Note: This chapter is adapted from Oh JK, Seward JB, Tajik AJ. The Echo Manual. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006, with permission.
The evaluation of pericardial disorders is of increasing importance in the management of patients with congenital heart disease. Previous cardiac surgery now accounts for over 25% of cases of constrictive pericarditis, and diagnosis can be challenging, especially in patients with congenital heart disease and coexisting myocardial dysfunction. This chapter will outline the echocardiographic evaluation of pericardial disorders, including the distinction between constrictive pericarditis and restrictive myocardial disease.
Normal pericardium consists of an outer sac, the fibrous pericardium, and an inner double-layered sac, the serous pericardium. The visceral layer of the serous pericardium, or epicardium, covers the heart and proximal great vessels. It is reflected to form the parietal pericardium, which lines the fibrous pericardium (Fig. 24.1). The pericardium provides mechanical protection for the heart and lubrication to reduce friction between the heart and surrounding structures. The pericardium also has a significant hemodynamic impact on the atria and ventricles. The nondistensible pericardium limits acute distention of the heart. Ventricular volume is greater at any given ventricular filling pressure with the pericardium removed than with the pericardium intact. The pericardium also contributes to diastolic coupling between two ventricles: the distention of one ventricle alters the filling of the other, an effect that is important in the pathophysiology of cardiac tamponade and constrictive pericarditis. Ventricular interdependence becomes more marked at high ventricular filling pressures. Abnormalities of the pericardium can range from the pleuritic chest pain of pericarditis to marked heart failure and even death from tamponade or constriction.
Figure 24.1. Pathology specimens demonstrating the double-layered pericardium with and without the heart in the fibrous pericardial cavity. (Courtesy of William Edwards, MD.)
Echocardiography is the most important clinical tool in the diagnosis and management of various pericardial diseases. Pericardial effusion, tamponade, pericardial cyst, and absent pericardium are readily recognized on two-dimensional (2D) echocardiography. The detection of pericardial effusion was clinically very difficult before the advent of echocardiography and was one of the most exciting initial clinical applications of cardiac ultrasonography 40 years ago. When a pericardial effusion needs to be drained, pericardiocentesis can be performed most safely under the guidance of 2D echocardiography. Although it usually is difficult to establish the diagnosis of constrictive pericarditis with 2D echocardiography alone, the characteristic respiratory variation in mitral inflow and hepatic vein Doppler velocities and tissue Doppler recording of mitral annulus velocity have added reliability and confidence to the noninvasive diagnosis of constrictive pericarditis. Transesophageal echocardiography (TEE) is helpful in measuring pericardial thickness, in evaluating diastolic function (for tamponade or constrictive physiology) from the pulmonary vein, and in detecting loculated pericardial effusion or other structural abnormalities of the pericardium. The various applications of echocardiography in the evaluation of pericardial diseases are illustrated in this chapter.
CONGENITALLY ABSENT PERICARDIUM
The congenital absence of the pericardium usually involves the left side of the pericardium. Complete absence of the pericardium on the right side is uncommon. The defect is more frequent in males, and it rarely creates symptoms such as chest pain, dyspnea, or syncope. Because of the pericardial defect, cardiac motion is exaggerated, especially the posterior wall of the left ventricle. The entire cardiac structure is shifted to the left; hence, the right ventricular (RV) cavity appears enlarged from the standard parasternal windows, mimicking the RV volume overload pattern on echocardiography. The absence of pericardium should be considered when the right ventricle appears enlarged from the parasternal window and is at the center of the usual apical image (Fig. 24.2A). This condition is also associated with a high incidence of atrial septal defect, bicuspid aortic valve, and bronchogenic cysts. It is readily recognized because of its typical 2D echocardiographic features, and the diagnosis can be confirmed with computed tomography (CT) or magnetic resonance imaging (MRI) (Fig. 24.2B).
Figure 24.2. Patient with a congenitally absent pericardium. A: Two-dimensional still-frame obtained from the normal apical position. Because of the leftward shift of the heart, the right ventricle (RV) is at the center of the apical image rather than the left ventricular (LV) apex; this is often confused with RV volume overload. Cardiac catheterization was performed elsewhere to evaluate an atrial septal defect and showed no shunt before this evaluation. RA, right atrium; LA, left atrium. B: Magnetic resonance image of the chest showing a marked shift of the heart to the left side of the chest because of the partial absence of the pericardium on the left side. Arrows indicate area of absent pericardium.
A pericardial cyst typically is a benign structural abnormality of the pericardium that usually is detected as an incidental mass lesion on a chest radiograph or as a cystic mass on echocardiography (Fig. 24.3A). Most frequently, pericardial cysts are located in the right costophrenic angle, but they also are found in the left costophrenic angle, hilum, and superior mediastinum. Pericardial cysts need to be differentiated from malignant tumors, cardiac chamber enlargement, and diaphragmatic hernia. Two-dimensional echocardiography is useful in differentiating a pericardial cyst from other solid structures, because a cyst is filled with clear fluid and appears as an echo-free structure. It also has a characteristic appearance on CT or MRI (Fig. 24.3B).
When the potential pericardial space is filled with fluid or blood, it is detected as an echo-free space. When the amount of effusion is greater than 25 mL, an echo-free space persists throughout the cardiac cycle. A smaller amount of pericardial effusion may be detected as a posterior echo-free space that is present only during the systolic phase. As pericardial effusion increases, movement of the parietal pericardium decreases. When the amount of pericardial effusion is massive, the heart may have a “swinging” motion in the pericardial cavity (Fig. 24.4A), which is responsible for the electrocardiographic manifestation of cardiac tamponade, “electrical alternans” (Fig. 24.4B). The swinging motion is not always present in cardiac tamponade, however. Cardiac tamponade can occur with a small amount of pericardial effusion, if the accumulation of pericardial effusion happens rapidly. A clinical example is myocardial perforation after acute myocardial infarction or during implantation of a pacemaker. Various M-mode and 2D echocardiographic signs have been reported in this life-threatening condition: early diastolic collapse of the right ventricle, late diastolic right atrial (RA) inversion, abnormal ventricular septal motion, respiratory variation in ventricle chamber size (Fig. 24.5), and plethora of the inferior vena cava with blunted respiratory changes. These findings are caused by the characteristic hemodynamics of tamponade. Diastolic collapse of the right atrium and right ventricle is related to intrapericardial pressure rising above the intracardiac pressures, and abnormal ventricular septal motion is related to respiratory variation in ventricular filling. Diastolic collapse of the right heart may not occur if right heart pressure is elevated. In case of acute myocardial rupture or proximal aortic dissection, clotted blood may be seen in the pericardial sac; this finding is highly suggestive of hemopericardium (Fig. 24.6). When there is air in the pericardial sac (pneumopericardium) as a result of esophageal perforation, cardiac imaging (both transthoracic echocardiography (TTE) and TEE) is difficult because ultrasound does not penetrate air well.
