Pericardial Disease

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12 Pericardial Disease

Peter von Homeyer

Introduction

Background

• The human pericardium is a double-layered sac around the heart, covering most of the surface of the heart and extending on to the proximal portion of the great vessels.
• The inner serous layer of the pericardium is attached to the myocardium, forming the visceral pericardium or epicardium.
• It reflects at the level of the great vessels and turns into the parietal pericardium, which is a fibroserous layer.
• Two sinuses are formed in the posterior pericardial cavity: The (upper) transverse sinus lies anterior to the superior vena cava and posterior to the pulmonary artery and ascending aorta. The (lower) oblique sinus lies posterior and inferior to the heart; the sinus is bounded by the reflection lines of both the left and the right pulmonary veins (Figure 12-1).
• Normal pericardial thickness is approximately 1 to 2 mm. Between the two layers, a small fluid collection of up to 30 mL is considered a normal finding. The pericardial fluid resembles an ultrafiltrate of plasma.
• The pericardium protects and restrains the heart as well as reduces friction. It isolates the heart from other structures in the mediastinum.
• A number of cardiac and systemic diseases involve the pericardial tissue, often with significant clinical consequences.
• Pericardial disease can impair cardiac chamber filling, especially on the thin-walled and low pressure right side of the heart, where constraint can decrease compliance.
• Usually, right ventricular (RV) compliance is greater than left ventricular (LV) compliance, and equalization can exaggerate the phenomenon of ventricular interdependence.
• Intrapericardial pressure is generally similar to intrapleural pressure, varying from approximately −6 mm Hg during inspiration to approximately −3 mm Hg at the end of expiration.
• When intrapericardial pressure drops during inspiration, RV filling and tricuspid inflow are enhanced.
• At the same time, the interventricular septum shifts to the left side of the heart, decreasing LV filling and transmitral flow; the opposite relationship is true for spontaneous exhalation.
image

Figure 12-1 Normal pericardial anatomy.

From Gray H. Anatomy of the Human Body. Philadelphia: Lea & Febiger, 1918; Bartleby.com, 2000.

Overview of Echocardiographic Approach

• Echocardiography is the most sensitive and specific method for evaluation of pericardial effusion (PE).
• Diagnostic echocardiography of the pericardium involves multiple views to fully understand the degree and localization of pericardial disease.
• Two-dimensional (2D) echocardiography is used for anatomic imaging of the pericardium and pericardial space (Figure 12-2).
• Transthoracic echocardiography (TTE) is the primary method in suspected pericardial disease, although in some cases, transesophageal views provide better images. The midesophageal (ME) four-chamber view, the ME RV inflow-outflow view, and the transgastric (TG) midpapillary short axis view are useful for anatomic imaging.
• M-mode echocardiography can be helpful for the diagnosis of PEs and interrogation of septal motion.
• Spectral Doppler echocardiography is used to interrogate cardiac chamber filling, hepatic and pulmonary vein flows, and overall diastolic function.
• Measurement of inferior vena cava (IVC) size and respiratory variation can be used to reconfirm pericardial disease in the setting of elevated RV filling pressures.
image

Figure 12-2 Normal echocardiographic appearance of the pericardium (arrow).

Key Points

• Pericardium is a double-layered sac surrounding the human heart.
• Normal thickness is 1 to 2 mm; a fluid collection of up to 30 mL is normal.
• Several cardiac and systemic diseases can involve the pericardium, the most common being pericarditis, PE with or without cardiac tamponade, and constrictive pericarditis.
• The most important clinical endpoint of pericardial disease is impaired cardiac chamber filling.
• On 2D echocardiography, the pericardium is shown as a bright linear echo image surrounding the heart.
• One should acquire images using different views to visualize the whole pericardial sac.
• In addition, M-mode and spectral Doppler echocardiography measurements can be useful to confirm and clarify the diagnosis of specific pericardial diseases.

Pericardial Effusion

Background

• A PE is an abnormal fluid collection in the pericardial space.
• A wide variety of diseases can cause PEs, but most commonly, this is seen after cardiac surgery, in congestive heart failure, acute type A aortic dissections, and end-stage renal disease (Table 12-1).
• PEs become a clinical syndrome as soon as the fluid accumulation causes an increase in intrapericardial pressure and the patient develops symptoms.
• The rate of how fast fluid accumulates in the pericardial space is important. An effusion that is caused by a slow increase in pericardial fluid can become quite large before clinical symptoms occur. Conversely, relatively small fluid collections can cause cardiac tamponade when developing rapidly.
• When the patient is in a supine position, PEs are initially located posterior to the heart. As more pericardial fluid accumulates, the effusion is surrounding the heart and can cause cardiac tamponade (see “Cardiac Tamponade”). Loculated effusions are also possible, especially after cardiac surgery.

