Diastolic wall strain: a simple marker of abnormal cardiac mechanics

Lifetime evaluation of left ventricular structure and function in male ApoE null mice after gamma and space-type radiation exposure

The space radiation (IR) environment contains high charge and energy (HZE) nuclei emitted from galactic cosmic rays with the ability to overcome current shielding strategies, posing increased IR-induced cardiovascular disease risks for astronauts on prolonged space missions. Little is known about the effect of 5-ion simplified galactic cosmic ray simulation (simGCRsim) exposure on left ventricular (LV) function. Three-month-old, age-matched male Apolipoprotein E (ApoE) null mice were irradiated with 137Cs gamma (γ; 100, 200, and 400 cGy) and simGCRsim (50, 100, 150 cGy all at 500 MeV/nucleon (n)). LV function was assessed using transthoracic echocardiography at early/acute (14 and 28 days) and late/degenerative (365, 440, and 660 days) times post-irradiation. As early as 14 and 28-days post IR, LV systolic function was reduced in both IR groups across all doses. At 14 days post-IR, 150 cGy simGCRsim-IR mice had decreased diastolic wall strain (DWS), suggesting increased myocardial stiffness. This was also observed later in 100 cGy γ-IR mice at 28 days. At later stages, a significant decrease in LV systolic function was observed in the 400 cGy γ-IR mice. Otherwise, there was no difference in the LV systolic function or structure at the remaining time points across the IR groups. We evaluated the expression of genes involved in hemodynamic stress, cardiac remodeling, inflammation, and calcium handling in LVs harvested 28 days post-IR. At 28 days post-IR, there is increased expression of Bnp and Ncx in both IR groups at the lowest doses, suggesting impaired function contributes to hemodynamic stress and altered calcium handling. The expression of Gals3 and β-Mhc were increased in simGCRsim and γ-IR mice respectively, suggesting there may be IR-specific cardiac remodeling. IR groups were modeled to calculate the Relative Biological Effectiveness (RBE) and Radiation Effects Ratio (RER). No lower threshold was determined using the observed dose-response curves. These findings do not exclude the possibility of the existence of a lower IR threshold or the presence of IR-induced cardiovascular disease (CVD) when combined with additional space travel stressors, e.g., microgravity.

Fasudil alleviates the vascular endothelial dysfunction and several phenotypes of Fabry disease

Fabry disease (FD), a lysosomal storage disorder, is caused by defective α-galactosidase (GLA) activity, which results in the accumulation of globotriaosylceramide (Gb3) in endothelial cells and leads to life-threatening complications such as left ventricular hypertrophy (LVH), renal failure, and stroke. Enzyme replacement therapy (ERT) results in Gb3 clearance; however, because of a short half-life in the body and the high immunogenicity of FD patients, ERT has a limited therapeutic effect, particularly in patients with late-onset disease or progressive complications. Because vascular endothelial cells (VECs) derived from FD-induced pluripotent stem cells display increased thrombospondin-1 (TSP1) expression and enhanced SMAD2 signaling, we screened for chemical compounds that could downregulate TSP1 and SMAD2 signaling. Fasudil reduced the levels of p-SMAD2 and TSP1 in FD-VECs and increased the expression of angiogenic factors. Furthermore, fasudil downregulated the endothelial-to-mesenchymal transition (EndMT) and mitochondrial function of FD-VECs. Oral administration of fasudil to FD mice alleviated several FD phenotypes, including LVH, renal fibrosis, anhidrosis, and heat insensitivity. Our findings demonstrate that fasudil is a novel candidate for FD therapy.

Thymidine Phosphorylase Deficiency or Inhibition Preserves Cardiac Function in Mice With Acute Myocardial Infarction

