Cardiac tamponade: Clinical sciences

Cardiac tamponade is a life-threatening condition characterized by excessive fluid accumulation in the pericardial sac. The excess fluid exerts pressure on the heart and decreases the filling of the cardiac chambers, eventually reducing cardiac output. Patients with cardiac tamponade are typically hemodynamically unstable and may quickly develop cardiovascular collapse and cardiac arrest, so they require prompt recognition and treatment with emergent drainage of the pericardial fluid to restore cardiac output.

Cardiac tamponade can occur due to bleeding, which is also known as hemopericardium, which typically occurs as result of chest trauma, aortic dissection, left ventricular free wall rupture, or iatrogenic as a result of medical intervention. Cardiac tamponade can also occur due to effusive-constrictive pericarditis, often as a result of infection, uremia, or malignancy.

Now, if an individual presents with signs or symptoms of cardiac tamponade, you should first perform an ABCDE assessment. These individuals are typically unstable, so immediately stabilize their airway, breathing and circulation. Next, obtain IV access, put your patient on continuous cardiac and vital sign monitoring, and provide supplemental oxygen if needed.

Now, here’s a clinical pearl to keep in mind! Cardiac tamponade is associated with decreased cardiac filling that can result in obstructive shock. So, be careful with the administration of IV fluids, since an excess of fluid could increase cardiac preload. In the setting of cardiac tamponade, where the cardiac filling is already impaired, an increase in the preload can potentially precipitate cardiovascular collapse. Similarly, mechanical ventilation can increase intrathoracic pressure, causing further impairment to venous return and cardiac output. Therefore, it’s best to avoid or delay it whenever possible.

Next, you should obtain a focused history and physical exam. History usually includes chest pain and shortness of breath. The physical exam may show tachycardia. A classic finding is Beck triad, which consists of hypotension, muffled heart sounds, and jugular venous distension or JVD. You may also observe the Kussmaul sign, where JVD worsens during inspiration due to a rise in jugular venous pressure. Lastly, some patients may show pulsus paradoxus, which is a drop in systolic blood pressure of 10 mmHg or more during inspiration. Keep in mind though that pulsus paradoxus might be absent in patients with atrial septal defect, aortic regurgitation, elevated diastolic pressures, or pulmonary hypertension.

If your patient presents with these signs and symptoms, you should suspect cardiac tamponade! Next, order a 12-lead ECG, chest X-ray, and bedside echocardiogram. The ECG usually shows sinus tachycardia, and you might also see a decreased QRS amplitude. In severe cases, you may notice electrical alternans, which is a beat-to-beat variation in QRS amplitude that occurs as the heart swings anteriorly and posteriorly within the enlarged pericardial space, varying the relative distance from the ECG leads on the anterior chest wall to the heart.

Chest X-ray typically demonstrates the water bottle sign, which is an enlargement of the cardiac silhouette in the shape of a water bottle. Finally, echocardiogram reveals pericardial effusion, collapse of the right atrium during ventricular systole, collapse of the right ventricle during ventricular diastole, and a dilated inferior vena cava. All of these findings help confirm the diagnosis of cardiac tamponade.

Now that you’ve confirmed your diagnosis, proceed with an emergent percutaneous pericardiocentesis to relieve the pericardial pressure. Ideally, for optimal results, percutaneous pericardiocentesis is performed under ultrasound guidance. If ultrasound isn’t readily available, pericardiocentesis can be performed using a blind approach. However, keep in mind there’s a higher risk of complications, such as pneumothorax and myocardial perforation. The procedure involves inserting a needle through the chest wall into the pericardial space to drain the excess fluid. Even just a few milliliters of fluid removal can improve cardiac function! After the pericardial fluid has been aspirated, a catheter can be left in place in order to allow further drainage and prevent reaccumulation of the effusion. Also, be sure to collect a sample of pericardial fluid for visual assessment and lab analysis.

Now that the pericardium has been decompressed, perform a visual assessment of the collected fluid for the presence of blood. If the pericardial fluid is grossly bloody, you’re dealing with a hemopericardium!

Your next step is to revisit the history and physical exam findings to determine the underlying cause. History might reveal previous trauma to the chest wall, such as blunt trauma from a motor vehicle accident. On physical exam, you could see an open chest wound, such as a stab wound, or a flail chest. If this is the case, the hemopericardium was probably caused by the chest trauma, so you should consult the surgical team.

On the other hand, if your patient presents with acute tearing chest pain, and on the physical exam you notice weak peripheral pulses, suspect aortic dissection and consult the surgical team.

Now, let’s say your patient has a history of recent myocardial infarction, and the physical exam reveals a new holosystolic murmur. In this case, suspect a left ventricular free wall rupture and, again, consult the surgical team.

Finally, if your patient had a recent cardiac procedure, like pacemaker lead placement or coronary angioplasty, suspect iatrogenic hemopericardium and, again, consult the surgical team.