Greater Left Ventricular Dilation Research Articles

Disparate impact of severe aortic and mitral regurgitation on left ventricular dilation.

In asymptomatic severe aortic (AR) and mitral regurgitation (MR), left ventricular (LV) dimension criteria were established to guide timing of valve replacement to prevent irreversible LV dysfunction. Given both lesions are primary LV volume overload ''leaks'', it might be expected that both lesions would induce similar impact on the LV and result in equivalent dimension criteria for intervention. However, the dimension-based intervention criteria for AR versus MR (developed through natural history studies), differ markedly. The pathophysiological foundations for such discordance have neither been fully elucidated nor emphasized. This case-based treatise compares the two regurgitant lesions with respect to: (a) ''total regurgitant circuits''; (b) ''driving pressures'' resulting in LV volume overload from each respective ''leak''; and (c) volume and afterload wall stresses imposed on the LV.Key points The ''total circuits'' of volume overload differ: The AR circuit includes the LV and systemic vasculature, whereas MR includes the LV ejecting into the left atrium/pulmonary veins and systemic circulation. The ''driving pressure'' of regurgitation and afterload are high with AR and low with MR. Differing ''total circuits'' and ''driving pressures'' impose disparate wall stresses upon the LV. Parallel and serial sarcomere replication occurs in AR, while only serial replication occurs in MR. It therefore follows that for regurgitation of similar severities, AR results in greater LV dilation at the point of irreversible myocardial dysfunction compared to MR. These considerations may explain, at least in part, the disparate dimension criteria employed for valve intervention for severe AR vs MR.

Insulin resistance and dysglycemia are associated with left ventricular remodeling after myocardial infarction in non-diabetic patients

BackgroundAdverse cardiac remodeling after ST-segment elevation myocardial infarction (STEMI) is a major cause for poor cardiovascular outcomes such as heart failure. The predisposing factors and underlying mechanisms remain not fully understood. This study investigates the association of insulin resistance and dysglycemia with left ventricular (LV) remodeling after STEMI in non-diabetic patients.MethodsA total of 485 non-diabetic subjects with STEMI who underwent primary percutaneous coronary intervention were consecutively enrolled and followed up for 12 months. Relation of homeostasis model assessment-estimated insulin resistance (HOMA-IR) and glucose levels to changes in echocardiography parameters was studied.ResultsLeft ventricular dilation was detected in 49.1% of subjects at 12-month follow-up after STEMI, and was more severe in subjects with impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and high HOMA-IR levels. HOMA-IR remained correlated to changes in LV dimensions after adjusting for confounding risk factors. Multivariate regression analysis demonstrated that higher HOMA-IR was independently associated with greater LV dilation after STEMI. A significant interaction term was present between HOMA-IR and IGT in the model (P = 0.001).ConclusionsOur study reveals that insulin resistance and dysglycemia are prevalent in non-diabetic patients with STEMI and are predictors of the post-infarction LV dilation.Trial registration Trials number, NCT02089360; registered on March 17, 2014

Differences in Presentation and Outcomes Between Children With Familial Dilated Cardiomyopathy and Children With Idiopathic Dilated Cardiomyopathy

Research comparing the survival of children with familial dilated cardiomyopathy (FDCM) to that of children with idiopathic dilated cardiomyopathy (IDCM) has produced conflicting results. We analyzed data from children with FDCM or IDCM using the National Heart, Lung, and Blood Institute-funded Pediatric Cardiomyopathy Registry. Compared to children with IDCM (n=647), children with FDCM (n=223) were older (mean 6.2 versus 4.5 years, P<0.001), less often had heart failure (64% versus 78%, P<0.001), had less-depressed mean left ventricular fractional shortening z scores (-7.85±3.98 versus -9.06±3.89, P<0.001) and lower end-diastolic dimension z scores (4.12±2.61 versus 4.91±2.57, P<0.001) at diagnosis. The cumulative incidence of death was lower for patients with FDCM compared with IDCM (P=0.04; hazard ratio 0.64, P=0.06), but no difference in risk of transplant or the combined death or transplant outcome. There was no difference in the proportion of children with echocardiographic normalization at 3 years of follow-up (FDCM, 30% versus IDCM, 26%; P=0.33). Multivariable analysis showed no difference in outcomes between FDCM and IDCM but for both groups older age, congestive heart failure, and increased left ventricular end-systolic dimension zscore at diagnosis were independently associated with an increased risk of death or heart transplantation (all Ps<0.001). There was no survival difference between FDCM and IDCM after adjustment for other factors. Older age, congestive heart failure, and greater left ventricular dilation at diagnosis were independently associated with increased risk of the combined end point of death or transplantation. URL: https://clinicaltrials.gov. Unique identifier: NCT00005391.

