A novel model of constrictive pericarditis associated with myocardial fibrosis in rats

An efficient animal model is fundamental for studies on the underlying mechanisms of constrictive pericarditis (CP). A novel CP rat model was established by pericardial injection composing of lipopolysaccharides (LPS) and talcum powder without thoracotomy. Pathological changes were confirmed by histological staining. E-flow Doppler of mitral valve, tissue Doppler E' in the medial mitral annular (E'sep ) and the lateral mitral annular (E'lat ) were measured to assess ventricular filling function. Circumferential, longitudinal, and radial strains (SC, SL and SR) and the respective strain rates (SrC, SrL and SrR) were analyzed in interventricular septum (IVS) and left ventricular free wall (LVFW). Rat cardiac fibroblasts (CFs) were treated with LPS. The activation of transforming growth factor β1 (TGF-β1) was confirmed by Q-PCR and western blot assays. Thickening of pericardium and fibrosis in pericardium and subepicardial myocardium were showed in the model group. Diastolic dysfunction in the CP group was indicated by decreased E'lat and E'lat /E'sep , increased E/E'lat , decreased EFW of SrC and SrL, increased AIVS and decreased E/A of SrC, SrL and SrR. Systolic dysfunction was indicated by decreased SCFW and SLFW in CP rats. The levels of TGF-β1, p-Smad2/3, α-smooth muscle actin (α-SMA), and collagen-I/III (COL-I/III) were increased in the CP group. The increased TGF-β1 that induced by LPS activated and phosphorylated Smad2/3 resulting in the secretion of α-SMA and COL-I/III. This model is of vital importance in studying the pathogenesis of CP.

A simple mouse model of pericardial adhesions

Background

Postoperative pericardial adhesions are considered a risk factor for redo cardiac surgery. Several large- and medium-size animal models of pericardial adhesions have been reported, but small animal models for investigating the development of anti-adhesion materials and molecular mechanisms of this condition are lacking. In this study, we aimed to establish a simple mouse model of pericardial adhesions to address this gap.

Methods

We administered blood, minocycline, picibanil, and talc into the murine pericardial cavity via one-shot injection. Micro-computed tomography analyses of contrast agent-injected mice were carried out for methodological evaluation. We investigated various dosages and treatment durations for molecules identified to be inducers of pericardial adhesion. The adhesive grade was quantified by scoring the strength and volume of adhesion tissues at sacrificed time points. Histological staining with hematoxylin and eosin and Masson’s trichrome, and immunostaining for F4/80 or αSMA was performed to investigate the structural features of pericardial adhesions, and pathological features of the pericardial adhesion tissue were compared with human clinical specimens.

Results

Administration of talc resulted in the most extensive pericardial adhesions. Micro-computed tomography imaging data confirmed that accurate injection into the pericardial cavity was achieved. We found the optimal condition for the formation of strong pericardial adhesions to be injection of 2.5 mg/g talc for 2 weeks. Furthermore, histological analysis showed that talc administration led to an invasion of myofibroblasts and macrophages in the pericardial cavity and epicardium, consistent with pathological findings in patients with left ventricular assistive devices.

Conclusions

We successfully established a simple mouse model of talc-induced pericardial adhesions, which mimics human pathology and could contribute to solving the clinical issues related to pericardial adhesions.

Novel echocardiographic techniques for the evaluation of athletes' heart: A focus on speckle-tracking echocardiography

BACKGROUND

The development and rapid dissemination of two-dimensional echocardiography led to important further advances in our understanding of athletes' heart that has been the subject of several echocardiographic studies involving many thousands of athletes. The description of ventricular chamber enlargement, myocardial hypertrophy and atrial dilatation has led to a more comprehensive understanding of cardiac adaptation to exercise conditioning. Most recently, advanced echocardiographic techniques have begun to clarify significant functional adaptations of the myocardium that accompany previously reported morphological features of athletes' heart. In particular, speckle-tracking echocardiography (STE) has recently provided further insights into the characterisation of myocardial properties.

DISCUSSION

STE is a relatively new, largely angle-independent, non-invasive imaging technique that allows for an objective and quantitative evaluation of global and regional myocardial function. STE has enhanced our understanding of athletes' heart through a comprehensive characterisation of biventricular and biatrial function, providing novel insights into the investigation of physiological adaptation of the heart to exercise conditioning. These peculiarities can provide further useful data to distinguish between athletes' heart and cardiomyopathies. Furthermore, STE represents a promising tool to address new concerns on right ventricular function and to increase understanding of the complexity of the non-systemic circulation, especially in the athletic population.

