Cardiac tamponade
In cardiac tamponade, a rapid, unchecked rise in intrapericardial pressure impairs diastolic filling of the heart. The rise in pressure usually results from blood or fluid accumulation in the pericardial sac. If fluid accumulates rapidly, this condition requires emergency lifesaving measures to prevent death. A slow accumulation and rise in pressure, as in pericardial effusion associated with malignant tumors, may not produce immediate symptoms, because the fibrous wall of the pericardial sac can gradually stretch to accommodate as much as 1 to 2 L of fluid.
Causes and incidence
Increased intrapericardial pressure and cardiac tamponade may be idiopathic (Dressler’s syndrome) or may result from:
❑ effusion (in cancer, bacterial infections, tuberculosis and, rarely, acute rheumatic fever)
❑ hemorrhage from trauma (such as gunshot or stab wounds of the chest and perforation by catheter during cardiac or central venous catheterization or postcardiac surgery)
❑ hemorrhage from nontraumatic causes (such as rupture of the heart or great vessels or anticoagulant therapy in a patient with pericarditis)
❑ acute myocardial infarction (MI)
❑ end stage lung cancer
❑ heart tumors
❑ radiation therapy
❑ hypothyroidism
❑ systemic lupus erythematosus
❑ uremia.
Cardiac tamponade occurs in 2 of every 10,000 people.
Signs and symptoms
Cardiac tamponade classically produces increased venous pressure with jugular vein distention, reduced arterial blood pressure, muffled heart sounds on auscultation, and pulsus paradoxus (an abnormal inspiratory drop in systemic blood pressure greater than 15 mm Hg). These classic symptoms represent failure of physiologic compensatory mechanisms to override the effects of rapidly rising pericardial pressure, which limits diastolic filling of the ventricles and reduces stroke volume to a critically low level. Generally, ventricular end-systolic volume may drop because of inadequate preload. The increasing pericardial pressure is transmitted equally across the heart cavities, producing a matching rise in intracardiac pressure, especially atrial and end-diastolic ventricular pressures. Cardiac tamponade may also cause dyspnea, diaphoresis, pallor or cyanosis, anxiety, tachycardia, narrow pulse pressure, restlessness, and hepatomegaly, but the lung fields will be clear. The patient typically sits upright and leans forward.
Diagnosis
❑ Chest X-ray shows slightly widened mediastinum and cardiomegaly.
❑ Electrocardiography (ECG) is rarely diagnostic of tamponade but is useful in ruling out other cardiac disorders. It may reveal changes produced by acute pericarditis.
❑ Pulmonary artery catheterization detects increased right atrial pressure, right ventricular diastolic pressure, and central venous pressure (CVP).
❑ Echocardiography, computed tomography scan, or magnetic resonance imaging shows pericardial effusion with signs of right ventricular and atrial compression.
Treatment
The goal of treatment is to relieve intrapericardial pressure and cardiac compression by removing accumulated blood or fluid. Pericardiocentesis (needle aspiration of the pericardial cavity) or surgical creation of an opening (pericardiectomy or pericardial window) dramatically improves systemic arterial pressure and cardiac output with aspiration of as little as 25 ml of fluid. Such treatment necessitates continuous hemodynamic and ECG monitoring in the intensive care unit. Trial volume loading with temporary I.V. normal saline solution with albumin, and perhaps an inotropic drug, such as isoproterenol or dopamine, is necessary in the hypotensive patient to maintain cardiac output. Although these drugs normally improve myocardial function, they may further compromise an ischemic myocardium after MI.
Depending on the cause of tamponade, additional treatment may include:
❑ in traumatic injury — blood transfusion or a thoracotomy to drain reaccumulating fluid or to repair bleeding sites
❑ in heparin-induced tamponade — the heparin antagonist protamine sulfate
❑ in warfarin-induced tamponade — vitamin K.
Resection of a portion or all of the pericardium to allow full communication with the pleura may be needed if repeated pericardiocentesis fails to prevent recurrence.
Special considerations
If the patient needs pericardiocentesis:
❑ Explain the procedure to him. Keep a pericardial aspiration needle attached to a 50-ml syringe by a three-way stopcock, an ECG machine, and an emergency cart with a defibrillator at the bedside. Make sure the equipment is turned on and ready for immediate use. Position him at a 45- to 60-degree angle. Connect the precordial ECG lead to the hub of the aspiration needle with an alligator clamp and connecting wire, and assist with fluid aspiration. When the needle touches the myocardium, you’ll see an ST-segment elevation or premature ventricular contractions.
❑ Monitor blood pressure and CVP during and after pericardiocentesis. Infuse I.V. solutions, as prescribed, to maintain blood pressure. Watch for a decrease in CVP and a concomitant rise in blood pressure, which indicate relief of cardiac compression.
❑ Watch for complications of pericardiocentesis, such as ventricular fibrillation, vasovagal response, or coronary artery or cardiac chamber puncture. Closely monitor ECG changes, blood pressure, pulse rate, level of consciousness, and urine output.
If the patient needs thoracotomy:
❑ Explain the procedure to him. Tell him what to expect postoperatively (chest tubes, drainage bottles, and oxygen administration). Teach him how to turn, deep breathe, and cough.
❑ Give antibiotics, protamine sulfate, or vitamin K, as ordered.
❑ Postoperatively, monitor critical parameters, such as vital signs and arterial blood gas values, and assess heart and breath sounds. Give pain medication as ordered. Maintain the chest drainage system and be alert for complications, such as hemorrhage and arrhythmias.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
Other Book Chapters Related to Heart symptoms
Read excerpts from these other book chapters related to Heart symptoms:
Medical Books Excerpts
- Cardiomegaly
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
- [ read ]
Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2008 Williams & Wilkins.
More About Causes of Heart symptoms
» Next page: Cardiomegaly (The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter)
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