Quantification of pericardial effusions by three-dimensional echocardiography

Contemporary management of pericardial effusion

Pericardial effusion is a relatively common clinical condition with a variety of clinical manifestations ranging from incidentally discovered asymptomatic cases to life-threatening cardiac tamponade. The etiology encompasses idiopathic cases and forms secondary to different conditions, including autoimmune diseases, malignancies, metabolic disorders, etc. While medical therapy should be offered to patients with elevation of inflammatory markers, in specific forms treatment should be appropriate to the underlying disorder. In cases with hemodynamic compromise pericardial drainage either with pericardiocentesis or pericardial "window" is indicated for therapeutic and diagnostic purposes. In the remainder, factors like comorbidities, size and location of the pericardial effusion will influence the clinical decision making. In asymptomatic or minimally symptomatic chronic large idiopathic pericardial effusions, according to recent evidence, a conservative approach with watchful waiting seems the most reasonable option. The prognosis of pericardial effusions largely depends on the underlying etiologies. Metastatic spread to the pericardium has an ominous prognosis whereas large to moderate effusions have been often associated with known or newly discovered specific underlying causes. Chronic small idiopathic effusions have an excellent prognosis and do not require specific monitoring. Large chronic idiopathic effusions in clinically stable patients require a 3 to 6-month assessment ideally in a specialized unit.

The Biplane Modified Simpson's Method Accurately Estimates Pericardial Effusion Volume: A Comparison with Pericardiocentesis

BACKGROUND

Pericardial effusion (PE) volume is often assessed semiqualitatively by echocardiography and categorized into minimal, small, moderate, or large. Several methods of echocardiographic quantification have been proposed, but their application is limited either by complexity or inaccuracy. We evaluated the accuracy of PE volume quantification by two-dimensional transthoracic echocardiogram (2DTTE) and commercially available volume quantification software in patients undergoing pericardiocentesis.

METHODS

In a retrospective case series, immediate preprocedure echocardiograms of 33 patients for pericardiocentesis were analyzed. 2DTTE using the Simpson's method was adopted for volume measurement in the apical two- and four-chamber views. Pericardial fluid volume was calculated by taking the difference between volumes obtained by tracing the epicardial border of the heart and the pericardium. Postprocedure echocardiograms were performed to verify adequate pericardiocentesis.

RESULTS

The mean pericardiocentesis fluid volume was 725.1 ± 299.5 mL (range, 250-1420 mL). The average volume estimated echocardiographically by the Simpson's method was 657.5 ± 276.9 mL (range, 205.7-1193.2 mL). There was strong direct linear correlation between echocardiographic and pericardiocentesis-derived volumes (P < 0.001, r = +0.823). Echocardiography underestimated PE volume by a mean of 9.3%.

CONCLUSION

Two-dimensional transthoracic echocardiography using biplane Simpson's method of disks can simply and accurately estimate PE volume.

Role of live/real time three-dimensional transthoracic echocardiography in pericardial disease

Despite the high sensitivity of two-dimensional transthoracic echocardiography (2DTTE) in diagnosing pericardial effusion, it has limitations in assessing its size and extent and in evaluating other pericardial pathologies. There are only limited reports so far, but live/real time three-dimensional transthoracic Echocardiography (3DTTE) has shown promise and potential advantages over 2DTTE in certain clinical situations. With its ability to crop and view cardiac structures from any desired angulation it offers incremental value in assessing the anatomy of the pericardium including echo densities within the effusion, fibrinous bands, and loculated effusions. It offers significant supplemental information over 2DTTE in clinical scenarios like post cardiac surgery follow up of hemopericardium, quantification of the effusion, evaluation of pericardial masses including granuloma, differentiating pericardial effusion from ascites and pleural effusion and in studying the extent of the disease in constrictive pericarditis. However, comprehensive studies are needed to further define its role in daily clinical practice.

