Will the real ventricular architecture please stand up?

Ventricular twisting, essential for cardiac function, is attributed to the contraction of myocardial helical fibers. The exact relationship between ventricular anatomy and function remains to be determined, but one commonly used explanatory model is the helical ventricular myocardial band (HVMB) model of Torrent-Guasp. This model has been successful in explaining many aspects of ventricular function, (Torrent-Guasp et al. Eur. J. Cardiothorac. Surg., 25, 376, 2004; Buckberg et al. Eur. J. Cardiothorac. Surg., 47, 587, 2015; Buckberg et al. Eur. J. Cardiothorac. Surg. 47, 778, 2015) but the model ignores important aspects of ventricular anatomy and should probably be replaced. The purpose of this review is to compare the HVMB model with a different model (nested layers). A complication when interpreting experimental observations that relate anatomy to function is that, in the myocardium, shortening does not always imply activation and lengthening does not always imply inactivation

Determination of regional bone blood flow by means of fluorescent microspheres using an automated sample-processing procedure

The determination of regional blood flow utilizing fluorescent microspheres (FMs) is an established method for numerous organs. Recent progress, in particular the automation of sample processing, has further improved this method. However, the FM method (reference sample technique), which allows repetitive measurement of regional organ blood flow, has so far not been used for the determination of blood flow in bone. The aim of the present study was to establish FM for the quantification of regional bone blood flow (RBBF). Female, anesthetized New Zealand rabbits (n = 6) received left ventricular injections of different amounts of FM at six subsequent time points. In order to examine the precision of RBBF determination, two different FM species were injected simultaneously at the sixth injection. At the end of the experiments the femoral and tibial condyles of each hind limb were removed and the fluorescence intensity in the tissue samples was measured by an automated procedure. In an in vitro study we have shown that acid digestion of the crystalline matrix has no effect on the fluorescence characteristics of FM. The determination of the number of spheres per tissue sample revealed that depending on the tissue sample size up to 3 x 10(6) spheres/injection were necessary to obtain about 400 microspheres in the individual bone samples. RBBF values of the tibial and femoral condyles did not differ at various injection intervals. The tibial blood flow values varied between 6.6 +/- 1.1 and 8.5 +/- 1.4 ml/min/100 g and were significantly higher than those of the femur (4.3 +/- 1.1 to 6.0 +/- 1.8 ml/min/100 g). The bone blood flow values obtained by simultaneous injection of two FM species correlated significantly (r = 0.96, slope = 1.06, intercept = 0.05), the mean difference was 0.39 +/- 1.11 ml/min/100 g. Our data demonstrate that the measurement of RBBF by means of FM allows a valid determination of RBBF. Copyright (C) 2003 S. Karger AG, Basel

Right ventricular architecture responsible for mechanical performance: Unifying role of ventricular septum

The right ventricle (RV) is composed of a free wall containing a wrap-around circumferential muscle at its base and a septum composed of helical fibers that are oblique and cross each other at 60° angles. This structure is defined by the helical ventricular myocardial band and defines RV function because the wrap-around transverse fibers constrict or compress to cause the bellows motion responsible for 20% of RV output, whereas the oblique fibers determine shortening and lengthening that produces 80% of RV systolic function. Clinical shortening is quantified by tricuspid annular plane systolic excursion and measured by echocardiography. Destruction of the free wall by electrocautery or patch replacement does not alter RV function if the septum is intact. Conversely, septal damage causes RV dysfunction if pulmonary vascular resistance is increased. The interaction between structure and function to cause RV failure and how these factors become corrected is defined for RV failure, RV relationship to LV failure, resynchronization, pacing, RV dysplasia, left ventricular assist device, intraoperative septal injury during myocardial protection, the septal role in tricuspid insufficiency, pharmacologic decisions on altering pulmonary vascular resistance in RV failure, congenital heart disease, and adult heart disease is considered in this overview. These structure–function relationships emphasize why clinical decisions must be based on knowledge of normality, recognizing how disease offsets normality, and introducing actions that rebuild normality

Surgical treatment of patients with heart failure through myocardial revascularization, ventricular reconstruction, and mitral valve surgery

