Diagnosis of Tamponade

The hemodynamic effects of a pericardial effusion may be acute or gradual, depending on the amount and rate of fluid accumulation. Normally, the pericardial space contains 15 to 50mL of fluid with an intrapericardial pressure that approximates intrapleural pressure (−5 to +5cm H₂O). Fluid accumulation and pericardial restraint lead to rises in intrapericardial pressure. Tamponade occurs when intrapericardial pressure exceeds intracardiac pressure, leading to impaired ventricular filling, increases in pulmonary venous and jugular venous pressures, and reduction in forward stroke volume. During interventional procedures, tamponade may be signaled by hypotension. Tachycardia, which usually occurs, may not be present in patients receiving beta blockers. A high index of suspicion of tamponade should accompany any procedure in which a distal guidewire position appears unusual or in which oversized stents are used. All procedures with rotational atherectomy have a higher incidence of perforation and subsequent tamponade.

Echocardiography

Two-dimensional and Doppler echocardiography are commonly used for diagnosing cardiac tamponade. Specific signs of tamponade include collapse of the right atrium and right ventricle, ventricular septal shifting with respiration, and plethora (enlargement) of the inferior vena cava (Fig. 18-2). Respiratory variation in the Doppler mitral inflow is a highly sensitive measure that occurs early in tamponade, and may precede changes in cardiac output, blood pressure, and other echocardiographic findings.

Figure 18-2 Echocardiographic image of pericardial tamponade with right-sided chamber collapse. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; Eff, (pericardial) effusion.

(From Holmes DR, et al. JACC Cardiovasc Interv 2009;2:705–717 with permission.)

Hemodynamics

The invasive hemodynamic hallmarks of cardiac tamponade include pulsus paradoxus on the arterial tracing (Fig. 18-3) and prominent x descents and blunted y descents in the atrial pressure tracings (Fig. 18-4). Preservation of the x descent occurs because of the decrease in intracardiac volume during systolic ejection, which leads to a temporary reduction in intrapericardial and right atrial pressures (See Kern (2011) The Cardiac Catheterization Handbook 5th ed., Chapter 3 Hemodynamics). Elevated intrapericardial pressure impairs ventricular filling during the remainder of the cardiac cycle, resulting in blunting of the y descent. In patients with cardiac tamponade, the driving pressure to fill the left ventricle falls during inspiration. Consequently, there is a reduction in left ventricular filling and stroke volume, which manifests as a decrease in aortic pulse pressure during inspiration in a manner analogous to the bedside finding of pulsus paradoxus (see Fig. 18-3).

Figure 18-3 Arterial pressure in a patient with dyspnea at rest demonstrating pulsus paradoxus due to cardiac tamponade.

Figure 18-4 Hemodynamics of right atrial (RA) pressure (red) and pericardial pressure (blue); scale is 0–40 mm Hg. There is matching of phasic waveforms but RA is higher due to zero offset.

On relief of pericardial pressure and removal of the effusion, right atrial pressure and pericardial pressure fall usually to normal values if no residual pericardial disease is present (Fig. 18-5). However, in some cases, although pericardiocentesis empties the pericardial space and pericardial pressure falls to near zero, right atrial pressure may be unaffected, signifying the syndrome of effusive-constrictive pericardial disease (Fig. 18-6).

Figure 18-5 Hemodynamics of arterial pressure before pericardiocentesis (left) and after pericardiocentesis (right). Pericardial pressure is reduced from 24 to 10 mm Hg (blue); scale is 0–40 mm Hg.

Figure 18-6 Hemodynamics of pericardiocentesis with near normalization of pericardial pressure without change in right atrial (RA) pressure consistent with effusive constrictive pericardial disease.

Cardiac tamponade should be suspected in any patient in the cardiac catheterization laboratory with unexplained hypotension, elevated venous pressure, and a compatible history. Unusual manifestations also can occur. Tamponade may occur without elevated jugular venous pressure because of low intracardiac filling pressures (i.e., low-pressure tamponade), such as in dehydrated patients with malignant effusions. Localized tamponade can result from loculated pericardial effusions, such as those that may be present adjacent to the atria in the postoperative setting. Of note, pericardiocentesis should not be performed in patients with tamponade and aortic dissection. In such patients, relief of the tamponade will lead to an abrupt increase in systolic blood pressure that may exacerbate the aortic dissection. Careful imaging with transthoracic or transesophageal echocardiography is required to determine the presence of these manifestations of tamponade.