Anesthesia and the patient with pericardial disease

PURPOSE

Pericardial diseases present unique perioperative considerations for the anesthesiologist. The purpose of this review is to provide a summary of the pertinent issues related to the etiology, diagnosis, pathophysiology, and perioperative management of patients presenting for operative treatment of pericardial disease.

SOURCE

A selective search of the anesthesia, cardiology, and cardiothoracic surgical literature was carried out with particular emphasis on acute pericarditis, effusion, tamponade, and constrictive pericarditis.

PRINCIPAL FINDINGS

The anesthesiologist needs to be well versed in the etiology (i.e., differential diagnosis), pathophysiology, and diagnostic modalities in order to best prepare the patient for surgery. Diagnosis and guidance of management requires a working knowledge of the specific associated hemodynamic consequences, particularly of the impaired diastolic function that can occur. Echocardiography is essential in the diagnosis and management of these patients.

CONCLUSIONS

Patients with acute and chronic pericardial diseases often require the need for surgical intervention. Several unique features of acute tamponade and constrictive pericarditis require careful perioperative consideration. With proper preparation and pre-anesthetic optimization, patients with a variety of pericardial diseases can be safely managed before, during, and after their surgical intervention.

Quantification of pericardial effusions by echocardiography and computed tomography

Echocardiography is a well-accepted tool for the diagnosis and quantification of pericardial effusion (PEff). Given the increasing use of computed tomographic (CT) scanning, more PEffs are being initially diagnosed by computed tomography. No study has compared quantification of PEff by computed tomography and echocardiography. The objective of this study was to assess the accuracy of quantification of PEff by 2-dimensional echocardiography and computed tomography compared to the amount of pericardial fluid drained at pericardiocentesis. We retrospectively reviewed an institutional database to identify patients who underwent chest computed tomography and echocardiography before percutaneous pericardiocentesis with documentation of the amount of fluid withdrawn. Digital 2-dimensional echocardiographic and CT images were retrieved and quantification of PEff volume was performed by applying the formula for the volume of a prolate ellipse, π × 4/3 × maximal long-axis dimension/2 × maximal transverse dimension/2 × maximal anteroposterior dimension/2, to the pericardial sac and to the heart. Nineteen patients meeting study qualifications were entered into the study. The amount of PEff drained was 200 to 1,700 ml (mean 674 ± 340). Echocardiographically calculated pericardial effusion volume correlated relatively well with PEff volume (r = 0.73, p <0.001, mean difference -41 ± 225 ml). There was only moderate correlation between CT volume quantification and actual volume drained (r = 0.4, p = 0.004, mean difference 158 ± 379 ml). In conclusion, echocardiography appears a more accurate imaging technique than computed tomography in quantitative assessment of nonloculated PEffs and should continue to be the primary imaging in these patients.

Echocardiography in the diagnosis and management of pericardial disease

This review covers the role of echocardiography in the diagnosis and management of the main pericardial disorders. The sensitivity of echocardiography in detecting pericardial fluid is very high and this technique allows the detection of effusion as well as the definition of the size of effusion (small, moderate and severe). The evaluation of the pericardial sac should be carefully performed through all the echocardiographic windows, differentiating diffuse from loculated (regional) effusions. Several echocardiographic and Doppler signs allow an accurate diagnosis of cardiac tamponade. The role of echocardiography is extremely important in atypical clinical presentation such as in patients in the postoperative period after cardiac surgery. Moreover, drainage of the effusion is mandatory in the presence of cardiac tamponade and in this regard echo-guided pericardiocentesis is the gold-standard method. Finally this review covers the echocardiographic diagnosis of pericardial cysts and masses and constrictive pericarditis.

