Matthew M. Townsley and Michael L. Shelton
1. Despite the many and varied etiologies, the manifestations of pericardial disease are primarily expressed as pericardial effusion, inflammation, and constriction. The common theme is impaired cardiac filling and diastolic dysfunction.
2. A relatively small amount of fluid (50 to 100 mL) that accumulates acutely within the closed pericardial space is sufficient to dramatically increase intrapericardial pressure and interfere with cardiac filling. Conversely, a chronic increase in pericardial fluid will produce tamponade only after a large volume of fluid accumulation, perhaps as great as a liter.
3. The primary abnormality in cardiac tamponade is impaired cardiac filling caused by increased intrapericardial pressure. The right heart is most vulnerable to compression due to its thin walls and lower chamber pressures.
4. Tamponade is often described as Beck’s Triad: muffled heart sounds, jugular venous distension, and hypotension.
5. Pulsus Paradoxus (drop in systolic pressure during inspiration) occurs secondary to septal shift crowding the left ventricle during right ventricular filling. The opposite occurs during expiration. This phenomenon is described as enhanced ventricular interdependence.
6. Electrical alternans is due to the swinging motion of the heart in the pericardial sac.
7. Diastolic collapse lasting more than one-third of diastole demonstrated on echocardiography is fairly specific for tamponade.
8. Anesthetic induction in patients with tamponade can lead to cardiovascular collapse. If pericardiocentesis cannot be performed in a compromised patient and a surgical procedure is utilized instead, the patient should be prepped and draped prior to anesthetic induction so that surgery can proceed immediately after intubation. Volume loading prior to general anesthetic induction as well as inotropes may be required. Expect further deterioration after positive pressure ventilation is initiated.
9. Constrictive pericarditis (CP) is a diagnosis that encompasses a wide-spectrum of disease, from acute and subacute cases that may resolve spontaneously or with medical therapy to classic chronic progressive CP.
10. Although manifestations of hemodynamic instability are less with chronic pericarditis than with tamponade, induction and maintenance of anesthesia must encompass the same concerns.
The clinical significance of pericardial disease encompasses a wide spectrum, ranging from asymptomatic subclinical disease to acute life-threatening emergencies. This spectrum is best appreciated with a thorough understanding of the physiologic derangements these disorders place upon the heart and its function. In addition, the perioperative care of these patients requires an appreciation of how this altered physiology is influenced by anesthetic techniques and pharmacology. Further complicating the management of these patients are the underlying conditions causing the pericardial dysfunction, which introduce additional management concerns of their own. Despite the many and varied etiologies, the manifestations of pericardial disease are primarily expressed as pericardial effusion, inflammation, and constriction. Regardless, the common theme of most all pericardial pathology is impaired cardiac filling and diastolic dysfunction. This chapter reviews the normal structure and function of the pericardium, as well as the most common etiologies leading to pericardial disease. The two most clinically relevant pericardial disorders will be discussed in detail: cardiac tamponade and constrictive pericarditis.
II. Pericardial anatomy and physiology
A. The normal pericardium is a dual-enveloped sac surrounding the heart and great vessels. It comprises two layers: the parietal pericardium and the visceral pericardium. The parietal pericardium is a thick, fibrous outer layer composed primarily of collagen and elastin. It attaches to the adventitia of the great vessels, diaphragm, sternum, and the vertebral bodies. The inner visceral pericardium rests on the surface of the heart. It is composed of a single layer of mesothelial cells, which adhere to the pericardium. Normal pericardial thickness is 1 to 2 mm.
B. Two distinct sinuses are formed at points where the pericardium appears to fold onto itself. The oblique sinus forms posteriorly, between the left atrium and pulmonary veins, and is a common location for blood to collect after cardiac surgery. The transverse sinus also forms posteriorly behind the left atrium, situated behind the aorta and pulmonary artery (Fig. 20.1).
Figure 20.1 Anatomy of the pericardium and pericardial sinuses. The left image (A) demonstrates the heart in situ with a section of the parietal pericardium cut away. The left panel (B), with the heart cut away, demonstrates the oblique sinus (arrow at 6 o’clock) and the transverse sinus (arrow at 3 o’clock). (Reused from Lachman N, Syed FF, Habib A, et al. Correlative anatomy for the electrophysiologist, part 1: The pericardial space, oblique sinus, transverse sinus. J Cardiovasc Electrophysiol. 2010;21(suppl 12):1421–1426).