TABLE 12-1 OVERVIEW OF PERICARDIAL DISEASE ETIOLOGIES AND ASSOCIATED SYNDROMES

Etiology Clinical Endpoints
Idiopathic  
Infectious  
Bacterial Acute pericarditis
Tuberculous Acute pericarditis, constrictive pericarditis
Viral Acute pericarditis
Parasitic Acute pericarditis
Connective tissue disease  
Systemic lupus erythematosus Pericarditis, pericardial effusion
Scleroderma Pericarditis
Rheumatoid arthritis Pericarditis, pericardial effusion
Wegener’s granulomatosis Pericarditis, pericardial effusion
Post-myocardial infarction  
Dressler’s syndrome Acute pericarditis, pericardial effusion
Ventricular rupture Pericardial effusion, cardiac tamponade
Metabolic  
Uremia Pericardial effusion
Myxedema Pericardial effusion
Trauma Pericardial effusion, cardiac tamponade
Postradiation Acute pericarditis, constrictive pericarditis
Postoperatively after cardiac surgery Pericardial effusion, cardiac tamponade, constrictive pericarditis
Neoplastic  
Primary pericardial and cardiac tumors Pericardial effusion, cardiac tamponade
Metastatic disease Pericardial effusion, cardiac tamponade
Congestive heart failure Pericardial effusion
Aortic dissection, left ventricular rupture Pericardial effusion, cardiac tamponade
Postoperatively after cardiac catheter or electrophysiologic procedures Pericardial effusion, cardiac tamponade

Overview of Echocardiographic Approach

• The sensitivity and specificity of echocardiography for the diagnosis of PE are very high.
• On 2D images, a PE will appear as an echo-free space between both pericardial layers (Figure 12-3). This is the most useful imaging modality for the diagnosis of effusions.
• Transesophageal echocardiography (TEE) is especially useful for detection of posterior effusions and in the postoperative setting where retrosternal hematoma can impair transthoracic image quality.
• M-mode echocardiography can be useful as an additional tool for the detection of smaller effusions.
• In large PEs, spectral Doppler echocardiography should be considered to assess for markers of possible cardiac tamponade (see “Cardiac Tamponade”).
image

Figure 12-3 2D echocardiographic image of a small to moderate PE.

Anatomic Imaging

Step 1: 2D Image Acquisition

• 2D echocardiography will show an echo-free space between the visceral and the parietal pericardium.
• Different views should be obtained in order to appreciate the extent of the PE (Table 12-2).
• M-mode echocardiography images are best acquired using the parasternal long axis view in TTE imaging and the TG mid short axis view in TEE.
• In some instances, saline contrast can help to discriminate the pericardial space from the heart itself.

TABLE 12-2 TRANSTHORACIC VERSUS TRANSESOPHAGEAL ECHOCARDIOGRAPHY VIEWS FOR THE IMAGING OF PERICARDIAL EFFUSIONS

  TTE TEE
Useful echocardiographic views Parasternal long axis ME four-chamber
Parasternal short axis ME RV inflow-outflow
Apical four-chamber subcostal Transgastric mid short axis
Benefits and limits Less invasive technique Better detection of posterior effusion
Poor image quality after cardiac surgery More invasive

ME, midesophageal; RV, right ventricular; TEE, transesophageal echocardiography; TTE, transthoracic echocardiography.

Step 2: Image Analysis

• The measured distance between both pericardial layers is used to grade PEs (Table 12-3).
• Although grading scales are neither standardized nor validated, there is obvious correlation between the measured distance and the pericardial fluid volume. This has to be put into the perspective of the patient’s clinical presentation.
• More exact measurements estimating pericardial fluid are impractical and not clinically relevant.

TABLE 12-3 ECHOCARDIOGRAPHIC GRADING OF PERICARDIAL EFFUSIONS

  Location of the Effusion Distance between Pericardial Layers
Small Posterior only <0.5 cm
Moderate Anterior and posterior 0.5-2 cm
Large Anterior and posterior >2 cm

Pitfalls

• Surrounding PEs are hard to miss, and generally easy to diagnose, but localized PEs can be more difficult to identify and also have a more complex differential diagnosis, such as intrapericardial hematoma or pericardial mass.
• Hemorrhagic PE may appear more echogenic than a PE caused by serous fluid.
• Not only large circumferential effusions can cause the clinical picture of cardiac tamponade. In some cases, localized PEs can cause a tamponade-like picture, although not compressing all of the cardiac chambers (Figure 12-4).
• An echo-free space only anterior to the heart is most commonly epicardial fat, and not fluid.
image

Figure 12-4 Posterior intrapericardial hematoma. Compression of the RA (left, arrow) and after surgical relief (right).

