Advanced imaging in valvular heart disease

A lipid activated color switchable probe for the imaging of diseased aortic valves

Lipid deposition has been considered one of the key factors in the occurrence of valvular heart disease (VHD) and a great potential target for the diagnosis of VHD. However, the development of lipid imaging technologies and efficient lipid specific probes is in urgent demand. In this work, we have prepared a lipid droplets (LDs) targeted fluorescence probe CPTM based on a push-pull electronic structure for the imaging of diseased aortic valves. CPTM showed obvious twisted intramolecular charge transfer (TICT) effect and its emission changed from 600 nm in water to 508 nm in oil. CPTM not only exhibited good biocompatibility and high photostability, but also impressive LDs specific imaging performance in human primary valvular interstitial cells and human diseased aortic valves. Moreover, the dynamic changes of intracellular LDs could be monitor in real-time after staining with CPTM. These results were expected to offer new ideals for the designing of novel LDs specific probes for further bioimaging applications.

Rationale and clinical applications of 4D flow cardiovascular magnetic resonance in assessment of valvular heart disease: a comprehensive review

BACKGROUND

Accurate evaluation of valvular pathology is crucial in the timing of surgical intervention. Whilst transthoracic echocardiography is widely available and routinely used in the assessment of valvular heart disease, it is bound by several limitations. Although cardiovascular magnetic resonance (CMR) imaging can overcome many of the challenges encountered by echocardiography, it also has a number of limitations.

MAIN TEXT

4D Flow CMR is a novel technique, which allows time-resolved, 3-dimensional imaging. It enables visualisation and direct quantification of flow and peak velocities of all valves simultaneously in one simple acquisition, without any geometric assumptions. It also has the unique ability to measure advanced haemodynamic parameters such as turbulent kinetic energy, viscous energy loss rate and wall shear stress, which may add further diagnostic and prognostic information. Although 4D Flow CMR acquisition can take 5-10 min, emerging acceleration techniques can significantly reduce scan times, making 4D Flow CMR applicable in contemporary clinical practice.

CONCLUSION

4D Flow CMR is an emerging CMR technique, which has the potential to become the new reference-standard method for the evaluation of valvular lesions. In this review, we describe the clinical applications, advantages and disadvantages of 4D Flow CMR in the assessment of valvular heart disease.

A novel technique to quantify aortic valve annulus deformation: A pilot study

OBJECTIVES

We evaluated the potential of cardiac magnetic resonance (CMR)-derived strain to assess aortic valve (AV) annulus deformation during the cardiac cycle in regurgitant and well-functioning AVs.

METHODS

Four patients with severe aortic regurgitation and seven healthy controls underwent CMR. Assessment of longitudinal strain was performed by hypothesizing the AV annulus would be the left ventricle in long-axis orientation. Longitudinal strain of the segments belonging to the muscular and fibrous AV annulus was weighted and averaged to obtain regional values (RLS).

RESULTS

Comparison of RLS between regurgitant and well-functioning AVs showed a considerably different deformation of the muscular AV annulus (i.e., median RLS: 4.18 % [patients] vs. -10.41 % [controls], p = .024). The fibrous AV annulus demonstrated comparable deformational changes in both groups.

CONCLUSION

CMR-derived strain allows for quantification of AV annulus deformation during the cardiac cycle and shows an altered RLS in the muscular AV annulus in patients with severe aortic regurgitation.

Multimodality Evaluation of Aortic Insufficiency and Aortitis in Rheumatologic Diseases

Aortic insufficiency is commonly observed in rheumatologic diseases such as ankylosing spondylitis, systemic lupus erythematosus, antiphospholipid syndrome, Behçet's disease, granulomatosis with polyangiitis, and Takayasu arteritis. Aortic insufficiency with an underlying rheumatologic disease may be caused by a primary valve pathology (leaflet destruction, prolapse or restriction), annular dilatation due to associated aortitis or a combination of both. Early recognition of characteristic valve and aorta morphology on cardiac imaging has both diagnostic and prognostic importance. Currently, echocardiography remains the primary diagnostic tool for aortic insufficiency. Complementary use of computed tomography, cardiac magnetic resonance imaging and positron emission tomography in these systemic conditions may augment the assessment of underlying mechanism, disease severity and identification of relevant non-valvular/extracardiac pathology. We aim to review common rheumatologic diseases associated with aortic insufficiency and describe their imaging findings that have been reported in the literature.