C. Normal cardiac function can still occur in the absence of the pericardium, making it nonessential for survival. However, it does provide several useful physiologic functions. It aids in the reducing friction between the heart and surrounding structures, limits acute dilatation of cardiac chambers, provides a barrier to infection, optimizes coupling of left and right ventricular filling and function, and limits excessive motion of the heart within the chest cavity. The pericardium is also metabolically active, secreting prostaglandins that affect coronary artery tone and cardiac reflexes .
D. The pericardium is a highly innervated structure. Pericardial inflammation or manipulation may produce severe pain or vagally mediated reflexes.
III. Causes of pericardial disease.
The etiologies of pericardial disease are numerous and can lead to pericardial inflammation, effusion, or both. Care of these patients must consider not only the pathological process of the pericardium, but the manifestations and complications of the underlying disease states. Pericardial disease can be caused by infection (e.g., viral, bacterial, fungal, tuberculosis), connective tissue disorders (e.g., systemic lupus erythematosus, sarcoidosis, rheumatoid arthritis), trauma, uremia, malignancy, post-myocardial infarction (Dressler’s Syndrome), or following cardiac surgery and other invasive cardiac procedures.
IV. Pericardial tamponade
A. Natural History
1. Etiology. The visceral pericardium is responsible for the production of pericardial fluid, which is an ultrafiltrate of plasma. This fluid provides lubrication to decrease friction between the pericardial layers. The pericardial space normally contains 10 to 50 mL of fluid, which is drained by the lymphatic system. As previously discussed, many conditions can cause fluid accumulation within the pericardial space, which may be serous, serosanguinous, purulent, or blood. However, the majority of cardiac effusions do not progress to tamponade. Tamponade occurs when the heart becomes extrinsically compressed by the contents of the pericardium, diminishing venous filling and, ultimately, cardiac output. In addition to effusion fluid, tamponade may also be caused by the accumulation of clot or air in the pericardial space. Acute, life-threatening tamponade most frequently results from bleeding into the pericardial space after cardiac surgery or other invasive cardiac procedures, following blunt chest trauma, or due to a ruptured ascending aortic aneurysm or aortic dissection . Tamponade may occur in as many as 8.8% of patients presenting for cardiac surgery, although it is more commonly seen after valve surgery than coronary artery bypass grafting (CABG). The onset is often in the immediate postoperative period, but may occur as late as several days following surgery. Frequently there is localized clot or effusion, which causes nonuniform compression of the cardiac chambers and manifests without the classical clinical features of tamponade (Fig. 20.2). The diagnosis of post-cardiac surgery tamponade can therefore be challenging, especially when considering the many potential causes of hemodynamic instability during this time period. Unfortunately, morbidity and mortality increases significantly the longer the diagnosis is delayed .
Figure 20.2 Regional tamponade following cardiac surgery. In this transesophageal (TEE) midesophageal four- chamber view, a localized clot is seen compressing both the right atrium and right ventricle (A). Chamber compression is relieved following clot removal (B). RA, right atrium; RV, right ventricle; LA, left atrium; LV, left ventricle. (Fontes ML, Skubas N, Osorio J. Cardiac tamponade. In: Yao FF, Fontes ML, Malhotra V, eds. Yao & Artusio’s Anesthesiology: Problem Oriented Patient Management. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008:327.)
2. Symptomatology. Symptoms of cardiac tamponade are usually rapid in onset, but depend upon the rate at which pericardial fluid accumulates. A relatively small amount of fluid (50 to 100 mL) that accumulates acutely within the closed pericardial space is sufficient to dramatically increase intrapericardial pressure and interfere with cardiac filling. However, a chronic increase in pericardial fluid will produce tamponade only after a large volume is present (>1 L). A gradual accumulation of fluid stretches the parietal pericardium, allowing larger volumes to be tolerated before symptoms occur. Lack of this pericardial stretch explains the abrupt onset of symptoms and clinical deterioration in the setting of acute tamponade. The primary symptoms of cardiac tamponade include dyspnea, orthopnea, diaphoresis, and chest pain. Dyspnea is often the first and most sensitive symptom .