CONCLUSION

This review article analyses new data on cardiac function in athletes by novel echocardiographic techniques with a particular attention to the application of STE to characterise biventricular and biatrial function in athletes.

European Association of Cardiovascular Imaging (EACVI) position paper: Multimodality imaging in pericardial disease

Although pericardial diseases are common in the daily clinical practice and can result in a significant morbidity and mortality, imaging of patients with suspected or known pericardial disorders remain challenging. Multimodality imaging is part of the management of pericardial diseases. Echocardiography, cardiac computed tomography, and cardiovascular magnetic resonance are often used as complementary imaging modalities. The choice of one or multiple imaging modalities is driven by the clinical context or conditions of the patient. The scope of the present document is to highlight the respective role of each technique according to the clinical context in the diagnosis and management of pericardial diseases.

Diagnostic concordance of echocardiography and cardiac magnetic resonance-based tissue tracking for differentiating constrictive pericarditis from restrictive cardiomyopathy

BACKGROUND

Variations in longitudinal deformation of the left ventricle have been suggested to be useful for differentiating chronic constrictive pericarditis (CP) and restrictive cardiomyopathy (RCM). We assessed left ventricular mechanics derived from cardiac magnetic resonance (CMR) cine-based and 2-dimensional echocardiography-based tissue tracking to determine intermodality consistency of diagnostic information for differentiating CP from RCM.

METHODS AND RESULTS

We retrospectively identified 92 patients who underwent both CMR and 2-dimensional echocardiography and who had a final diagnosis of CP (n=28), RCM (n=30), or no structural heart disease (n=34). Global longitudinal strain from long-axis views and circumferential strain from short-axis views were measured on 2-dimensional echocardiographic and CMR cine images using the same offline software. Logistic regression models with receiver operating characteristics curves, continuous net reclassification improvement, and the integrated discrimination improvement (IDI) were used for assessing the incremental predictive performance. Global longitudinal strain was higher in patients with CP than in those with RCM (P<0.001), and both techniques were found to have similar diagnostic value (area under the curve, 0.84 versus 0.88 for CMR and echocardiography, respectively). For echocardiography, the addition of global longitudinal strain to respiratory septal shift and early diastolic mitral annular velocity resulted in improved continuous net reclassification improvement (P<0.001 for both) and integrated discrimination improvement (P=0.005 and 0.024) for both models. Similarly, for CMR, the addition of global longitudinal strain to septal shift and pericardial thickness resulted in improved continuous net reclassification improvement (P<0.001 for both) and integrated discrimination improvement (P=0.003 and <0.001).

CONCLUSIONS

CMR and echocardiography tissue tracking-derived left ventricular mechanics provide comparable diagnostic information for differentiating CP from RCM.

Left ventricular torsion changes post kidney transplantation

Background

To quantify changes of left ventricular (LV) torsion in patients' pre and post kidney transplantation.

Methods

A prospective study was conducted on 48 patients who received kidney transplantation for end stage renal disease and without myocardial infarction. The rotation, twist and torsion of LV were studied pre and post kidney transplantation (6 months post transplantation) using velocity vector imaging by echocardiography. The data is expressed as mean ± standard deviation and compared by paired t-test at the p < 0.05 significance level.

Results

Six months post kidney transplantation, left ventricular ejection fraction (from 40.33 ± 11.42 to 61.00 ± 13.68%), ratio of mitral early and late diastolic filling velocity (from 1.04 ± 0.57 to 1.21 ± 0.52), rotation of basal LV (from 4.48 ± 2.66 to 5.65 ± 2.64 degree), rotation of apical LV (from 4.27 ± 3.08 to 5.50 ± 4.25 degree), LV twist (8.75 ± 4.45 to 11.14 ± 5.25 degree) and torsion (from 1.06 ± 0.54 to 1.33 ± 0.61 degree/cm) were increased significantly (p < 0.05). Interventricular septum thickness (from 11.67 ± 2.39 to 9.67 ± 0.48 mm), left ventricular mass index (from 104.00 ± 16.47 to 95.50 ± 21.44 g/m²), systolic blood pressure (from 143.50 ± 34.99 to 121.50 ± 7.09 mmHg), serum blood urea nitrogen (from 42.40 ± 7.98 to 30.43 ± 13.85 mg/dL) and creatinine (from 4.53 ± 1.96 to 2.73 ± 2.57 mg/dL) were decreased significantly (p < 0.05).