Quantitative assessment of pericardial effusion volume by two-dimensional echocardiography

The clinical applicability of a method for quantifying pericardial effusion (PE) was studied. The pericardial and cardiac volumes were determined from border tracings of 2-dimensional echocardiograms fitted with 3-dimensional disk models. The PE volume was the difference between pericardial and cardiac volumes. A phantom study included 54 cases with different volumes and viewing geometry showed a correlation coefficient r = 0.98 and an accuracy of +/- 6%. A clinical study included 20 cases showing that the estimated PE volume correlated well with that drained surgically (between 100 mL and 1200 mL): y = 0.81 x + 120 mL; r = 0.91, P <.0001. The percent error, determined by the standard error of the estimate (114 mL) over mean (548 mL), was 20%. Intraobserver variability was 4% and interobserver variability 6%. The 3-dimensional disk method provides a quick and convenient way to quantify PE from 2-dimensional echocardiograms with acceptable accuracy and reproducibility.

Heterogeneous expression of Gap junction channels in the heart leads to conduction defects and ventricular dysfunction

BACKGROUND

- Heterogeneous remodeling of gap junctions is observed in many forms of heart disease. The consequent loss of synchronous ventricular activation has been hypothesized to result in diminished cardiac performance. To directly test this hypothesis, we designed a murine model of heterogeneous gap junction channel expression. Methods and Results-- We generated chimeric mice formed from connexin43 (Cx43)-deficient embryonic stem cells and wild-type or genetically marked ROSA26 recipient blastocysts. Chimeric mice developed normally, without histological evidence of myocardial fibrosis or hypertrophy. Heterogeneous Cx43 expression resulted in conduction defects, however, as well as markedly depressed contractile function. Optical mapping of chimeric hearts by use of voltage-sensitive dyes revealed highly irregular epicardial conduction patterns, quantified as significantly greater negative curvature of the activation wave front (-1.86+/-0.40 mm in chimeric mice versus -0.86+/-0.098 mm in controls; P<0.01; n=6 for each group). Echocardiographic studies demonstrated significantly reduced fractional shortening in chimeric mice (26.6+/-2.3% versus 36.5+/-1.6% in age-matched 129/SvxC57BL/6F1 wild-type controls; P<0.05).

CONCLUSIONS

- These data suggest that heterogeneous Cx43 expression, by perturbing the normal pattern of coordinated myocardial excitation, may directly depress cardiac performance.

Conduction slowing and sudden arrhythmic death in mice with cardiac-restricted inactivation of connexin43

Cardiac arrhythmia is a common and often lethal manifestation of many forms of heart disease. Gap junction remodeling has been postulated to contribute to the increased propensity for arrhythmogenesis in diseased myocardium, although a causative role in vivo remains speculative. By generating mice with cardiac-restricted knockout of connexin43 (Cx43), we have circumvented the perinatal lethal developmental defect associated with germline inactivation of this gap junction channel gene and uncovered an essential role for Cx43 in the maintenance of electrical stability. Mice with cardiac-specific loss of Cx43 have normal heart structure and contractile function, and yet they uniformly (28 of 28 conditional Cx43 knockout mice observed) develop sudden cardiac death from spontaneous ventricular arrhythmias by 2 months of age. Optical mapping of the epicardial electrical activation pattern in Cx43 conditional knockout mice revealed that ventricular conduction velocity was significantly slowed by up to 55% in the transverse direction and 42% in the longitudinal direction, resulting in an increase in anisotropic ratio compared with control littermates (2.1+/-0.13 versus 1.66+/-0.06; P:<0.01). This novel genetic murine model of primary sudden cardiac death defines gap junctional abnormalities as a key molecular feature of the arrhythmogenic substrate.