The Reproducibility and Absolute Values of Echocardiographic Measurements of Left Ventricular Size and Function in Children Are Algorithm Dependent

Several quantification algorithms for measuring left ventricular (LV) size and function are used in clinical and research settings. The aims of this study were to investigate the effects of measurement algorithm and beat averaging on the reproducibility of measurements of the left ventricle and to assess the magnitude of agreement among the algorithms in children with dilated cardiomyopathy. Echocardiograms were obtained in 169 children from eight clinical centers. Inter- and intrareader reproducibility was assessed on measurements of LV volumes using the biplane Simpson, modified Simpson, and 5/6 × area × length (5/6AL) algorithms. Percentage error was calculated as inter- or intrareader difference/mean × 100. Single-beat measurements and the three-beat average (3BA) were compared. Intraclass correlation coefficients were calculated to assess agreement. Single-beat interreader reproducibility was lowest (percentage error was highest) using biplane Simpson; 5/6AL and modified Simpson were similar but significantly better than biplane Simpson (P<.05). Single-beat intrareader reproducibility was highest using 5/6AL (P<.05). The 3BA improved reproducibility for almost all measures (P<.05). Reproducibility in both single-beat and 3BA values fell with greater LV dilation and systolic dysfunction (P<.05). Intraclass correlation coefficients were >0.95 across measures, although absolute volume and mass values were systematically lower for biplane Simpson compared with modified Simpson and 5/6AL. The reproducibility of LV size and functional measurements in children with dilated cardiomyopathy is highest using the 5/6AL algorithm and can be further improved by using the 3BA. However, values derived from different algorithms are not interchangeable.

Toll‐Like Receptor‐2 Mediates Adaptive Cardiac Hypertrophy in Response to Pressure Overload Through Interleukin‐1β Upregulation via Nuclear Factor κB Activation

BackgroundInflammation is induced in the heart during the development of cardiac hypertrophy. The initiating mechanisms and the role of inflammation in cardiac hypertrophy, however, remain unclear. Toll‐like receptor‐2 (TLR2) recognizes endogenous molecules that induce noninfectious inflammation. Here, we examined the role of TLR2‐mediated inflammation in cardiac hypertrophy.Methods and ResultsAt 2 weeks after transverse aortic constriction, Tlr2−/− mice showed reduced cardiac hypertrophy and fibrosis with greater left ventricular dilatation and impaired systolic function compared with wild‐type mice, which indicated impaired cardiac adaptation in Tlr2−/− mice. Bone marrow transplantation experiment revealed that TLR2 expressed in the heart, but not in bone marrow–derived cells, is important for cardiac adaptive response to pressure overload. In vitro experiments demonstrated that TLR2 signaling can induce cardiomyocyte hypertrophy and fibroblast and vascular endothelial cell proliferation through nuclear factor–κB activation and interleukin‐1β upregulation. Systemic administration of a nuclear factor–κB inhibitor or anti–interleukin‐1β antibodies to wild‐type mice resulted in impaired adaptive cardiac hypertrophy after transverse aortic constriction. We also found that heat shock protein 70, which was increased in murine plasma after transverse aortic constriction, can activate TLR2 signaling in vitro and in vivo. Systemic administration of anti–heat shock protein 70 antibodies to wild‐type mice impaired adaptive cardiac hypertrophy after transverse aortic constriction.ConclusionsOur results demonstrate that TLR2‐mediated inflammation induced by extracellularly released heat shock protein 70 is essential for adaptive cardiac hypertrophy in response to pressure overload. Thus, modulation of TLR2 signaling in the heart may provide a novel strategy for treating heart failure due to inadequate adaptation to hemodynamic stress.

Abstract 333: Deficiency of DJ-1 Leads to Increased Injury following Myocardial Ischemia by Enhancing Apoptosis and Oxidative Stress

Background: DJ-1 is a ubiquitously expressed protein that has typically been associated with the development of early onset Parkinson’s disease. Recent data suggests that it also plays a role in the cellular response to stress. Although much is known about DJ-1 in the brain, very little has been investigated in the heart. Here, we tested the hypothesis that a deficiency in DJ-1 would enhance myocardial ischemia-reperfusion (MI/R) injury. Methods and Results: Wild-type (WT) control and DJ-1 knockout (DJ-1 KO) mice were subjected to 45 min of left coronary artery ischemia followed by 24 hrs of reperfusion. The deficiency of DJ-1 significantly increased myocardial infarct size relative to both the area-at-risk and entire left ventricle, as well as increased circulating troponin-I levels (Panels A-B). Echocardiography and hemodynamic analysis at 1 week of reperfusion revealed that DJ-1 KO mice experienced greater left ventricular dilatation and hypertrophy, displayed exacerbated left ventricular dysfunction, and displayed worse contractility and relaxation when compared to WT controls. In an effort to evaluate the signaling mechanism responsible for the increased injury in DJ-1 KO mice, additional WT and KO animals were subjected to 45 min of ischemia followed by 4 hrs of reperfusion. DJ-1 KO hearts were found to display higher levels of oxidative stress, greater caspase-3 activity (Panel C), enhanced phosphorylation of Jnk, and enhanced activation of the mitochondrial fission protein, dynamin-related protein 1 (Drp1). Conclusions: These findings provide important information that DJ-1 plays a protective role in heart against acute MI/R injury.

