The Distensibility of the Human Vena Cava and Its Importance to In Vitro Studies of Venous Compression Syndromes: A Search for a Suitable Polymer for 3-Dimensional Printing.

BACKGROUND: Venous compression syndromes are clinical conditions in which the large veins are compressed by other anatomical structures. Laboratory simulations may help us better understand the hemodynamics in venous compressions by creating situations similar to those seen in vivo. The aim of this study is to produce a model of the caval bifurcation using a polymer with distensibility similar to the human vena cava. METHODS: Fragments of the inferior vena cava were collected from 13 deceased kidney donors (aged 15-37 years) and were tested for deformation (strain) when subjected to distension at 50 N/cm2. Strips of 5 different polymers-thermic polyurethane and Agilus30 with Vero Magenta (AV) (in 3 different hardnesses) and silicone-were subjected to the same biomechanical tests and compared with the vena cava. A model of the caval bifurcation was produced with 3-D printing. RESULTS: The deformation (strain) of the vena cava wall was 0.16 ± 0.9 when submitted to stress close to 50 N/cm2. Silicone showed a strain higher than the standard deviation of venous fragments. The strain of AV resin 95 Shore was lower than the standard deviation of the venous fragments. AV Resins 70 and 85 Shore showed strains within the standard deviation of the venous specimen, with 70 Shore being closest to the mean venous strain. Therefore, this material was selected for modeling the caval bifurcation. The computed tomography scan image generated a computer model of the caval bifurcation and was printed in 3 dimensions. In addition, the segments of 2 adjacent vertebrae were also printed to reference the compression site. CONCLUSIONS: The 3-D printing of large veins can produce models with anatomy and biomechanics similar to those of human veins and opens a field of investigation into the hemodynamics of venous compression syndromes. Polymers with Shore A70 appear to have biomechanical properties similar to those of the vena cava wall. The model obtained in this study can be used in several in vitro studies of May-Thurner Syndrome.

Late gadolinium enhancement magnetic resonance imaging in the diagnosis and prognosis of endomyocardial fibrosis patients.

BACKGROUND: Endocardial fibrous tissue (FT) deposition is a hallmark of endomyocardial fibrosis (EMF). Echocardiography is a first-line and the standard technique for the diagnosis of this disease. Although late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) allows FT characterization, its role in the diagnosis and prognosis of EMF has not been investigated. METHODS AND RESULTS: Thirty-six patients (29 women; age, 54±12 years) with EMF diagnosis after clinical evaluation and comprehensive 2-dimensional Doppler echocardiography underwent cine-CMR for assessing ventricular volumes, ejection fraction and mass, and LGE-CMR for FT characterization and quantification. Indexed FT volume (FT/body surface area) was calculated after planimetry of the 8 to 12 slices obtained in the short-axis view at end-diastole (mL/m(2)). Surgical resection of FT was performed in 16 patients. In all patients, areas of LGE were confined to the endocardium, frequently as a continuous streak from the inflow tract extending to the apex, where it was usually most prominent. There was a relation between increased FT/body surface area and worse New York Heart Association functional class and with increased probability of surgery (P<0.05). The histopathologic examination of resected FT showed typical features of EMF with extensive endocardial fibrous thickening, proliferation of small vessels, and scarce inflammatory infiltrate. In multivariate analysis, the patients with FT/body surface area >19 mL/m(2) had an increased mortality rate, with a relative risk of 10.8. CONCLUSIONS: Our study provides evidence that LGE-CMR is useful in the diagnosis and prognosis of EMF through quantification of the typical pattern of FT deposition.

Adenoviral expression of calmodulin antisense reduces hypertrophy in cultured cardiomyocytes.

