Left Ventricular Deformation and Vortex Analysis in Heart Failure: From Ultrasound Technique to Current Clinical Application

Computational modeling of left ventricular flow using PC-CMR-derived four-dimensional wall motion

Intracardiac hemodynamics plays a crucial role in the onset and development of cardiac and valvular diseases. Simulations of blood flow in the left ventricle (LV) have provided valuable insight into assessing LV hemodynamics. While fully coupled fluid-solid modelings of the LV remain challenging due to the complex passive-active behavior of the LV wall myocardium, the integration of imaging-driven quantification of structural motion with computational fluid dynamics (CFD) modeling in the LV holds the promise of feasible and clinically translatable characterization of patient-specific LV hemodynamics. In this study, we propose to integrate two magnetic resonance imaging (MRI) modalities with the moving-boundary CFD method to characterize intracardiac LV hemodynamics. Our method uses the standard cine cardiac magnetic resonance (CMR) images to estimate four-dimensional myocardial motion, eliminating the need for involved myocardial material modeling to capture LV wall behavior. In conjunction with CMR, phase contrast-MRI (PC-MRI) was used to measure temporal blood inflow rates at the mitral orifice, serving as an additional boundary condition. Flow patterns, including velocity streamlines, vortex rings, and kinetic energy, were characterized and compared to the available data. Moreover, relationships between LV wall kinematic markers and flow characteristics were determined without myocardial material modeling and using a non-rigid image registration (NRIR) method. The fidelity of the simulation was quantitatively evaluated by validating the flow rate at the aortic outflow tract against respective PC-MRI measures. The proposed methodology offers a novel and feasible toolset that works with standard PC-CMR protocols to improve the clinical assessment of LV characteristics in prognostic studies and surgical planning.

Role of speckle tracking echocardiography beyond current guidelines in cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is a device-based treatment applied to patients with a specific profile of heart failure. According to current guidelines, indication for CRT is given on the basis of QRS morphology and duration, and traditional transthoracic echocardiography is mainly used to estimate left ventricular (LV) ejection fraction. However, the identification of patients who may benefit from CRT remains challenging, since the application of the above-mentioned guidelines is still associated with a high rate of non-responders. The assessment of various aspects of LV mechanics (including contractile synchrony, coordination and propagation, and myocardial work) performed by conventional and novel ultrasound technologies, first of all speckle tracking echocardiography (STE), may provide additional, useful information for CRT patients' selection, in particular among non-LBBB patients, who generally respond less to CRT. A multiparametric approach, based on the combination of ECG criteria and echocardiographic indices of LV dyssynchrony/discoordination would be desirable to improve the prediction of CRT response.

Cardiac reverse remodelling by imaging parameters with recent changes to guideline medical therapy in heart failure

Recently established heart failure therapies, including sodium glucose co-transporter 2 inhibitors, angiotensin-neprilysin inhibitors, and cardiac resynchronization therapy, have led to both clinical and structural improvements. Reverse remodelling describes the structural and functional responses to therapy and has been shown to correlate with patients' clinical response, acting as a biomarker for treatment success. The introduction of these new therapeutic agents in addition to advances in non-invasive cardiac imaging has led to an expansion in the evaluation and the validation of cardiac reverse remodelling. Methods including volumetric changes as well as strain and myocardial work have all been shown to be non-invasive end-points of reverse remodelling, correlating with clinical outcomes. Our review summarizes the current available evidence on reverse remodelling in heart failure by the non-invasive cardiac imaging techniques, in particular transthoracic echocardiography.

Multimodality imaging in decompensated heart failure

Heart failure (HF) is usually suspected by clinical history, symptoms, physical examination, electrocardiogram findings, and natriuretic peptides' values. However, echocardiography and other imaging techniques play an essential role in supporting HF diagnosis. Thanks to its non-invasiveness and safety, transthoracic echocardiography is the first-level technique of choice to assess myocardial structure and function, trying to establish the diagnosis of HF with reduced, mildly reduced, and preserved ejection fraction. The role of echocardiography is not limited to diagnosis but it represents a crucial tool in guiding therapeutic decision-making and monitoring response to therapy. Over the last decades, several technological advancements were made in the imaging field, aiming at better understanding the morphofunctional abnormalities occurring in cardiovascular diseases. The purpose of this review article is to summarize the incremental role of imaging techniques (in particular cardiac magnetic resonance and myocardial scintigraphy) in HF, highlighting their essential applications to HF diagnosis and management.

Exercise Training: The Holistic Approach in Cardiovascular Prevention

Nowadays, there are robust clinical and pathophysiological evidence supporting the beneficial effects of physical activity on cardiovascular (CV) system. Thus, the physical activity is considered a key strategy for CV prevention. In fact, exercise training exerts favourable effects on all risk factors for CV diseases (i.e. essential hypertension, type 2 diabetes mellitus, hypercholesterolemia, obesity, metabolic syndrome, etc…). In addition, all training modalities such as the aerobic (continuous walking, jogging, cycling, etc.) or resistance exercise (weights), as well as the leisure-time physical activity (recreational walking, gardening, etc) prevent the development of the major CV risk factors, or delay the progression of target organ damage improving cardio-metabolic risk. Exercise training is also the core component of all cardiac rehabilitation programs that have demonstrated to improve the quality of life and to reduce morbidity in patients with CV diseases, mostly in patients with coronary artery diseases. Finally, it is still debated whether or not exercise training can influence the occurrence of atrial and ventricular arrhythmias. In this regard, there is some evidence that exercise training is protective predominantly for atrial arrhythmias, reducing the incidence of atrial fibrillation. In conclusion, the salutary effects evoked by physical acitvity are useful in primary and secondary CV prevention.