B. Pathophysiology. The primary abnormality in cardiac tamponade is impaired diastolic filling of the heart, caused by increased intrapericardial pressure that leads to compression of the atria and ventricles. The right heart is most vulnerable to the compression due to its thinner walls and lower chamber pressures. Diastolic filling pressures (e.g., central venous pressure [CVP], left atrial pressure [LAP], pulmonary capillary wedge pressure [PCWP], left ventricular end-diastolic pressure [LVEDP] and right ventricular end-diastolic pressure [RVEDP]) become elevated and are nearly equal to each other, as well as the intrapericardial pressure, hence the terminology in tamponade of equalization of pressures. Physiologic manifestations of pericardial fluid, as previously discussed, are contingent upon the rate and amount of fluid accumulation, with a continuum ranging from clinically insignificant to severe hemodynamic collapse (Fig. 20.3). Ventricular preload and volume is critically reduced, which translates into decreased stroke volume, cardiac output, and systemic blood pressure. Compensatory sympathetic responses attempt to offset this reduction in stroke volume, with elevated levels of plasma catecholamines resulting in systemic vasoconstriction and tachycardia. This may temporarily maintain cardiac output and systemic perfusion; however, sudden hemodynamic collapse may rapidly occur with the depletion of catecholamines and/or continued elevation of intrapericardial pressure.
Figure 20.3 Pressure–volume relationship in acute versus chronic pericardial effusions. Intrapericardial pressure is contingent upon the change in intrapericardial volume. Pressure is relatively stable until a critical volume occurs. At this point, minimal increases in volume will lead to significant changes in intrapericardial pressure. With chronic effusions, pericardial stretch allows for a greater amount of volume to accumulate before critical increases in pressure occur. The lack of pericardial stretch explains the significant elevations in pressures seen with only small amounts of rapidly accumulating intrapericardial fluid. (Figure from Avery EG, Shernan SK. Echocardiographic evaluation of pericardial disease. In: Savage RM, Aronson SA, Shernan SK, eds. Comprehensive Textbook of Perioperative Transesophageal Echocardiography. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:726.)
C. Diagnostic evaluation and assessment
1. Clinical evaluation
a. Acute tamponade is often described by Beck’s triad: muffled heart sounds, jugular venous distention (JVD) due to increased venous pressure, and hypotension. Other common findings include tachypnea and tachycardia.
b. Pulsus paradoxus although not specific for tamponade, may be observed. This is defined as a decrease of more than 10 mm Hg in systolic arterial pressure occurring with inspiration. Tamponade physiology leads to respiratory variability in ventricular diastolic filling where the negative intrathoracic pressure accompanying inspiration leads to enhanced right-sided filling. Since total intrapericardial volume is fixed by the effusion, as the right ventricle (RV) fills, it will lead to a shift of the interventricular septum toward the left ventricle (LV). This crowding of the LV impedes its filling, decreasing LV stroke volume and explaining the exaggerated decline in systolic blood pressure seen with inspiration. The opposite is true during expiration, with diminished RV and enhanced LV filling. This phenomenon is described as enhanced ventricular interdependence, in which the diastolic filling characteristics of one ventricle can have pronounced influence on the filling of the other ventricle. Pulsus paradoxus is also seen in patients with chronic lung disease, right ventricular dysfunction, and CP.
c. Chest x-rays may show an enlarged, globular, bottle-shaped cardiac silhouette, with widening of the mediastinum. The right costophrenic angle is reduced to less than 90 degrees and the lung fields are clear. Pericardial fat lines in a lateral film are an uncommon, but highly specific, finding.
d. The ECG is nonspecific but may demonstrate sinus tachycardia, low-voltage QRS, nonspecific ST-T wave abnormalities, and electrical alternans. Electrical alternans (Fig. 20.4) is due to a swinging motion of the heart in the pericardial sac, leading to beat-to-beat changes in the electrical axis.
Figure 20.4 Electrical alternans with cardiac tamponade. Lead V3 demonstrates the variation in the R-wave axis in alternate beats. Note that this phenomenon is not seen in all electrocardiographic leads. (Figure from Hensley FA, Martin DE, Gravlee GR. A Practical Approach to Cardiac Anesthesia.3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2003:476.)
e. Table 20.1 summarizes the classic clinical manifestations most commonly described in cardiac tamponade.
Table 20.1 Cardiac tamponade-clinical manifestations
2. Catheterization data. Cardiac tamponade is a clinical diagnosis that cannot be made with catheterization data alone. However, common patterns of intracardiac pressures are usually seen. There is elevation and near equalization of the CVP, RVEDP, PCWP, LAP, and LVEDP. Increased central venous and right atrial pressures are seen with a prominent x-descent and a diminished or absent y-descent (Fig. 20.5).
Figure 20.5 Right atrial (RA) and pericardial pressures in cardiac tamponade. A: Note equal RA and pericardial pressures and the diminished y-descent of the RA waveform. B: After removal of 100 mL of fluid, the pericardial pressure is lower than RA pressure, and the normal large descent has returned. (Figure from Hensley FA, Martin DE, Gravlee GR. A Practical Approach to Cardiac Anesthesia. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2003:475.)
