Left ventricular high frame rate echo-particle image velocimetry: clinical application and comparison with conventional imaging

BACKGROUND: Echo-Particle Image Velocimetry (echoPIV) tracks speckle patterns from ultrasound contrast agent(UCA), being less angle-sensitive than colour Doppler. High frame rate (HFR) echoPIV enables tracking of high velocity flow in the left ventricle (LV). We aimed to demonstrate the potential clinical use of HFR echoPIV and investigate the feasibility and accuracy in patients. METHODS: Nineteen patients admitted for heart failure were included. HFR contrast images were acquired from an apical long axis view (ALAX), using a fully-programmable ultrasound system. A clinical UCA was continuously infused with a dedicated pump. Additionally, echocardiographic images were obtained using a clinical system, including LV contrast-enhanced images and pulsed-wave (PW) Doppler of the LV inflow and outflow in ALAX. 11 patients underwent CMR and 4 cardiac CT as clinically indicated. These CMR and CT images were used as reference. In 10 patients with good echoPIV tracking and reference imaging, the intracavitary flow was compared between echoPIV, conventional and UCA echocardiography. RESULTS: EchoPIV tracking quality was good in 12/19 (63%), moderate in 2/19 (10%) and poor in 5/19 (26%) subjects. EchoPIV could determine inflow velocity in 17/19 (89%), and outflow in 14/19 (74%) patients. The correlation of echoPIV and PW Doppler was good for the inflow (R(2) = 0.77 to PW peak; R(2) = 0.80 PW mean velocity) and moderate for the outflow (R(2) = 0.54 to PW peak; R(2) = 0.44 to PW mean velocity), with a tendency for echoPIV to underestimate PW velocities. In selected patients, echoPIV was able in a single acquisition to demonstrate flow patterns which required multiple interrogations with classical echocardiography. Those flow patterns could also be linked to anatomical abnormalities as seen in CMR or CT. CONCLUSION: HFR echoPIV tracks multidirectional and complex flow patterns which are unapparent with conventional echocardiography, while having comparable feasibility. EchoPIV tends to underestimate flow velocities as compared to PW Doppler. It has the potential to provide in one acquisition all the functional information obtained by conventional imaging, overcoming the angle dependency of Doppler and low frame rate of classical contrast imaging. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12947-022-00283-4

Prognostic significance of left atrial strain in sarcomere gene variant carriers without hypertrophic cardiomyopathy

BACKGROUND: Genetic testing of relatives of hypertrophic cardiomyopathy (HCM) patients has led to a large group of genotype-positive, phenotype-negative (G+/Ph-) subjects. Prediction of progression to overt HCM in these subjects is challenging. While left atrial (LA) strain is reduced in HCM patients it is currently unknown whether this parameter can be used to predict HCM phenotype progression. METHODS: This study includes 91 G+/Ph- subjects and 115 controls. Standard echocardiographic parameters as well as left ventricular global longitudinal strain (LV GLS) and LA reservoir strain (LASr) were assessed for each patient. Logistic and Cox proportional hazard regression analyses were used to investigate predictors of G+/Ph- status and HCM during follow-up. RESULTS: Independent predictors of G+ status included pathological Q waves (OR 1.60 [1.15-2.23], p < .01), maximal wall thickness (MWT: OR 1.10 [1.07-1.14], p < .001), mitral inflow E wave (OR 1.06 [1.02-1.10, p = .001), A wave (OR 1.06 [1.03-1.10], p < .001), LV GLS (OR .96 [.94-.98], p < .001), and LASr (OR .99 [.97-.99], p = .03). In univariable Cox regression analysis, male sex (HR 2.78 [1.06-7.29], p = .04), MWT (HR 1.72 [1.14-2.57], p = .009) and posterior wall thickness (HR 1.65 [1.17-2.30], p = .004) predicted HCM during a median follow-up of 5.9 [3.2-8.6] years, whereas LASr did not (HR .95 [.89-1.02], p = .14). There were no significant predictors of HCM after multivariable adjustment. CONCLUSION: LASr is significantly impaired in G+/Ph- subjects and is an independent predictor of G+/Ph- status, but did not predict HCM development during follow-up

Optimization of Microbubble Concentration and Acoustic Pressure for Left Ventricular High Frame Rate EchoPIV in Patients

High-frame-rate (HFR) echo-particle image velocimetry (echoPIV) is a promising tool for measuring intracardiac blood flow dynamics. In this study, we investigate the optimal ultrasound contrast agent (UCA: SonoVue) infusion rate and acoustic output to use for HFR echoPIV (PRF = 4900 Hz) in the left ventricle (LV) of patients. Three infusion rates (0.3, 0.6, and 1.2 ml/min) and five acoustic output amplitudes (by varying transmit voltage: 5, 10, 15, 20, and 30 V - corresponding to mechanical indices of 0.01, 0.02, 0.03, 0.04, and 0.06 at 60-mm depth) were tested in 20 patients admitted for symptoms of heart failure. We assess the accuracy of HFR echoPIV against pulsed-wave Doppler acquisitions obtained for mitral inflow and aortic outflow. In terms of image quality, the 1.2-ml/min infusion rate provided the highest contrast-to-background ratio (CBR) (3-dB improvement over 0.3 ml/min). The highest acoustic output tested resulted in the lowest CBR. Increased acoustic output also resulted in increased microbubble disruption. For the echoPIV results, the 1.2-ml/min infusion rate provided the best vector quality and accuracy; mid-range acoustic outputs (corresponding to 15-20-V transmit voltages) provided the best agreement with the pulsed-wave Doppler. Overall, the highest infusion rate (1.2 ml/min) and mid-range acoustic output amplitudes provided the best image quality and echoPIV results.ImPhys/Medical Imagin

Longitudinal changes of thoracic aortic diameters in the general population aged 55 years or older

Objective Longitudinal data on age-related changes in the diameters of the thoracic aorta are scarce. To better understand normal variation and to identify factors influencing this process, we aimed to report male-female-specific and age-specific aortic growth rate in the ageing general population and identify factors associated with growth rate. Methods From the prospective population-based Rotterdam Study, 943 participants (52.0% females, median age at baseline 65 years (62-68)) underwent serial non-enhanced cardiac CT. We measured the diameters of the ascending (AA) and descending aorta (DA) at two time points and expressed absolute and relative differences. Linear mixed effects analysis was performed to identify determinants associated with change in aortic diameters. Results Mean AA diameter at baseline was 37.3±3.6 mm in male population and 34.7±3.2 mm in female population, mean DA diameter was 29.6±2.3 in male population and 26.9±2.2 mm in female population. The median absolute change in diameters during follow-up (mean scan interval 14.1±0.3 years) was 1 mm (0-2) for both the AA and DA. Absolute change per decade in AA diameter was significantly larger in males than in females (0.72 mm/decade (0.00-1.43) vs 0.70 mm/decade (0.00-1.41), p=0.006), as well as absolute change in AD diameter (0.71 mm/decade (0.00-1.42) vs 0.69 mm/decade (0.00-1.36), p=0.008). There was no significant difference between male and female population in relative change of their aortic diameters during follow-up. Age, male sex, higher body mass index (BMI) and higher diastolic blood pressure (DBP) showed a statistically significant independent association with increase in AA and DA diameters over time. Conclusions Some degree of increase in thoracic aortic diameters is typical in both men and women of an aging population. Factors associated with this change in thoracic aortic diameters were sex, age, BMI and DBP