.Blood flow patterns estimation in the left ventricle with low-rate 2D and 3D dynamic contrast-enhanced ultrasound

a b s t r a c t Background and Objective : Left ventricle (LV) dysfunction always occurs at early heart-failure stages, pro- ducing variations in the LV flow patterns. Cardiac diagnostics may therefore benefit from flow-pattern analysis. Several visualization tools have been proposed that require ultrafast ultrasound acquisitions. However, ultrafast ultrasound is not standard in clinical scanners. Meanwhile techniques that can handle low frame rates are still lacking. As a result, the clinical translation of these techniques remains limited, especially for 3D acquisitions where the volume rates are intrinsically low. Methods : To overcome these limitations, we propose a novel technique for the estimation of LV blood velocity and relative-pressure fields from dynamic contrast-enhanced ultrasound (DCE-US) at low frame rates. Different from other methods, our method is based on the time-delays between time-intensity curves measured at neighbor pixels in the DCE-US loops. Using Navier-Stokes equation, we regularize the obtained velocity fields and derive relative-pressure estimates. Blood flow patterns were characterized with regard to their vorticity, relative-pressure changes (dp/dt) in the LV outflow tract, and viscous energy loss, as these reflect the ejection efficiency. Results : We evaluated the proposed method on 18 patients (9 responders and 9 non-responders) who un- derwent cardiac resynchronization therapy (CRT). After CRT, the responder group evidenced a significant (p < 0.05) increase in vorticity and peak dp/dt, and a non-significant decrease in viscous energy loss. No significant difference was found in the non-responder group. Relative feature variation before and after CRT evidenced a significant difference (p < 0.05) between responders and non-responders for vorticity and peak dp/dt. Finally, the method feasibility is also shown with 3D DCE-US. Conclusions : Using the proposed method, adequate visualization and quantification of blood flow patterns are successfully enabled based on low-rate DCE-US of the LV, facilitating the clinical adoption of the method using standard ultrasound scanners. The clinical value of the method in the context of CRT is also shown

Clinical Characteristics and Outcomes of Patients With Cutibacterium acnes Endocarditis

Importance: It is suggested that patients with Cutibacterium acnes endocarditis often present without fever or abnormal inflammatory markers. However, no study has yet confirmed this statement. Objective: To assess the clinical characteristics and outcomes of patients with C acnes endocarditis. Design, Setting, and Participants: A case series of 105 patients presenting to 7 hospitals in the Netherlands and France (4 university hospitals and 3 teaching hospitals) with definite endocarditis according to the modified Duke criteria between January 1, 2010, and December 31, 2020, was performed. Clinical characteristics and outcomes were retrieved from medical records. Cases were identified by blood or valve and prosthesis cultures positive for C acnes, retrieved from the medical microbiology databases. Infected pacemaker or internal cardioverter defibrillator lead cases were excluded. Statistical analysis was performed in November 2022. Main Outcomes and Measures: Main outcomes included symptoms at presentation, presence of prosthetic valve endocarditis, laboratory test results at presentation, time to positive results of blood cultures, 30-day and 1-year mortality rates, type of treatment (conservative or surgical), and endocarditis relapse rates. Results: A total of 105 patients (mean [SD] age, 61.1 [13.9] years; 96 men [91.4%]; 93 patients [88.6%] with prosthetic valve endocarditis) were identified and included. Seventy patients (66.7%) did not experience fever prior to hospital admission, nor was it present at hospitalization. The median C-reactive protein level was 3.6 mg/dL (IQR, 1.2-7.5 mg/dL), and the median leukocyte count was 10.0 × 103/µL (IQR, 8.2-12.2 × 103/µL). The median time to positive blood culture results was 7 days (IQR, 6-9 days). Surgery or reoperation was indicated for 88 patients and performed for 80 patients. Not performing the indicated surgical procedure was associated with high mortality rates. Seventeen patients were treated conservatively, in accordance with the European Society of Cardiology guideline; these patients showed relatively high rates of endocarditis recurrence (5 of 17 [29.4%]). Conclusions and Relevance: This case series suggests that C acnes endocarditis was seen predominantly among male patients with prosthetic heart valves. Diagnosing C acnes endocarditis is difficult due to its atypical presentation, with frequent absence of fever and inflammatory markers. The prolonged time to positivity of blood culture results further delays the diagnostic process. Not performing a surgical procedure when indicated seems to be associated with higher mortality rates. For prosthetic valve endocarditis with small vegetations, there should be a low threshold for surgery because this group seems prone to endocarditis recurrence.</p