Quantitative assessment of aortic stenosis by three-dimensional echocardiography

The purpose of this study was to assess the feasibility of three-dimensional echocardiography in aortic stenosis. Planimetric determination of valve area and dynamic volume-rendered display were performed. Three-dimensional echocardiography permits display of any desired plane of the cardiac structure. Thus in the case of aortic stenosis, the plane used for planimetric evaluation can be positioned exactly through the valve orifice. Dynamic volume-rendered display may provide a spatial demonstration of the stenotic valve. In 48 patients aortic valve area was measured by planimetry. The three-dimensional data set was acquired by a workstation in the course of a multiplane transesophageal examination. Results were compared with those obtained by multiplane transesophageal two-dimensional planimetric technique and invasive measurement. A dynamic three-dimensional reconstruction was displayed. Planimetric determination of valve area was possible in 42 (88%) of 48 cases. Statistical analysis of the data acquired showed a good agreement between three-dimensional echocardiography and transesophageal echocardiography (mean difference +0.018 cm2; SD = 0.086) and between three-dimensional echocardiography and the invasive technique (mean difference +0.012 cm2; SD = 0.12). Dynamic volume-rendered display was possible in 42 of 48 cases. Three-dimensional echocardiography permits accurate and reliable determination of aortic valve area. Preoperative spatial recognition of the stenotic valve is possible by dynamic volume-rendered display.

Quantitative Echocardiographic Assessment in Pericardial Disease

Although echocardiography has been used for diagnosing pericardial effusions since 1965, the grading of such effusions for size, and also the diagnosis of tamponade have depended almost entirely on qualitative observations or "signs." The categorization of pericardial effusions into small, moderate, or large according to the width of pericardial space is very roughly semiquantitative. Diagnostic criteria for tamponade are based on altered ventricular or atrial wall contour, and on phasic respiratory fluctuations of ventricular size and flow velocities. We review a new approach to pericardial effusion volume estimation, based on assessing the pericardial sac volume as well as cardiac volume by the ellipsoid formula. A new quantitative criteria for tamponade (i.e., biatrial width to cardiac width) (annular level) ratio may be useful, a ratio < 0.85 indicating tamponade, reflecting late diastolic biatrial collapse. The echo diagnosis of pericardial constriction depends on pericardial thickening combined with various abnormalities of septal and ventricular wall motion, some of them subtle. We review a new two-dimensional echo "sign" present in some cases of pericardial constriction: abnormal posterior displacement of the left atrial posterior wall, and reduced angle (<150 degrees ) between it and left ventricular wall in long-axis view. Measurements reflecting the fluctuation of certain Doppler parameters can also be useful in diagnosis of this entity.

Determination of left ventricular mass and circumferential wall thickness by three-dimensional reconstruction: in vitro validation of a new method that uses a multiplane transesophageal transducer

Elevated left ventricular mass and increased wall thickness have important prognostic implications in clinical medicine. However, these parameters have been incompletely characterized by one- and two-dimensional echocardiography. Therefore this study was performed to validate in vitro measurement of left ventricular mass and circumferential wall thickness with a multiplane transesophageal transducer and three-dimensional reconstruction. Results for mass measurements were also compared with a standard method for the determination of left ventricular mass, the Penn convention. Fourteen necropsied left ventricles were scanned in a water bath by a volume-rendering, three-dimensional reconstruction system. There was an excellent correlation and high agreement for determination of three-dimensional left ventricular mass (r = 0.98; standard error of the estimate [SEE] = 9.6 gm; y = 1.02x + 0.46) and wall thickness (r = 0.93; SEE = 1.4 mm; y = 0.95x + 1.64) compared with anatomic measurements. Left ventricular mass by a simulated Penn convention revealed a lower correlation and larger error compared with three-dimensional measurements (r = 0.72; SEE = 42.8 gm; y = 1.01x + 9.61). Therefore determination of left ventricular mass by three-dimensional reconstruction was validated in vitro and was superior to one-dimensional echocardiographic methods.

Insights from three-dimensional echocardiographic laser stereolithography. Effect of leaflet funnel geometry on the coefficient of orifice contraction, pressure loss, and the Gorlin formula in mitral stenosis

BACKGROUND

Three-dimensional echocardiography can allow us to address uniquely three-dimensional scientific questions, for example, the hypothesis that the impact of a stenotic valve depends not only on its limiting orifice area but also on its three-dimensional geometry proximal to the orifice. This can affect the coefficient of orifice contraction (Cc = effective/anatomic area), which is important because for a given flow rate and anatomic area, a lower Cc gives a higher velocity and pressure gradient, and Cc, routinely assumed constant in the Gorlin equation, may vary with valve shape (60% for a flat plate, 100% for a tube). To date, it has not been possible to study this with actual valve shapes in patients.