Figure 24.3. Pericardial cyst. A: Subcostal view showing a large pericardial cyst (asterisk) adjacent to the right atrium (RA). It has a typical echo-free appearance with a smooth boundary. LV, left ventricle. RV, right ventricle. B: MRI of the same patient as in A with a large pericardial cyst (asterisk).
Figure 24.4. Pericardial effusion. A: Parasternal long-axis views showing a large pericardial effusion with a swinging motion of the heart. LV, left ventricle. B: With a large amount of pericardial effusion, the heart has a swinging motion, which is an ominous sign of cardiac tamponade. When the left ventricular cavity is close to the surface (left), the QRS voltage increases on the electrocardiogram, but it decreases when the LV swings away from the surface (right), producing electrical alternans.
Doppler echocardiographic features of pericardial effusion/tamponade are more sensitive than the 2D echocardiographic features mentioned earlier. The Doppler findings of cardiac tamponade are based on the following characteristic respiratory variations in intrathoracic and intracardiac hemodynamics (Fig. 24.7). Normally, intrapericardial pressure (hence, left atrial [LA] and left ventricular [LV] diastolic pressures) and intrathoracic pressure (hence, pulmonary capillary wedge pressure) fall the same degree during inspiration, but in cardiac tamponade intrapericardial (and intracardiac) pressure falls substantially less than intrathoracic pressure. Therefore, the LV filling pressure gradient (from pulmonary wedge pressure to LV diastolic pressure [the shaded area in Fig. 24.7]) decreases with inspiration. Consequently, mitral valve opening is delayed, which lengthens the isovolumic relaxation time (IVRT) and decreases mitral E velocity. In cardiac tamponade, the degree of ventricular filling depends on the other ventricle because of the relatively fixed combined cardiac volume (ventricular interdependence); thus, reciprocal changes occur in the right heart chambers (Fig. 24.8). Increased venous return to the right heart chambers with inspiration also contributes to the increased ventricular interdependence.
The respiratory flow velocity changes across the mitral and tricuspid valves are also reflected in the pulmonary and hepatic venous flow velocities, respectively: inspiratory decrease and expiratory increase in pulmonary vein diastolic forward flow, and expiratory decrease in hepatic vein forward flow and increase in expiratory reversal flow (Fig. 24.9).
Echocardiographically Guided Pericardiocentesis
The most effective treatment for cardiac tamponade is removal of the pericardial fluid. Although pericardiocentesis is lifesaving, a blind percutaneous attempt has a high rate of complications, including pneumothorax, puncture of the cardiac wall, or death. Two-dimensional echocardiography can guide pericardiocentesis by locating the optimal site of puncture (Fig. 24.10), by determining the depth of the pericardial effusion and the distance from the puncture site to the effusion, and by monitoring the results of the pericardiocentesis, usually from the subcostal view. The position of the pericardiocentesis needle can be checked by imaging with administration of agitated saline. Figure 24.11demonstrates contrast (arrows) in the pericardial space, not in the right ventricle. Under most circumstances, a pigtail (6 or 7 French) catheter is introduced and left in the pericardial sac for several days with intermittent drainage (every 4 to 6 hours), which has markedly curtailed the rate of recurrent effusion and use of a sclerosing agent. At Mayo Clinic, most pericardiocentesis procedures are performed with the guidance of 2D echocardiography. The most common location of needle entry is in the parasternal area, but this depends on 2D echocardiographic findings. In our consecutive 1127 echo-guided pericardiocenteses, malignant effusion was most common (34%), followed by postoperative (25%), and complication of catheter-bases procedures (10%) (Fig. 24.12). The procedure was successful in 97%, and complications occurred in 4.4%, mostly minor. Major complications were death (1 patient), cardiac laceration (5), vessel laceration (1), pneumothorax (5), infection (1), and sustained ventricular tachycardia (1).
PERICARDIAL EFFUSION VERSUS PLEURAL EFFUSION
A pericardial effusion usually is located circumferentially. If there is an echo-free space anteriorly only, it more likely is an epicardial fat pad than pericardial effusion. Posteriorly, a pericardial effusion is located anterior to the descending thoracic aorta, whereas a pleural effusion is present posterior to the aorta (Fig. 24.13). Two-dimensional ultrasonographic imaging of pleural effusion is also helpful in planning for a thoracentesis to locate the optimal puncture site. Pleural effusion on the left side allows cardiac imaging from the back (Fig. 24.14).
Figure 24.5. Pericardial effusion with tamponade. A: M-mode echocardiogram from the parasternal window in a patient with cardiac tamponade and large circumferential pericardial effusion (PE). The M-mode was recorded simultaneously with the respirometer tracing at the bottom (upward arrowindicates onset of inspiration and downward arrow indicates onset of expiration). The left ventricular (LV) dimension during inspiration (EDi) becomes smaller than with expiration (EDe). The opposite changes occur in the right ventricle (RV). The ventricular septum (arrowheads) moves toward the LV with inspiration and toward the RV with expiration, accounting for the abnormal ventricular septum in patients with cardiac tamponade. Parasternal long-axis (B) and short-axis (C) views of a patient with tamponade during systole and diastole. The pericardial effusion (double arrows in B; PE in C) appears small in the long axis and moderate in the short axis during systole, but during early diastole, the RV free wall collapses (arrow at top). VS, ventricular septum. D: Apical four-chamber view demonstrating late diastolic (arrowhead on electrocardiograph) collapse of right atrium (RA) wall (arrow). This sign is sensitive but not specific for tamponade. When RA inversion lasts longer than a third of the RR interval, it is specific for hemodynamically significant pericardial effusion.