3. Echocardiography. Echocardiography is the diagnostic modality of choice in evaluating cardiac tamponade. It is the most sensitive tool for making the diagnosis of pericardial effusion. Initial evaluation should focus on the presence, size, and extent (circumferential versus localized/loculated) of the pericardial effusion. This is seen as an echo-free space surrounding the heart. The effusion should be measured to estimate its severity (Table 20.2).
Table 20.2 Estimation of effusion severity
Although echocardiography alone cannot definitively diagnose tamponade, in the presence of a pericardial effusion, there are several echocardiographic features consistently associated with tamponade physiology. With tamponade, right atrial (RA) collapse is a sensitive sign, typically beginning in end-diastole and continuing through systole. Systolic RA collapse persisting for more than one-third of the cardiac cycle is specific for tamponade. Diastolic RV collapse is observed, and when lasting for more than one-third of diastole is thought to be even more specific than systolic RA collapse for the identification of tamponade. End-diastolic dimensions of the RV will be reduced, reflective of diminished ventricular filling. Paradoxical motion of the interventricular septum is a frequent finding, reflecting the reciprocal respiratory variability in diastolic filling. These changes are also reflected with Doppler transmitral and transtricuspid inflow velocity profiles (Figs. 20.6–20.9).
Figure 20.6 Pericardial tamponade. Compression of both the right atrium and right ventricle by a large pericardial fluid collection. (Reused from Lobato EB, Muehlschlegel JD. Transesophageal echocardiography in the intensive care unit. In: Perrino AC, Reeves ST, eds. A Practical Approach to Transesophageal Echocardiography. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008:355.)
Figure 20.7 Pericardial effusion (EF) causing systolic right atrial (RA) collapse as seen in a TEE midesophageal four-chamber view. (From Avery EG, Shernan SK. Echocardiographic evaluation of pericardial disease. In: Savage RM, Aronson SA, Shernan SK, eds. Comprehensive Textbook of Perioperative Transesophageal Echocardiography. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:733.)
Figure 20.8 Diastolic right ventricular (RV) collapse in a patient with cardiac tamponade as seen in a TEE transgastric long-axis RV inflow view. RV collapse is indicated by the orange arrow. (From Avery EG, Shernan SK. Echocardiographic evaluation of pericardial disease. In: Savage RM, Aronson SA, Shernan SK, eds. Comprehensive Textbook of Perioperative Transesophageal Echocardiography. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:733.)
Figure 20.9 The pericardial space is occupied by a large amount of clot (marked by the orange arrows), seen adjacent to the lateral wall of the left ventricle (LV) in a transgastric short-axis midpapillary TEE view. (ECHO image from Avery EG, Shernan SK. Echocardiographic evaluation of pericardial disease. In: Savage RM, Aronson SA, Shernan SK, eds. Comprehensive Textbook of Perioperative Transesophageal Echocardiography. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:733.)
D. Treatment. Definitive treatment of cardiac tamponade is emergent drainage, which may be accomplished through either pericardiocentesis or surgical decompression.
1. Pericardiocentesis. Pericardiocentesis may be performed with or without imaging guidance (e.g., echocardiography, fluoroscopy). Imaging is often preferred to assist in safely guiding the needle tip through the pericardium to the most optimal location for drainage, as well as assessing the adequacy of fluid removal. Without imaging there is a significantly higher risk of complications, such as cardiac perforation, puncture of coronary or internal mammary arteries, and pneumothorax. In the setting of severe hemodynamic instability, however, it may be necessary to proceed without imaging due to the significant risk of rapid and profound clinical deterioration. A catheter is frequently left in the pericardial space to allow for continuous drainage (Fig. 20.10).
Figure 20.10 The most common needle insertion points for pericardiocentesis, including the paraxiphoid and apical approaches. When using the paraxiphoid approach, the needle tip should be directed toward the left shoulder. With the apical approach, the needle tip is aimed internally. (From Spodick DH. Acute cardiac tamponade. N Engl J Med. 2003;349:684–690.)
In addition to the previously discussed complications, several reports of post-pericardiocentesis pulmonary edema are reported in the literature. In some cases, severe pulmonary edema associated with life-threatening acute left ventricular dysfunction has been described. While the exact mechanism of this complication remains unclear, most agree that it is likely precipitated by the rapid removal of a large amount of fluid. Since systemic vascular resistance is usually elevated to compensate for tamponade physiology, rapid improvement in ventricular filling and volume following pericardiocentesis may precipitate ventricular distension and a detrimental increase in LV wall stress, leading to diminished forward stroke volume and pulmonary edema. If LV dysfunction is observed, it usually transient, with ventricular function returning to baseline in most cases, leading many to believe that myocardial stunning is also a component of this phenomenon. Pulmonary edema may be observed following the drainage of both acute and chronic fluid collections, however, and the anesthesiologist must be especially prepared for this complication whenever a large volume of fluid is rapidly removed in either circumstance .
