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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.
tam·po·nade, tamponage (tam'pŏ-nād', tam'pŏ-nij), Avoid the mispronunciation tam-pō-nahd'.
tamponadeCardiology See Balloon tamponade Medtalk A pathologic plugging of an organ–eg, cardiac tamponade, caused by massive accumulation of pericardial fluid, resulting in a mechanical limitation of organ function. See Cardiac tamponade.
tam·pon·ade, tamponage (tam'pŏ-nād', -nazh')
tamponade, tamponage (tam?po-nad') (tam'po-noj) [Fr., tampon, rag (used as a) plug]
Cardiac tamponade may result from injuries to the heart or great vessels, from cardiac rupture, or from other conditions that produce large pericardial effusions. If fluid accumulates rapidly, as little as 150 mL can impair the filling of the heart. Slow accumulation, as in pericardial effusion associated with cancer, may not produce immediate signs and symptoms because the fibrous wall of the pericardial sac can gradually stretch to accommodate as much as 1 to 2 L of fluid.
Cardiac tamponade may be idiopathic (Dressler syndrome) or may result from any of the following causes: effusion (in cancer, bacterial infections, tuberculosis, and, rarely, acute rheumatic fever); hemorrhage from trauma (as from gunshot or stab wounds of the chest, perforation by catheter during cardiac or central venous catheterization, or after cardiac surgery); hemorrhage from nontraumatic causes (as from rupture of the heart or great vessels, or anticoagulant therapy in a patient with pericarditis); viral, postirradiation, or idiopathic pericarditis; acute myocardial infarction; chronic renal failure; drug reaction (as from procainamide, hydralazine, minoxidil, isoniazid, penicillin, methysergide, or daunorubicin); or connective tissue disorders (such as rheumatoid arthritis, systemic lupus erythematosus, rheumatic fever, vasculitis, and scleroderma). Classic signs of tamponade include persistent hypotension despite fluid bolusing, muffled heart sounds, distended jugular veins, and pulsus paradoxus (a drop in systolic blood pressure of more than 10 mm Hg on inspiration).
Cardiac tamponade is suggested by chest radiograph (slightly widened mediastinum and enlargement of the cardiac silhouette), ECG (reduced QRS amplitude, electrical alternans of the P wave, QRS complex, and T wave and generalized ST-segment elevation), and pulmonary artery pressure monitoring (increased right atrial pressure, right ventricular diastolic pressure, and central venous pressure). It is definitively diagnosed with echocardiography, or MRI or CT of the chest.
Pericardiocentesis (needle aspiration of the pericardial cavity) or surgical creation of a pericardial window dramatically improves systemic arterial pressure and cardiac output. In patients with malignant tamponade, a balloon pericardiotomy (a balloon-aided opening in the pericardium) may be made.
The patient is assessed for a history of disorders that can cause tamponade and for symptoms such as chest pain and dyspnea. Oxygen is administered via nonrebreather mask, and intravenous access is established via one or two large-bore catheters for fluid resuscitation. Airway, breathing, circulation, and level of consciousness are closely monitored.
If the patient is unstable, he or she requires arterial blood gas analysis and hemodynamic monitoring and support. Prescribed inotropic drugs and intravenous solutions maintain the patient's blood pressure, and oxygen and ventilatory support are administered as necessary and prescribed.
Pain is assessed, and appropriate analgesia is provided. The patient is prepared for central line insertion, pericardiocentesis, thoracotomy, or other therapeutic measures as indicated; brief explanations of procedures and expected sensations are provided; and the patient is reassured to decrease anxiety. The patient is observed for a decrease in central venous pressure and a concomitant rise in blood pressure after treatment, which indicate relief of cardiac compression. If the patient is not acutely ill, he or she is educated about the condition, including its cause and its planned treatment, e.g., by surgery to place a pericardial window. The importance of immediately reporting worsening symptoms is stressed. The patient is followed with repeat echocardiography and chest x-rays as deemed necessary.