Additive effect of aortic regurgitation degree on left ventricular strain in patients with type 2 diabetes mellitus evaluated via cardiac magnetic resonance tissue tracking

Background

Type 2 diabetes mellitus causes left ventricular (LV) remodeling and increases the risk of aortic regurgitation (AR), which causes further heart damage. This study aimed to investigate whether AR aggravates LV deformation dysfunction and to identify independent factors affecting the global peak strain (PS) of LV remodeling in patients with type 2 diabetes mellitus (T2DM) who presented with AR and those without T2DM.

Methods

In total, 215 patients with T2DM and 83 age- and sex-matched healthy controls who underwent cardiac magnetic resonance examination were included. Based on the echocardiogram findings, T2DM patients with AR were divided into three groups (mild AR [n = 28], moderate AR [n = 21], and severe AR [n = 17]). LV function and global strain parameters were compared, and multivariate analysis was performed to identify the independent indicators of LV PS.

Results

The T2DM patients with AR had a lower LV global PS, peak systolic strain rate (PSSR), and peak diastolic strain rate (PDSR) in three directions than those without AR and non-T2DM controls. Patients without AR had a lower PS (radial and longitudinal) and PDSR in three directions and higher PSSR (radial and longitudinal) than healthy controls. Further, regurgitation degree was an independent factor of LV global radial, circumferential, and longitudinal PS.

Conclusion

AR may aggravate LV stiffness in patients with T2DM, resulting in lower LV strain and function. Regurgitation degree and sex were independently correlated with LV global PS in patients with T2DM and AR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01471-2.

Feature Point Extraction and Motion Tracking of Cardiac Color Ultrasound under Improved Lucas-Kanade Algorithm

The purpose of this research is to study the application effect of Lucas–Kanade algorithm in right ventricular color Doppler ultrasound feature point extraction and motion tracking under the condition of scale invariant feature transform (SIFT). This study took the right ventricle as an example to analyze the extraction effect and calculation rate of SIFT algorithm and improved Lucas–Kanade algorithm. It was found that the calculation time before and after noise removal by the SIFT algorithm was 0.49 s and 0.46 s, respectively, and the number of extracted feature points was 703 and 698, respectively. The number of feature points extracted by the SIFT algorithm and the calculation time were significantly better than those of other algorithms (P < 0.01). The mean logarithm of the matching points of the SIFT algorithm for order matching and reverse order matching was 20.54 and 20.46, respectively. The calculation time and the number of feature points for the SIFT speckle tracking method were 1198.85 s and 81, respectively, and those of the optical flow method were 3274.19 s and 80, respectively. The calculation time of the SIFT speckle tracking method was significantly lower than that of the optical flow method (P < 0.05), and there was no statistical difference in the number of feature points between the SIFT speckle tracking method and the optical flow method (P > 0.05). In conclusion, the improved Lucas–Kanade algorithm based on SIFT significantly improves the accuracy of feature extraction and motion tracking of color Doppler ultrasound, which shows the value of the algorithm in the clinical application of color Doppler ultrasound.

Reproducibility of reading echocardiographic parameters to assess severity of mitral regurgitation. Insights from a French multicentre study

BACKGROUND

Poor reproducibility in assessment of mitral regurgitation (MR) has been reported.

AIM

To investigate the robustness of echocardiographic MR assessment in 2019, based on improvements in technology and the skill of echocardiographists regarding MR quantification.

METHODS

Reproducibility in parameters of MR severity and global rating were tested using transthoracic echocardiography in 25 consecutive patients independently analysed by 16 junior and senior cardiologists specialized in echocardiography (400 analyses per parameter).

RESULTS

Overall interobserver agreement for mechanism definition, effective regurgitant orifice area (EROA) and regurgitant volume (RVol) was moderate, and was lower in secondary MR. Interobserver agreement was substantial for EROA [0.61, 95% confidence interval (CI) 0.45-0.75] and moderate for RVol with the PISA method (0.50, 95% CI 0.33-0.56) in senior physicians and was fair in junior physicians (0.33, 95% CI 0.19-0.51 and 0.36, 95% CI 0.36-0.43, respectively). Using a multiparametric approach, overall interobserver agreement for grading MR severity was fair (0.30), was slightly better in senior than in junior physicians (0.31 vs. 0.28, respectively) with substantial or almost perfect agreement more frequently observed in senior versus junior physicians (52% vs. 36%, respectively).