Pericardial versus Pleural Effusion

• Not every echo-free space around the heart is a PE. Differential diagnoses include pleural effusions, and a dilated descending thoracic aorta. On occasion a massively dilated left atrium (LA) may be mistaken for a pericardial effusion.
• Left-sided pleural effusions are visualized as echo-free spaces posterolateral to the descending thoracic aorta on the left (Figure 12-5). The partially collapsed lung is often visualized.
• In contrast, PEs are generally found between the descending thoracic aorta and the LA (Figure 12-6A). On occasion, an effusion may be first appreciated surrounding the left atrial appendage (LAA; see Figure 12-6B).
• Right-sided pleural effusions appear as echo-free spaces adjacent to the right atrium (RA). As opposed to PEs, right-sided pleural effusions are bounded inferiorly to the convex-shaped dome of the diaphragm adjacent to the liver. Similarly to the left side, the partially collapsed lung is often visualized (Figure 12-7).
image

Figure 12-5 Left-sided pleural effusion in short axis (left) and long axis (right).

image

Figure 12-6 PE insinuated between the descending aorta (arrow) and the LA.

image

Figure 12-7 Right-sided pleural effusion (arrow).

Key Points

• Echocardiography is the method of choice for the diagnosis of PE.
• A PE appears as an echo-free space surrounding the heart.
• Small PEs are mostly located posterior to the heart.
• The most common cause for PE is recent cardiac surgery.
• A distance of more than 2 cm between the pericardial layers is consistent with a large PE.
• PE is an echocardiographic finding, and a patient has to show symptoms in order to make it a clinical syndrome.
• An echolucent space only anterior to the heart is usually caused by epicardial fat, and pleural effusions can be mistaken for pericardial fluid.

Cardiac Tamponade

Background

• The pericardium can be somewhat stretched but can accommodate only a limited amount of fluid.
• Whenever there is a rapid or massive collection of pericardial fluid, the pressure inside the pericardium increases and will eventually overcome the intracardiac pressure, leading to impaired cardiac chamber filling.
• Thin-walled chambers on the right side of the heart are usually affected first, unless there is loculated pericardial hematoma adjacent to the left heart causing localized compression.
• As the intrapericardial pressure rises, venous pressures increase in order to maintain cardiac chamber filling.
• The clinical picture includes tachycardia, elevated right atrial (RA) pressure as well as systemic hypotension and decreased cardiac output.
• Pulsus paradoxus is an exaggerated clinical sign of impaired LV filling during inspiration causing a decrease in systolic arterial blood pressure. Patients may feel dizzy and complain of chest pain.
• Blood accumulation in the pericardium is the most common etiology for cardiac tamponade, but clot, exudates, or pus can also be the cause.

Overview of Echocardiographic Approach

• Echocardiography is the key imaging technique in the emergent clinical setting of suspected cardiac tamponade (Figure 12-8).
• Anatomic echocardiographic imaging modalities used are similar to the diagnosis of PE (see “Pericardial Effusion”).
• Spectral Doppler echocardiography is critical in the diagnosis of tamponade, but image acquisition should not delay treatment of this life-threatening syndrome.
image

Figure 12-8 Differential diagnosis of post cardiac surgery hypotension. Echocardiography is essential in establishing the diagnosis of pericardial tamponade. IABP, intra-aortic balloon pump; ICU, intensive care unit.

Anatomic Imaging

Step 1: Image Acquisition

• 2D imaging will confirm the presence of a PE that is usually moderate or large in size (Figure 12-9).
• Images should be acquired using multiple views to evaluate the extent of the effusion and confirm chamber compression.
• 2D echocardiography is used to visualize the IVC and hepatic veins.
• M-mode echocardiography of the interventricular septum can be helpful in some cases.
image

Figure 12-9 Large PE in a patient with clinical symptoms of cardiac tamponade. The RV is collapsed in early diastole when intracavitary pressure is at its lowest.

Step 2: Image Analysis

• The presence of a moderate to large PE is a classic finding in patients with cardiac tamponade.
• The RA shows inversion or collapse in systole. This is usually an early sign due to the thin wall and low pressure of the RA (Figure 12-10).
• A more specific and later sign is RV diastolic collapse. This can be best seen at the level of the right ventricular outflow tract (RVOT; Figure 12-11).
• There is exaggeration of the phenomenon of ventricular interdependence, which results from an increase in RV volume and pressure during inspiration and a leftward shift of the interventricular septum in the first diastole after inspiration. As well, the LA pressure is more dramatically lowered in inspiration. The result is reduced LV filling and systemic hypotension (pulsus paradoxus). Normalization of septal motion and decrease in RV volume is seen in the first diastole after expiration.
• There is IVC plethora, which is defined as a dilated IVC (>2 cm) with a less than 50% inspiratory diameter reduction (Figure 12-12). This is a sensitive, but not a very specific, sign.
image

Figure 12-10 RA systolic collapse (arrow).

image

Figure 12-11 RVOT diastolic collapse (arrow).

image

Figure 12-12 Dilated IVC.