Background Ischemic cardiovascular disease is the leading cause of death worldwide. Current pharmacologic therapy has multiple limitations, and patients remain symptomatic despite maximal medical therapies. Deficiency or inhibition of thymidine phosphorylase (TYMP) in mice reduces thrombosis, suggesting that TYMP could be a novel therapeutic target for patients with acute myocardial infarction (AMI). Methods and Results A mouse AMI model was established by ligation of the left anterior descending coronary artery in C57BL/6J wild-type and TYMP-deficient (Tymp-/-) mice. Cardiac function was monitored by echocardiography or Langendorff assay. TYMP-deficient hearts had lower baseline contractility. However, cardiac function, systolic left ventricle anterior wall thickness, and diastolic wall strain were significantly greater 4 weeks after AMI compared with wild-type hearts. TYMP deficiency reduced microthrombus formation after AMI. TYMP deficiency did not affect angiogenesis in either normal or infarcted myocardium but increased arteriogenesis post-AMI. TYMP deficiency enhanced the mobilization of bone marrow stem cells and promoted mesenchymal stem cell (MSC) proliferation, migration, and resistance to inflammation and hypoxia. TYMP deficiency increased the number of larger MSCs and decreased matrix metalloproteinase-2 expression, resulting in a high homing capability. TYMP deficiency induced constitutive AKT phosphorylation in MSCs but reduced expression of genes associated with retinoid-interferon-induced mortality-19, a molecule that enhances cell death. Inhibition of TYMP with its selective inhibitor, tipiracil, phenocopied TYMP deficiency, improved post-AMI cardiac function and systolic left ventricle anterior wall thickness, attenuated diastolic stiffness, and reduced infarct size. Conclusions This study demonstrated that TYMP plays an adverse role after AMI. Targeting TYMP may be a novel therapy for patients with AMI.

Amplifying effect of chronic lisinopril therapy on diastolic function and the angiotensin-(1-7) Axis by the G1 agonist in ovariectomized spontaneously hypertensive rats

G protein-coupled estrogen receptor (GPER) activation by G1 attenuates diastolic dysfunction from estrogen loss, which may be partly due to suppression of angiotensin II pathological actions. We aimed to determine the independent effects of 8 weeks of G1 (100 µg/kg/d, subcutaneous pellet), ACE-inhibition (ACEi; lisinopril 10 mg/kg, drinking water), or combination therapy versus vehicle in the ovariectomized (OVX) spontaneously hypertensive rat (SHR) on cardiac function and morphometrics (echocardiography), serum equilibrium of angiotensins (mass spectroscopy) and cardiac components of the RAS (Western blotting). G1 alone and when combined with ACEi enhanced myocardial relaxation (é: 30 and 17%) and diastolic wall strain (DWS: 76 and 68%) while reducing relative wall thickness (RWT: 20 and 33%) and filling pressures (E/é: 30 and 37%). Cardiac expression levels of Mas receptor (Mas-R) and ACE2 also increased in the presence of G1. Strong antihypertensive effects of lisinopril monotherapy were associated with reductions in RWT, collagen deposition and E/é without overtly altering é or DWS. Chronic ACEi also increased cardiac levels of Mas-R and AT₁-R and tilted the circulating RAS toward the formation of Ang-(1-7), which was amplified in the presence of G1. In vitro studies further revealed that an inhibitor to prolyl endopeptidase (PEP), but not to neprilysin, significantly reduced serum Ang-(1-7) levels in G1-treated rats, suggesting that G1 might be increasing Ang-(1-7) formation via PEP. We conclude that activating GPER with G1 augments components of the cardiac RAS and improves diastolic function without lowering blood pressure, and that lisinopril-induced blood pressure control and cardiac alterations in OVX SHR are permissive in facilitating G1 to augment Ang-(1-7) in serum, thereby strengthening its cardioprotective benefits.

Speckle-tracking echocardiography combined with imaging mass spectrometry assesses region-dependent alterations

Left ventricular (LV) contraction is characterized by shortening and thickening of longitudinal and circumferential fibres. To date, it is poorly understood how LV deformation is altered in the pathogenesis of streptozotocin (STZ)-induced type 1 diabetes mellitus-associated diabetic cardiomyopathy and how this is associated with changes in cardiac structural composition. To gain further insights in these LV alterations, eight-week-old C57BL6/j mice were intraperitoneally injected with 50 mg/kg body weight STZ during 5 consecutive days. Six, 9, and 12 weeks (w) post injections, echocardiographic analysis was performed using a Vevo 3100 device coupled to a 30-MHz linear-frequency transducer. Speckle-tracking echocardiography (STE) demonstrated impaired global longitudinal peak strain (GLS) in STZ versus control mice at all time points. 9w STZ animals displayed an impaired global circumferential peak strain (GCS) versus 6w and 12w STZ mice. They further exhibited decreased myocardial deformation behaviour of the anterior and posterior base versus controls, which was paralleled with an elevated collagen I/III protein ratio. Additionally, hypothesis-free proteome analysis by imaging mass spectrometry (IMS) identified regional- and time-dependent changes of proteins affecting sarcomere mechanics between STZ and control mice. In conclusion, STZ-induced diabetic cardiomyopathy changes global cardiac deformation associated with alterations in cardiac sarcomere proteins.