CONCLUSION

Reproducible transthoracic echocardiography MR quantification remains challenging in 2019, despite the expected high skills of echocardiographers regarding MR at the time of dedicated percutaneous intervention. The multiparametric approach does not entirely alleviate the substantial dispersion in measurement of MR severity parameters, whereas reader experience seems to partially address the issue. Our study emphasizes the continuing need for multimodality imaging and education in the evaluation of MR among cardiologists.

Association between late gadolinium enhancement and global longitudinal strain in patients with rheumatic mitral stenosis

The correlation between the extent of myocardial fibrosis and subclinical left ventricle (LV) systolic dysfunction in rheumatic mitral stenosis (MS) has not been widely studied. We sought to evaluate the correlation between the extent of LV myocardial fibrosis quantified by late gadolinium enhancement (LGE) using cardiac magnetic resonance (CMR) and global longitudinal strain (GLS) by speckle tracking echocardiography (STE) in patients with rheumatic MS. We prospectively evaluated 36 consecutive rheumatic MS patients who were planning to undergo mitral valve surgery. Then we evaluate the correlation between the extent of LV myocardial fibrosis quantified by LGE CMR and the systolic LV function by GLS using STE. Thirty-six patients with mean age of 45.7 ± 9.9 years old, showed mean LGE was 4.9 ± 2.7%. The mean LV ejection fraction (EF) measured by CMR was 50 ± 10.8%, and the mean LV GLS was 13.5 ± 3.9%. There was a moderate correlation between GLS and LGE (r - 0.432, p = 0.009). There were no correlations between GLS with mitral valve area (MVA) with r 0.149, p = 0.385, mean mitral valve gradient (MVG) with r -0.078, p = 0.653, and LVEF (r 0.299, p = 0.076). There was a moderate correlation between LGE and GLS in patients with rheumatic MS.

Imaging of Myocardial Fibrosis and Its Functional Correlates in Aortic Stenosis: A Review and Clinical Potential

Patients with severe aortic stenosis (AS) show progressive fibrotic changes in the myocardium, which may impair cardiac function and patient outcomes even after successful aortic valve replacement. Detection of patients who need an early operation remains a diagnostic challenge as myocardial functional changes may be subtle. In recent years, speckle tracking echocardiography (STE) and cardiac magnetic resonance mapping have been shown to provide complementary information for the assessment of left ventricular mechanics and identification of subtle damage by focal or diffuse myocardial fibrosis, respectively. Little is known, however, about how focal and diffuse myocardial fibrosis occurring in severe AS are related to measurable functional changes by echocardiography and to which extent both parameters have prognostic and diagnostic value. The aims of this review are to discuss the occurrence of focal and diffuse myocardial fibrosis in patients with severe AS and to explore their relation with myocardial function, determined by STE, as well as the prognostic and diagnostic potential of both parameters.

Feasibility of Self-Powering and Energy Harvesting Using Cardiac Valvular Perturbations

In this paper, we investigate the feasibility of harvesting energy from cardiac valvular perturbations to self-power a wireless sonomicrometry sensor. Compared to the previous studies involving piezoelectric patches or encasings attached to the cardiac or aortic surface, the proposed study explores the use of piezoelectric sutures that can be implanted in proximity to the valvular regions, where non-linear valvular perturbations could be exploited for self-powering. Using an ovine animal model, the magnitude of valvular perturbations are first measured using an array of sonomicrometry crystals implanted around the tricuspid valve. These measurements were then used to estimate the levels of electrical energy that could be harvested using a simplified piezoelectric suture model. These results were revalidated across seven different animals, before and after valvular regurgitation was induced. Our study shows that power harvested from different annular planes of the tricuspid valve (before and after regurgitation) could range from nano-watts to milli-watts, with the maximum power harvested from the leaflet plane. We believe that these results could be useful for determining optimal surgical placement of wireless and self-powered sonomicrometry sensor, which in turn could be used for investigating the pathophysiology of ischemic regurgitation.

