Cardiac Tamponade
Definition
Cardiac tamponade occurs when the heart is squeezed by fluid that collects inside the sac that surrounds it.
Description
The heart is surrounded by a sac called the pericardium. When this sac becomes filled with fluid, the liquid presses on the heart, preventing the lower chambers of the heart from properly filling with blood.
Because the lower chambers (the ventricles) cannot fill with the correct amount of blood, less than normal amounts of blood reach the lungs and the rest of the body. This condition is very serious and can be fatal if not treated.
Causes and symptoms
Fluid can collect inside the pericardium and compress the heart when the kidneys do not properly remove waste from the blood, when the pericardium swells from unknown causes, from infection, or when the pericardium is damaged by cancer. Blunt or penetrating injury from trauma to the chest or heart can also result in cardiac tamponade when large amounts of blood fill the pericardium. Tamponade can also occur during heart surgery.
When the heart is compressed by the surrounding fluid, three conditions occur: a reduced amount of blood is pumped to the body by the heart, the lower chambers of the ventricles are filled with a less than normal amount of blood, and higher than normal blood pressures occur inside the heart, caused by the pressure of the fluid pushing in on the heart from the outside.
When tamponade occurs because of trauma, the sound of the heart beats can become faint, and the blood pressure in the arteries decreases, while the blood pressure in the veins increases.
In cases of tamponade caused by more slowly developing diseases, shortness of breath, a feeling of tightness in the chest, increased blood pressure in the large veins in the neck (the jugular veins), weight gain, and fluid retention by the body can occur.
Diagnosis
When cardiac tamponade is suspected, accurate diagnosis can be life-saving. The most accurate way to identify this condition is by using a test called an echocardiogram. This test uses sound waves to create an image of the heart and its surrounding sac, making it easy to visualize any fluid that has collected inside the sac.
Treatment
If the abnormal fluid buildup in the pericardial sac is caused by cancer or kidney disease, drugs used to treat these conditions can help lessen the amount of fluid collecting inside the sac. Drugs that help maintain normal blood pressure throughout the body can also help this condition; however, these drugs are only a temporary treatment. The fluid within the pericardium must be drained out to reduce the pressure on the heart and restore proper heart pumping.
The fluid inside the pericardium is drained by inserting a needle through the chest and into the sac itself. This allows the fluid to flow out of the sac, relieving the abnormal pressure on the heart. This procedure is called pericardiocentesis. In severe cases, a tube (catheter) can be inserted into the sac or a section of the sac can be surgically cut away to allow for more drainage.
Prognosis
This condition is life-threatening. However, drug treatments can be helpful, and surgical treatments can successfully drain the trapped fluid, though it may reaccumulate. Some risk of death exists with surgical drainage of the accumulated fluid.
Resources
Organizations
American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.
Key terms
Pericardiocentesis — A procedure used to drain fluid out of the sac surrounding the heart. This is done by inserting a needle through the chest and into the sac.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
tamponade
[tam″po-nād´]1. surgical use of a tampon.
2. pathologic compression of a part.
cardiac tamponade compression of the heart due to collection of fluid or blood in the pericardium. It may be either chronic or acute. Chronic cardiac tamponade occurs when fluid slowly enters the pericardial sac, allowing time for the membrane's expansion to accommodate the fluid, which can be as much as 1 liter. This gradual filling may or may not produce changes in cardiac hemodynamics. However, if there is rapid filling of the pericardial sac, as little as 200 ml can precipitate a life-threatening emergency. The ultimate effect of cardiac tamponade is reduced cardiac output and inadequate tissue perfusion.
Causes of acute cardiac tamponade include pericarditis with effusion of serosanguineous fluid into the sac, and either surgical or accidental trauma with leakage of blood into the sac. Occasionally, anticoagulant therapy can lead to extensive bleeding around the heart and cardiac tamponade.