Myocardial stiffness as assessed by diastolic wall strain in adult survivors of childhood leukaemias with preserved left ventricular ejection fraction

Aims

We tested the hypothesis that myocardial stiffness as assessed by diastolic wall strain (DWS) is altered in adult survivors of childhood leukaemias with preserved left ventricular (LV) ejection fraction and explored its association with myocardial fibrosis and diastolic deformation.

Methods and results

Ninety-four (53 males) adult survivors of childhood leukaemias aged 22.2 ± 5.5 years and 66 (36 males) healthy controls were studied retrospectively. Diastolic wall strain and calibrated integrated backscatter (cIB) were measured as indices of myocardial stiffness and fibrosis, respectively. Left and right ventricular (RV) diastolic and torsional mechanics were interrogated using speckle tracking echocardiography. Patients had significantly lower LV DWS, and hence stiffer LV myocardium, and greater myocardial cIB in patients than controls (all P < 0.001). Left ventricular longitudinal, radial, and circumferential early diastolic strain rates, circumferential late diastolic strain rate, and peak twisting and untwisting velocities, tricuspid annular early diastolic velocity, and RV-free wall longitudinal early diastolic strain rate were significantly lower in patients than controls (all P < 0.05). Diastolic wall strain correlated inversely with myocardial cIB, and positively with LV longitudinal, radial, and circumferential early diastolic strain rates (all P < 0.05), while myocardial cIB correlated inversely with LV radial and circumferential early diastolic strain rates, circumferential late diastolic strain rate, peak twisting and untwisting velocities, and tricuspid annular e velocity (all P < 0.05).

Conclusion

In adult survivors of childhood leukaemias, despite the preservation of LV ejection fraction, increased stiffness of the LV myocardium is evident and is associated with myocardial fibrosis and impaired ventricular diastolic function.

Predictors of Prognosis in Light-Chain Amyloidosis and Chronological Changes in Cardiac Morphology and Function

Immune light-chain (AL) amyloidosis with cardiac involvement is associated with a high mortality despite improved therapeutic regimens, but there are few reports on prognostic predictors and chronological changes in cardiac morphology and function. Prognosis and its predictors were evaluated in 36 consecutive patients with cardiac AL amyloidosis. Chronological changes in cardiac morphology and function were also evaluated. The median follow-up period was 0.95 years. The median survival time and the 3-year death-free rate after diagnosis in all-cause and cardiac deaths were 0.85 and 1.06 years and 26% and 36%, respectively. Differences in the median survival time due to left ventricular (LV) wall thickness at diagnosis were not evident. Being female and diastolic wall strain (DWS), as a measure of diastolic stiffness, were independent predictors of all-cause death in the multivariable analysis. The receiver operating characteristic analysis revealed that a DWS cut-off value of 0.189 had a sensitivity of 78% and a specificity of 72% for predicting all-cause death within 1 year after diagnosis (area under the curve = 0.726). The LV size and the stroke volume decreased and DWS worsened during the short-term follow-up period in patients who died within 1 year compared with patients who were alive after 1 year. The prognosis for patients with cardiac AL amyloidosis was poor, and DWS may be a significant predictor of prognosis. Narrowing of the LV cavity and progressive diastolic dysfunction were evident in patients with a poor prognosis.