Conclusion

Kidney transplantation in end stage renal disease without myocardial infarction results in improvement in left ventricular structure, function and myocardial mechanics as detected by echocardiography and velocity vector imaging. Velocity vector imaging provided valuable information for detection and follow-up of cardiac abnormalities in patients with end stage renal disease.

Impact of diet and exercise training-induced weight loss on myocardial mechanics in severely obese adolescents

OBJECTIVE

Recent findings indicated silent incipient myocardial dysfunction in juvenile obesity despite normal global cardiac function. The present study investigated whether lifestyle intervention is able to favorably impact these obesity-related myocardial abnormalities and whether improvements are related to changes in insulin resistance and cardiac remodeling.

DESIGN AND METHODS

Twenty-eight severe obese adolescents (OB) participated in a 9 month lifestyle intervention program (LIP) based on aerobic exercise and diet. Twenty healthy adolescents (CG) served as controls. Conventional echocardiography and myocardial mechanics were obtained at baseline and follow-up along with insulin resistance.

RESULTS

Insulin sensitivity improved (P < 0.001) and body weight decreased (P < 0.001) consecutive to LIP. At baseline, OB had depressed longitudinal (L) strain (CG: -18.3 ± 2.6, OB: -14.2 ± 3.6%, P < 0.001) and enhanced twist compared to controls. The LIP in OB restored L strain to normal values (-16.9 ± 3.5%, NS), whereas it did not affect twist mechanics. From stepwise multiple regression analysis, only baseline L strain and changes in BMI Z-score (r(2) -adjusted = 0.49, P < 0.001) emerged as independent predictors of L strain changes.

CONCLUSIONS

Juvenile obesity is associated with myocardial mechanic abnormalities that can be partly corrected by lifestyle intervention. Restoration of longitudinal myocardial function occurs in the absence of left ventricular remodeling changes and is not associated with insulin resistance improvements.

Two-dimensional strain and twist by vector velocity imaging in adolescents with severe obesity

The prevalence of severe obesity is increasing worldwide in adolescents. Whether it is associated with functional myocardial abnormalities remains largely unknown, potentially because of its frequent association with other cardiovascular risk factors and also use of insensitive techniques to detect subclinical changes in myocardial function. We used 2D vector velocity imaging (VVI) to investigate early changes in left ventricular (LV) myocardial function in youths with isolated severe obesity. Thirty-seven asymptomatic severely obese adolescents free of diabetes and hypertension, and 24 lean controls were enrolled. LV longitudinal, basal, and apical circumferential strain, strain rate (SR), rotations, and LV twist were measured. Obese adolescents had greater LV mass and reduced systolic and early diastolic tissue Doppler imaging (TDI) velocities than lean counterparts. L strain (-24%) and systolic and early diastolic SR were also diminished in the obese, whereas no intergroup differences existed for the circumferential deformation indexes. LV twist was more pronounced in the obese (+1.7°, P < 0.01) on account of greater apical rotation only (4.1 ± 0.9 vs. 5.2 ± 1.2°, P < 0.01), potentially compensating for the loss in longitudinal function. Systolic-diastolic coupling, an important component of early filling and diastolic function, was maintained with severe obesity. No intergroup differences were reported regarding time to peak values for all VVI indexes highlighting that dynamics of strain and twist/untwist along the cardiac cycle was preserved with severe obesity. Isolated severe obesity in adolescents, at a preclinical stage, is associated with changes in myocardial deformation and torsional mechanics that could be in part related to alterations in relaxation and contractility properties of subendocardial fibers.

Improved method for quantification of regional cardiac function in mice using phase-contrast MRI

Phase-contrast magnetic resonance imaging is a technique that allows for characterization of regional cardiac function and for measuring transmural myocardial velocities in human hearts with high temporal and spatial resolution. The application of this technique (also known as tissue phase mapping) to murine hearts has been very limited so far. The aim of our study was to implement and to optimize tissue phase mapping for a comprehensive assessment of murine transmural wall motion. Baseline values for regional motion patterns in mouse hearts, based on the clinically used American Heart Association's 17-segment model, were established, and a detailed motion analysis of mouse heart for the entire cardiac cycle (including epicardial and endocardial motion patterns) is provided. Black-blood contrast was found to be essential to obtain reproducible velocity encoding. Tissue phase mapping of the mouse heart permits the detailed assessment of regional myocardial velocities. While a proof-of-principle application in a murine ischemia-reperfusion model was performed, future studies are warranted to assess its potential for the investigation of systolic and diastolic functions in genetically and surgically manipulated mouse models of human heart disease.

