Computational modeling of volumetric soft tissue growth: application to the cardiac left ventricle.

As an initial step to investigate stimulus-response relations in growth and remodeling (G&R) of cardiac tissue, this study aims to develop a method to simulate 3D-inhomogeneous volumetric growth. Growth is regarded as a deformation that is decomposed into a plastic component which describes unconstrained growth and an elastic component to satisfy continuity of the tissue after growth. In current growth models, a single reference configuration is used that remains fixed throughout the entire growth process.

Chronic left ventricular pacing preserves left ventricular function in children.

Chronic right ventricular (RV) pacing can induce structural and functional cardiac deterioration. Because animal studies showed a benefit of left ventricular (LV) over RV pacing, this study compared the effects of chronic RV and LV pacing in children. Retrospectively, echocardiographic data were evaluated from 18 healthy children (control subjects) and from children undergoing chronic epicardial RV pacing (7 RVP) or LV pacing (7 LVP).

Computational analysis of the myocardial structure: adaptation of cardiac myofiber orientations through deformation.

Deformation and structure of the cardiac wall can be assessed non-invasively by imaging techniques such as magnetic resonance imaging. Understanding the (patho-)physiology that underlies the observed deformation and structure is critical for clinical diagnosis. However, much about the genesis of deformation and structure is unknown.

Structure and torsion of the normal and situs inversus totalis cardiac left ventricle. I. Experimental data in humans.

In 1926, the famous American pediatric cardiologist, Dr. Helen B. Taussig, observed that in situs inversus totalis (SIT) main gross anatomical structures and the deep muscle bundles of the ventricles were a mirror image of the normal structure, while the direction of the superficial muscle bundles remained unchanged (H.

Structure and torsion in the normal and situs inversus totalis cardiac left ventricle. II. Modeling cardiac adaptation to mechanical load.

Mathematical models provide a suitable platform to test hypotheses on the relation between local mechanical stimuli and responses to cardiac structure and geometry. In the present model study, we tested hypothesized mechanical stimuli and responses in cardiac adaptation to mechanical load on their ability to estimate a realistic myocardial structure of the normal and situs inversus totalis (SIT) left ventricle (LV). In a cylindrical model of the LV, 1) mass was adapted in response to myofiber strain at the beginning of ejection and to global contractility (average systolic pressure), 2) cavity volume was adapted in response to fiber strain during ejection, and 3) myofiber orientations were adapted in response to myofiber strain during ejection and local misalignment between neighboring tissue parts.

Cardiac resynchronization: insight from experimental and computational models.

Cardiac resynchronization therapy (CRT) is a promising therapy for heart failure patients with a conduction disturbance, such as left bundle branch block. The aim of CRT is to resynchronize contraction between and within ventricles. However, about 30% of patients do not respond to this therapy.

Left ventricular apical torsion and architecture are not inverted in situs inversus totalis.

Occasionally, individuals have a complete, mirror-image reversal of their internal organ position, called situs inversus totalis (SIT). Whereas gross anatomy is mirror-imaged in SIT, this might not be the case for the internal architecture of organs, e.g.

Physiology of cardiac pacing in children: the importance of the ventricular pacing site.

Children with congenital or acquired atrioventricular block are provided with ventricular rate support from a pacing lead that traditionally is positioned at the right ventricular (RV) apex. However, RV apical pacing causes dyssynchronous electrical activation and left ventricular (LV) contraction, resulting in decreased LV function. Chronic RV apical pacing leads to deterioration of LV function and morphology, resulting in cardiac failure in approximately 7% of children.

Modeling ventricular interaction: a multiscale approach from sarcomere mechanics to cardiovascular system hemodynamics.

Direct ventricular interaction via the interventricular septum plays an important role in ventricular hemodynamics and mechanics. A large amount of experimental data demonstrates that left and right ventricular pump mechanics influence each other and that septal geometry and motion depend on transmural pressure. We present a lumped model of ventricular mechanics consisting of three wall segments that are coupled on the basis of balance laws stating mechanical equilibrium at the intersection of the three walls.

Magnetic resonance imaging of the coronary arteries.

Despite progress in prevention and early diagnosis, coronary artery disease (CAD) remains one of the leading causes of mortality in the world. For many years, invasive X-ray coronary angiography has been the method of choice for the diagnosis of significant CAD. However, up to 40% of patients referred for elective X-ray coronary angiography have no clinically significant stenoses.

Ebstein's anomaly: factors associated with death in childhood and adolescence: a multi-centre, long-term study.

Aims: The objective of this study is to establish factors associated with death after diagnosis of Ebstein's anomaly (EA) during childhood and adolescence.

Methods And Results: This study is a retrospective chart review. All paediatric patients were diagnosed with EA and followed in tertiary-care university hospitals between 1980 and 2005.

Both type 1 and type 2a muscle fibers can respond to enzyme therapy in Pompe disease.

