Tissue Doppler, Strain and Strain Rate in ischemic heart disease “How I do it”

Echocardiography is the standard method for assessing myocardial function in patients with ischemic heart disease. The acquisition and interpretation of echocardiographic images, however, remains a highly specialized task which often relies entirely on the subjective visual assessment of the reader and requires therefore, particular training and expertise. Myocardial deformation imaging allows quantifying myocardial function far beyond what can be done with sole visual assessment. It can improve the interpretation of regional dysfunction and offers sensitive markers of induced ischemia which can be used for stress tests. In the following, we recapitulate shortly the pathophysiological and technical basics and explain in a practical manner how we use this technique in investigating patients with ischemic heart disease

Sheep can be used as animal model of regional myocardial remodeling and controllable work

Background: Pacing the right heart has been shown to induce reversible conduction delay and subse­quent asymmetric remodeling of the left ventricle (LV) in dogs and pigs. Both species have disadvantages in animal experiments. Therefore the aim of this study was to develop a more feasible and easy-to-use animal model in sheep. Methods: Dual-chamber (DDD) pacemakers with epicardial leads on the right atrium and right ven­tricular free wall were implanted in 13 sheep. All animals underwent 8 weeks of chronic rapid pacing at 180 bpm. Reported observations were made at 110 bpm. Results: DDD pacing acutely induced a left bundle branch block (LBBB) — like pattern with almost doubling in QRS width and the appearance of a septal flash, indicating mechanical dyssynchrony. Atrial pacing (AAI) resulted in normal ventricular conduction and function. During 8 weeks of rapid DDD pacing, animals developed LV remodeling (confirmed with histology) with septal wall thinning (–30%, p < 0.05), lateral wall thickening (+22%, p < 0.05), LV volume increase (+32%, p < 0.05), decrease of LV ejection fraction (–31%, p < 0.05), and functional mitral regurgitation. After 8 weeks, segmental pressure-strain-loops, representing regional myocardial work, were recorded. Switching from AAI to DDD pacing decreased immediately work in the septum and increased it in the lateral wall (–69 and +41%, respectively, p < 0.05). Global LV stroke work and dP/dtmax decreased (–27% and -25%, respectively, p < 0.05). Conclusions: This study presents the development a new sheep model with an asymmetrically remod­eled LV. Simple pacemaker programing allows direct modulation of regional myocardial function and work. This animal model provides a new and valuable alternative for canine or porcine models and has the potential to become instrumental for investigating regional function and loading conditions on regional LV remodeling

Finding New Insights in Cardiac Resynchronization Therapy and the Pathophysiology behind Left Ventricular Dyssynchrony

Over the past two decades, cardiac resynchronization therapy (CRT) became an established treatment option for patients with symptomatic heart failure [...

Tissue Doppler, Strain and Strain Rate in ischemic heart disease "How I do it"

Echocardiography is the standard method for assessing myocardial function in patients with ischemic heart disease. The acquisition and interpretation of echocardiographic images, however, remains a highly specialized task which often relies entirely on the subjective visual assessment of the reader and requires therefore, particular training and expertise. Myocardial deformation imaging allows quantifying myocardial function far beyond what can be done with sole visual assessment. It can improve the interpretation of regional dysfunction and offers sensitive markers of induced ischemia which can be used for stress tests. In the following, we recapitulate shortly the pathophysiological and technical basics and explain in a practical manner how we use this technique in investigating patients with ischemic heart disease.status: publishe

How to Define End-Diastole and End-Systole? Impact of Timing on Strain Measurements

AbstractObjectivesThis study aimed to investigate to what extent timing definitions influence strain measurements and which surrogates are reliable and feasible to define end-diastole (ED) and end-systole (ES) during speckle-tracking (STI) analysis.BackgroundCurrent STI-based strain measurements are highly automated. It remains unclear when a particular analysis software defines the zero baseline and the systolic strain measurement position.MethodsA total of 60 subjects (20 healthy volunteers, 20 patients with coronary artery disease, and 20 patients with typical left bundle-branch block) underwent a complete echocardiographic examination. In one-half of them, a real M-mode through the mitral valve was acquired for each electrocardiographic (ECG) lead of the echo machine. Timing of peak R and automatic ECG trigger were compared with mitral valve closure for every electrode. Mitral and aortic valve closure, as observed in the apical 3-chamber view, served as reference for ED and ES. With the use of these references, end-systolic global longitudinal strain (ES-GLS) and end-systolic segmental longitudinal strain (ES-SLS) longitudinal end-systolic strain were measured at baseline and after changing the definition of either ED or ES by ±4 frames. Furthermore, strain and volume curves derived from the same tracking, as well as the Doppler interrogation of the valves, were compared with the references.ResultsDepending on the selected lead, timing of the ECG-derived time markers changed considerably compared with mitral valve closure. Changing the definition of ED and ES resulted in significantly different ES-GLS and ES-SLS values in all subjects. ES-SLS in dyssynchronous hearts showed the highest sensitivity to timing definition. From all methods, spectral Doppler was the most reliable time marker in all subjects (p > 0.05).ConclusionsExact temporal definition of ED and ES has a major impact on the accuracy of strain measurements. After direct observation of the valves, Doppler evaluation is the best means for characterizing ED and ES for STI analysis

