Differentiation of constrictive pericarditis and restrictive cardiomyopathy by radionuclide ventriculography

Nuclear imaging in cardiac amyloidosis

Amyloidosis is a disease characterized by depositions of amyloid in organs and tissues. It can be localized (in just one organ) or systemic. Cardiac amyloidosis is a debilitating disease and can lead to arrhythmias, deterioration of heart function and even sudden death. We reviewed PubMed/Medline, without time constraints, on the different nuclear imaging modalities that are used to visualize myocardial amyloid involvement. Several SPECT tracers have been used for this purpose. The results with these tracers in the evaluation of myocardial amyloidosis and their mechanisms of action are described. Most clinical evidence was found for the use of (123)I-MIBG. Myocardial defects in MIBG activity seem to correlate well with impaired cardiac sympathetic nerve endings due to amyloid deposits. (123)I-MIBG is an attractive option for objective evaluation of cardiac sympathetic level and may play an important role in the indirect measurement of the effect of amyloid myocardial infiltration. Other, less sensitive, options are (99m)Tc-aprotinin for imaging amyloid deposits and perhaps (99m)Tc-labelled phosphate derivatives, especially in the differential diagnosis of the aetiology of cardiac amyloidosis. PET tracers, despite the advantage of absolute quantification and higher resolution, are not yet well evaluated for the study of cardiac amyloidosis. Because of these advantages, there is still the need for further research in this field.

Assessment of cardiac function: magnetic resonance and computed tomography

A complete cardiac study requires both anatomic and physiologic evaluation. Cardiac function can be evaluated noninvasively by magnetic resonance imaging (MRI)or ultrafast computed tomography (CT). MRI allows for evaluation of cardiac function by cine gradient echo imaging of the ventricles and flow analysis across cardiac valves and the great vessels. Cine gradient echo imaging is useful for evaluation of cardiac wall motion, ventricular volumes and ventricular mass. Flow analysis allows for measurement of velocity and flow during the cardiac cycle that reflects cardiac function. Ultrafast CT allows for measurement of cardiac indices similar to that provided by gradient echo imaging of the ventricles.

The effect of respiration on left ventricular diastolic filling as assessed by radionuclide ventriculography

Left ventricular function is modified by respiration and pericardial constraint. The aim of this study was to compare left ventricular systolic and diastolic function during inspiration and expiration in four patient groups: patients (1) without cardiac disease, (2) with severe pulmonary disease, (3) with cardiac amyloid and (4) with pericardial constriction (before and after pericardiectomy). Using blood-pool left ventriculography with modified gating, we obtained time-activity curves at the onset of inspiration and expiration. On inspiration and expiration, patients with pericardial constriction and patients with cardiac amyloid were significantly different from those without cardiac disease and those with severe pulmonary disease, in that left ventricular ejection fraction (LVEF) was less, peak filling rate was greater, time to peak filling rate was shorter, and rapid filling fraction was increased. When inspiration and expiration were compared, time to left ventricular peak filling rate was shorter (P = 0.05) on inspiration (118 +/- 48 ms) than on expiration (168 +/- 35 ms) in patients with pericardial constriction. No other measures differed between inspiration and expiration in pericardial constriction, and left ventricular function was unaffected by respiration in the other groups. Time to left ventricular peak filling rate was 49 +/- 69 ms less on inspiration than on expiration in pericardial constriction and this difference was significantly different (P = 0.04) from that in patients with cardiac amyloid (34 +/- 58 ms greater), patients without cardiac disease (2 +/- 69 ms greater) and patients with severe pulmonary disease (19 +/- 63 ms less). In pericardial constriction, pericardial resection caused an increase in LVEF without a change in left ventricular diastolic filling but abolished the differences present between inspiration and expiration in time to left ventricular peak filling rate. This respiratory response in time to left ventricular peak filling rate may be valuable in the diagnosis of pericardial constriction.