Analysis of Maternal and Fetal Cardiovascular Systems During Hyperglycemic Pregnancy in the Nonobese Diabetic Mouse

Preconception or gestationally induced diabetes increases morbidities and elevates long-term cardiovascular disease risks in women and their children. Spontaneously hyperglycemic (d)-NOD/ShiLtJ female mice, a type 1 diabetes model, develop bradycardia and hypotension after midpregnancy compared with normoglycemic, age- and gestational day (GD)-matched control (c-NOD) females. We hypothesized that onset of the placental circulation at GD 9-10 and rapid fetal growth from GD 14 correlate with aberrant hemodynamic outcomes in d-NOD females. To develop further gestational time-course correlations between maternal cardiac and renal parameters, high-frequency ultrasonography was applied to d- and c-NOD mice (virgin and at GD 8-16). Cardiac output and left ventricular (LV) mass increased in c-NOD but not in d-NOD mice. Ultrasound and postmortem histopathology showed overall greater LV dilation in d-NOD than in c-NOD mice at mid to late gestation. These changes suggest blunted remodeling and altered functional adaptation of d-NOD hearts. Umbilical cord ultrasounds revealed lower fetal heart rates from GD 12 and lower umbilical flow velocities at GD 14 and GD 16 in d-NOD versus c-NOD pregnancies. From GD 14 to GD 16, d-NOD fetal losses exceeded c-NOD fetal losses. Similar aberrant responses in pregnancies of women with diabetes may elevate postpartum maternal and child cardiovascular risk, particularly if mothers lack adequate prenatal care or have poor glycemic control during gestation.

Type 5 Adenylyl Cyclase Increases Oxidative Stress by Transcriptional Regulation of Manganese Superoxide Dismutase via the SIRT1/FoxO3a Pathway

For reasons that remain unclear, whether type 5 adenylyl cyclase (AC5), 1 of 2 major AC isoforms in heart, is protective or deleterious in response to cardiac stress is controversial. To reconcile this controversy we examined the cardiomyopathy induced by chronic isoproterenol in AC5 transgenic (Tg) mice and the signaling mechanisms involved. Chronic isoproterenol increased oxidative stress and induced more severe cardiomyopathy in AC5 Tg, as left ventricular ejection fraction fell 1.9-fold more than wild type, along with greater left ventricular dilation and increased fibrosis, apoptosis, and hypertrophy. Oxidative stress induced by chronic isoproterenol, detected by 8-OhDG was 15% greater, P=0.007, in AC5 Tg hearts, whereas protein expression of manganese superoxide dismutase (MnSOD) was reduced by 38%, indicating that the susceptibility of AC5 Tg to cardiomyopathy may be attributable to decreased MnSOD expression. Consistent with this, susceptibility of the AC5 Tg to cardiomyopathy was suppressed by overexpression of MnSOD, whereas protection afforded by the AC5 knockout (KO) was lost in AC5 KO×MnSOD heterozyous KO mice. Elevation of MnSOD was eliminated by both sirtuin and MEK inhibitors, suggesting both the SIRT1/FoxO3a and MEK/ERK pathway are involved in MnSOD regulation by AC5. Overexpression of AC5 exacerbates the cardiomyopathy induced by chronic catecholamine stress by altering regulation of SIRT1/FoxO3a, MEK/ERK, and MnSOD, resulting in oxidative stress intolerance, thereby shedding light on new approaches for treatment of heart failure.