Sustained myocardial hypertrophy is associated with an increased risk of sudden death and progression to heart failure. Multiple signal pathways are involved in cardiac hypertrophy and understanding their interaction may point to new therapeutic targets. In this work, we tested the hypothesis that adenovirus-mediated calmodulin (CaM) antisense expression will reduce the intracellular availability of CaM and inhibit the hypertrophic response. Three recombinant adenoviruses were constructed: AdASCaM, containing the AntiSense sequence of CaM and the enhanced green fluorescent protein (GFP) coding sequence; AdCaM, containing the coding sequence of CaM and the GFP sequence; and the AdGFP, containing the GFP coding sequence. Neonatal rat ventricular cardiomyocytes were infected with AdASCaM, AdCaM, or AdGFP and stimulated with phenylephrine (PE, 50 microM) or angiotensin II (AngII, 10 microM) for 48 h and cell surface area measured with planimetry. After PE treatment, the surface areas of cardiomyocytes infected with AdASCaM or AdGFP were 411 +/- 174.3 micro(2) and 832.6 +/- 372.3 micro(2), respectively (P < 0.01). After AngII treatment, the surface areas of cardiomyocytes infected with AdASCaM or AdGFP were 441.5 +/- 149.2 micro(2) and 726 +/- 328.3 micro(2), respectively (P < 0.01). Adenoviral expression of the CaM antisense (AdASCaM) significantly inhibited PE or AngII-induced cardiomyocyte hypertrophy. Cardiomyocytes infected with the AdCaM showed increased area when compared with those infected with the AdGFP. These results suggest that adenovirus-mediated changes in CaM expression may alter hypertrophy in cardiac myocytes.

Echocardiographic assessment of global ventricular function using the myocardial performance index in rats with hypertrophy.

Myocardial hypertrophy is the hallmark of chronic pressure overload and the myocardial performance index (MPI) is an easily recordable measurement of Doppler time intervals. In this study, the utility of using MPI to assess the progression of hypertrophy in the aortic-banded rat model was evaluated. Male Wistar rats (70-90 g) underwent ascending aorta constriction (n = 4) or a sham operation (n = 5). High-resolution echocardiography was performed 4, 7, 10, and 12 weeks after the surgery. Over this follow-up interval, animals in the aortic-banded group demonstrated an increase in their mean left ventricular (LV) mass and MPI compared with controls. MPI reflects ventricular performance in small animals with LV hypertrophy, showing alterations early after aorta constriction.

Noninvasive assessment of hemodynamic parameters in experimental stenosis of the ascending aorta.

We sought to noninvasively evaluate left ventricular (LV) function after cardiac hypertrophy induced by experimental stenosis of the ascending aorta. Male Wistar rats (70-90 g) underwent ascending aorta constriction by the surgical placement of a titanium clip (n=5) or sham operation (n=6). High-resolution bidimensional, pulsed-wave Doppler (PWD) and pulsed-wave tissue Doppler imaging (TDI) were performed 22 weeks after surgery. PWD was used to obtain mitral flow velocities, and TDI was used to obtain velocities along the septal mitral annulus and LV posterior wall. Clip placement produced myocardial hypertrophy with decreased systolic myocardial peak velocity in both the long and short axes. Increased myocardial mass, that is, posterior wall and septal thickness, was indicative of ventricular remodeling. Diastolic dysfunction was observed, with an increased early to late ratio of mitral velocities and increased left atrium dimension, consistent with a left ventricular restrictive filling pattern.

Um circuito simples com bomba única para circulação extracorpórea com oxigenação autógena / A simple circuit with only centrifugal pump for extracorporeal circulation with autogenous oxygenation

Material e Métodos: Foi testado em 30 cães um circuito capaz de promover circulação extracorpórea (CEC) com oxigenação autógena (OA) do sangue, usando apenas uma bomba centrífuga. Esta montagem dispensou bombeamento para o lado direito: o gradiente de pressão bastante para vencer a resistência arterial pulmonar foi vencido aumentando-se a pressão nas artérias pulmonares pela expansão da volemia e diminuindo-se a pressão do átrio esquerdo pela drenagem dessa câmara mediante um sifão. O coração foi mantido em ritmo de fibrilação ventricular durante o período de perfusão e ao seu término, o ritmo próprio foi recuperado mediante cardioversão elétrica.Resultados: Este circuito permitiu a manutenção de parâmetros hemodinâmicos e gases sangüíneos adequados durante a perfusão. O campo operatório e a mobilidade do coração foram similares aos proporcionados pela CEC convencional. Conclusão: Concluímos que o uso de bomba centrífuga única simplifica a OA, podendo tornar-se uma escolha prática nos procedimentos de revascularização do miocárdio(AU)#S#as#BR