It is the compression of the heart through the infiltration of fluid in the pericardial sac.
The pericardial sac surrounds the heart and allows the heart to expand and pump easily.
When blood, pus, or fluid enters this sac, it can compress the heart and keep it from pumping as easily as it should.
If fluid builds up over time, the sac can expand to accommodate some fluid; however, if it happens immediately, the pericardial sac will not be able to hold much more than 100 ml of fluid.
As the fluid builds up, it compresses the heart until it cannot beat. This leads to decreased cardiac output, loss of perfusion, and eventually cardiac arrest.
Unfortunately, cardiac arrest cannot be reversed unless the tamponade is relieved, and this generally does not occur unless there is surgical intervention.
The most common causes of tamponade are trauma and cardiac rupture .
After cardiac surgery, the risk of tamponade is much higher, and patients must be closely monitored to ensure that the sac does not begin to fill.
Progressive tamponade may progress slowly over time, but will eventually require treatment.
Sudden tamponade is a medical emergency and must be treated right away.
Causes of cardiac tamponade
There are not many conditions that can cause a slow pericardial effusion.
One of them is hypothyroidism , and sometimes the pericardial sac can expand to hold more than a liter of fluid when accumulation is slow.
The most common reason for cardiac tamponade is penetrating trauma. This can occur in the heart itself or in the vessels that serve the heart.
Blood floods into the sac and causes compression of the heart.
Blunt trauma to the chest can also cause cardiac tamponade, so all trauma patients who experience trauma to the trunk should be screened for this condition.
Another possible cause is heart rupture. It is a rare cause of tamponade and can occur after an MI weakens the heart muscle.
Patients receiving anticoagulant therapy are also at risk for tamponade due to the possibility of excessive bleeding within the pericardial sac.
Those undergoing cardiac surgery should be monitored for 48 hours afterward to make sure the vessels do not bleed into the pericardial sac.
The act of manipulating the heart during surgery can sometimes lead to bleeding that can compress the heart.
Although it is usually the blood that causes the blockage, pus is another possible cause of the blockage.
Symptoms of cardiac tamponade
It is difficult to diagnose cardiac tamponade because it has many differential diagnoses. For example, tension pneumothorax can mimic some of the symptoms of cardiac tamponade.
One way to determine that this condition is present is by looking for Beck’s triad .
The hypotension is the first sign, but is not related to hypovolemia. Jugular venous distention is often seen as the veins begin to recede.
Finally, muffled heart sounds are heard when the chest is auscultated. This is because the fluid present decreases the conduction of the sound of the heartbeat.
Other signs may be seen, including pulsus paradoxus, which is a drop of at least 10 mm Hg in blood pressure when the patient inhales.
Additionally, an EKG will reveal ST wave changes and low-voltage QRS complexes. Of course, signs of shock can also be present.
Symptoms such as tachycardia, loss of consciousness, and shortness of breath are very common in this condition, although they can be misinterpreted as signs of some other condition.
An echocardiogram can show the fluid around the heart and provide a more definitive diagnosis.
Treatment of cardiac tamponade
Treatment for cardiac tamponade can begin in the prehospital setting. Unfortunately, there is little that paramedics can do to treat this condition in the field.
Treatment usually consists of managing the symptoms of hypotension and shock, and then transporting the patient to the hospital as quickly as possible.
Some prehospital units are equipped with the equipment to perform pericardiocentesis, but this is not common.
This procedure involves inserting a large needle into the pericardial sac with anatomical markers to evacuate the fluid.
It is dangerous and not performed frequently, but it is sometimes the only life-saving treatment that can be performed when cardiac tamponade is acute and life-threatening.
In the hospital, the treatment is more aggressive. Pericardiocentesis is the first line of treatment; A cannula is placed to help evacuate more fluid if it continues to build up.
Although landmarks can aid in the placement of this cannula, it is much safer and more accurate when inserted under ultrasound guidance.
If facilities are available, a pericardial window can be surgically performed, allowing fluid to drain.
When the cause of the tamponade is found, the window can be surgically closed. Post-open heart patients will need immediate surgery to evacuate the fluid.
A decrease in chest tube secretions after these procedures may indicate that a tamponade is developing.