Pitfalls

• Absence of a PE in the clinical setting of suspected cardiac tamponade is a diagnostic challenge. This is a trigger for extensive anatomic imaging. Especially after cardiac surgery, loculated effusion or hematoma can cause a tamponade-like syndrome with compression of sometimes only one cardiac chamber (i.e., the LA).
• If echocardiography shows no PE whatsoever, the hemodynamic compromise is probably not due to cardiac tamponade. Conversely, if a patient with a typical hemodynamic pattern suspicious for cardiac tamponade has a moderate to large PE, this virtually always confirms the diagnosis.
• There are idiopathic hemodynamically insignificant large PEs that do not result in tamponade physiology. Conversely, low-pressure cardiac tamponade exists where even a small increase in pericardial pressure (and volume) produces the full clinical picture, particularly in patients who are hypovolemic.
• Evaluation of respiratory changes of IVC size is a sensitive, but not a very specific, sign. Dilatation greater than 2 cm and loss of respiratory variation simply reflect elevated RA pressures regardless of cause. In the mechanically ventilated patient, measurements of IVC respiratory variations are clinically meaningless.

Step 1: Acquisition of Physiologic Data

• Spectral Doppler echocardiography is used to measure inflow velocities through the mitral and tricuspid valves by pulsed wave Doppler.
• These measurements can be done using the ME four-chamber view in TEE or an apical four-chamber view in TTE. The Doppler sample should be placed at the leaflet tips, and the sample size should be 3 to 5 mm.
• The examination should also include recording of pulsed wave Doppler flow in the pulmonary and hepatic veins.
• Tissue Doppler imaging and color M-mode of transmitral inflow are additional means of gathering physiologic data for the diagnosis of cardiac tamponade.
• In some cases, comparison of aortic and pulmonic velocity time integrals can be helpful. This will require TG long axis views and upper esophageal aortic arch short axis views in TEE, respectively.

Step 2: Analysis of Physiologic Data

• Spectral Doppler recordings will demonstrate exaggerated respiratory changes in diastolic filling of the ventricles.
• This will result in increased transtricuspid and decreased transmitral flow velocities during spontaneous inspiration.
• Respiratory variations can also be seen in aortic and pulmonic velocity time integral measurements.
• Tissue Doppler imaging of the mitral annular velocity (E′) will show a reduction in the presence of cardiac tamponade. There is usually no respiratory variation seen with this type of measurement.

Pitfalls

• Common problems in spectral Doppler imaging can alter findings and potentially make the diagnosis more difficult. The most important problem is an incorrect angle between the Doppler beam and the flow sample of interest.
• Differentiation of tamponade physiology from normal respiratory changes can be difficult, but generally, respiratory changes in flow velocities of more than 25% are considered abnormal.
• In the intraoperative setting with the patient being mechanically ventilated, the classic picture of exaggerated respiratory variation of ventricular volumes and filling is offset and does not contribute to the diagnosis of cardiac tamponade.
• Although spectral Doppler findings in cardiac tamponade overlap with the findings in pericardial constriction, the difference between the two is the presence or, in the latter case, absence of a significant PE. There is, however, the rare case of so-called effusive-constrictive pericarditis that includes both pericardial thickening and effusion.

Alternative Approaches

• Even though echocardiography is an excellent modality to visualize PE, in some cases, it can be difficult to differentiate effusion from adjacent structures and cavities.
• Computed tomography (CT) and magnetic resonance imaging (MRI) might be of diagnostic help if there is a question of pericardial tumor or cyst (see “Other Pericardial Diseases”).
• Diagnostic pericardiocentesis can be indicated whenever there is the suspicion of infectious or malignant PE. This can be a diagnostic as well as a therapeutic procedure at the same time (see “Surgical Considerations”).

Key Points

• Because echocardiography is the preferred method to diagnose a PE, it is also an invaluable tool in the diagnosis of cardiac tamponade.
• Classic echocardiographic findings in tamponade physiology include RA systolic collapse, RV diastolic collapse, and respiratory changes in ventricular volumes leading to a leftward shift of the interventricular septum with spontaneous inspiration.
• Although 2D echocardiography is the modality of choice, spectral Doppler can be useful for diagnosis confirmation, but should not delay treatment.
• However, cardiac tamponade is a clinical diagnosis with a typical hemodynamic pattern and cannot be based solely on echocardiographic findings.