2. Surgical drainage. Indications for surgical drainage include unsuccessful pericardiocentesis, localized/loculated effusions, removal of clot, and ongoing intrapericardial bleeding (e.g., acute aortic dissection, trauma, following cardiac surgery or percutaneous cardiac procedures). Surgical approach is primarily via subxiphoid pericardial window or a small anterior thoracotomy. The subxiphoid approach is easier to perform but offers a limited exposure, while a thoracotomy provides excellent exposure and is indicated if a larger surgical field is required. Both approaches allow for open exploration, facilitating the removal of clot and fibrinous debris. With hemorrhagic tamponade following cardiac surgery, full mediastinal exploration is needed to locate the source of bleeding and stabilize the patient. In the setting of malignant effusions, diagnostic pericardial biopsies can be obtained with a surgical approach to drainage . Some patients may continue to experience recurrent pericardial effusions, requiring consideration of pericardiectomy. This is most commonly seen in patients with malignant effusions or uremia .
E. Goals of perioperative management. The hemodynamic state of the patient will dictate the sequence of anesthesia and surgery. While general anesthesia is frequently used, it may contribute to clinical decompensation in severely compromised patients. Direct myocardial depression, systemic vasodilation, and diminished preload accompanying the induction of general anesthesia can lead to a profound decrease in cardiac output. Potentially life-threatening cardiac collapse can ensue. In this scenario, pericardiocentesis or subxiphoid pericardial window can be performed under local anesthesia. Frequently, hemodynamic instability is dramatically improved with the removal of only a small amount of fluid. This is due to the steep curve of the pressure-volume relationship of the pericardial contents . Following this initial drainage, the patient may become stable enough to tolerate the institution of general anesthesia for the remainder of the procedure.
1. Premedication with anxiolytics or opioids is best avoided in patients with true cardiac tamponade. Even small doses of these medications can precipitate acute cardiac collapse.
2. To facilitate ventricular filling, preload must be optimized with intravenous fluids prior to induction. Any manipulations that decrease venous return should be avoided or minimized as much as possible.
3. In addition to standard noninvasive monitors, an arterial line should be considered prior to induction to allow for beat-to-beat monitoring of systemic blood pressure. Adequate intravenous access is needed for volume replacement and drug administration. Central venous access may be beneficial, but is not always essential. In a severely unstable patient, however, surgical intervention should not be delayed for the placement of lines or monitors.
4. Before proceeding with induction, the patient should be fully prepped and draped. The surgical team should be standing at the operating room table and ready to make an immediate incision in the event of hemodynamic collapse upon induction.
5. The perioperative anesthetic plan should have the following hemodynamic goals (Table 20.3):
Table 20.3 Hemodynamic goals in cardiac tamponade
Heart rate should remain high and contractility optimized to preserve cardiac output, as these patients will have a fixed and reduced stroke volume. Adequate preload is essential to promote right ventricular filling. Decreases in systemic vascular resistance must be avoided, as this will reduce systemic perfusion pressure.
6. Positive-pressure ventilation can cause a dramatic decline in preload and cardiac output. It is suggested that patients with tamponade be allowed to breathe spontaneously until the pericardial sac is opened and drained. If spontaneous ventilation is not possible, ventilation with high respiratory rates and low tidal volumes should be considered to minimize mean airway pressure.
7. Careful consideration should be given to the selection of induction drugs, with particular attention aimed at minimizing myocardial depression and peripheral vasodilation. Etomidate is a reasonable induction agent, producing minimal decreases in contractility and systemic vascular resistance. Hypotension may still occur, however, as hypovolemia and tamponade physiology will magnify its typically minimal hemodynamic effects. Benzodiazepines are also a reasonable choice. Many advocate the use of ketamine in this setting, relying on the sympathetic stimulation it provides to minimize hemodynamic compromise. However, many patients have a diminished ability to increase their own sympathetic nervous system activity and these effects are not observed. In these patients, the myocardial depressant properties of ketamine will be unmasked and significant hypotension is likely to occur. Opioids should be given with caution, as vagally mediated bradycardia can lead to a decline in cardiac output.