Universidade Federal de São Paulo (UNIFESP) EPMUNIFESP, EPMSciEL

Non-invasive measurements of atherosclerosis in adult cystinosis patients

Item does not contain fulltextBACKGROUND: Cystinosis is characterized by intralysosomal cystine accumulation, causing end stage renal disease around 10 years of age if not treated with cysteamine. Cystine accumulation in blood vessels might increase atheroma formation or arterial stiffness and therefore increase the risk for cardiovascular disease (CVD). This study aimed to investigate the risk for CVD by non-invasive measures of atherosclerosis (NIMA) and to evaluate the effect of cysteamine treatment. PATIENTS AND METHODS: Thirteen Dutch adult cystinosis patients were included. White blood cell (WBC) cystine levels, glomerular filtration rate (GFR) and concommitant medications were obtained from medical records. NIMA included carotid intima-media thickness (cIMT, n = 13), pulse wave velocity (PWV, n = 8) and pulse wave analysis (PWA, n = 6). Results : GFR ranged between 4-95 mL/min/1.73 m(2). All but one patient were treated with cysteamine, mean WBC cystine values ranged between 0.34-1.64 nmol cystine/mg protein, 8 patients had mean WBC cystine levels <1 nmol cystine/mg protein. When compared to healthy subjects, cIMT and PWV levels were above normal values in 1 patient for each measure. PWA measurements showed high augmentation index in three patients who did not receive lipid-lowering medication. When corrected for renal function, cIMT and PWV levels were within the normal range. CONCLUSION: Young adult cystinosis patients treated with cysteamine have no additional risk for CVD when compared to patients with chronic kidney disease of other causes

Does the Plaintiff Matter?: An Empirical Analysis of Lead Plaintiffs in Securities Class Actions

With the enactment of the Private Securities Litigation Reform Act of 1995 (PSLR) the U.S. Congress introduced sweeping substantive and procedural reforms for securities class actions. A central provision of the Act is the lead plaintiff provision, which creates a rebuttable presumption that the investor with the largest financial interest in a securities fraud class action should be appointed the lead plaintiff for the suit. The lead plaintiff provision was adopted to encourage a class member with a large financial stake to become the class representative. Congress expected that such a plaintiff would actively monitor the conduct of a securities fraud class action so as to reduce the litigation agency costs that may arise when class counsel\u27s interests diverge from those of the shareholder class. Now, more than ten years after the enactment of the lead plaintiff provision, the claim that the lead plaintiff, and particularly the lead plaintiff that is an institutional investor, is a more effective monitor of class counsel in securities fraud class actions continues to be intuitively appealing, but remains unproven. In this study, Professors Cox and Thomas inquire anecdotally and empirically whether the lead plaintiff provision has performed as projected. The anecdotal evidence they uncover is mixed: in some instances demonstrating the virtues of the lead plaintiff provision, while in others showing that the provision has encountered difficulties, including hesitance among institutional lead plaintiffs to take on the burden of serving as lead plaintiff (though recently more institutional investors are taking on the role of lead plaintiff) and allegations of pay-to-play schemes between plaintiffs\u27 law firms and potential lead plaintiffs. Professors Cox and Thomas then conduct a series of statistical analyses of the lead plaintiff provision\u27s costs and benefits. Surprisingly, their results indicate that the ratio of settlement amounts to estimated provable losses in securities class actions---the most important indicator of whether investors have been compensated for their damages---has been lower since the passage of the PSLRA and that settlement size has not increased since the passage of PSLRA. However, they also find that the presence of an institutional investor increases the dollar amount of settlements in those cases in which they appear, suggesting that the current trend for institutional investors to be lead plaintiffs in securities class actions will positively affect average settlement size in such actions in the future. Their analysis also sheds new light on the relative impacts other types of lead plaintiffs, such as individuals versus an aggregation of individuals, have on the outcome of settlements. They conclude with a discussion of the policy implications of their findings

Editorial: Defining The Relationship Between Akinesia And Dyskinesia And The Cause Of Left Ventricular Failure After Anterior Infarction And Reversal Of Remodeling To Restoration

AbstractJ Thorac Cardiovasc Surg 1998;116:47-