Constrictive pericarditis is caused by thickened, inflamed, adherent, or calcific pericardium limiting the diastolic filling of the heart (Fig. 24.15). Constrictive pericarditis is not an uncommon condition but frequently escapes clinical detection because it is not clinically considered in many cases and no one diagnostic test alone can ensure the diagnosis of constrictive pericarditis with high confidence. Since this is a curable entity causing severe heart failure, constrictive pericarditis should be considered in all patients with heart failure, especially when systolic function is normal and/or there is a predisposing factor. Currently, previous cardiac surgery is the most common cause for constriction, followed by pericarditis, episodes of pericardial effusion, and radiation therapy. Figure 24.16 demonstrates the multiple underlying etiologies of constriction in more than 400 patients who underwent pericardiectomy since 1985 at the Mayo Clinic. Patients with constrictive pericarditis present with dyspnea, peripheral edema, ascites, pleural effusion, fatigue, or anasarca. Jugular venous pressure is almost always elevated with typical rapid “y” descent (Fig. 24.17). Kussmaul sign and pericardial knock are other typical physical findings. Because of their abdominal symptoms and elevation of liver enzymes because of hepatic venous congestion, many patients are labeled as having a liver or gastrointestinal disease and undergo noncardiac procedures such as liver biopsy, endoscopy, or even abdominal exploration before the diagnosis of constrictive pericarditis is made. The diagnosis of pericardial constriction can be particularly challenging in patients with operated or unoperated congenital heart disease as a result of coexisting lesions and myocardial dysfunction, making the correct diagnosis more elusive. In many patients with congenital heart disease and pericardial constriction, restrictive myocardial disease and residual hemodynamic lesions may contribute to the clinical presentation and findings.
Figure 24.6. Hemopericardium. A: This echocardiogram was obtained from a 73-year-old man who is septic with Streptococcus mitis and is hypotensive. There was a moderate amount of circumferential pericardial effusion with soft-tissue density (arrows) over the right ventricle (RV), characteristic for coagulate tamponade or hemopericardium. B: Soon after this echocardiogram, the patient died. Pathology showed hemopericardium (left) because of a perforation of the proximal aorta (arrow) with aortic valve endocarditis (right).
Figure 24.7. Diagram of intrathoracic and intracardiac pressure changes with respiration in normal and tamponade physiology. The shaded area indicates left ventricle (LV) filling pressure gradients (difference between pulmonary capillary wedge pressure and LV diastolic pressure). At the bottom of each drawing is a schematic mitral inflow Doppler velocity profile reflecting LV diastolic filling. In tamponade, there is a decrease in LV filling after inspiration (Insp) because the pressure decrease in the pericardium and LV cavity is smaller than the pressure fall in the pulmonary capillaries (PC). LV filling is restored after expiration (Exp). PV, pulmonary vein. (Modified from Sharp JT, Bunnell IL, Holland JF, et al. Hemodynamics during induced cardiac tamponade in man. Am J Med. 1960;29:640–646.)
Figure 24.8. Typical pulsed-wave Doppler pattern of tamponade recorded with a nasal respirometer. A: Mitral inflow velocity decreases (single arrowhead) after inspiration (Insp) and increases (double arrowheads) after expiration (Exp). B: Tricuspid inflow velocity has the opposite changes. E velocity increases (double arrowheads) after inspiration and decreases (single arrowhead) after expiration. (From Oh JK, Hatle LK, Mulvagh SL, Tajik AJ. Transient constrictive pericarditis: diagnosis by two-dimensional Doppler echocardiography. Mayo Clin Proc. 1993;68:1158–1164.)
Pericardial calcification on chest radiography is helpful but is present in only 23% of cases (Fig. 24.18). Thickened pericardium is a usual finding in this condition, but pericardial thickness may be normal in up to 20% of cases. Pericardial thickness can be evaluated by echocardiography (most accurately by TEE) and by CT and MRI. In patients with congenital heart disease and univentricular physiology, the evaluation of pericardial thickness is of increased importance in suspected constrictive pericarditis, given the inability to evaluate interventricular hemodynamics. Traditional invasive hemodynamic features do have a large overlap with those found in restrictive cardiomyopathy or other myocardial diseases. New insights into the mechanism of constrictive pericarditis have allowed development of more reliable and specific diagnostic criteria for constriction using comprehensive echocardiography including 2D, Doppler, and tissue Doppler imaging. Subsequent to this observation, new diagnostic criteria of invasive hemodynamic features of constriction have been proposed.
Figure 24.9. Pulmonary vein and hepatic vein Doppler patterns of tamponade. A: Diastolic forward pulmonary venous flow decreases (single arrowhead) after inspiration (Insp) and increases (double arrowheads) after expiration (Esp). B: The hepatic vein has a significant reduction in diastolic forward flow and an increase in diastolic reversals (DR) after expiration. D, diastolic flow; S, systolic flow. (From Oh JK, Hatle LK, Mulvagh SL, Tajik AJ. Transient constrictive pericarditis: diagnosis by two-dimensional Doppler echocardiography. Mayo Clin Proc. 1993;68:1158–1164.)
The M-mode (Fig. 24.19) and 2D echocardiographic features of constrictive pericarditis include thickened pericardium, abnormal ventricular septal motion, flattening of the LV posterior wall during diastole, respiratory variation in ventricular size, and a dilated inferior vena cava, but these findings are not sensitive or specific. Hatle et al. described the Doppler features typical of constriction, which are distinct from those of restrictive hemodynamics. Although the underlying pathologic mechanism is different from that of cardiac tamponade, the hemodynamic events of constriction in regard to respiratory variation in LV and RV filling are similar to those of tamponade.
To establish the diagnosis of constrictive pericarditis, the following two hemodynamic characteristics need to be demonstrated either by 2D/Doppler echocardiography or by cardiac catheterization:
1.Disassociation between intrathoracic and intracardiac pressures
2.Exaggerated ventricular interdependence
Figure 24.10. Echocardiographically guided pericardiocentesis.