Excessive fluid within the pericardial sac causes pressure against the cardiac structures, interferes with ventricular and atrial filling, and compromises blood supply to the myocardium via the coronary vessels. These conditions occur because of the following events: The compressed atria cannot fill as they normally would and so less blood is available for the ventricles; thus preload (the volume of blood in the ventricles at the end of diastole) is reduced. Ventricular filling is further impaired by compression of the ventricles. As pressure within the ventricles rises because of tamponade, pressure differences between the atria and ventricles are reduced, causing the valves between the two chambers to close before the ventricles have had time to fill completely. Increasing pressure within the heart chambers and in the pericardium impinges on the coronary arteries and veins, reducing blood supply to the myocardium, slowing contractility, and further reducing cardiac output.
Clinical features of cardiac tamponade include increased central venous pressure, falling arterial blood pressure, tachycardia, faint or muffled heart sounds, a narrowing pulse pressure, and an exaggerated inspiratory fall in systolic blood pressure (pulsus paradoxus). Hypoxia of cerebral tissues can produce confusion, restlessness, agitation, panic, and a sense of impending doom. Peripheral hypoxia is signaled by changes in the color, temperature, and excessive sweating.
Diagnosis can be confirmed by echocardiography and other radiologic studies. However, if the situation is acute, these tests cannot be done without endangering the life of the patient; thus diagnosis must be based on clinical findings. Once tamponade is suspected, fluids are administered and a pericardiocentesis is done to remove the compressing fluid.
Causes of acute cardiac tamponade include pericarditis with effusion of serosanguineous fluid into the sac, and either surgical or accidental trauma with leakage of blood into the sac. Occasionally, anticoagulant therapy can lead to extensive bleeding around the heart and cardiac tamponade.
Excessive fluid within the pericardial sac causes pressure against the cardiac structures, interferes with ventricular and atrial filling, and compromises blood supply to the myocardium via the coronary vessels. These conditions occur because of the following events: The compressed atria cannot fill as they normally would and so less blood is available for the ventricles; thus preload (the volume of blood in the ventricles at the end of diastole) is reduced. Ventricular filling is further impaired by compression of the ventricles. As pressure within the ventricles rises because of tamponade, pressure differences between the atria and ventricles are reduced, causing the valves between the two chambers to close before the ventricles have had time to fill completely. Increasing pressure within the heart chambers and in the pericardium impinges on the coronary arteries and veins, reducing blood supply to the myocardium, slowing contractility, and further reducing cardiac output.
Clinical features of cardiac tamponade include increased central venous pressure, falling arterial blood pressure, tachycardia, faint or muffled heart sounds, a narrowing pulse pressure, and an exaggerated inspiratory fall in systolic blood pressure (pulsus paradoxus). Hypoxia of cerebral tissues can produce confusion, restlessness, agitation, panic, and a sense of impending doom. Peripheral hypoxia is signaled by changes in the color, temperature, and excessive sweating.
Diagnosis can be confirmed by echocardiography and other radiologic studies. However, if the situation is acute, these tests cannot be done without endangering the life of the patient; thus diagnosis must be based on clinical findings. Once tamponade is suspected, fluids are administered and a pericardiocentesis is done to remove the compressing fluid.
Pericardiocentesis is performed to remove compressing fluid in cardiac tamponade. From Polaski and Tatro, 1996.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
car·di·ac tam·po·nade
compression of the heart due to critically increased volume of fluid in the pericardium.
Synonym(s): heart tamponade
Farlex Partner Medical Dictionary © Farlex 2012
cardiac tamponade
Interference with the venous return of blood to the heart 2º to accumulation of fluids or blood in pericardium, resulting in ↑ mean right atrial pressure and near-equalization with intrapericardiac pressure, which has a wide range of clinical and hemodynamic effects Etiology 2º to dissecting aneurysm, HTN, post-MI, renal failure, pericarditis, hypothyroidism, autoimmune disease–eg, SLE, chest trauma, CA Diagnosis Echocardiogram Management Pericardiocentesis, ie needle aspiration, pericardial windowMcGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
car·di·ac tam·pon·ade
(kahr'dē-ak tam'pŏ-nād')Compression of the heart due to critically increased volume of fluid in the pericardium.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
cardiac tamponade
Abnormal compression of the heart from outside. This may occur as a result of penetrating injuries or a collection of blood or fluid in the sac surrounding the heart (the PERICARDIUM). Tamponade seriously interferes with heart action and calls for urgent relief.Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005