Constrictive pericarditis: clinical and pathophysiologic characteristics

Constrictive pericarditis is an uncommon disorder with various causes. Although most often idiopathic, it may also occur after cardiovascular surgery, radiation therapy, and tuberculosis, especially in developing countries. The encasement of the heart by a rigid, nonpliable pericardium results in characteristic pathophysiologic effects, including impaired diastolic filling of the ventricles, exaggerated ventricular interdependence, and dissociation of intracardiac and intrathoracic pressures during respiration. Constrictive pericarditis typically presents with chronic insidious signs and symptoms of predominantly systemic venous congestion. Notoriously difficult to diagnose and distinguish from restrictive cardiomyopathy (RCM), the use of cardiac catheterization, echocardiography (transthoracic and transesophageal), central venous (hepatic and pulmonary) and transvalvular Doppler measurements, and magnetic resonance imaging should secure the diagnosis in most cases, eliminating the need for diagnostic thoracotomy. Although medical treatment may temporarily alleviate symptoms of heart failure, patients do poorly without pericardiectomy.

Ventricular function

Multiple modalities contribute to the evaluation of ventricular function. The role of cineangiography, echocardiography, MR imaging, ultrafast CT, and nuclear medicine continue to evolve and improve our understanding of the physiology and pathophysiology of ventricular function. This article discusses the use and limitation of each modality.

Right and left ventricular wall motion velocities as diagnostic indicators of constrictive pericarditis

The purpose of this study was to examine the usefulness of pulsed tissue Doppler imaging for diagnosing constrictive pericarditis. Motion velocities of the ventricular septum (VS) and left ventricular (LV) posterior wall along the short axis, and those of the anterior right ventricular (RV) wall, VS, and LV posterior wall along the long axis were recorded using pulsed tissue Doppler imaging in 12 patients with constrictive pericarditis, who were diagnosed by cardiac catheterization, and also in 20 normal subjects. Peak early diastolic and atrial systolic velocities (Ew and Aw, respectively) were calculated, and the time between the aortic component of the second heart sound and the peak of the early diastolic velocity (IIA-Ew) was determined. The peak Ew and II A-Ew along the short and long axes were significantly higher and shorter, respectively, in the patient group than in the normal group. In the patient group, the motion velocity of the VS along the short axis showed a "backward" motion with a sharp and marked peak velocity immediately before Ew, or a biphasic early diastolic wave; a clear "downward" motion immediately after Ew was observed in the motion velocities of the anterior RV wall, VS, and LV posterior wall along the long axis. These distinctive backward and downward motions were not observed in any of the ventricular walls of the normal subjects. In conclusion, the early diastolic RV and LV wall motion velocity patterns along the short and long axes as measured by pulsed tissue Doppler imaging provide important information for the diagnosis of constrictive pericarditis.

Effects of changes in atrioventricular gradient and contractility on left ventricular filling in human diastolic cardiac dysfunction

The factors responsible for abnormalities in diastolic filling indexes as assessed by noninvasive testing in human beings have been extensively studied but are not completely understood. We therefore investigated left ventricular diastolic filling indexes by radionuclide angiography during right atrial pacing simultaneously with assessment of a directly measured left atrioventricular gradient and a time constant of isovolumic relaxation in 11 patients with hypertension and diastolic dysfunction. Loading conditions were altered with nitroprusside and phenylephrine, and contractility was improved by dobutamine infusion. The maximum left atrioventricular gradient at constant heart rates was determined by loading conditions and was not significantly affected by increases in contractility or an improvement in isovolumic relaxation rate. The peak filling rate according to radionuclide angiography was highly dependent on the atrioventricular gradient and was not affected by enhancement of the isovolumic relaxation rate.