STEP 1. Locate an area on the chest or subcostal region from which the largest amount of pericardial effusion can be visualized, and mark it (A–C).
STEP 2. Determine the depth of effusion from the marked position and the optimal angulation.
STEP 3. After sterile preparation and local anesthesia, perform pericardiocentesis (D).
STEP 4. When in doubt about the location of the needle, inject saline solution through the needle and image it from a remote site to locate the bubbles.
STEP 5. Monitor the completeness of the pericardiocentesis by repeat echocardiography.
STEP 6. Place a 6F or 7F pigtail catheter in the pericardial space to minimize reaccumulation of fluid (E).
STEP 7. Drain any residual fluid or fluid that has reaccumulated via the pigtail catheter every 4 to 6 hours. If after 2 to 3 days pericardial fluid has not reaccumulated, as demonstrated echocardiographically, the pigtail catheter may be removed. Always have the pericardial fluid analyzed: cell counts, glucose and protein measurements, culture, and cytology. (Modified from Callahan JA, Seward JB, Tajik AJ, et al. Pericardiocentesis assisted by two-dimensional echocardiography. J Thorac Cardiovasc Surg. 1983:85:877–879.)
Figure 24.11. Appearance of agitated saline in the pericardial sac (arrows). If agitated saline is seen in any of cardiac chambers, surgical consultation should be obtained immediately before any attempt to remove pericardiocentesis needle or catheter.
Figure 24.12. Distribution of underlying etiologies for pericardial effusion requiring pericardiocentesis.
A thickened or inflamed pericardium prevents full transmission of the intrathoracic pressure changes that occur with respiration to the pericardial and intracardiac cavities, creating respiratory variations in the left-side filling pressure gradient (the pressure difference between the pulmonary vein and the left atrium). With inspiration, intrathoracic pressure falls (3 to 5 mm Hg normally) and the pressure in other intrathoracic structures (pulmonary vein, pulmonary capillaries) falls to a similar degree. This inspiratory pressure change is not fully transmitted to the intrapericardial and intracardiac cavities. As a result, the driving pressure gradient for LV filling decreases immediately after inspiration and increases with expiration. This characteristic hemodynamic pattern is best illustrated by simultaneous pressure recordings from the left ventricle and the pulmonary capillary wedge together with mitral inflow velocities (Fig. 24.20).
Diastolic filling (or distensibility) of the left and right ventricles rely on each other because the overall cardiac volume is relatively fixed within the thickened or noncompliant (adherent) pericardium. Hence, reciprocal respiratory changes occur in the filling of the left and right ventricles. With inspiration, decreased LV filling allows increased filling in the right ventricle. As a result, the ventricular septum shifts to the left, and tricuspid inflow E velocity and hepatic vein diastolic forward flow velocity increase (Fig. 24.21). With expiration, LV filling increases, causing the ventricular septum to shift to the right, which limits RV filling. Tricuspid inflow decreases and hepatic vein diastolic forward flow decreases, with significant flow reversals during diastole. Usually, diastolic forward flow velocity is higher than systolic forward flow velocity in the hepatic vein, which corresponds to the Y and X waves of systemic venous pressure, respectively. It needs to be emphasized that the respiratory variation in ventricular filling is initiated from the left side, which is also evident from careful inspection of simultaneous pressure tracings from the left and right ventricles.
Ideally, demonstration of a respiratory variation of 25% or greater in the mitral inflow E velocity and increased diastolic flow reversal with expiration in the hepatic vein establish the diagnosis of constrictive pericarditis (Fig. 24.22). Further clinical observations, however, indicate that up to 50% of patients with constrictive pericarditis demonstrate less than 25% of respiratory variation in mitral E velocity. This may be related to (a) mixed constriction and restriction, (b) marked increase of atrial pressures, or (c) more clinical experience of using 2D/Doppler echocardiography in the diagnosis of constrictive pericarditis. If LA pressure is markedly increased, mitral valve opening occurs at the steep portion of the LV pressure curve, when the respiratory change has little effect on the transmitral pressure gradient. In this case, a Doppler echocardiographic examination may be repeated after an attempt to reduce preload (i.e., head-up tilt or sitting position). In any event, the lack of respiratory variation in mitral inflow velocities does not, and should not, exclude the diagnosis of constrictive pericarditis. Other features of constriction should be looked for, such as hepatic vein velocity changes or mitral septal annular velocity of greater than 7 cm/s, especially when mitral inflow velocity indicates restrictive filling or high filling pressures (i.e., E/A ratio of 1.5 with deceleration time of less than 160 ms). Mitral annular velocity recorded by TDI has become a valuable Doppler parameter in establishing the diagnosis of constriction and in differentiating it from a myocardial disease or restrictive cardiomyopathy (Fig. 24.23). In myocardial disease, mitral septal annular early diastolic velocity (e’) is reduced (less than 7 cm/s) since myocardial relaxation is abnormal, but in constrictive pericarditis, the mitral annular e’ velocity, and especially the septal annular velocity, are relatively normal or even increased (Fig. 24.23A). This is because of the limitation of ventricular filling by lateral expansion of the heart caused by the constrictive pericardium with most of the ventricular filling accomplished by exaggerated longitudinal motion of the heart. Myocardial relaxation is relatively well preserved in constriction unless the myocardium is also involved, as is seen in radiation heart injury. The longitudinal motion, hence mitral septal annular velocity, becomes more increased as the constriction worsens, with resultant higher filling pressure, paradoxical to its change in myocardial disease. The phenomenon has been termed annulus paradoxus. E/e’ is, therefore, inversely proportional to pulmonary capillary wedge pressure in constriction, whereas E/e’ is positively related to pulmonary capillary wedge pressure in myocardial disease. Normally, lateral annular e’ velocity is higher than medial or septal e’ velocity. That is the case for restrictive cardiomyopathy with reduced e’ velocities compared to normal values. However, in constriction, lateral e’ velocity is lower than septal e’ velocity in 80% of cases since the lateral annulus is usually tethered by the constrictive pericardium. This phenomenon has been termed “annulus reversus.”