METHODS AND RESULTS

Three-dimensional echocardiography reconstructed valve geometries typical of the spectrum in patients with mitral stenosis: mobile doming, intermediate conical, and relatively flat immobile valves. Each geometry was constructed with orifice areas of 0.5, 1.0 and 1.5 cm2 by stereolithography (computerized laser polymerization) (total, nine valves) and studied at physiological flow rates. Cc varied prominently with shape and was larger for the longer, tapered dome (more gradual flow convergence proximal and distal to the limiting orifice): for an anatomic orifice of 1.5 cm2, Cc increased from 0.73 (flat) to 0.87 (dome), and for an area of 0.5 cm2, from 0.62 to 0.75. For each shape, Cc increased with increasing orifice size relative to the proximal funnel (more tubelike). These variations translated into important differences of up to 40% in pressure gradient for the same anatomic area and flow rate (greatest for the flattest valves), with a corresponding variation in calculated Gorlin area (an effective area) relative to anatomic values.

CONCLUSIONS

The coefficient of contraction and the related net pressure loss are importantly affected by the variations in leaflet geometry seen in patients with mitral stenosis. Three-dimensional echocardiography and stereolithography, with the use of actual information from patients, can address such uniquely three-dimensional questions to provide insight into the relations between cardiac structure, pressure, and flows.

Evaluation of gallbladder volume and emptying with a novel three-dimensional ultrasound system: comparison with the sum-of-cylinders and the ellipsoid methods

To overcome the geometrical limitations of current methods to calculate gallbladder volume from two-dimensional sonographic images, we evaluated the accuracy and precision of a novel three-dimensional ultrasound system (3D). In vitro accuracy of 3D volumetry (10 mL to 55 mL) was 98.1 +/- 7.1% (mean+/-SD) with a mean difference of 0.7 mL between the measured and the true volume (p < 0.003). Compared with the sum-of-cylinders (SC) and the ellipsoid (EL) methods, 3D was characterized by a significantly smaller systematic bias and closer limits of agreement with the true volume. The variation coefficient was smallest with 3D (2.4%, p < 0.02) and largest with EL (4.2%). In vivo, gallbladder volumes were on average 1.4 mL (9%) smaller with 3D than with SC (p < 0.0001) and 2.4 mL (14%) larger with EL than with SC (p < 0.0001). 3D ultrasonography accurately measures gallbladder volume and emptying.

Automatic border detection and three-dimensional reconstruction with echocardiography

This article reviews two important innovations in echocardiography resulting from the recent advances in the capabilities of microprocessors. The first, automatic endocardial border detection, has been implemented on computers contained entirely within echocardiograph machines and is gaining wide clinical use. The second, three-dimensional imaging, is currently under intense investigation and shows great promise for clinical application. It requires, however, further development of the specialized transducer apparatus necessary for image acquisition and the sophisticated computer-processing capability necessary for image reconstruction and display.

Role of echocardiography in perioperative management of patients undergoing open heart surgery

TEE has assumed a pivotal role in the perioperative management of patients undergoing open-heart surgery. The information obtained influences important therapeutic decisions in thoracic aortic surgery, valvular surgery, and coronary artery bypass surgery. TEE also assists in determining the reason for failure to wean from cardiopulmonary bypass and allows rapid detection of the etiology of hypotension in the patient after surgery. Advances in technology have resulted in three-dimensional images of cardiac structures, and this will further enhance the usefulness of echocardiography for the surgeon. TEE should no longer be regarded as an imaging tool available only in academic centers, but should be routinely used by qualified operators in centers performing open-heart surgery.