Radionuclide angiography and magnetic resonance imaging: complementary non-invasive methods in the diagnosis of constrictive pericarditis

Constrictive pericarditis presents with a suggestive clinical picture, and its diagnosis is based on a haemodynamic pattern revealing impaired ventricular filling. In this study of 15 patients with pure isolated constrictive pericarditis, we attempted to evaluate the diagnostic value of two non-invasive methods not usually employed in this indication: radionuclide angiography (RNA) and magnetic resonance imaging (MRI). Whilst RNA permits analysis of the functional pattern of the global and segmental left ventricular filling impairment, MRI allows measurement of the thickness of the pericardium. RNA revealed increased early diastolic filling as evidenced by a shorter one-third filling time (TF1/3; P<0.0001 with respect to a normal population), a higher peak filling rate (PFR; P<0.01) and its early occurrence (P<0.001), increased one-third and mid diastolic filling fractions (P<0.01), and the ratio of the PFR over the peak ejection rate (P<0.01). During late diastole, the atrial filling fraction decreased (NS). The patients with constrictive pericarditis also showed a decrease in the physiological filling asynchrony, as assessed by segmental evaluations. Seven patients underwent MRI. The pericardium was thickened in all the patients, varying from 6 to 14 mm (normal: 2.5+/-0.7 mm), without any systolo-diastolic variation. Pericardial thickening appeared as a dark low-intensity signal band, demonstrating the fibrocalcific nature of the pericardial contents. Sagittal and coronal cross-sections were particularly well-suited to show the non-uniformity of the pericardial thickening. These results indicate that RNA and MRI are complementary non-invasive methods, and can provide the functional and anatomical information required for the diagnosis of constrictive pericarditis.

Mechanisms, diagnosis, and treatment of diastolic heart failure

Diastolic heart failure, in the absence of LV systolic dysfunction, is a common clinical condition that can be demonstrated in as many as one third of patients with congestive heart failure. Diastolic dysfunction caused by abnormalities in LV filling can be a result of many pathologic conditions, including hypertrophy, infiltrative cardiomyopathies, or myocardial ischemia. The major physiologic determinants of LV filling can be divided into cellular mechanisms, hemodynamic characteristics, and hormonal influences. Cellular mechanisms for impaired LV inactivation are determined by the handling of calcium within the myocyte during excitation-contraction-relaxation coupling. The hemodynamic characteristics of LV diastolic filling are determined by loading conditions, the time constant of isovolumic relaxation, heart rate, ventricular nonuniformity, pericardial restraint, myocardial elasticity, chamber compliance, and coronary blood flow. The sympathetic nervous system and the renin-angiotensin system are important modulators of diastolic filling, directly or indirectly. The diagnosis of heart failure is confirmed by a combination of clinical tests including invasive and noninvasive techniques, each of which has advantages and disadvantages. Treatment of medical conditions in which diastolic heart failure is a prominent component include pharmacotherapy with calcium channel antagonists, beta-adrenergic blocking agents, diuretic agents, and angiotensin-converting-enzyme inhibitors. Certain conditions associated with diastolic filling abnormalities such as pericardial disease or severe ischemic heart disease may be best managed by surgical or percutaneous intervention. Future research will include further delineation of the cellular mechanisms of active myocardial relaxation and clinical investigation into treatment directed at improving outcome.