Constrictive Pericarditis

Background

• Constrictive pericarditis is a disease involving chronic fibrotic changes to the pericardium, pericardial thickening, and fusion of both pericardial layers.
• This can occur as a consequence of virtually any pericardial injury or disease, but the most common etiologies today are prior cardiac surgery and radiation of the mediastinum. The incidence of constrictive pericarditis after cardiac surgery is reported to be approximately 0.3%. Historically, infectious diseases, particularly tuberculosis, have been a major cause of constrictive pericarditis (see Table 12-1).
• Pathophysiologically, pericardial constriction causes a biventricular decrease of compliance and diastolic dysfunction (Table 12-4).
• During cardiac catheterization, the ventricular pressure loops show a typical dip-and-plateau pattern or square-root sign indicating an elevated early-diastolic pressure plateau (Figure 12-13).
• As opposed to cardiac tamponade, in which there is filling impairment throughout diastole, in constrictive pericarditis, early filling is usually normal or enhanced.
• The clinical endpoint of pericardial constriction is decreased diastolic filling of the ventricles due to the thick and inelastic pericardium encasing the heart. This goes along with systemic venous congestion and reduced cardiac output.
• Clinical symptoms often develop over months, and patients present with fatigue, dyspnea, peripheral edema, and ascites.
• It is important to recognize constrictive pericarditis, because it is likely curable by surgery. Also, it is important to differentiate it from other conditions in which ventricular filling is impaired (i.e., restrictive cardiomyopathy).

TABLE 12-4 PATHOPHYSIOLOGY OF PERICARDIAL CONSTRICTION

1 High atrial pressures increase early filling of the ventricles
2 Ventricular filling is quickly offset by the constriction resulting in a rapid rise of the intraventricular pressure in diastole
3 RV systolic pressure is only mildly elevated, whereas RV diastolic pressures are markedly increased (usually more than one third of systolic pressure)
4 In classic constrictive pericarditis, there is equalization and elevation of diastolic pressures in all cardiac chambers
5 Ventricular volume is limited by pericardial constraint
6 Increased early diastolic RV filling goes along with decreased early diastolic LV filling, which is referred to as exaggerated ventricular interdependence

LV, left ventricular; RV, right ventricular.

image

Figure 12-13 Dip-and-plateau pattern of ventricular pressure loops in the setting of pericardial constriction.

Overview of Echocardiographic Approach

• Echocardiography is a useful imaging technique for the diagnosis of constrictive pericarditis.
• TTE and TEE can complement each other for better image quality.
• Spectral Doppler echocardiography is of paramount importance for the diagnosis and differential diagnosis of pericardial constriction.
• Ancillary techniques include M-mode, tissue Doppler imaging, and color M-mode.

Anatomic Imaging

Step 1: Image Acquisition

• 2D echocardiography can be used to assess pericardial thickening. TEE is reported to be more useful in imaging pericardial thickness.
• Again, images should be acquired using multiple views in order to appreciate the extent of pericardial disease.
• M-mode of the interventricular septum can be helpful in some cases.
• The IVC should also be assessed for size and respiratory variation.

Step 2: Image Analysis

• Thickened pericardium will appear brighter than normal pericardium.
• Pericardial thickening and calcification can be ubiquitous or loculated.
• LV size and function are generally normal in patients with constrictive pericarditis.
• Atrial dimensions are often increased due to chronically elevated filling pressures.
• The IVC is usually dilated (>2 cm) because of elevated RA pressures.
• M-mode echocardiography will show the so-called septal bounce, which is the echocardiographic correlate of the dip-and-plateau sign on the LV pressure tracing, and appears as abrupt posterior motion of the septum in early diastole.

Pitfalls

• Reverberation artifacts from calcified pericardium are not uncommon and can potentially affect measurements.
• Even TEE is far from being exact in terms of measuring pericardial thickness. Other imaging techniques such as CT are more accurate in evaluating the magnitude of pericardial thickening.
• Although reports have demonstrated that the septal bounce is a consistent echocardiographic sign of constrictive pericarditis, this finding can be very subtle and also blunted in the setting of mechanical ventilation.
• Similarly, respiratory variations of IVC size are of no diagnostic value in mechanically ventilated patients.
• Echocardiographic findings of constrictive pericarditis and cardiac tamponade can have a lot in common, but in constriction, there is usually no PE, unless it is a (rare) case of effusive-constrictive pericarditis.

Step 1: Acquisition of Physiologic Data

• Spectral Doppler imaging should include pulsed wave Doppler interrogation of mitral and tricuspid inflow as well as hepatic and pulmonary vein flows.
• Any echocardiographic view yielding an appropriate line-up of the Doppler beam and the flow sample can be used (i.e., an apical four-chamber view with TTE imaging). Correct placement of the sample volume at the level of the leaflet tips is important.
• Tissue Doppler of the septal mitral annulus and color M-mode of the mitral inflow will complete the physiologic echocardiography examination.