Technique for Pericardiocentesis

The basic technique of pericardiocentesis is discussed in Table 18-1 lists the equipment used for the procedure. For most patients, pericardiocentesis is performed with echocardiographic guidance. In some cases, additional use of hemodynamic monitoring through the pericardial needle adds important information during both puncture and after withdrawal of fluid to verify procedural findings. Certainly, in emergent situations where echocardiography is not immediately available, pericardiocentesis can be performed in a blinded or electrocardiogram (ECG)-guided fashion, usually from the subxiphoid approach. However, adjunctive echocardiography plays a significant role in the evaluation of patients with cardiac tamponade and will reduce the incidence of complications related to pericardiocentesis. Figure 18-7 shows several points of pericardial access.

^{Table 18-1} Equipment for Pericardiocentesis

Figure 18-7 A, Locations for pericardiocentesis. (1, 2, 3) Xiphoid approaches, (4) Fifth left intercostal space at sternal border, (5) Fifth right intercostal space at the sternal border, (6) Apical approach, (7) Approach for major fluid accumulation on the right side. (Modified from Spodick DH. Acute pericarditis. New York: Grune & Stratton, 1959.) B, Passing a flexible J-curve guidewire through pericardial needle into the pericardial space.

(From Tilkian AG, Daily EK. Cardiovascular procedures: diagnostic techniques and therapeutic procedures. St Louis, MO: Mosby, 1986.)

For all patients, volume resuscitation can help provide hemodynamic stability and should be performed in patients with cardiac tamponade. Reversal of anticoagulation and antiplatelet therapy should be performed as clinically permitted. During pericardiocentesis, right heart catheterization with simultaneous measurement of right atrial and pulmonary capillary wedge pressures assist in the diagnosis and for determining efficacy of the procedure.

Patient positioning. The patient usually is positioned with head raised approximately 30 degrees to facilitate inferior and apical pooling of the pericardial effusion.

Site of entry. Echocardiography helps to determine the most appropriate site of entry and needle direction. Most frequently, the echocardiographic window that is closest to the effusion is selected. Common portals of entry are subxiphoid and apical, but other locations have included axillary, and left or right parasternal (see Fig. 18-7). Advantages of the subxiphoid approach are a lower risk of pneumothorax and laceration of internal mammary or intercostal arteries. For the subxiphoid approach, the needle must be angled clear below the bottom rib as it attaches to the inferolateral surface above the xiphoid process (typically one fingerbreadth inferior and lateral to the edge of the xiphoid).Punctures that are too high and near the recess at the xiphoid angle can pose challenges to delivering the needle under the rib. When using a parasternal approach, the needle should pass 1 cm lateral to the sternum to avoid injury to the internal mammary artery; the risk of pneumothorax increases with further lateral positioning. For intercostal approaches, the needle should pass superior to the rib margins to reduce the risk of injury to the neurovascular bundle. The angle of entry and direction should be transfixed in the operator’s mind. The site of entry can be marked with an indelible pen. The precordial or subxiphoid area is sterilized with antiseptic solution and covered with a sterile drape.

Needle insertion. Following local anesthesia, an 18-gauge, thin-walled polytef-sheathed needle is inserted at the entry site using the predetermined angulation. The needle is advanced with gentle aspiration into the pericardial space. Aggressive aspiration may cause tissue occlusion of the needle and inhibit detection of pericardial fluid. Once fluid has been obtained, the needle is advanced slightly further (~2 mm) to ensure placement of the sheath into the pericardial space. Figure 18-8 shows a pericardial needle and stopcock arrangement designed to check pericardial pressure and then aspirate pericardial fluid and discharge the fluid into a pericardial drainage bag. Alternately, a needle and sheath system can be used. Once the needle is in the pericardial space, the polytef sheath then is advanced over the needle, followed by withdrawal of the needle. The needle should not be re-advanced once it has been removed from the sheath.

Figure 18-8 Pericardial needle attached to stopcocks which connect to pressure line and drainage bag. (Courtesy of Merit Medical, Inc.)

