal approach has the added risk of puncturing the internal mammary artery in particular.
A long 16-18 gauge needle is inserted between the xiphoid process and left subcostal margin at a 45 degree angle and directed toward the patient’s left shoulder. The needle should be advanced while aspirating until there is return of fluid. (Photo from lifeinthefastlane.com)
A quick trick to see if one is in the correct space is by seeing if the fluid aspirated clots or not. Effusion should not clot while blood obviously would. For more information you can check out sources below.
Hoit, B. Cardiac tamponade. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on October 1, 2015.)
Chuttani K, Tischler MD, Pandian NG, et al. Diagnosis of cardiac tamponade after cardiac surgery: Relative value of clinical, echocardiographic, and hemodynamic signs. Am Heart J. 1994;127:913–918
Kilpatrick ZM, Chapman CB. On pericardiocentesis. Am J Cardiol. 1965; 16 (5): 722–728.
Spodick DH. Acute cardiac tamponade. N Engl J Med. 2003;349:684–90.
Kennedy UM, Mahony NJ. A cadaveric study of complications associated with the subxiphoid and transthoracic approaches to emergency pericardiocentesis. Eur J Emerg Med. 2006 Oct;13(5):254-9.
Nickson, Chris. Pericardiocentesis. Life in the Fast Lane. http://lifeinthefastlane.com/ccc/pericardiocentesis. May 4, 2014. Accessed October 1, 2015.