Pericardial Effusion and Cardiac Tamponade

PERICARDIAL EFFUSION AND CARDIAC TAMPONADE

Pathophysiology

Pericardial effusion refers to the accumulation of fluid in the peri-cardial sac. This occurrence may accompany pericarditis, advanced HF, metastatic carcinoma, cardiac surgery, trauma, or nontraumatic hemorrhage.

 Normally, the pericardial sac contains less than 50 mL of fluid, which is needed to decrease friction for the beating heart. An in-crease in pericardial fluid raises the pressure within the pericardial sac and compresses the heart. This has the following effects:

• Increased right and left ventricular end-diastolic pressures

• Decreased venous return

• Inability of the ventricles to distend adequately and to fill

Pericardial fluid may accumulate slowly without causing no-ticeable symptoms. A rapidly developing effusion, however, can stretch the pericardium to its maximum size and, because of in-creased pericardial pressure, reduce venous return to the heart and decrease CO. The result is cardiac tamponade (compression of the heart).

Clinical Manifestations

The patient may complain of a feeling of fullness within the chest or may have substantial or ill-defined pain. The feeling of pres-sure in the chest may result from stretching of the pericardial sac. Because of increased pressure within the pericardium, venous pressure tends to rise, as evidenced by engorged neck veins. Other signs include shortness of breath and a drop and fluctuation in blood pressure. Systolic blood pressure that is detected during ex-halation but not heard with inhalation is called pulsus para-doxus. The difference in systolic pressure between the point thatit is heard during exhalation and the point that it is heard during inhalation is measured. Pulsus paradoxus exceeding 10 mm Hg is abnormal. The cardinal signs of cardiac tamponade are falling systolic blood pressure, narrowing pulse pressure, rising venous pressure (increased jugular venous distention), and distant (muf-fled) heart sounds (Chart 30-7).

Assessment and Diagnostic Findings

Pericardial effusion is detected by percussing the chest and notic-ing an extension of flatness across the anterior aspect of the chest. An echocardiogram may be performed to confirm the diagnosis. The clinical signs and symptoms and chest x-ray findings are usu-ally sufficient to diagnose pericardial effusion.

Medical Management

PERICARDIOCENTESIS

If cardiac function becomes seriously impaired, pericardiocen-tesis (puncture of the pericardial sac to aspirate pericardial fluid)is performed to remove fluid from the pericardial sac. The major goal is to prevent cardiac tamponade, which restricts normal heart action.

During the procedure, the patient is monitored by ECG and hemodynamic pressure measurements. Emergency resuscitative equipment should be readily available. The head of the bed is el-evated to 45 to 60 degrees, placing the heart in proximity to the chest wall so that the needle can be inserted into the pericardial sac more easily. If a peripheral intravenous device is not already in place, one is inserted, and a slow intravenous infusion is started in case it becomes necessary to administer emergency medications or blood products.

The pericardial aspiration needle is attached to a 50-mL sy-ringe by a three-way stopcock. Several possible sites are used for pericardial aspiration. The needle may be inserted in the angle be-tween the left costal margin and the xiphoid, near the cardiac apex; at the fifth or sixth intercostal space at the left sternal mar-gin; or on the right sternal margin of the fourth intercostal space. The needle is advanced slowly until it has entered the epicardium and fluid is obtained. The ECG can help determine when the needle has contacted the epicardium. The cable of a precordial lead is attached to the aspirating needle with alligator clamps; con-tact with the epicardium is seen by ST segment elevation on the ECG. During the procedure, drainage fluid must be checked for clotting. Although not entirely accurate, the guideline is that peri-cardial blood does not clot readily, whereas blood obtained from inadvertent puncture of one of the heart chambers does clot.

A resulting fall in central venous pressure and an associated rise in blood pressure after withdrawal of pericardial fluid indi-cate that the cardiac tamponade has been relieved. The patient almost always feels immediate relief. If there is a substantial amount of pericardial fluid, a small catheter may be left in place to drain recurrent accumulation of blood or fluid. Pericardial fluid is sent to the laboratory for examination for tumor cells, bacterial culture, chemical and serologic analysis, and differential blood cell count.

Complications of pericardiocentesis include ventricular or coronary artery puncture, dysrhythmias, pleural laceration, gas-tric puncture, and myocardial trauma. After pericardiocentesis, the patient’s heart rhythm, blood pressure, venous pressure, and heart sounds are monitored to detect any possible recurrence of cardiac tamponade. If it recurs, repeated aspiration is necessary. Cardiac tamponade may require treatment by open pericardial drainage (pericardiotomy). The patient is ideally in an intensive care unit.

PERICARDIOTOMY

Recurrent pericardial effusions, usually associated with neoplastic diseases, may be treated by a pericardiotomy (pericardial window). The patient receives a general anesthetic, but cardiopulmonary bypass is seldom necessary. A portion of the pericardium is ex-cised to permit the pericardial fluid to drain into the lymphatic system. Uncommonly, catheters are placed between the peri-cardium and abdominal cavity to drain the pericardial fluid. The nursing care is the same as that described for other cardiac surgery .