Step 2: Analysis of Physiologic Data

• E-wave velocity of transmitral inflow is increased and deceleration time is shortened (Table 12-5).
• The classic Doppler finding is enhanced changes in transmitral and transtricuspid inflow velocities with respiration. Mitral inflow is reduced, and tricuspid inflow is increased during spontaneous inspiration, whereas the opposite is the case with spontaneous exhalation. Isovolumic relaxation time (IVRT) is prolonged during spontaneous inspiration and will become shorter with expiration.
• Pulmonary vein flow velocities will also change throughout the respiratory cycle. There is systolic blunting and a prominent D-wave, consistent with pronounced early diastolic filling.
• Interrogation of hepatic vein flow usually shows prominent A-waves, and also deep y descents. This is indicative of rapid early diastolic filling in the presence of high RA pressures (A-wave) and a sudden dip in atrial pressure with ventricular filling (y descent). Flow velocities increase with spontaneous inspiration.
• Tissue Doppler imaging of the septal mitral annulus is normal or even increased (>8 cm/s) because there is no intrinsic myocardial disease and rapid early filling. Flow propagation velocity by color M-mode will also show normal results (>45 cm/s).

TABLE 12-5 COMPARISON OF CONSTRICTIVE PERICARDITIS AND RESTRICTIVE CARDIOMYOPATHY

  Constrictive Pericarditis Restrictive Cardiomyopathy
Hemodynamics    
RA pressure Elevated Elevated
Pulmonary artery pressures Mildly elevated At least moderately elevated
2D    
  Pericardial thickening and fusion of both layers, no effusion LV hypertrophy, normal systolic function
  Septal bounce Usually normal septal motion
Spectral Doppler    
  Transmitral and transtricuspid inflow
E > a
Increased E-wave velocity
Shortened deceleration time
Respiratory variation of E-wave velocity and IVRT		 Transmitral and transtricuspid inflow
E < A (early stage)
E >> A (late stage)
No respiratory variations
  Pulmonary veins
Blunted S-wave, large D-wave		  
  Hepatic veins
Large A-wave
Prominent y descent		  
Tissue Doppler    
  E′ > 8 cm/s E′ < 8 cm/s
Color M-mode    
  Flow propagation > 45 cm/s Flow propagation < 45 cm/s

IVRT, isovolumic relaxation time; LV, left ventricular; RA, right atrial; 2D, two-dimensional.

Pitfalls

• Reports demonstrated that up to 25% of patients lack those classic respiratory variations. This can be the case when there is concomitant intrinsic heart disease leading to ventricular dysfunction and markedly elevated filling pressures.
• Spectral Doppler interrogations are obviously more difficult in patients with atrial fibrillation. One has to use multiple beats to obtain a reliable picture of respiratory variations.
• In the intraoperative examination, respiratory changes will be blunted in the setting of mechanical ventilation.
• Tissue Doppler imaging of the lateral mitral annulus can be abnormal because of pericardial adhesion of the lateral wall. Therefore, tissue Doppler measurement should be performed interrogating the septal mitral annulus.

Differential Diagnosis of Constrictive Pericarditis

• Restrictive cardiomyopathy is a challenging differential diagnosis.
• In contrast to constrictive pericarditis, restrictive cardiomyopathy is an intrinsic heart disease characterized by ventricular noncompliance, higher degrees of diastolic dysfunction, and relatively normal systolic function. Possible etiologies include cardiac amyloidosis, sarcoidosis, or radiation.
• Hence, 2D and M-mode echocardiography are unreliable measures to differentiate because, in both diseases, the findings include normal chamber size and normal systolic function. Pericardial thickening and septal motion can also be somewhat difficult to assess.
• Spectral Doppler echocardiography is a key for successful differential diagnosis (see Table 12-5), and most importantly, patients with restrictive cardiomyopathy lack the classic respiratory variability of ventricular filling seen in patients with constrictive pericarditis.
• Tissue Doppler imaging is another tool to investigate whether there is “true” diastolic dysfunction or filling abnormality caused by pericardial constraint. Patients with restrictive cardiomyopathy will show reduced E′ velocities, whereas in constriction, E′ velocity is normal or even increased.

Alternative Approaches

• Several other imaging modalities are able to confirm the diagnosis of constrictive pericarditis whenever a comprehensive echocardiographic examination is inconclusive.
• Echocardiographic spectral Doppler measurements can be inaccurate owing to poor image quality and acquisition, or respiratory variations can be blunted by mechanical ventilation.
• Cardiac catheterization is an alternative diagnostic procedure to show the hemodynamic consequences of constriction, although complete equalization of diastolic pressures is not a consistent finding.
• Pericardial calcification can be seen on a regular chest x-ray, but for the exact evaluation of pericardial thickening, CT and MRI are the most definitive diagnostic tools (Figure 12-14).
• Endomyocardial biopsy may be needed to differentiate restrictive cardiomyopathy from constrictive pericarditis.
image

Figure 12-14 Thickened and calcified pericardium (arrows) seen with TEE (A), CT scan (B), chest x-ray (C), and MRI (D).