Uptitration of Renin-Angiotensin System Blocker and Beta-Blocker Therapy in Patients Hospitalized for Heart Failure With Reduced Versus Preserved Left Ventricular Ejection Fractions

In ambulatory patients with heart failure (HF) and reduced ejection fraction (rEF), renin-angiotensin system (RAS) and β-blockers at guideline-recommended target dose reduce all-cause mortality and readmissions. Benefits in HF with preserved ejection fraction (pEF), as well as uptitration after a hospitalization, remain uncertain. This study assesses the impact of RAS- and β-blocker uptitrations in patients with HFrEF versus HFpEF during and immediately after a hospital admission. In consecutive patients (209 HFrEF with left ventricular ejection fraction <40% and 108 HFpEF with left ventricular ejection fraction ≥40%), RAS- and β-blocker dose changes were followed during 6 months after an index HF hospitalization. Patients with a RAS- and β-blocker dose increase of ≥10% of the recommended target dose were compared with patients without uptitration. Patients who received uptitration were significantly younger, with a higher heart rate and better renal function, and received spironolactone more often. Both RAS- and β-blocker uptitrations were associated with significant reductions in the composite end-point of all-cause mortality or HF readmissions in HFrEF (hazard ratio [HR] 0.36, 95% confidence interval [CI] 0.22 to 0.60 and HR 0.51, 95% CI 0.32 to 0.81, respectively). After correction for age, heart rate, blood pressure, renal function, and spironolactone use, this association remained significant for RAS blockers (HR 0.54, 95% CI 0.31 to 0.93, p = 0.027) but not for β-blockers (HR 0.65, 95% CI 0.39 to 1.09, p = 0.101). No benefit of RAS- or β-blocker uptitration was observed in HFpEF. In conclusion, uptitration of neurohumoral blockers after an HF hospitalization is more frequently performed in younger patients with low co-morbidity burden. RAS-blocker uptitration independently predicts clinical outcome in patients with HFrEF but not in those with HFpEF.status: publishe

Analysis of partial volume correction on quantification and regional heterogeneity in cardiac PET

The partial volume correction (PVC) of cardiac PET datasets using anatomical side information during reconstruction is appealing but not straightforward. Other techniques, which do not make use of additional anatomical information, could be equally effective in improving the reconstructed myocardial activity.status: accepte

Impact of CT-based Attenuation Correction on the Registration Between Dual-gated Cardiac PET and High-Resolution CT

© 1963-2012 IEEE. A high-resolution CT (HRCT) used as anatomical prior information during PET reconstruction can enhance the quality of a corresponding low-resolution PET image, provided that it is accurately registered to the PET dataset of interest. In this work, the impact of different PET/CT attenuation correction (AC) protocols on the registration between a dual-gated cardiac 18F-FDG PET image and an HRCT image is investigated. The aim is to explore the impact of AC on PET-to-HRCT registration, and to identify the AC strategy that yields the best alignment between the left-ventricles in the PET and the HRCT images for subsequent partial volume correction. Simulations were performed using XCAT phantoms. Shallow breathing and a regular beating pattern were simulated and both noise-free and noisy data were evaluated. Respiratory motion during the acquisition of the CT used for attenuation correction strongly affected the dual-gated PET reconstructions, resulting in artefacts and quantification errors in the PET image and poor PET-to-HRCT registration accuracy. The blurring introduced by the beating heart, on the other hand, proved to have a negligible effect on PET-CT registration. Dual-gated PET images reconstructed without attenuation correction could be well registered to the HRCT if a good initial alignment between the starting images was provided. A commercially available strategy to deal with an AC CT that is acquired in the wrong respiratory phase was also evaluated, and yielded not only enhanced quantitative accuracy but also accurate PET-to-HRCT registration. The effect of a high level of noise, as present in a dual-gated cardiac PET study, was also investigated. Registrations proved to be sensitive to noise, but noise is not a major limiting factor for PET-to-HRCT registration. A selection of the investigated attenuation correction procedures was also evaluated using cardiac PET/CT data measured in sheep. The PET-to-HRCT registration performance confirmed the XCAT-based predictions.status: publishe

Lesion quantification and detection in myocardial F-18-FDG PET using edge-preserving priors and anatomical information from CT and MRI: a simulation study

The limited spatial resolution of the clinical PET scanners results in image blurring and does not allow for accurate quantification of very thin or small structures (known as partial volume effect). In cardiac imaging, clinically relevant questions, e.g. to accurately define the extent or the residual metabolic activity of scarred myocardial tissue, could benefit from partial volume correction (PVC) techniques. The use of high-resolution anatomical information for improved reconstruction of the PET datasets has been successfully applied in other anatomical regions. However, several concerns linked to the use of any kind of anatomical information for PVC on cardiac datasets arise. The moving nature of the heart, coupled with the possibly non-simultaneous acquisition of the anatomical and the activity datasets, is likely to introduce discrepancies between the PET and the anatomical image, that in turn might mislead lesion quantification and detection. Non-anatomical (edge-preserving) priors could represent a viable alternative for PVC in this case. In this work, we investigate and compare the regularizing effect of different anatomical and non-anatomical priors applied during maximum-a-posteriori (MAP) reconstruction of cardiac PET datasets. The focus of this paper is on accurate quantification and lesion detection in myocardial (18)F-FDG PET.status: publishe