Constrictive pericarditis: its history and current status

The diagnosis of constrictive pericarditis remains a challenge because it is often mimicked by restrictive cardiomyopathy. The last few years have seen numerous advances in our ability to differentiate between these two conditions which often have similar physical findings and hemodynamics. This review begins with a brief history of constrictive pericarditis; this is followed by an extensive discussion of newer etiologies, and then the classical clinical history and physical examination findings are described. Radiologic, electrocardiographic, and angiographic findings are discussed. The hemodynamics of constrictive pericarditis are reviewed. Recent results of echocardiographic and echo-Doppler investigations are presented. Emphasis is placed upon the limitations of M-mode echocardiography in the diagnosis of constrictive pericarditis. The value of echocardiographic Doppler studies of mitral and tricuspid flow velocity patterns, as well as of those in the pulmonary veins and hepatic veins, is described. Nuclear ventriculograms and angiocardiograms tend to show more rapid ventricular filling in constrictive pericarditis than in restrictive cardiomyopathy. Although only a small number of patients has been studied, these evaluations seem to have merit in separating restrictive cardiomyopathy from constrictive pericarditis. The role of computed tomography scanning and magnetic resonance imaging studies of pericardial thickness in confirming the presence of constrictive pericarditis is discussed. Abnormal pericardial thickening (> 3 mm) confirms the diagnosis of constrictive pericarditis, but only if the characteristic hemodynamic pattern is present. The usefulness of endomyocardial biopsy in recognizing specific varieties of restrictive cardiomyopathy is presented.(ABSTRACT TRUNCATED AT 250 WORDS)

Accurate preoperative diagnosis of pericardial constriction using cine computed tomography

OBJECTIVES

The purpose of this study was to determine the accuracy of cine computed tomography in the diagnosis of constrictive pericarditis.

BACKGROUND

Constrictive pericarditis is characterized by abnormalities of both cardiac structure and function. Accurate diagnosis requires detection of both a thickened pericardium and abnormal ventricular diastolic filling. At present, no one diagnostic technique has demonstrated sufficient accuracy in this setting. Cine computed tomography is a relatively new cardiac imaging mode with very high time and spatial resolution that has the potential to accurately diagnose constrictive pericarditis.

METHODS

Twelve consecutive patients were retrospectively identified who had catheterization findings suggestive of constrictive physiology, had undergone a cine computed tomographic examination and had pathologic data that delineated the status of the pericardium. Group 1 (with constrictive pericarditis; n = 5) had surgical confirmation of thickened pericardium and improved clinically after pericardiectomy. Group 2 (no constrictive pericarditis; n = 7) had cardiomyopathy with normal pericardium. Seven normal volunteers (Group 3) were also studied. Cine computed tomograms were obtained for the entire heart (8-mm slices, 17 frames/s, nonionic contrast medium). Pericardial thickness was measured at 10 degrees intervals at three ventricular levels in each subject. The rapidity of diastolic filling was assessed by calculating the percent filling fraction in early diastole.

RESULTS

Pericardial thickness was 10 +/- 2 mm (mean +/- SD) in Group 1, 2 +/- 1 mm in Group 2 and 1 +/- 1 mm in Group 3 (p < 0.05, constrictive pericarditis vs. no constrictive pericarditis). Left ventricular filling fraction was 83 +/- 6% in Group 1, 62 +/- 9% in Group 2 and 44 +/- 5% in Group 3. Right ventricular filling fraction was 93 +/- 5% in Group 1, 62 +/- 14% in Group 2 and 35 +/- 6% in Group 3 (p < 0.05, Group 1 vs. Groups 2 and 3). Both indexes provided a clear-cut distinction between patients with and without constriction.

CONCLUSIONS

Cine computed tomography simultaneously provides both anatomic and physiologic data that allow accurate preoperative diagnosis of pericardial constriction.

The differentiation between restrictive cardiomyopathy and constrictive pericarditis: the impact of the imaging techniques

The differentiation between constrictive pericarditis and restrictive cardiomyopathy remains a difficult problem for clinical cardiologists. Recent advances in imaging techniques and the understanding of diastolic function have created a new diagnostic approach to this problem. In this article we will summarize the recent advances in the understanding of the pathophysiology of both disorders and how this is reflected mainly in the use of flow imaging techniques, such as Doppler echocardiography and radionuclide angiography. Combined with the advances in the radiological imaging of the pericardium by means of computed tomography and magnetic resonance imaging, an integrated approach to the differential diagnostic problem is proposed and an algorithm for clinical use has been designed.