Key Points

• Constrictive pericarditis is characterized by pericardial thickening and fusion and is most commonly a consequence of prior cardiac surgery or radiation to the mediastinum.
• The pathophysiologic mechanism is decreased biventricular compliance. A rapid early filling is followed by an abrupt filling impairment due to the constraint of an inelastic pericardium.
• 2D echocardiography can be used to detect and measure pericardial thickness; however, other imaging techniques like CT or MRI are more accurate.
• The hallmark of pericardial constriction is the reciprocal respiratory changes in ventricular inflow during spontaneous inspiration measured by pulsed wave Doppler echocardiography.
• Differentiation of pericardial constriction and restriction caused by intrinsic heart disease can be difficult and involves comprehensive echocardiography and other diagnostic studies. This is highly important because constrictive pericarditis is a disease that is surgically treatable whereas restrictive cardiomyopathy is treated medically.

Other Pericardial Diseases

Acute Pericarditis

• Acute pericarditis is an inflammatory disease of the pericardium and has numerous potential causes (see Table 12-1).
• The clinical picture shows chest pain, changes on the electrocardiogram, and pericardial friction rub on auscultation.
• The echocardiographic signs include PE and possible pericardial thickening. 2D imaging using multiple views can show the extent of the disease.
• However, these findings can be subtle or even absent, making an echocardiographic diagnosis somewhat difficult.
• Acute pericarditis is a clinical diagnosis, and echocardiography can serve as a tool to identify PE and to detect possible complications such as cardiac tamponade.

Epicardial Fat

• Epicardial fat is ubiquitously found on the surface of the heart. It serves as a visceral fat reserve for the heart, and its embryologic origin is brown adipose tissue.
• Owing to the close proximity of epicardial fat and the myocardium, metabolic, inflammatory and hormonal interactions are present. Although it serves as a buffer and energy reserve, detrimental effects on the coronary vasculature have been described.
• Epicardial fat thickness strongly correlates with diabetes, atherosclerosis, and coronary artery disease. 2D echocardiography is a very capable and inexpensive tool to measure epicardial fat thickness. There are no established normal values yet, but studies suggest the upper limit to be about 7 mm.
• TTE using the parasternal windows is the preferable ultrasound technique. Epicardial fat is visualized as an echo-free space anterior to the heart and can be mistaken for an anterior PE. However, there are usually some fine echoes found inside the epicardial fat pad, and in some cases, the fat can even have a hyperechoic appearance.

Congenital Absence of the Pericardium

• Congenital malformations of the pericardium are rare and are often first diagnosed when patients undergo cardiac or thoracic surgical procedures for other reasons.
• Partial or complete absence of the pericardium is the most common abnormality.
• Studies have demonstrated that complete absence of the pericardium is virtually always asymptomatic, but partial absence can cause clinical symptoms ranging from chest pain to potentially life-threatening myocardial ischemia or arrhythmias caused by herniation or incarceration of cardiac structures.
• CT or MRI is most commonly used for the diagnosis of congenital absence, but reports have shown that echocardiography can be successfully used to make this diagnosis.
• 2D TTE imaging is the modality of choice, and changing the patient’s position during the examination can verify cardiac hypermobility, which is a highly suggestive sign for absence of the pericardium.

Pericardial Cysts and Tumors

• Pericardial cysts are congenital abnormalities but, in some cases, can be acquired after cardiothoracic surgical procedures.
• The typical position is the cardiophrenic angles; they contain water-like fluid and are variable in size.
• These cysts are usually incidental findings, but some patients develop symptoms that are caused by cardiac chamber compression.
• 2D echocardiography is the best noninvasive method for diagnosis of pericardial cysts. Color Doppler echocardiography can help to delineate cysts from blood vessels and cardiac chambers.
• Differentiation among pericardial cysts, effusion, and epicardial fat can be challenging in some cases.
• Pericardial tumors are rare. The most common primary tumors are mesotheliomas.
• The diagnosis is often made in advanced disease when tumor compression of cardiac chambers or significant PE is present.
• In this setting, 2D echocardiography can be used to both detect a PE as well as the actual tumor. In some cases, TEE might be more useful depending on the tumor location.
• Cysts and tumors causing clinical symptoms can be treated surgically with a pericardial window or a pericardiectomy.

Surgical Considerations

Pericardiocentesis

• Pericardiocentesis can be performed using local anesthesia at the patient’s bedside or in the setting of a cardiac catheterization suite.
• It is usually done when there is suspected PE causing clinical symptoms to confirm the diagnosis and provide an immediate treatment option.
• In some cases, diagnostic pericardiocentesis is used as a truly diagnostic method in order to acquire pericardial fluid samples for bacteriologic or cytologic analysis.
• The approach is transcutaneous from the left xiphocostal area. Once pericardial fluid is aspirated with the needle, a pressure line should be attached to measure intrapericardial pressure. If necessary, a drain can be placed to continue drainage until clinical symptoms of tamponade resolve.
• Echocardiography can increase the success rate and decrease complications of percutaneous pericardiocentesis, and should, therefore, be used to guide this procedure.
• TTE imaging is the preferred method to visualize the effusion, define the optimal anatomic location for needle placement, confirm that the needle tip is inside the pericardial space, ensure adequate fluid drainage, and guide the subsequent placement of a pericardial drain.