Figure 24.13. Two-dimensional imaging of pleural effusion (PL) from the parasternal long-axis (A) and apical long-axis (B) views. Pericardial effusion is present between the descending thoracic aorta (Ao) and the posterior cardiac walls, whereas pleural effusion is present behind the descending thoracic aorta. LA, left atrium; LV, left ventricle; RV, right ventricle.
Figure 24.14. Two-dimensional echocardiographic examination from the back through a pleural effusion (PL). This unique view may be the only available ultrasound window to the heart in some patients. Ao, aorta; LA, left atrium; LV, left ventricle; RV, right ventricle.
Pitfalls and Caveats
Several other clinical entities can produce a similar respiratory variation in mitral inflow velocities: acute dilatation of the heart, pulmonary embolism, RV infarct, pleural effusion, and chronic obstructive lung disease. Most of these conditions do not present a significant diagnostic problem in the interpretation of Doppler findings because their clinical and 2D echocardiographic features are different from those of constrictive pericarditis. Patients with increased respiratory effort as in asthma, chronic lung disease, or obesity, however, may have symptoms of right-sided heart failure similar to those of constrictive pericarditis.
Several Doppler echocardiographic features can be used to distinguish between situations with increased respiratory effort and constrictive pericarditis:
1.In patients with increased respiratory effort, individual mitral inflow velocities usually are not restrictive because the LV filling pressure is not increased. However, in young individuals with normal diastolic function, the mitral inflow Doppler velocity pattern may appear restrictive.
2.With increased respiratory effort, the highest mitral E velocity occurs toward the end of expiration, but it occurs immediately after the onset of expiration in constrictive pericarditis. This difference, however, may not be that helpful, especially when the patient is tachypneic.
3.The Doppler finding that most reliably distinguishes between these two entities is superior vena caval flow velocities. When respiratory effort is increased, superior vena cava flow is markedly increased with inspiration (Fig. 24.24), because the underlying mechanism for respiratory variation in this setting is a greater decrease in intrathoracic pressure with inspiration, which generates greater negative pressure changes in the thorax. This enhances flow to the right atrium from the superior vena cava with inspiration. In constrictive pericarditis, superior vena caval systolic Doppler flow velocities do not change significantly with respiration (Fig. 24.25); the difference in systolic forward flow velocity between inspiration and expiration is rarely 20 cm/s in constrictive pericarditis. It needs to be emphasized that it is important to compare systolic, not diastolic, flow velocities in the superior vena cava with respiration.
Figure 24.15. Cardiac specimens from two patients who died with constrictive pericarditis. A: The pericardium is thickened and calcified. B: The pericardial thickness is relatively normal, but adhered to the epicardium. In both situations, diastolic filling to right and left cardiac chambers was markedly reduced.
Figure 24.16. Distribution of underlying etiologies for constrictive pericarditis. There was only one patient with tuberculosis since 1985 at the Mayo Clinic, Rochester.
4.Hepatic vein Doppler may not be helpful if there is superimposed severe tricuspid regurgitation. However, if hepatic vein flow reversal happens during diastole in patients with severe tricuspid regurgitation, concomitant constrictive pericarditis should be suspected.
5.In patients after mitral valve replacement, mitral inflow Doppler will still demonstrate respiratory variation with a deceleration time shorter than expected for a mitral prosthesis (Fig. 24.26). Mitral annular velocity may not be increased because of the mitral prosthesis sewn to the annulus. However, the hepatic vein should demonstrate characteristic Doppler changes.
Figure 24.17. Simultaneous jugular venous pressure (JVP) tracing and pulsed-wave Doppler recording of hepatic vein (HV) velocities. There is the characteristic Y descent. D, diastolic flow; S, systolic flow; X and Y, jugular venous pressure waveforms.
Figure 24.18. Lateral and posteroanterior (PA) chest radiographs showing pericardial calcification (arrows). This calcification is most common in the diaphragmatic portion of the pericardium.
6.Mitral annular velocity is reduced when the adjacent myocardium is abnormal, such as after previous cardiac surgery or myocardial infarction. In a patient with an inferior wall myocardial infarction, the septal mitral annular velocity is reduced even when the patient has constrictive pericarditis. Hepatic vein Doppler velocity still should have characteristic diastolic flow reversal with expiration.
7.Hepatic vein Doppler velocities are mostly lower than 60 cm/s and reversal flow velocities are even lower. To augment the display of characteristic hepatic vein Doppler velocities in constriction, the pulsed-wave Doppler filter and velocity scale should be set low.
Atrial fibrillation makes the interpretation of respiratory variation in Doppler velocities difficult. Patients with constrictive pericarditis and atrial fibrillation will still have the typical 2D echocardiographic features but will require longer observation of Doppler velocities to detect velocity variation with respiration, regardless of the underlying cardiac cycle length. Hepatic vein diastolic flow reversal with expiration is an important Doppler finding to suggest constrictive pericarditis, even when mitral inflow velocity pattern is not diagnostic. Occasionally, it may be necessary to achieve a regular rhythm, even with a temporary pacemaker, to evaluate the respiratory variation of Doppler velocities. Respirometer recording may have a phase delay up to 1000 ms, which may make the timing of velocity variation erroneous. A good rule is to remember that the lowest mitral inflow velocity usually occurs during inspiration. It also is important to instruct the patient to breathe smoothly during Doppler recording. An erratic breathing pattern distorts the timing of Doppler flow velocities.
Complex congenital heart disease, including univentricular physiology, presents a particular challenge in the diagnosis of pericardial constriction, despite an increased risk of this diagnosis in those who have undergone previous cardiac surgery. Patients with previous surgical intervention for congenital heart disease are also at increased risk of coexisting myocardial disease, further confounding the diagnosis of pericardial constriction. Tissue Doppler imaging may be helpful in such patients, particularly if higher than expected e’ velocity is present. In addition, the lack of variation in superior vena cava Doppler flow velocity also suggests pericardial constriction.
Figure 24.19. Typical M-mode echocardiograms of constrictive pericarditis. A: There is a typical respiratory shift of the ventricular septal motion, which comes toward the left ventricle (LV) with inspiration (INSP) and toward the right ventricle (RV) with expiration (EXP). This is a result of increased interventricular dependence. Posterior wall (PW) is flattened soon after early diastole (arrows). B. With tachycardia, flattening of the posterior wall could not be well demonstrated, but there is a typical ventricular septal shift with respiration (downward arrow indicates inspiration and upward arrow indicates expiration).