Muscle weakness is the main symptom of Pompe disease, a lysosomal storage disorder for which major clinical benefits of enzyme replacement therapy (ERT) have been documented recently. Restoration of skeletal muscle function is a challenging goal. Type 2 muscle fibers of mice with Pompe disease have proven resistant to therapy.

Two Dutch brothers with Borrone dermato-cardio-skeletal syndrome.

In 1993, Borrone et al. described two Italian brothers affected by a syndrome of severe acne, mitral valve prolapse, dysmorphic facies, and Scheuermann-like changes of the vertebral column. Since then, no further cases have been reported.

The relation between organ anatomy and pre-existent vertebral rotation in the normal spine: magnetic resonance imaging study in humans with situs inversus totalis.

Study Design: In this cross-sectional magnetic resonance imaging study, vertebral rotation was measured in the transverse plane of the normal, nonscoliotic spine of persons with a complete mirror image reversal of the internal body organs, called situs inversus totalis.

Objectives: To determine if a pattern of rotation exists in the normal spine of persons with situs inversus totalis, opposite of what was found in humans with normal organ anatomy.

Summary Of Background Data: In humans, as well as in quadrupeds, the mid and lower thoracic vertebrae of the normal, nonscoliotic spine show a pre-existent pattern of rotation to the right side.

Pacing-induced dyssynchrony during early reperfusion reduces infarct size.

Objectives: Considering the recent discovery of postconditioning, we investigated whether intermittent dyssynchrony immediately upon reperfusion induces cardioprotection as well.

Background: Intermittent dyssynchrony, induced by ventricular pacing, preconditions myocardium.

Methods: Isolated ejecting rabbit hearts were subjected to 30-min coronary occlusion and 2-h reperfusion.

Genetic and biophysical basis for bupivacaine-induced ST segment elevation and VT/VF. Anesthesia unmasked Brugada syndrome.

Background: Brugada syndrome is an inherited disease associated with sudden cardiac death. The electrocardiographic pattern associated with Brugada syndrome has been linked to the use of sodium channel blockers, including antiarrhythmics, trycyclics and anesthetics.

Objective: We report a case of bupivacaine-induced Brugada syndrome, in which we investigated the genetic, biophysical and path physiological mechanism involved.

Pacing-induced dys-synchrony preconditions rabbit myocardium against ischemia/reperfusion injury.

Background: Because increased mechanical load induces preconditioning (PC) and dys-synchrony increases loading in late-activated regions, we investigated whether dys-synchrony induced by ventricular pacing (VP) at normal heart rate leads to cardioprotection.

Methods And Results: Isolated working rabbit hearts were subjected to 35 minutes of global ischemia and 2 hours of reperfusion. Seven hearts underwent VP PC (3 periods of 5 minutes VP at the posterior left ventricular [LV] wall), 7 hearts underwent ischemic preconditioning (IPC) (3 periods of 5 minutes of global ischemia), and 9 hearts served as control (C).

Towards model-based analysis of cardiac MR tagging data: relation between left ventricular shear strain and myofiber orientation.

Many cardiac pathologies are reflected in abnormal myocardial deformation, accessible through magnetic resonance tagging (MRT). Interpretation of the MRT data is difficult, since the relation between pathology and deformation is not straightforward. Mathematical models of cardiac mechanics could be used to translate measured abnormalities into the underlying pathology, but, so far, they even fail to correctly simulate myocardial deformation in the healthy heart.

Impaired subendocardial contractile myofiber function in asymptomatic aged humans, as detected using MRI.

With aging, structural and functional changes occur in the myocardium without obvious impairment of systolic left ventricular (LV) function. Transmural differences in myocardial vulnerability for these changes may result in increase of transmural inhomogeneity in contractile myofiber function. Subendocardial fibrosis and impairment of subendocardial perfusion due to hypertension might change the transmural distribution of contractile myofiber function.

Stenting of hypoplastic aortic segments with mild pressure gradients and arterial hypertension.

Objective: To determine the safety, feasibility and effectiveness of stent expansion of hypoplastic aortic segments with pressure gradients in patients with arterial hypertension.

Design: Non-randomised prospective clinical trial.

Setting: Tertiary referral centre, congenital cardiac unit.

Electrocardiographic changes predicting sudden death in propofol-related infusion syndrome.

Background: The occurrence of metabolic acidosis, rhabdomyolysis, hyperkalemia, and sudden cardiac death after long-term, high-dose propofol infusion has been referred to as propofol infusion syndrome (PRIS).

Objectives: The purpose of this study was to explore the ECG abnormalities observed in a patient with PRIS in order to identify possible pathophysiologic mechanisms of the syndrome.

Methods: ECG changes in the index case were characterized by down-sloping ST-segment elevation in precordial leads V1 to V3 (Brugada-like ECG pattern).

Late fenestration of the extracardiac conduit in a Fontan circuit by sequential stent flaring.

Recent Fontan circuits frequently involve an extracardiac conduit. We report on a new technique to create a late fenestration in such an extracardiac circuit by sequential flaring of a stent in the fenestration.