New echocardiographic parameters in the diagnosis of heart failure with preserved ejection fraction

Heart failure with preserved ejection fraction (HFpEF) is a serious clinical disease. The pathophysiology of HFpEF is complex, and specific diagnostic criteria have evolved over time. Limited data are available on the quantification of diastolic function using two-dimensional real-time echocardiography, and a simple parameter has not yet been established. The aim of this work is to evaluate new echocardiographic parameters-the diastolic wall strain of the posterior wall (DWS PW) and the vortex formation time (VFT). Echocardiographic data from 111 subjects with exertional dyspnea and normal left ejection fraction (Group A) and 20 healthy volunteers (Group B) were retrospectively evaluated. In addition to the standard parameters used in the diagnosis of HFpEF, DWS PW and VFT were assessed in all patients. HFpEF was diagnosed in 38 patients with dyspnea (Group A1). The remaining 73 patients did not meet the established criteria for a positive diagnosis of HFpEF (Group A2). We discovered that both observed parameters were significantly lower in patients with HFpEF than in other groups. Multivariate analysis revealed that both DWS PW and VFT independently predicted the presence of HFpEF. DWS PW and VFT are simple parameters in the evaluation of diastolic function and may play a potential role as a part of an integrated approach to the assessment of HFpEF.

Increased Left Ventricular Diastolic Stiffness Is Associated With Heart Failure Symptoms in Aortic Stenosis Patients With Preserved Ejection Fraction

BACKGROUND

Clinical risk factors associated with heart failure (HF) symptoms in aortic stenosis (AS) patients with preserved ejection fraction (EF) have not been fully identified. We hypothesized that left ventricular (LV) diastolic stiffness is associated with HF symptoms in patients with AS.

METHODS AND RESULTS

We retrospectively evaluated 275 patients with at least moderate AS (aortic valve area <1.5 cm²) and preserved EF (≥50%). LV diastolic stiffness was evaluated with the use of echocardiographic parameters, diastolic wall strain (DWS, a measure of LV wall stiffness), and K_LV (a marker of LV chamber stiffness). There were 69 patients with HF. Patients with HF were older, were more likely to be African American, had a higher body mass index, and had more hypertension and coronary artery disease (P < .05 for all). Aortic valve area index and mean pressure gradient across the aortic valve were not different between patients with and without HF. Despite similar echocardiographic parameters of AS severity, patients with HF had stiffer LV (DWS 0.21 ± 0.06 vs 0.25 ± 0.06 [P < .01], K_LV 0.17 ± 0.11 vs 0.13 ± 0.08 [P < .01]). Logistic regression analyses revealed that after adjusting for age, race, body mass index, history of hypertension, and coronary artery disease, LV diastolic stiffness parameters remained significantly associated with HF symptoms.

CONCLUSIONS

LV diastolic stiffness is independently associated with HF in AS patients with preserved EF.

Potential usefulness of diastolic parameters measured by strain imaging echocardiography in the early prediction of chemotherapy-induced cardiotoxicity

Over the past decades, chemotherapy has significantly increased the overall prognosis and survival of several patients diagnosed with cancer. However, the usefulness of some chemotherapeutic agents has been hindered by a collateral dose-dependent cardiotoxicity. To date, although extensive efforts have been directed to the early detection of subclinical toxicity in patients treated with these drugs, it remains unclear which approach would be best in order to prevent chemotherapy-induced cardiotoxicity (CIC). For many years, conventional echocardiography has been among preferred noninvasive imaging modality to monitor left ventricular ejection fraction (LVEF) in patients undergoing chemotherapy. Unfortunately, a significant reduction in LVEF is not recognized early on after chemotherapy-induced myocardial damage. Moreover, delayed recognition has been associated with poor recovery potential and poor clinical outcome. Thus, there is a critical need to identify early, reliable parameters of subclinical injury. Myocardial deformation imaging, also known as strain imaging echocardiography (SIE), is becoming readily available for advanced routine echocardiography and has shown value in detecting subclinical ventricular dysfunction in several clinical scenarios. Abnormalities in systolic deformation parameters have been identified as early manifestation but left ventricular diastolic properties remain less well defined. We hypothesize that onset as well as progression of cardiotoxicity not only should disturb deformation curves of myocardial contraction, but also relaxation. Hence, SIE may detect subtle myocardial changes in diastole that could be of potential benefit in the early prediction of CIC. If this premise is proven correct, the use of a standardized advanced echocardiographic imaging protocol using both, systolic and diastolic strain imaging, will prove to be a powerful noninvasive tool as baseline and follow-up of these patients. Furthermore, it will foster the developing of more effective screening strategies in at risk cancer survivor populations, or identify the best time to start cardioprotective therapy to prevent CIC. Also, this experience might be extrapolated to other non-oncologic patient population in need of a surveillance tool to early recognize cardiac injury secondary to the use of cardiotoxic medications.