A fatal case of constrictive pericarditis due to a marked, selective pericardial accumulation of amyloid

Distinguishing constrictive pericarditis from restrictive cardiomyopathy, usually due to amyloidosis, is a relatively frequent and difficult diagnostic problem. This report describes, for the first time, a patient with constrictive pericarditis caused by direct, extensive infiltration of the pericardium by amyloid, with only minimal amyloid in the myocardium, and a normal heart weight of 320 g. This patient demonstrates that amyloid may be predominantly deposited in the pericardium and actually cause constrictive pericarditis, as well as simulate its hemodynamic presentation by myocardial deposition. Given a clinical and hemodynamic presentation compatible with either constrictive or restrictive disease, an endomyocardial biopsy or other biopsy revealing amyloidosis does not necessarily rule out pericardial constriction that may be due to amyloid infiltration. The relationship between constrictive pericarditis, seen in this patient, and the other more common manifestations of amyloid heart disease, and the hemodynamic profiles of amyloid cardiomyopathy and constrictive pericarditis are reviewed.

Constrictive pericarditis versus restrictive cardiomyopathy: a reappraisal and update of diagnostic criteria

Distinguishing constrictive pericarditis from restrictive cardiomyopathy is a difficult clinical challenge. We review published reports in which hemodynamic criteria were used to differentiate these two diagnoses. There were 82 cases of constriction and 37 cases of restriction. The overall predictive accuracy of the difference between right and left ventricular end-diastolic pressures (RVEDP and LVEDP), RV systolic pressure, and the ratio of RVEDP to RV systolic pressure were 85%, 70%, and 76%, respectively. If all three criteria were concordant, the probability of having correctly classified the patient was greater than 90%. However, one fourth of patients could not be classified by hemodynamic criteria. There are few data to support the use of hemodynamic measurements after exercise or volume infusion to separate these two groups. Numerous recent studies have reported on the ability of left ventriculography, Doppler echocardiography, or radionuclide angiography to distinguish constriction from restriction. Many of the proposed indices appear promising, but these studies suffer from small sample size, potential selection bias, and complexity of the proposed criteria, which have limited their widespread application. New imaging technologies, such as CT scanning or MRI have been applied in a limited number of cases, but appear to be a sensitive means of detecting abnormal pericardium. Endomyocardial biopsy has proven useful in establishing the diagnosis of infiltrative cardiomyopathies, eliminating in those cases the need for surgical intervention. The finding of myocarditis must be considered a nonspecific finding that does not preclude thoracotomy. Since constrictive pericarditis is a surgically curable condition, the distinction between constrictive and restrictive disease is of critical importance. Taking into account the relative contribution of data derived from hemodynamic, imaging,and biopsy studies, we propose an algorithm for the selection of appropriate candidates for pericardial biopsy and stripping.

Constrictive pericarditis versus restrictive cardiomyopathy: the role of Doppler echocardiography in differential diagnosis

Doppler ultrasound recordings of velocities of flow across the mitral and tricuspid valves and in the hepatic veins, and their variation with respiration, were recorded in seven patients with constrictive pericarditis and in six patients with restrictive cardiomyopathy. Deceleration of mitral and tricuspid flow was also evaluated during apnea. Color flow Doppler was performed in order to evaluate mitral and tricuspid regurgitation. Eight healthy adults served as controls. The patients with constrictive pericarditis showed higher peak diastolic velocities of mitral flow, as well as marked increase of velocity of flow at the onset of expiration and decrease at the onset of inspiration. Reciprocal respiratory variation of the velocities were also observed across the tricuspid valve. The patients with restrictive cardiomyopathy showed moderate or severe mitral and tricuspid regurgitation. They also showed shorter deceleration of flow across the mitral and tricuspid valves during apnea. The pattern of flow in the hepatic veins showed reversal during systole with accentuated reversion during inspiration. These results suggest that patient with constrictive pericarditis and restrictive cardiomyopathy can be differentiated by comparing Doppler echocardiographic data, along with changes induced by respiration.