Pericardial Window

• A pericardial window or partial pericardiectomy is performed to drain fluid into the pleural or peritoneal compartments in patients with recurring PE.
• This procedure usually requires general anesthesia; operative approaches are thoracoscopic, via an anterior thoracotomy or through a subxiphoid incision.
• After fluid is released, a drain is usually left in the pericardial space. The surgeon will excise enough pericardium to make it an effective fluid drain, but excising too much leads to the potential problem of cardiac prolapse or herniation.
• TEE should be used to confirm adequate drainage of the PE.

Pericardiectomy

• Pericardiectomy is the standard surgical treatment for chronic pericardial constriction.
• Precise preoperative workup is necessary, as mentioned previously, to properly delineate pericardial constriction and intrinsic myocardial diseases that are subject to medical therapy (see “Constrictive Pericarditis”).
• It is a technically challenging operation, and the surgeon will encounter dense adhesions, calcifications, and sometimes, myocardial infiltration.
• The standard approach is a median sternotomy, and in some cases, cardiopulmonary bypass is necessary. A left anterior thoracotomy is an alternative surgical approach.
• The general goal is excision of the whole pericardium from one phrenic nerve to the other. In some cases, total excision, especially posterior to the heart, is not feasible and a partial pericardiectomy is performed.
• The LV is preferentially unroofed first in order to avoid the sudden increase in LV volume and pressure that often results if the RV is unroofed first.
• In most of the cases, a substantial decrease in filling pressures can be seen early after the procedure.
• Nonetheless, operative mortality is reported to be as high as 20%, and long-term outcome is largely dependent on the etiology of constrictive pericarditis. Whereas pericardiectomy for idiopathic constrictive pericarditis has an excellent long-term outcome, outcomes in patients undergoing this procedure for postsurgical or postradiation constrictive pericarditis are reported to be poor.
• TEE can be helpful in these cases for hemodynamic monitoring purposes and evaluation of ventricular function throughout the procedure.

Suggested Readings

1 Goldstein JA. Cardiac tamponade, constrictive pericarditis, and restrictive cardiomyopathy. Curr Probl Cardiol. 2004;29:503-567.

A comprehensive review of the normal anatomy and function of the human pericardium. The pathophysiology and clinical diagnosis of cardiac tamponade and pericardial constriction are meticulously described and illustrated with a number of useful figures.

2 Khandaker MH, Espinosa RE, Nishimura RA, et al. Pericardial disease: Diagnosis and management. Mayo Clin Proc. 2010;85:572-593.

A nicely illustrated overview on the clinical management of pericardial disease including several flow charts and diagnostic algorithms.

3 Wann S, Passen E. Echocardiography in pericardial disease. J Am Soc Echocardiogr. 2008;21:7-13.

A concise review on pericardial diseases with the focus on echocardiography as the diagnostic method. It contains explanations of different imaging techniques, matching illustrations, and echocardiographic images.

4 D’Cruz IA, Kanuru N. Echocardiography of serous effusions adjacent to the heart. Echocardiography. 2001;18:445-456.

This article is dedicated to the anatomic imaging and differentiation of pericardial effusion, pleural effusions, and ascites using echocardiography.

5 Reddy PS. Spectrum of hemodynamic changes in cardiac tamponade. Am J Cardiol. 1990;66:1487-1491.

This study in 77 patients with pericardial effusion is a great example for the hemodynamic impact of tamponade with respect to pressure equalization and the response to pericardiocentesis.

6 Yared K, Baggish AL, Picard MH, et al. Multimodality imaging of pericardial disease. J Am Coll Cardiol Imaging. 2010;3:650-660.

A good review looking at different imaging modalities for the diagnosis of pericardial diseases. An emphasis is put on the comparison of echocardiography with other imaging studies.

7 Hatle LK, Appleton CP, Popp RL. Differentiation of constrictive pericarditis and restrictive cardiomyopathy by Doppler echocardiography. Circulation. 1989;79:357-370.

An excellent study focused on the pathophysiology of pericardial constriction. Patients with constrictive pericarditis showed respiratory variation of ventricular inflow velocities, whereas patients with restrictive cardiomyopathy did not. These findings are also illustrated using ventricular pressure tracings.

8 Schwefer M, Aschenbach R, Heidemann J, et al. Constrictive pericarditis, still a diagnostic challenge: Comprehensive review of clinical management. Eur J Cardiothorac Surg. 2009;36:502-510.

A review of the pathophysiology and clinical presentation of constrictive pericarditis, but the focus is on the clinical management, especially the surgical aspects of pericardiectomy and associated outcomes.

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