Current and evolving echocardiographic techniques for the quantitative evaluation of cardiac mechanics: ASE/EAE consensus statement on methodology and indications endorsed by the Japanese Society of Echocardiography

Echocardiographic imaging is ideally suited for the evaluation of cardiac mechanics because of its intrinsically dynamic nature. Because for decades, echocardiography has been the only imaging modality that allows dynamic imaging of the heart, it is only natural that new, increasingly automated techniques for sophisticated analysis of cardiac mechanics have been driven by researchers and manufacturers of ultrasound imaging equipment. Several such techniques have emerged over the past decades to address the issue of reader's experience and inter-measurement variability in interpretation. Some were widely embraced by echocardiographers around the world and became part of the clinical routine, whereas others remained limited to research and exploration of new clinical applications. Two such techniques have dominated the research arena of echocardiography: (1) Doppler-based tissue velocity measurements, frequently referred to as tissue Doppler or myocardial Doppler, and (2) speckle tracking on the basis of displacement measurements. Both types of measurements lend themselves to the derivation of multiple parameters of myocardial function. The goal of this document is to focus on the currently available techniques that allow quantitative assessment of myocardial function via image-based analysis of local myocardial dynamics, including Doppler tissue imaging and speckle-tracking echocardiography, as well as integrated back- scatter analysis. This document describes the current and potential clinical applications of these techniques and their strengths and weaknesses, briefly surveys a selection of the relevant published literature while highlighting normal and abnormal findings in the context of different cardiovascular pathologies, and summarizes the unresolved issues, future research priorities, and recommended indications for clinical use.

Constrictive pericarditis and restrictive cardiomyopathy in the modern era

The differentiation between constrictive pericarditis and restrictive cardiomyopathy can be clinically challenging. Pericardial constriction results from scarring and consequent loss of pericardial elasticity leading to impaired ventricular filling. Restrictive cardiomyopathy is characterized by a nondilated rigid ventricle, severe diastolic dysfunction and restrictive filling producing hemodynamic changes, similar to those in constrictive pericarditis. While constrictive pericarditis is usually curable by surgical treatment, restrictive cardiomyopathy requires medical therapy and in appropriate patients, the definitive treatment is cardiac transplantation. Sufficient differences exist between the two conditions to allow noninvasive differentiation, but no single diagnostic tool can be relied upon to make this distinction. Newer echocardiographic techniques such as speckle-track imaging, velocity vector imaging, as well as cardiac computed tomography and cardiac MRI can help differentiate constriction from restriction with high sensitivity and specificity. Outcomes are better with early diagnosis of constriction in particular and early surgical resection.

Current and evolving echocardiographic techniques for the quantitative evaluation of cardiac mechanics: ASE/EAE consensus statement on methodology and indications endorsed by the Japanese Society of Echocardiography

Echocardiographic imaging is ideally suited for the evaluation of cardiac mechanics because of its intrinsically dynamic nature. Because for decades, echocardiography has been the only imaging modality that allows dynamic imaging of the heart, it is only natural that new, increasingly automated techniques for sophisticated analysis of cardiac mechanics have been driven by researchers and manufacturers of ultrasound imaging equipment.Several such technique shave emerged over the past decades to address the issue of reader's experience and inter measurement variability in interpretation.Some were widely embraced by echocardiographers around the world and became part of the clinical routine,whereas others remained limited to research and exploration of new clinical applications.Two such techniques have dominated the research arena of echocardiography: (1) Doppler based tissue velocity measurements,frequently referred to as tissue Doppler or myocardial Doppler, and (2) speckle tracking on the basis of displacement measurements.Both types of measurements lend themselves to the derivation of multiple parameters of myocardial function. The goal of this document is to focus on the currently available techniques that allow quantitative assessment of myocardial function via image-based analysis of local myocardial dynamics, including Doppler tissue imaging and speckle-tracking echocardiography, as well as integrated backscatter analysis. This document describes the current and potential clinical applications of these techniques and their strengths and weaknesses,briefly surveys a selection of the relevant published literature while highlighting normal and abnormal findings in the context of different cardiovascular pathologies, and summarizes the unresolved issues, future research priorities, and recommended indications for clinical use.

