Exploring the mechanisms responsible for reduced systolic function in high-gradient aortic stenosis.

Objective: To characterise the mechanics responsible for the reduced ejection fraction (rEF) in high-gradient severe aortic stenosis (AS).

Methods: 21 patients with high-gradient severe AS (aortic valve area (AVA) <1.0 cm and mean gradient (MG) >40 mm Hg) were included.

In-silico modelling of the impact of hypertension on the mean transvalvular gradients in aortic stenosis.

Introduction: The influence of hypertension on the diagnostic assessment of aortic stenosis (AS) severity is unclear, yet clinically relevant. To clarify the effect of hypertension on transvalvular gradients, requires a better understanding of the impact that blood pressure change has on mean flow rate. Also, the effect of various degrees of AS severity, the valve geometry and intrinsic left ventricular contractile function (elastance) on this interaction, needs to be clarified.

Estimation of Simulated Left Ventricle Elastance Using Lumped Parameter Modelling and Gradient-Based Optimization With Forward-Mode Automatic Differentiation Based on Synthetically Generated Noninvasive Data.

The present study evaluates a parameter discovery approach based on a lumped parameter model of the cardiovascular system in conjunction with optimization to approximate important cardiac parameters, including simulated left ventricle elastances. Important parameters pertaining to ventricular function were estimated using gradient optimization and synthetically generated measurements. Forward-mode automatic differentiation was used to estimate the cost function-parameter matrices and compared to the common finite differences approach.

Dynamic simulation of aortic valve stenosis using a lumped parameter cardiovascular system model with flow regime dependent valve pressure loss characteristics.

Valvular heart diseases are growing concern in impoverished parts of the world, such as Southern-Africa, claiming more than 31 % of total deaths related to cardiovascular diseases. The ability to model the effects of regurgitant and obstructive lesions on the valve body can assist clinicians in preparing personalised treatments. In the present work, a multi-compartment lumped parameter model of the human cardiovascular system is developed, with a newly proposed valve modelling approach which accounts for geometry and flow regime dependent pressure drops along with the valve cusp motion.

Subacute dual stent thromboses in a COVID-19-positive patient.

The hypercoagulable state of COVID-19 is resulting in an increasing number of unexpected venous and arterial thromboses in patients. We report a case of subacute dual coronary stent thrombosis in the setting of COVID-19 and we provide a brief review of current management recommendations.

Sporotrichosis in renal transplant patients: two case reports and a review of the literature.

Introduction: Sporotrichosis is a rare fungal infection in transplant patients; among these patients, it occurs mostly in renal transplant patients. Sporothrix schenkii is the primary pathogen responsible. A high index of suspicion is required to make the diagnosis keeping important differential diagnoses in mind.

A "Vanishing", Tuberculous, Pericardial Effusion.

We present an iatrogenic, pleuro-pericardial connection resulting from pericardiocentesis of a large, tuberculous, pericardial effusion. Recognition of this situation is paramount when one is unable to aspirate pericardial fluid after a successful, initial puncture. Such knowledge will help prevent myocardial or coronary artery injury with further attempts at aspiration.