8. Inotropes (e.g., epinephrine, norepinephrine) and vasoconstrictors (e.g., phenylephrine, vasopressin) may be needed to maintain cardiac output and peripheral perfusion, but serve only as a temporizing measure until tamponade can be definitively treated with drainage.
9. Tamponade physiology is rarely seen in patients presenting for surgical drainage of chronic, recurrent pericardial effusions. In this scenario, however, it is still essential to obtain as much information as possible regarding the clinical significance and severity of the effusion. This should include a review of the preoperative echocardiogram, a thorough discussion with the surgeon, and a detailed history and physical examination, focusing in particular on any vital sign abnormalities. Although tamponade physiology is rare, a high index of suspicion should be maintained for the potential of perioperative hemodynamic instability.
V. Constrictive pericarditis
A. Natural history
1. Etiology. CP is a diagnosis that encompasses a wide spectrum of disease, from acute or subacute cases that may resolve spontaneously or with medical therapy, to the classic chronic, progressive CP, which will be the focus of this section. Other entities noted in the literature include effusive-constrictive pericarditis, in which patients present with cardiac effusion or tamponade but retain characteristics of CP following drainage of the effusion; localized CP, involving only parts of the pericardium with variable hemodynamic sequelae; and occult CP, in which rapid infusion of intravenous fluids can provoke the signs and symptoms of the disease . While many etiologies have been documented, the most common include idiopathic, viral, post-cardiac surgery, mediastinal radiation, and, in developing countries, tuberculosis.
2. Symptomatology. CP presents most commonly as chronic and progressive fatigue, orthopnea, dyspnea on exertion, peripheral edema, and abdominal distention. Given the nonspecific nature of these findings, care must be taken to differentiate this disease process from others such as hepatic failure, right ventricular failure, tricuspid valve disease, and, most importantly, restrictive cardiomyopathy. As the pathophysiology underlying these conditions is markedly different, the medical and surgical management will vary considerably as well.
B. Pathophysiology. The hallmark of CP is a thickened, often calcified, adherent pericardium, which effectively confines the heart inside a rigid shell. From a pathophysiologic perspective, this has three major consequences :
1. Impaired diastolic filling. The noncompliant pericardium limits filling of all cardiac chambers, with elevation and near-equalization of end-diastolic pressures. Ventricular filling occurs rapidly during early diastole but ceases abruptly as the volume, and thus pressure, in the ventricle reaches a critical point. This results in the characteristic “dip and plateau,” or “square root sign,” noted in ventricular pressure tracings (Fig. 20.11). Atrial systole does little to augment LV filling, and cardiac output is maintained by a compensatory increase in heart rate.
Figure 20.11 Waveform characteristics commonly seen during catheterization of patients with CP before (A) and after (B) pericardiectomy. Note the “square root sign” in the right ventricular (RV) pressure tracing, and the “M” waveform in the central venous pressure (CVP) tracing prior to pericardiectomy. ECG, electrocardiogram; PA, pulmonary artery. (Figure from Skubas NJ, Beardslee M, Barzilai B, et al. Constrictive pericarditis: intraoperative hemodynamic and echocardiographic evaluation of cardiac filling dynamics. Anesth Analg.2001;92:1424–1426.)
2. Dissociation of intrathoracic pressures. The rigid pericardium isolates the cardiac chambers from the negative pressure generated during inspiration, resulting in a decreased gradient between the pulmonary veins and the left atrium. Consequently, left heart filling, and thus cardiac output, are decreased.
3. Ventricular interdependence. As discussed previously, left and right heart filling are not independent events. Increases in right heart filling may cause a leftward shift in the interventricular septum at the expense of left heart filling. Expiration, as would be expected, reverses this pattern. This phenomenon is known as ventricular interdependence, and is exaggerated in CP.
One of the most important consequences of pericardial constriction is significant respiratory variation in left and right ventricular filling patterns. This is an important consideration in the diagnosis of CP, and provides the foundation for the diagnostic workup to be discussed later. Of note, this respiratory variation is maintained, but reversed, in patients on mechanical ventilation .