Manganese-Enhanced T1 Mapping in the Myocardium of Normal and Infarcted Hearts

Background

Manganese-enhanced MRI (MEMRI) has the potential to identify viable myocardium and quantify calcium influx and handling. Two distinct manganese contrast media have been developed for clinical application, mangafodipir and EVP1001-1, employing different strategies to mitigate against adverse effects resulting from calcium-channel agonism. Mangafodipir delivers manganese ions as a chelate, and EVP1001-1 coadministers calcium gluconate. Using myocardial T1 mapping, we aimed to explore chelated and nonchelated manganese contrast agents, their mechanism of myocardial uptake, and their application to infarcted hearts.

Methods

T1 mapping was performed in healthy adult male Sprague-Dawley rats using a 7T MRI scanner before and after nonchelated (EVP1001-1 or MnCl2 (22 μmol/kg)) or chelated (mangafodipir (22-44 μmol/kg)) manganese-based contrast media in the presence of calcium channel blockade (diltiazem (100-200 μmol/kg/min)) or sodium chloride (0.9%). A second cohort of rats underwent surgery to induce anterior myocardial infarction by permanent coronary artery ligation or sham surgery. Infarcted rats were imaged with standard gadolinium delayed enhancement MRI (DEMRI) with inversion recovery techniques (DEMRI inversion recovery) as well as DEMRI T1 mapping. A subsequent MEMRI scan was performed 48 h later using either nonchelated or chelated manganese and T1 mapping. Finally, animals were culled at 12 weeks, and infarct size was quantified histologically with Masson's trichrome (MTC).

Results

Both manganese agents induced concentration-dependent shortening of myocardial T1 values. This was greatest with nonchelated manganese, and could be inhibited by 30-43% with calcium-channel blockade. Manganese imaging successfully delineated the area of myocardial infarction. Indeed, irrespective of the manganese agent, there was good agreement between infarct size on MEMRI T1 mapping and histology (bias 1.4%, 95% CI -14.8 to 17.1 P>0.05). In contrast, DEMRI inversion recovery overestimated infarct size (bias 11.4%, 95% CI -9.1 to 31.8 P=0.002), as did DEMRI T1 mapping (bias 8.2%, 95% CI -10.7 to 27.2 P=0.008). Increased manganese uptake was also observed in the remote myocardium, with remote myocardial ∆T1 inversely correlating with left ventricular ejection fraction after myocardial infarction (r=-0.61, P=0.022).

Conclusions

MEMRI causes concentration and calcium channel-dependent myocardial T1 shortening. MEMRI with T1 mapping provides an accurate assessment of infarct size and can also identify changes in calcium handling in the remote myocardium. This technique has potential applications for the assessment of myocardial viability, remodelling, and regeneration.

Clinical applications of intra-cardiac four-dimensional flow cardiovascular magnetic resonance: A systematic review

BACKGROUND

Four-dimensional flow cardiovascular magnetic resonance (4D flow CMR) is an emerging non-invasive imaging technology used to visualise and quantify intra-cardiac blood flow. The aim of this systematic review is to assess the literature on the current clinical applications of intra-cardiac 4D flow CMR.

METHODS

A systematic review was conducted to evaluate the literature on the intra-cardiac clinical applications of 4D flow CMR. Structured searches were carried out on Medline, EMBASE and the Cochrane Library in October 2016. A modified Critical Skills Appraisal Programme (CASP) tool was used to objectively assess and score the included studies. Studies were categorised as 'highly clinically applicable' for scores of 67-100%, 'potentially clinically applicable' for 34-66% and 'less clinically applicable' for 0-33%.

RESULTS

Of the 1608 articles screened, 44 studies met eligibility for systematic review. The included literature consisted of 22 (50%) mechanistic studies, 18 (40.9%) pilot studies and 4 (9.1%) diagnostic studies. Based on the modified CASP tool, 27 (62%) studies were 'highly clinically applicable', 9 (20%) were 'potentially clinically applicable' and 8 (18%) were 'less clinically applicable'.

CONCLUSIONS

There are many proposed methods for using 4D flow CMR to quantify intra-cardiac flow. The evidence base is mainly mechanistic, featuring single-centred designs. Larger, multi-centre studies are required to validate the proposed techniques and investigate the clinical advantages that 4D flow CMR offers over standard practices. PROSPERO=CRD42016051438.

Review of Diagnostic and Therapeutic Approach to Canine Myxomatous Mitral Valve Disease

The most common heart disease that affects dogs is myxomatous mitral valve disease. In this article, we review the current diagnostic and therapeutic approaches to this disease, and we also present some of the latest technological advancements in this field.