Impact of pericardial adhesions on diastolic function as assessed by vortex formation time, a parameter of transmitral flow efficiency

Background

Pericardial adhesions are a pathophysiological marker of constrictive pericarditis (CP), which impairs cardiac filling by limiting the total cardiac volume compliance and diastolic filling function. We studied diastolic transmitral flow efficiency as a new parameter of filling function in a pericardial adhesion animal model. We hypothesized that vortex formation time (VFT), an index of optimal efficient diastolic transmitral flow, is altered by patchy pericardial-epicardial adhesions.

Methods

In 8 open-chest pigs, the heart was exposed while preserving the pericardium. We experimentally simulated early pericardial constriction and patchy adhesions by instilling instant glue into the pericardial space and using pericardial-epicardial stitches. We studied left ventricular (LV) function and characterized intraventricular blood flow with conventional and Doppler echocardiography at baseline and following the experimental intervention.

Results

Significant decreases in end-diastolic volume, ejection fraction, stroke volume, and late diastolic filling velocity reflected the effects of the pericardial adhesions. The mean VFT value decreased from 3.61 ± 0.47 to 2.26 ± 0.45 (P = 0.0002). Hemodynamic variables indicated the inhibiting effect of pericardial adhesion on both contraction (decrease in systolic blood pressure and +dP/dt decreased) and relaxation (decrease in the magnitude of -dP/dt and prolongation of Tau) function.

Conclusion

Patchy pericardial adhesions not only negatively impact LV mechanical functioning but the decrease of VFT from normal to suboptimal value suggests impairment of transmitral flow efficiency.

Evaluation of left ventricular rotation in obese subjects by velocity vector imaging

AIMS

Obesity is a well-known risk factor in the development of cardiovascular disease. We hypothesize that early left ventricular (LV) dysfunction secondary to obesity could be signalled by abnormal LV rotation.

METHODS AND RESULTS

This prospective study examined 60 subjects divided into two groups: obese group with body mass index (BMI) >or=30 and control group with BMI <25. The peak rotation, twist, and torsion of the left ventricle were studied in obese and control subjects, using velocity vector imaging. Age and gender were comparable between the two groups. Obese subjects had higher BMI, waist circumference, fasting glucose, triglycerides, systolic and diastolic blood pressure, low-density lipoprotein cholesterol, and lower high-density lipoprotein cholesterol (P < 0.05). In obese subjects, LV mass and LV mass index were increased, and the ratio of mitral early and late diastolic filling velocity was decreased (P < 0.05). In obese subjects, the peak twist and torsion of the left ventricle displayed a lower trend, and the peak rotation of the left ventricle apex decreased significantly (3.81 +/- 2.09 degrees vs. 5.77 +/- 3.27 degrees , P < 0.001).

CONCLUSION

Obesity was associated with changes in LV rotation. Velocity vector imaging is a feasible and reproducible echocardiographic technique for the detection of early subclinical LV dysfunction.

Spectrum of pericardial disease: part II

Pericardial disease is a common disorder seen in varying clinical settings, and may be the first manifestation of an underlying systemic disease. In part I, we focused on the current knowledge and management of the more common pericardial diseases: acute pericarditis, pericardial effusion, cardiac tamponade, chronic pericarditis and relapsing pericarditis. In part II, we will focus on the knowledge and management of pericardial involvement in chylous pericardial effusion cholesterol pericarditis, radiation pericarditis, pericardial involvement in systemic inflammatory diseases, autoreactive pericarditis, pericarditis in renal failure, pericardial constriction and effusive constrictive pericarditis.

Spectrum of pericardial disease: part I

Pericardial disease is a common disorder seen in varying clinical settings and may be the first manifestation of an underlying systemic disease. It may be due to multiple causes. Epidemiologic studies are lacking, and the exact incidence and prevalence are unknown. New diagnostic techniques have improved diagnosis, allowing early diagnosis and management. There are few randomized data to guide physicians in the management of pericardial diseases. Part I of our review focuses on the current state of knowledge and management of the more common pericardial diseases: acute pericarditis, pericardial effusion, cardiac tamponade, chronic pericarditis and relapsing pericarditis.