RESTRICTION VERSUS CONSTRICTION
The clinical and hemodynamic profiles of restriction (myocardial diastolic heart failure) and constriction (pericardial diastolic heart failure) are similar, although their pathophysiologic mechanisms are distinctly different. Both are caused by limited or restricted diastolic filling, with relatively preserved global systolic function. Diastolic dysfunction in restrictive cardiomyopathy or myocardial disease is the result of stiff and noncompliant ventricular myocardium, but in constrictive pericarditis, it is related to a thickened and/or noncompliant pericardium. Both disease processes limit diastolic filling and result in diastolic heart failure. Restrictive cardiomyopathy resulting from infiltrative cardiomyopathy is the abnormality easiest to diagnose because it has typical 2D echocardiographic and biochemical features. A noninfiltrative type of restrictive cardiomyopathy is more difficult to diagnose. The myocardium becomes noncompliant because of fibrosis and scarring, and systolic function (or at least ejection fraction) is usually maintained. Because of limited diastolic filling and increased diastolic pressure, the atria become enlarged. In contrast, myocardial compliance usually is not decreased in constrictive pericarditis. The thickened and/or adherent pericardium limits diastolic filling, resulting in hemodynamic features that are similar but distinctly different from those of restrictive cardiomyopathy. Atrial enlargement is less prominent in constriction than in restrictive cardiomyopathy, but it can be as large. When restrictive cardiomyopathy affects both ventricles, clinical signs because of abnormalities of right-sided heart failure are apparent, with increased jugular venous pressure and peripheral edema. An early diastolic gallop (S3) is a rule in restriction, but it often is difficult to differentiate this sound from a pericardial knock which occurs at the nadir of the rapid “y” descent. Similar physical findings are present in patients with constrictive pericarditis although ascites is more common in patients with constrictive pericarditis.
Figure 24.20. Simultaneous pressure recordings from the left ventricle (LV) and pulmonary capillary wedge together with mitral inflow velocity on a Doppler echocardiogram. The onset of the respiratory phase is indicated at the bottom. Exp, expiration; Insp, inspiration. With the onset of expiration, pulmonary capillary wedge pressure (PCW) increases much more than LV diastolic pressure, creating a large driving pressure gradient (large arrowhead). With inspiration, however, PCW decreases much more than LV diastolic pressure, with a very small driving pressure gradient (three small arrowheads). These respiratory changes in the LV filling gradient are well reflected by the changes in the mitral inflow velocities recorded on Doppler echocardiography.
Figure 24.21. Hemodynamic filling patterns in constriction. A: Diagram of a heart with a thickened pericardium to illustrate the respiratory variation in ventricular filling and the corresponding Doppler features of the mitral valve, tricuspid valve, pulmonary vein (PV), and hepatic vein (HV). These changes are related to discordant pressure changes in the vessels in the thorax, such as pulmonary capillary wedge pressure (PCW) and intrapericardial (IP) and intracardiac pressures. Hatched area under curve indicates the reversal of flow. Thicker arrowsindicate greater filling. D, diastolic flow; S, systolic flow. B: Typical mitral inflow and hepatic vein pulsed-wave Doppler recordings in constrictive pericarditis along with simultaneous recording of respiration at the bottom (onset of inspiration at upward deflection and onset of expiration at downward deflection). Left: The first mitral inflow is at the onset of inspiration and the fourth mitral inflow is soon after the onset of expiration. Mitral inflow E velocity is decreased with inspiration (first and sixth beats). Right: There is a marked diastolic flow reversal (arrow) with expiration in the hepatic vein (sixth beat soon after the downward deflection of respirometer recording). Insp, inspiration; Exp, expiration.
Figure 24.22. Calculation of the extent of respiratory variation in mitral inflow E velocity is shown in the diagram and Doppler recording. Percent respiratory changes calculated as the difference between peak E velocity at expiration (E exp) and peak E velocity at inspiration (E insp) divided by E insp. In this example, E exp is 0.9 m/s and E insp is 0.6 m/s. Therefore, the difference in E velocity is 0.3 m/s, or 50% of E insp. RA, right atrium; RV, right ventricle; LA, left atrium; LV, left ventricle.
Electrocardiographic and chest radiographic findings are nonspecific. A calcified pericardium (which is present in about 20% of patients with constriction) should point to constrictive pericarditis. Echocardiographically, it may be difficult to distinguish between restriction and constriction only on the basis of M-mode and 2D findings, although diagnostic abnormalities may be detected with careful observation. In constrictive pericarditis, the most striking finding is ventricular septal motion abnormalities, which can be explained on the basis of respiratory variation in ventricular filling. The pericardium usually is thickened, but this may not be obvious on TTE. TEE measurements of pericardial thickness correlate well with those of electron-beam CT; however, other 2D, Doppler, and TDI findings should be able to differentiate a myopathic restrictive process from a pericardial constriction process as described above. In restrictive cardiomyopathy, mitral inflow Doppler velocity rarely shows respiratory variation (unless the patient also has chronic obstructive lung disease). However, each Doppler velocity pattern appears similar to that of constriction, with increased E velocity, an E/A ratio usually greater than 2.0, and a short deceleration time (DT) usually less than 160 ms. Hepatic vein Doppler flow reversals are more prominent with inspiration in restrictive cardiomyopathy, although it is not unusual to see significant diastolic flow reversals in the hepatic vein during both inspiration and expiration in patients with advanced constriction or with combined constriction and restriction. The Doppler features of constriction and restriction are summarized in Figure 24.27. Despite the significant difference in the pathophysiologic mechanisms of restriction and constriction, there is significant overlap in hemodynamic parameters between these two entities. Increased atrial pressures, equalization of end-diastolic pressures, and a dip-and-plateau or square root sign of the ventricular diastolic pressure recording have been advocated as hemodynamic features typical of constrictive pericarditis (Table 24.1). Hemodynamic pressure tracings can also be almost identical in constriction versus restrictive cardiomyopathy. Therefore, in addition to these hemodynamic features, respiratory variation in ventricular filling should be demonstrated to diagnose constriction, either invasively or noninvasively. The dissociation between intrathoracic and intracardiac pressure changes with inspiration are well demonstrated in simultaneous recordings of LV and pulmonary capillary wedge pressures. In constrictive pericarditis, the fluctuation in the pulmonary capillary wedge pressure is more marked in parallel with intrathoracic pressure changes than with changes in LA and LV diastolic pressure. Ventricular interdependence also is observed in simultaneous recordings of LV and RV pressures. With inspiration, which induces less filling of the left ventricle, LV peak systolic pressure decreases; the opposite changes occur in the right ventricle so that RV peak systolic pressure increases with inspiration. Ejection time also varies with respiration in opposite directions in the left and right ventricles. This discordant pressure change between the left and right ventricles in constrictive pericarditis does not occur in restrictive cardiomyopathy (Fig. 24.28).