Sonomicrometry-Based Analysis of Post-Myocardial Infarction Regional Mechanics

Following myocardial infarction (MI), detrimental changes to the geometry, composition, and mechanical properties of the left ventricle (LV) are initiated in a process generally termed adverse post-MI remodeling. Cumulatively, these changes lead to a loss of LV function and are deterministic factors in the progression to heart failure. Proposed therapeutic strategies to target aberrant LV mechanics post-MI have shown potential to stabilize LV functional indices throughout the remodeling process. The in vivo quantification of LV mechanics, particularly within the MI region, is therefore essential to the continued development and evaluation of strategies to interrupt the post-MI remodeling process. The present study utilizes a porcine MI model and in vivo sonomicrometry to characterize MI region stiffness at 14 days post-MI. Obtained results demonstrate a significant dependence of mechanical properties on location and direction within the MI region, as well as cardiac phase. While approaches for comprehensive characterization of LV mechanics post-MI still need to be improved and standardized, our findings provide insight into the issues and complexities that must be considered within the MI region itself.

Prognostic value of diastolic wall strain in patients with chronic heart failure with reduced ejection fraction

Left ventricular (LV) diastolic dysfunction plays a crucial role in heart failure with reduced ejection fraction (HFrEF). LV stiffness is a main component of diastolic function, but its role and prognostic value in HFrEF patients remains unclear. This study aimed to determine whether diastolic wall strain (DWS) as a noninvasive and simple marker of LV stiffness can predict the prognosis of HFrEF patients who were administrated chronic beta blockade enough. We enrolled 75 HFrEF patients who were administrated chronic beta blockade. We evaluated the echocardiographic parameters and plasma brain natriuretic peptide (BNP) before the induction of beta blockade and also obtained pulmonary artery wedge pressure (PAWP) from the right heart catheterization. DWS was obtained from standard M-mode echocardiography as follows: DWS = [(LV posterior wall thickness (LVPWT) at end-systole - LVPWT at end-diastole)/LVPWT] at end-systole. DWS did not correlate with other echocardiographic parameters and PAWP. We defined primary outcome as HF hospitalization or cardiovascular death and followed for 7 years. The incidence rate was higher in low DWS than high DWS patients (p = 0.04). Other echocardiographic parameters could not be significant predictors of HFrEF outcome under the condition of enough beta blocker therapy. In multivariate analysis, DWS was the independent contributor to the event-free time. Impaired LV stiffness evaluated with DWS was associated with worse outcome and DWS might be an independent prognostic factor in HFrEF patients with chronic beta blockade.

Decreased diastolic wall strain is associated with adverse left ventricular remodeling even in patients with normal left ventricular diastolic function

Background

The pathophysiology of diastolic dysfunction is complex, but can be simply described as impaired LV myocardial relaxation and/or increased LV stiffness. The objective of this study is to clarify true normal left ventricular (LV) diastolic function and early stage of diastolic dysfunction before relaxation abnormality develops in patients with normal LV diastolic function using simple diastolic wall strain (DWS) in South Korea.

Methods

DWS which is a non-invasive, load-independent, and reproducible estimator of LV stiffness using two-dimensional echocardiography using the difference between posterior wall thickness in systole and diastole to approximate LV stiffness. A total of 349 consecutive patients with normal LV diastolic function by echocardiography were enrolled. According to DWS, patients were divided into two groups: high DWS (≥median 175) vs. low DWS (<median 174).

Results

Patients with low DWS were more obese and showed higher blood pressure, and had more prevalent hypertension and hyperlipidemia. In addition, those with low DWS had higher LV end-systolic volume, LV mass index, E/E’ and lower ejection fraction and E’ velocity. Among them, higher LVESV and LVMI were independently associated with low DWS.

Conclusions

These data suggests that simple DWS might be helpful in identifying a subgroup of subtle diastolic dysfunction. Our data suggest that early change of diastolic dysfunction might start with abnormal LV geographic changes preceding functional changes.