Beck’s Triad is a set of three cardiovascular signs that indicate cardiac tamponade. These three signs got their name from the American cardiothoracic surgeon, Dr. Claude Beck, in 1935. In order to fully make sense of Beck’s triad and what it means, it's essential to understand cardiac tamponade.
Cardiac tamponade is an acute condition in which blood surrounds the heart, putting so much pressure on it that it can no longer effectively pump blood. You can think of it essentially as something squeezing the heart until it stops.
Surrounding the heart, there is a pericardial sac that is made up of two layers. Together, these two layers make up the pericardium. The space between the two layers of the pericardium is normally filled with about 25-50 mL of fluid. This fluid acts as a lubricant to allow the heart to contract and expand smoothly by minimizing friction. When excess fluid, such as blood fills into the pericardial space fast enough, the pericardium is unable to stretch or expand to accommodate the increase in fluid. If the pressure from the fluid becomes greater than the pressure in the chambers of the heart, the heart will begin to compress and lose its ability to pump blood to the lungs and the rest of the body.
Fluid can build up in the pericardial space rapidly, such as in cardiac tamponade, or slowly over the course of several days or weeks, in what is known as pericardial effusion. When fluid slowly fills the pericardial space, it takes more of it until the patient becomes symptomatic because it allows time for the pericardium to expand and adjust to the increase in pressure.
The three classic signs of cardiac tamponade are:
- Increased jugular vein distention (JVD)
- Muffled heart sounds
Due to the pressure exerted on the right ventricle, diastolic filling decreases. This causes blood to back up into the right atria and the veins that return blood to the heart, most notably the jugular veins. In a patient with cardiac tamponade, jugular vein distension will be present even when they are sitting upright.
Muffled heart sounds occur because of the insulating effect of the fluid in the pericardial sac. When sound travels through fluid, it sounds distant or suppressed because it is traveling through a thicker median.
Hypotension occurs because the heart is hindered in its ability to pump blood. When the heart cannot work efficiently, the rest of the body does not get supplied with the necessary amount of blood. This can result in the body going into shock and even cardiac arrest.
Other symptoms of cardiac tamponade that accompany Beck’s Triad:
• Rapid heart rate (tachycardia)
• Cold, clammy extremities
• Anxiety, restlessness