Confirmation of location. Agitated saline is injected into the sheath via a three-way stopcock with echocardiographic imaging (Fig. 18-9). If the agitated saline does not enhance the pericardial space, then repositioning of the needle by either withdrawal or another needle passage is performed. Radiographic contrast can also be administered under fluoroscopy. Small test injections should be given initially to exclude myocardial positioning, which is seen as myocardial staining. Contrast swirling will indicate a ventricular location, while pooling suggests intrapericardial positioning. Alternatively, the needle (before it is withdrawn) or the sheath can be connected to tubing connectors for pressure transduction. Intrapericardial pressure will be similar to the atrial pressure, while ventricular systolic pressure waveforms can immediately alert the operator to inadvertent ventricular perforation. For operators using an ECG-guided approach, the needle is connected to an alligator-tipped electrode. With myocardial contact, ST-segment elevation (i.e., injury current) will be detected that may not appear on other electrocardiographic leads (Fig. 18-10).

Figure 18-9 Use of agitated saline contrast medium for confirmation of sheath position in pericardial space. Pericardial effusion was visualized by imaging from subcostal position remote from entry site on chest wall, before injection of agitated saline contrast medium (left). Injection of agitated saline contrast medium provides dense opacification of pericardial space, confirming sheath position (right). LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; VS, ventricular septum; *, pericardial space.

(Reprinted with permission from Tsang TS, Freeman WK, Sinak LJ, et al. Echocardiographically guided pericardiocentesis: evolution and state-of-the-art technique. Mayo Clin Proc 1998;73:647–652.)

Figure 18-10 A, Electrocardiographic monitoring of pericardial needle tip. Note normal ST segment while tip is not touching the epicardium. B, When needle tip touches epicardium, current of injury (“contact” current) with elevated ST segment is seen. (From Tilkian AG, Daily EK. Cardiovascular procedures: diagnostic techniques and therapeutic procedures. St. Louis, MO: Mosby, 1986.)

Catheter placement. Following confirmation of position, a J-tipped guidewire is inserted through the polytef sheath into the pericardial space. A small skin incision with a scalpel is made, followed by exchange for a 5F or 6F introducer sheath and removal of the dilator. A multihole pigtail catheter is then inserted, followed by removal of the introducer sheath, leaving only the smooth-walled pigtail catheter in place. Positioning of the pigtail catheter can be reconfirmed using either echocardiography or pressure measurement.

Aspiration. Manual techniques or vacuum bottle can be used to remove the pericardial effusion. For patients with tamponade due to cardiac perforation, care should be taken to remove as much pericardial fluid as possible as this will facilitate sealing of the perforated site. For patients with other causes of pericardial effusion, complete apposition of the parietal and visceral layers also will reduce risk of recurrence. Inability to aspirate despite a persistent pericardial effusion on echocardiography should lead to repositioning of the pigtail catheter. Occasionally, puncture of a tense pericardium will lead to discharge of pericardial contents into a pleural space, resulting in less than expected removal via aspiration. Normalization of atrial pressures documented with simultaneous right heart catheterization helps to ensure successful removal of the pericardial effusion and relief of cardiac tamponade. For patients with large volume removal due to acute hemorrhage, cell savers often are used to minimize blood loss.

Post-pericardiocentesis management. The pigtail catheter is sutured to the chest wall, connected to a stopcock, and flushed every 4 to 6 hours with heparinized saline to maintain patency. Standard indwelling catheter care with complete dressing changes every 72 hours is recommended. When drainage becomes minimal (<25 mL/day) and echocardiography shows no recurrent effusion, the pigtail catheter can be removed. For completely drained pericardial effusions, the risk of recurrence is low (<10%) with the exception of certain etiologies (e.g., bacterial infection, malignancy).

Complications

When pericardiocentesis is performed by experienced operators, complications are infrequent (<1.5% of patients). The most serious complication is laceration of a coronary artery. Perforation of either the right or left ventricle also may occur, but this is rarely of clinical significance. Bleeding and tamponade from coronary or ventricular perforation can be detected by continuous monitoring of atrial pressure, which will increase in the event of these complications. Acute left ventricular failure with pulmonary edema has been reported as a complication of pericardiocentesis, but the cause of this phenomenon is not known.

While most pericardial effusions can be treated percutaneously, a surgical approach may still be required. Loculated effusions, posterior effusions, or pericardial clot formation from recent hemorrhage may be difficult to remove percutaneously. Large surgical drainage often is required for effusions due to bacterial infection. For patients with refractory pericardial effusions (e.g., due to malignancy), balloon pericardiotomy to allow drainage into the pleural or peritoneal space may be a therapeutic option.