Figure 24.23. Tissue Doppler imaging of the septal mitral annulus in constriction (A) and restriction (B). A: Early diastolic septal mitral annular velocity (Ε’) is 15 cm/s, which indicates relatively normal or even greater than normal longitudinal motion of the mitral annulus. In patients with heart failure and elevated jugular venous pressure, E’ velocity >8 cm/s should be equated with constrictive pericarditis (CP) until proved otherwise. B: E’ is markedly reduced (3 cm/s) in this patient with myocardial disease and heart failure. Reduced E’ correlates with abnormality in myocardial relaxation, which is reduced in almost all forms of cardiomyopathies. C: There is a very little overlap of E’ between constriction (CP) and myocardial disease. Distribution of septal mitral annulus E’ velocity in CP, cardiac amyloid, and primary restrictive cardiomyopathy (RCM). (From Ha J, Ommen S, Tajik A, et al. Differentiation of constrictive pericarditis from restrictive cardiomyopathy using mitral annular velocity by tissue Doppler echocardiography. Am J Cardiol. 2004;94:316–319.)
Figure 24.24. Doppler echocardiography in chronic obstructive lung disease. A: Pulsed-wave Doppler recording of mitral inflow velocity (MV) showing respiratory variation in a 50-year-old woman with chronic obstructive lung disease. There is 100% change in E velocity (from 0.6 m/s with inspiration to 1.2 m/s with expiration. Insp, inspiration; Exp, expiration. B: Pulsed-wave Doppler recording from the superior vena cava (SVC) showing a marked increase in SVC flow velocity with inspiration and a marked diminution with expiration. D, diastolic flow; DR, diastolic flow reversal; S, systolic flow
Figure 24.25. Pulsed-wave Doppler recording from the hepatic vein and superior vena cava (SVC) in a patient with constrictive pericarditis. Diastolic flow reversal (DR) increases (double arrowheads) in the hepatic vein with expiration (Exp) compared with DR with inspiration (Insp) (single arrowhead). However, there is a smaller diastolic flow reversal (double arrows) in the SVC during expiration compared with that in the hepatic vein. Diastolic flow reversal during inspiration is minimal (single arrow). Also, there was no significant change in the SVC forward flow velocity during inspiration and expiration, compared with SVC flow in chronic obstructive lung disease.
Figure 24.26. Mitral inflow Doppler velocity in a patient who developed constriction after mitral valve replacement. There is the typical respiratory variation in mitral E (early diastolic) velocity. Deceleration time is shortened despite the presence of mechanical mitral prosthesis because of increased left atrial pressure. Arrowhead, closing of mitral prosthesis. Exp, expiration; Insp, inspiration.
Figure 24.27. Diagram of Doppler velocities from mitral inflow (MV), mitral annular velocity, and hepatic vein (HV) and the electrocardiographic (ECG) and respirometer recordings (Resp) indicating inspiration (i) and expiration (e). D, diastolic flow; DR, diastolic flow reversal; DT, deceleration time; S, systolic flow; SR, systolic flow reversal; Blackened areas under curve, flow reversal. Typically, mitral inflow has respiratory variation, but not always.
Figure 24.28. Simultaneous LV and RV pressure tracings in restrictive cardiomyopathy (RCM) and constriction. See text for details. Again, the changes in LV and RV are opposite between RCM and constriction.
Effusive-constrictive pericarditis is an interesting condition that represents a unique clinical situation of combined pericardial effusion and constrictive pericarditis. Usually, a patient presents initially with pericardial effusion and clinical/hemodynamic evidence of increased filling pressures or tamponade/constriction. These constrictive hemodynamics persist even after removal or disappearance of the pericardial effusion. In some patients, the underlying constrictive pericarditis requires pericardiectomy, while in other patients, constrictive pericarditis is caused by a reversible inflammation of the pericardium (related to the same cause for pericardial effusion) and may resolve spontaneously or after treatment with antiinflammatory agent(s). The later condition has been termed transient constrictive pericarditis.
TRANSIENT CONSTRICTIVE PERICARDITIS
About 7% to 10% of patients with acute pericarditis or after pericardiocentesis have a transient constrictive phase. These patients usually have at least a moderate amount of pericardial effusion, and as the pericardial effusion disappears, the pericardium remains inflamed, thickened, and noncompliant, resulting in constrictive hemodynamics. The typical patient presents with dyspnea, peripheral edema, increased jugular venous pressure, and, sometimes, ascites, as in patients with chronic constrictive pericarditis. This transient constrictive phase may last 2 to 3 months before it gradually resolves either spontaneously or with treatment with antiinflammatory agents (Fig. 24.29). When hemodynamics and findings typical of constriction develop in patients with acute pericarditis, initial treatment is indomethacin (Indocin) for 2 to 3 weeks and, if there is no response, the use of steroids for an additional 1 to 2 months (60 mg daily for 1 week, then tapered over 6 to 8 weeks). An infectious etiology of the pericarditis should be ruled out before steroid therapy. Increased pericardial thickness usually returns to normal thickness with concomitant resolution of constrictive hemodynamics. The patients with transient constriction can be also detected by increased inflammatory biomarkers (sedimentation rate and c-reactive protein) and marked inflammation of the pericardium shown by delayed enhancement of the pericardium.