C. Diagnostic evaluation and assessment
1. Clinical evaluation
a. The diagnosis of CP is difficult to make on history and physical examination alone, but must be considered in patients presenting with the signs and symptoms of venous congestion mentioned previously. On examination, JVD with Kussmaul’s sign (an increase in JVD on inspiration) and Friedreich’s sign (a rapid decrease in JVD during early diastole) may be present. Pulsus paradoxus, initially described by Kussmaul in patients with CP, may be present but is more common in patients with cardiac tamponade or in those with concurrent effusion with tamponade physiology . On cardiac auscultation, a “pericardial knock” may be noted. This is a high-pitched sound in early diastole that is caused by the sudden cessation of ventricular filling, and is a highly specific but insensitive clue to the diagnosis. Pulmonary edema is often absent, and pulsatile hepatomegaly may be noted on abdominal examination.
b. Laboratory investigation may reveal organ dysfunction secondary to the disease process (e.g., kidney injury, elevated liver enzymes). Natriuretic peptide levels, which are released in response to myocardial stretch and are increased in many cases of heart failure, are usually normal or only slightly elevated. This is attributed to the rigid pericardium limiting the amount of chamber dilation possible.
c. ECG findings are nonspecific and may include sinus tachycardia, atrial fibrillation, conduction delays, p-mitrale, and ST-segment and T-wave changes.
d. While calcification of the pericardium is not universal, its presence on the lateral chest x-ray may suggest CP. A thickened pericardium (>2 mm) may be appreciated on CT or MRI, and other imaging techniques may demonstrate the pericardium adherent to the myocardium.
2. Catheterization data. As in tamponade, cardiac catheterization is not always necessary for the diagnosis of CP. However, it may be helpful in the diagnosis of effusive-constrictive pericarditis, with some suggesting its routine use during the drainage of pericardial effusions. Certain waveform characteristics may be seen during placement of invasive monitors in the operating room. Right atrial pressure tracings may show “M” or “W” waveforms with a prominent y-descent, the diagnostic equivalent of Friedreich’s sign. Ventricular pressure tracings may show the characteristic “dip and plateau,” or “square root sign,” as previously described. The end-diastolic pressures in all chambers are elevated and nearly equal (≤5 mm Hg difference), and RV systolic pressures are usually <50 mm Hg with an RV end-diastolic to RV systolic ratio of >1:3.
3. Echocardiography. Echocardiography is essential to the diagnosis of CP, and more advanced techniques have become useful in its differentiation from other disease processes. Two-dimensional and M-mode examination may show a thickened, hyperechoic pericardium; diastolic flattening of the LV posterior wall, reflective of the abrupt cessation of ventricular filling; a ventricular septal “bounce,” caused by the sudden changes in the transseptal pressure gradient; premature closure of the mitral valve and opening of the pulmonic valve, indicative of high chamber pressures; enlarged hepatic veins; and IVC plethora, where the vessel remains dilated and lacks the normal change in diameter during the respiratory cycle. Doppler evaluation of transmitral, transtricuspid, and pulmonary vein flow show characteristic tracings with profound respiratory variation (often >25%; Fig. 20.12), and newer techniques such as Doppler tissue imaging (DTI) of the mitral annulus and color Doppler M-mode of transmitral flow (propagation velocity; Fig. 20.13) allow further characterization and differentiation from restrictive cardiomyopathy  (Table 20.4).
Table 20.4 Clues to the differentiation of constrictive pericarditis and restrictive cardiomyopathy
Figure 20.13 TEE image of the transmitral color M-mode (propagation velocity, Vp) profile of a patient with CP. The slope of the first aliasing velocity is used in this determination and is depicted by the pink line. (ECHO image from Avery EG, Shernan SK. Echocardiographic evaluation of pericardial disease. In: Savage RM, Aronson SA, Shernan SK, eds. Comprehensive Textbook of Perioperative Transesophageal Echocardiography. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:738.)
Figure 20.12 TEE pulsed wave transmitral Doppler profile in a patient with CP during positive pressure ventilation. Note the preserved, but reversed, respiratory variation as opposed to that which would be seen in a spontaneously ventilating patient. Insp, inspiration; Exp, expiration. (From Avery EG, Shernan SK. Echocardiographic evaluation of pericardial disease. In: Savage RM, Aronson SA, Shernan SK, eds. Comprehensive Textbook of Perioperative Transesophageal Echocardiography. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2011:737.)
D. Treatment. As mentioned, some cases of acute constriction may resolve spontaneously or with medical management. The definitive management of chronic CP, however, is usually surgical. Pericardiectomy, or pericardial decortication, is often performed via left thoracotomy or midline sternotomy, depending on the extent of resection necessary. The goal of treatment is total resection of both the visceral and parietal pericardium, and while this can often be performed without the use of cardiopulmonary bypass (CPB), its use may be indicated in more difficult dissections. Despite improvements in surgical technique, operative mortality remains as high as 10%, with poor predictors including prior cardiac surgery, radiation, malignancy, and advanced heart failure on presentation. As opposed to patients with tamponade, where surgical drainage may provide immediate improvement in hemodynamic and clinical status, an immediate improvement in symptoms is not generally observed.