Atrioventricular and interventricular delay optimization in cardiac resynchronization therapy: physiological principles and overview of available methods

In this review, the physiological rationale for atrioventricular and interventricular delay optimization of cardiac resynchronization therapy is discussed including the influence of exercise and long-term cardiac resynchronization therapy. The broad spectrum of both invasive and non-invasive optimization methods is reviewed with critical appraisal of the literature. Although the spectrum of both invasive and non-invasive optimization methods is broad, no single method can be recommend for standard practice as large-scale studies using hard endpoints are lacking. Current efforts mainly investigate optimization during resting conditions; however, there is a need to develop automated algorithms to implement dynamic optimization in order to adapt to physiological alterations during exercise and after anatomical remodeling

A Spatial Near-Field Clutter Reduction Filter Preserving Tissue Speckle in Echocardiography

Near-field (NF) clutter in echocardiography is depicted as a diffuse haze hindering the visualization of the myocardium and the blood-pool, thereby degrading its diagnostic value. Several clutter filters have been developed, which are limited in patients with contraction motion and rhythm anomalies, and in 3-D ultrasound (US). This study introduces a new NF clutter reduction method, which preserves US speckles required for strain imaging. The filter developed detects the NF clutter region in the spatial frequency domain. The filter employs an oriented, multiscale approach, and assumes the NF clutter to be predominantly present in the highest and lowest bandpass images. These bandpass images were filtered, whilst sparing features in the myocardium and NF clutter-free regions. The performance of the filter was assessed in a volunteer study, in ten 3-D apical and parasternal view acquisitions, and in a retrospective clinical study composed of 20 cardiac patients with different indications for echocardiography. The filter reduced NF clutter in all data sets, whilst preserving all or most of the myocardium. Additionally, it demonstrated a consistent enhancement of image quality, with an increase in contrast of 4.3 dB on average, and generated a clearer myocardial boundary distinction. Furthermore, the speckles were preserved according to the quality index based on local variance, the structural similarity index method, and normalized cross correlation values, being 0.82, 0.92, and 0.95 on average, respectively. Global longitudinal strain measurements on NF clutter reduced images were improved or equivalent compared to the original acquisitions, with an average increase in strain signal-to-noise ratio of 34%

Dynamic velocity vector and relative pressure estimation in the left ventricle with dynamic contrast-enhanced ultrasound of low frame rates

Clinical studies indicate that dysfunction of the left ventricle occurs at an early stage of heart-failure. As ventricular dysfunction and cardiac disease affect the intraventricular flow patterns, analysis of blood flow and relative pressure may aid diagnosis. Several visualization tools exist that are generally based on speckle-tracking techniques using ultrafast ultrasound acquisitions. Yet, there is a need for techniques that can deal with low frame rates, in particular when envisioning future translation to 3D imaging. Here, blood flow velocity and relative pressure are estimated with low-frame-rate dynamic contrast-enhanced ultrasound (DCE-US). Different from standard speckle-tracking techniques, here we propose a method based on estimation of time-delays between indicator dilution curves measured from a set of neighboring pixels in the DCE-US video. An improved estimation of the velocity vectors is then obtained by Navier-Stokes regularization. Using the regularized velocity vectors, relative pressures can be calculated. Blood flow patterns were characterized in terms of vorticity, quantified by the curl of the velocity vectors, and changes in relative pressure (dp/dt) around the aortic valve, since these are linked to the ejection efficiency. Eighteen patients, who underwent cardiac resynchronization therapy (CRT) (9 for CRT-responder and 9 for CRT-non-responder), were tested with the algorithm. In the responder group, vorticity and peak dp/dt were significantly increased after CRT, while no significant difference was found in the non-responder group