Figure 24.29. Computed tomography of the chest demonstrating increased pericardial thickness and pleural effusion (A), which disappeared after a course of steroid treatment (B). The patient has been free of constrictive symptoms since.
PERICARDIAL EFFUSION ASSOCIATED WITH MALIGNANCY
One of the more common primary tumors of the heart associated with pericardial effusion (PE) is angiosarcoma. A characteristic example is shown in Figure 24.30, in which a mass in the right atrium infiltrates the RA wall. The prognosis is very poor. Other malignant tumors associated with pericardial effusion include lymphoma, breast cancer, and lung cancer.
When TTE is not adequate for obtaining satisfactory imaging of the pericardium and hemodynamic assessment of ventricular filling, TEE should be considered. A hemodynamically compromising loculated pericardial effusion may be difficult to detect on TTE. TEE has been especially helpful in postoperative patients with tamponade because of loculated hemopericardium. TEE also is useful to obtain pulmonary venous pulsed-wave Doppler velocities with a simultaneous respirometer recording to more optimally evaluate constrictive pericarditis. Furthermore, TEE is helpful in measuring the thickness of the pericardium and in evaluating abnormal structures near the pericardium (e.g., pericardial cyst, metastatic tumor).
Echocardiography is typically one of the first diagnostic procedures used in patients in whom a pericardial abnormality is suspected. This noninvasive modality is capable of providing a complete assessment of the pericardial effusion (how much and how significant), identifying the best site for pericardiocentesis, and helping to establish or suggest the diagnosis of constrictive pericarditis. In some patients, constrictive pericarditis is transient, usually after acute pericarditis or pericardiocentesis. The development and resolution of transient constrictive hemodynamics are readily assessed with serial 2D and Doppler echocardiography. Detection of respiratory variation in mitral flow and central venous flow velocities may be the initial diagnostic clue to constrictive pericarditis, even in patients without any clinical suspicion of a pericardial abnormality. Comprehensive 2D and Doppler echocardiography with simultaneous recording of respiration should be able to distinguish constriction from restriction in nearly all patients. Detection of patients with constrictive pericarditis has improved greatly using echocardiography over the past 25 years at the Mayo Clinic as evidenced in the increasing volume of pericardiectomy for constrictive pericarditis (Fig. 24.31).
Figure 24.30. Apical four-chamber view showing a right atrial (RA) mass along with pericardial effusion. This is an example of malignant angiosarcoma.
Figure 24.31. Number of pericardiectomy cases for constriction since 1985 at Mayo Clinic.
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1.In the current era, what is the most common cause for constrictive pericarditis?
B.History of pericardial effusion
C.History of radiation therapy
D.Previous cardiac surgery
2.What is the outer sac of the normal pericardium called?
3.Which of the following is true in congenital absence of the pericardium?
B.More frequent in males
C.Chest pain is a frequent symptom
D.Unexplained syncope is a frequent symptom
4.In patients with congenital absence of the pericardium, which associated defects are frequently detected?
A.Tetralogy of Fallot
C.Left ventricular noncompaction
5.In a patient who has tamponade but no diastolic collapse of the right atrium or right ventricle, what is the expected right atrial pressure?
D.Cannot be determined
6.How is the mitral valve opening in constriction?
C.Effected by shortening of the IVRT
7.Which of the following findings would one expect in constriction?
A.Expiratory decrease in hepatic vein forward flow
B.Decrease in hepatic expiratory reversal flow
C.Inspiratory increase in pulmonary vein diastolic forward flow
D.Expiratory decrease in pulmonary vein diastolic forward flow
8.In constriction, which of the following is true?
A.Mitral septal e’ velocity is reduced
B.Mitral septal e’ velocity < mitral lateral annulus e’ velocity
C.Mitral septal e’ velocity > mitral lateral annulus e’ velocity
D.Mitral septal e’ velocity is not helpful
9.What is the term for the phenomenon described in Question #8?
10.Pericardial thickening and calcification can be observed with echocardiography in patients with constriction. What percent of patients with constriction have a calcified pericardium?
1.Answer: D. In the current era, previous cardiac surgery accounts for 25% of cases of constrictive pericarditis. The diagnosis can be challenging, especially in patients with congenital heart disease and coexisting myocardial dysfunction.
2.Answer: A. The normal pericardium consists of an outer sac (fibrous pericardium) and an inner sac (serous pericardium, which is divided into two layers (visceral and parietal layers).
3.Answer: B. Congenital absence of the pericardium is usually left-sided. It is more frequent in males and rarely creates symptoms such as chest pain, dyspnea, or syncope.
4.Answer: D. There is a high incidence of ASD, bicuspid aortic valve, and bronchogenic cysts in patients with congenital absence of the pericardium.
5.Answer: A. Diastolic collapse of the right atrium and right ventricle related to intrapericardial pressure rise above intracardiac pressure is a characteristic hemodynamic finding in tamponade. However, not all patients with tamponade will have a collapse of the right heart chambers. If right-sided pressures are elevated, no diastolic collapse may be evident.
6.Answer: D. Mitral valve opening is delayed in constriction. It is related to lengthening of the isovolumic relaxation time (IVRT) and is evident by a decrease in mitral valve E wave velocity with expiration.
7.Answer: A. The respiratory flow velocity changes across the mitral and tricuspid valves are also reflected in the pulmonary and hepatic flow velocities. Inspiratory decrease and expiratory increase in pulmonary vein diastolic forward flow, expiratory decrease in hepatic vein forward flow and increase in expiratory reversal flow.
8.Answer: C. Normally, lateral annulus e’ velocity is > septal e’ velocity. In restrictive cardiomyopathy, this is the case and e’ velocities are reduced. In constriction, septal e’ velocity is ≥ lateral annulus e’ velocity.
9.Answer: C. Kussmaul sign refers to inspection of the elevated jugular venous pressure in the neck veins during respiration in a patient with tamponade. Pulsus paradoxus refers to the drop in systolic blood pressure during respiration. Annulus paradoxus occurs inversely proportional to pulmonary capillary wedge pressure in constriction.
10.Answer: B. It may be difficult to distinguish pericardial thickening with echocardiography alone. CT and MRI are useful adjunctive imaging modalities in patients with suspected constriction.