Preoperative and mid-term right ventricular systolic function assessment, at rest and during exercise, with speckle-tracking echocardiography after left ventricular assist device implantation.

OBJECTIVES: The study aimed to compare pre- and postoperative resting as well as postprocedural resting and exertional right ventricular speckle-tracking echocardiographic parameters at a mid-term follow-up after left ventricular assist device (LVAD) implantation. METHODS: Patients with implanted third-generation LVADs with hydrodynamic bearings were prospectively enrolled (NCT05063006). Myocardial deformation was evaluated before pump implantation and at least three months after the procedure, both at rest and during exercise. RESULTS: We included 22 patients, 7.3 months (IQR, 4.7-10.2) after the surgery. The mean age was 58.4 ± 7 years, 95.5% were men, and 45.5% had dilated cardiomyopathy. The RV strain analysis was feasible in all subjects both at rest and during exercise. The RV free wall strain (RVFWS) worsened from -13% (IQR, -17.3 to -10.9) to -11.3% (IQR, -12.9 to -6; p = 0.033) after LVAD implantation with a particular decline in the apical RV segment [-11.3% (IQR, -16.4 to -6.2) vs -7.8% (IQR, -11.7 to -3.9; p = 0.012)]. The RV four-chamber longitudinal strain (RV4CSL) remained unchanged [-8.5% (IQR, -10.8 to -6.9) vs -7.3% (IQR, -9.8 to -4.7; p = 0.184)]. Neither RVFWS (-11.3% (IQR, -12.9 to -6) vs -9.9% (IQR, -13.5 to -7.5; p = 0.077) nor RV4CSL [-7.3% (IQR, -9.8 to -4.7) vs -7.9% (IQR, -9.8 to -6.3; p = 0.548)] changed during the exercise test. CONCLUSIONS: In patients who are pump-supported, the right ventricular free wall strain tends to worsen after LVAD implantation and remains unchanged during a cycle ergometer stress test.

Echo-guided left ventricular assist device speed optimisation for exercise maximisation.

OBJECTIVE: Current generation left ventricular assist devices (LVADs) operate with a fixed rotation speed and no automated speed adjustment function. This study evaluates the concept of physiological pump speed optimisation based on aortic valve opening (AVO) imaging during a cardiopulmonary exercise test (CPET). METHODS: This prospective crossover study (NCT05063006) enrolled patients with implanted third-generation LVADs with hydrodynamic bearing. After resting speed optimisation, patients were randomised to a fixed-modified speed or modified-fixed speed CPET sequence. Fixed speed CPET maintained baseline pump settings. During the modified speed CPET, the LVAD speed was continuously altered to preserve periodic AVO. RESULTS: We included 22 patients, the mean age was 58.4±7 years, 4.5% were women and 54.5% had ischaemic cardiomyopathy. Exertional AVO assessment was feasible in all subjects. Maintaining periodic AVO allowed to safely raise the pump speed from 2900 (IQR 2640-3000) to 3440 revolutions per minute (RPM) (IQR 3100-3700; p<0.001). As a result, peak oxygen consumption increased from 11.1±2.4 to 12.8±2.8 mL/kg/min (p<0.001) and maximum workload from 1.1 (IQR 0.9-1.5) to 1.2 W/kg (IQR 0.9-1.7; p=0.028). The Borg scale exertion level decreased from 15.2±1.5 to 13.5±1.2 (p=0.005). CONCLUSIONS: Transthoracic AVO imaging is possible during CPETs in patients with LVAD. Dynamic echo-guided pump speed adjustment based on the AVO improves exercise tolerance and augments peak oxygen consumption and maximum workload.

Colour-Based Binary Discrimination of Scarified Quercus robur Acorns under Varying Illumination.

Efforts to predict the germination ability of acorns using their shape, length, diameter and density are reported in the literature. These methods, however, are not efficient enough. As such, a visual assessment of the viability of seeds based on the appearance of cross-sections of seeds following their scarification is used. This procedure is more robust but demands significant effort from experienced employees over a short period of time. In this article an automated method of acorn scarification and assessment has been announced. This type of automation requires the specific setup of a machine vision system and application of image processing algorithms for evaluation of sections of seeds in order to predict their viability. In the stage of the analysis of pathological changes, it is important to point out image features that enable efficient classification of seeds in respect of viability. The article shows the results of the binary separation of seeds into two fractions (healthy or spoiled) using average components of regular red-green-blue and perception-based hue-saturation-value colour space. Analysis of accuracy of discrimination was performed on sections of 400 scarified acorns acquired using two various setups: machine vision camera under uncontrolled varying illumination and commodity high-resolution camera under controlled illumination. The accuracy of automatic classification has been compared with predictions completed by experienced professionals. It has been shown that both automatic and manual methods reach an accuracy level of 84%, assuming that the images of the sections are properly normalised. The achieved recognition ratio was higher when referenced to predictions provided by professionals. Results of discrimination by means of Bayes classifier have been also presented as a reference.

An automated method for fibrin clot permeability assessment.

The fibrin clot permeability coefficient (Ks) is a useful measure of porosity of the fibrin network, which is determined by a number of genetic and environmental factors. Currently available methods to evaluate Ks are time-consuming, require constant supervision and provide only one parameter. We present an automated method in which drops are weighed individually, buffer is dosed by the pump and well defined clot washing is controlled by the software. The presence of a straight association between drop mass and their dripping time allows to shorten the measurement time twice. In 40 healthy individuals, Ks, the number of drops required to reach the plateau (DTP), the time to achieve the plateau (TTP) and the DTP/TTP ratio (DTR) were calculated. There was a positive association between Ks (r = 0.69, P < 0.0001) evaluated by using the manual [median of 4.17 (3.60-5.18) ·10⁻9 cm²) and the automated method [median of 4.35 (3.74-5.38) ·10⁻9 cm²]. The correlation was stronger (r = 0.85, P < 0.001) in clots with DTP of 7 or less (n = 12). DTP was associated with total homocysteine (tHcy) (r = 0.35, P < 0.05) and activated partial thromboplastin time (APTT) (r = -0.34, P < 0.05), TTP with Ks (r = -0.55, P < 0.01 for the manual method and r = -0.44, P < 0.01 for the automated method) and DTP (r = 0.75, P < 0.0001), and DTR with Ks (r = 0.70, P < 0.0001 for the manual method and r = 0.76, P < 0.0001 for the automated method), fibrinogen (r = -0.58, P < 0.0001) and C-reactive protein (CRP) (r = -0.47, P < 0.01). The automated method might be a suitable tool for research and clinical use and may offer more additional parameters describing fibrin clot structure.