Left ventricular flow dynamics by cardiac imaging techniques in heart failure patients: state of the art

Fig. 1. Schematic of a long-axis view of the heart (middle) illustrating vortex motion inside the left ventricle (LV) cavity. On both the right and left side, image examples of four different cardiac imaging techniques for assessment of intracardiac flow dynamics are shown. Ao: aorta. Echo-PIV: echocardiographic particle imaging velocimetry. 4D-Flow MRI: four-dimensional flow magnetic resonance imaging. LA: left atrium. LVOT: left ventricle outflow tract

Fig. 2. Normal flow pattern inside the left ventricular (LV) cavity during a cardiac cycle in a schematic drawing of the long-axis view of the heart. KE: kinetic energy. LA: left atrium. LVOT: left ventricle outflow tract. MV: mitral valve

Fig. 3. Left ventricle (LV) longitudinal (apical-basal) hemodynamic forces (HDFs) in a normal athlete. Left top. Time profile of the apical-basal LV HDFs. The main intracardiac events during individual time intervals are indicated, together with markers of end-diastole (ED) and end-systole (ES). Left bottom. LV volume curve. Right. Intensity-weighted polar histogram, showing the distribution and intensity of the LV HDFs during the entire heartbeat as red isosceles triangles. HDFs are directed longitudinally (apex-base direction). ECG: electrocardiogram

Fig. 4. Illustration of blood flow components inside the left ventricle (LV) cavity of a normal subject. (A) The 4 components of the LV end-diastolic volume (EDV) are represented using different colors: direct flow (DF) in green, retained inflow (RI) in yellow, residual volume (RV) in red and delayed ejection flow (DEF) in blue. (B) The pie chart shows the normal percentage of the 4 components of the LV EDV. (C) The graph illustrates the temporal distribution of blood kinetic energy (KE) for each of the 4 components of the LV EDV. (D) Motion of the 4 components of the LV EDV is illustrated at different times during the cardiac cycle

Fig. 5. Top line: different stages of left ventricle (LV) remodeling compared to a normal LV. Bottom line: intensity-weighted polar histograms representing the distribution and intensity of the LV hemodynamic forces (HDFs) occurring during an entire heartbeat

Fig. 6. Physiological and pathological responses to left ventricular (LV) hemodynamic forces. ANP: atrial natriuretic peptide. BNP: brain natriuretic peptide. Col1A: collagen type I alpha. eNOS: endothelial nitric oxide synthase. IGF-1: insulin like growth factor. PGC-1α: peroxisome proliferator-activated receptor-gamma coactivator. PI3K: phosphatidylinositol 3-kinase. β-MHC: myosin heavy chain. TGF1β: transforming growth factor 1β. TRP: transient receptor potential

Fig. 7. Examples of steady-streaming flow images of the left ventricle of a normal subject and a patient with dilated cardiomyopathy. The steady-streaming flow field evaluates the overall circulatory pattern in the left ventricle during one heartbeat. Images were obtained using the HyperDoppler technique (modified from reference [5]). Geometrical measures of the main vortex are reported

Fig. 8. Factors relative to abnormal flow dynamics which favor development of apical thrombosis of the left ventricle (LV). KE: kinetic energy

Fig. 9. Different patterns of longitudinal hemodynamic forces (HDFs) within the left ventricle (LV) cavity. Compared to the normal HDF curve, in the obstructive hypertrophic cardiomyopathy (HCM) there is a reduction of both systolic and diastolic HDFs, with alterations of systolic and diastolic time indices: the systolic time index (TI, time interval to systolic peak) reduces and the suction TI (interval including late systolic deceleration and early diastolic suction) increases. The duration of the systolic LV impulse also decreases. In the left bundle branch block (LBBB), the amplitude of the longitudinal HDFs is maintained but the asynchronous activation of the LV myocardium generates multiple waves in systole and diastole, due to the uncoordinated contraction and relaxation. In dilated cardiomyopathy (DCM) there is a generalized reduction of the longitudinal HDFs. EF: ejection fraction

Fig. 10. Factors related to abnormal flow dynamics which favor development of left ventricle (LV) thrombosis, hemolysis and bleeding in patients with left ventricular assist device (LVAD). Modulating factors are also indicated. Ao: aorta. LA: left atrium. LVOT: left ventricular outflow tract. RBC: red blood cell. Vel.: velocity. vWF: von Willebrand factor