E. Goals of perioperative management. The hemodynamic instability of patients with CP is generally less than those patients with acute tamponade, unless a concurrent effusion with tamponade physiology is present. However, many of the same principles can be applied to the perioperative management of the patients.
1. Premedication with benzodiazepines and/or opioids must be titrated according to the patient’s preoperative status.
2. In addition to standard noninvasive monitors, the intraoperative and postoperative management of patients with CP often requires invasive monitors. An arterial line is beneficial for blood gas analysis, especially with surgery via thoracotomy, as well as continuous blood pressure monitoring during cardiac manipulation and when CPB is utilized. The decision to place this preoperatively or after induction of anesthesia must take into account the patient’s clinical status. Adequate intravenous access must be obtained given the possibility of marked and precipitous blood loss (cardiac chamber or coronary artery perforation, myocardial injury due to stripping of the pericardium, etc.), with central venous access allowing the rapid infusion of IV fluids, blood components, and vasoactive drugs, as well as the monitoring of CVP. Volume status and continuous cardiac output monitoring via a pulmonary artery catheter may be beneficial as well, as low cardiac output syndrome may persist into the postoperative period . While echocardiography plays a more important role in the preoperative diagnosis of CP, intraoperative TEE can provide useful information for both the surgeon and the anesthesiologist.
3. Pericardiectomy requires general anesthesia, and care must be taken to avoid hemodynamic deterioration during the induction and maintenance of anesthesia. Preload must be maintained, and often augmented, to ensure cardiac filling, and reductions in either preload or afterload may be poorly tolerated. Heart rate plays an important role in maintaining cardiac output, and bradycardia must be avoided. While the atrial “kick” does little to enhance ventricular filling in patients with CP, extreme tachycardia, such as atrial fibrillation with a rapid ventricular rate, may be poorly tolerated. Contractility should be maintained as well, as significant myocardial depression will adversely impact cardiac output and systemic flow.
4. Although the manifestations of hemodynamic instability are less than with tamponade, induction and maintenance of anesthesia must include the same considerations. Vasoactive medications must be readily available to offset any perturbations caused by the anesthetic agents or surgical manipulations, most notably decreased preload, afterload, contractility, and heart rate.
1. Little WC, Freeman GL. Contemporary reviews in cardiovascular medicine: pericardial disease. Circulation. 2006;113: 1622–1632.
2. O’Connor CJ, Tuman KJ. The intraoperative management of patients with cardiac tamponade. Anesthesiology Clin. 2010;28: 87–96.
3. Oliver WC, Mauermann WJ, Nuttall GA. Uncommon cardiac diseases. In: Kaplan JA, Reich DL, Savino JS, eds. Kaplan’s Cardiac Anesthesia: The Echo Era. 6th ed. St. Louis, MO: Elsevier Saunders; 2011:706–713.
4. Gandhi S, Schneider A, Mohiuddin S, et al. Has the clinical presentation and clinician’s index of suspicion of cardiac tamponade changed over the past decade? Echocardiography. 2008;25:237–241.
5. Bernal JM, Pradhan J, Li T, et al. Acute pulmonary edema following pericardiocentesis for cardiac tamponade. Can J Cardiol. 2007;23(suppl 14):1155–1156.
6. Dinardo JA, Zvara DA. Anesthesia for Cardiac Surgery. 3rd ed. Malden, MA: Blackwell Publishing; 2008:289–303.
7. Sagrista-Salueda J. Pericardial constriction: Uncommon patterns. Heart. 2004;90:257–258.
8. Myers RB, Spodick DH. Constrictive pericarditis: Clinical and pathophysiologic characteristics. Am Heart J. 1999;138: 219–232.
9. Abdalla IA, Murray RD, Awad HE, et al. Reversal of the pattern of respiratory variation of Doppler inflow velocities in constrictive pericarditis during mechanical ventilation. J Am Soc Echocardiogr.2000;13:827–831.
10. Bilchick KC, Wise RA. Paradoxical physical findings described by Kussmaul: Pulsus paradoxus and Kussmaul’s sign. Lancet. 2002;359(suppl 9321):1940–1942.
11. Rajagopalan N, Garcia MJ, Rodriguez L, et al. Comparison of new Doppler echocardiographic methods to differentiate constrictive pericardial heart disease and restrictive cardiomyopathy. Am J Cardiol. 2001;87:86–94.