Glucose 6-Phosphate Dehydrogenase Deficiency Increases Redox Stress and Moderately Accelerates the Development of Heart Failure

Glucose 6-phosphate dehydrogenase (G6PD) is the most common deficient enzyme in the world. In failing hearts, G6PD is upregulated and generates reduced nicotinamide adenine dinucleotide phosphate (NADPH) that is used by the glutathione pathway to remove reactive oxygen species but also as a substrate by reactive oxygen species-generating enzymes. Therefore, G6PD deficiency might prevent heart failure by decreasing NADPH and reactive oxygen species production. This hypothesis was evaluated in a mouse model of human G6PD deficiency (G6PDX mice, ≈40% normal activity). Myocardial infarction with 3 months follow-up resulted in left ventricular dilation and dysfunction in both wild-type and G6PDX mice but significantly greater end diastolic volume and wall thinning in G6PDX mice. Similarly, pressure overload induced by transverse aortic constriction (TAC) for 6 weeks caused greater left ventricular dilation in G6PDX mice than wild-type mice. We further stressed transverse aortic constriction mice by feeding a high fructose diet to increase flux through G6PD and reactive oxygen species production and again observed worse left ventricular remodeling and a lower ejection fraction in G6PDX than wild-type mice. Tissue content of lipid peroxidation products was increased in G6PDX mice in response to infarction and aconitase activity was decreased with transverse aortic constriction, suggesting that G6PD deficiency increases myocardial oxidative stress and subsequent damage. Contrary to our hypothesis, G6PD deficiency increased redox stress in response to infarction or pressure overload. However, we found only a modest acceleration of left ventricular remodeling, suggesting that, in individuals with G6PD deficiency and concurrent hypertension or myocardial infarction, the risk for developing heart failure is higher but limited by compensatory mechanisms.

No-Reflow Phenomenon: Maintaining Vascular Integrity

The no-reflow phenomenon relates to the inability to reperfuse regions of the myocardium after ischemia, despite removal of the large epicardial coronary artery occlusion. The mechanism involves microvascular obstruction. In experimental studies, using markers for flow (thioflavin S, carbon black, microspheres), perfusion defects associated with no-reflow demonstrated ultrastructural evidence of localized endothelial swelling and blebs that appeared to obstruct flow. In humans no-reflow is more complicated due to the microemboli of atherosclerotic debris and thrombi generated by percutaneous coronary intervention. The no-reflow zone expands during the first few hours of reperfusion suggesting an element of reperfusion injury. In animal models, extensive no-reflow was associated with worse infarct expansion. The phenomenon of no-reflow following reperfusion therapy for myocardial infarction in humans has been demonstrated by magnetic resonance imaging, echo contrast agents, thallium, technecium-99m-labeled albumin microspheres, Thrombolysis In Myocardial Infarction (TIMI) scores, and myocardial blush grade. Patients exhibiting no-reflow following reperfusion therapy for myocardial infarction have greater left ventricular dilation and remodeling, more congestive heart failure, shock, and reduced survival. Certain vasodilators (adenosine, nitroprusside, nicorandil, and calcium blockers) are used acutely in the catheterization laboratory and appear to improve no-reflow, but systematic studies on therapy for no-reflow are needed. There is now clinical evidence that no-reflow is a strong predictor of long-term mortality that is independent of and beyond that provided by infarct size. Identifying and treating no-reflow may have important benefits including enhancing delivery of nutrients and cells required for healing and reducing infarct expansion and ventricular remodeling, which ultimately may reduce congestive heart failure and mortality.

Inverse shift in serum polyunsaturated and monounsaturated fatty acids is associated with adverse dilatation of the heart

BackgroundCardiac dilatation is associated with impaired pump function, progression of heart failure and electrical instability. Risk of sudden death is associated with a low blood level of n-3 polyunsaturated fatty...

Treating Children With Idiopathic Dilated Cardiomyopathy (from the Pediatric Cardiomyopathy Registry)

In 40% of children with symptomatic idiopathic dilated cardiomyopathy (IDC), medical therapy fails within 2 years of diagnosis. Strong evidence-based therapies are not available for these children, and how evidence-based therapies for adults with IDC should be applied to children is unclear. Using data from the National Heart, Lung, and Blood Institute's Pediatric Cardiomyopathy Registry, we compared practice patterns of initial therapies for children with IDC diagnosed from 1990 to 1995 (n = 350) and from 2000 to 2006 (n = 219). At diagnosis, 73% had symptomatic heart failure (HF), and 7% had > or =1 family member with IDC. Anti-HF medications were most commonly prescribed initially. Anti-HF medication use was similar across the 2 periods (84% and 87%, respectively), as was angiotensin-converting enzyme inhibitor use (66% and 70%, respectively). These medications were used more commonly in children with greater left ventricular dilation and poorer left ventricular fractional shortening and functional class (p <0.001). Beta-blocker use was 4% to 18% over the 2 periods. Treatments for pediatric IDC have changed little over the previous 25 years. Anti-HF medications remain the most common treatment, and they are often given to children with asymptomatic left ventricular dysfunction. Children with asymptomatic left ventricular dysfunction are often not offered angiotensin-converting enzyme inhibitors without echocardiographic evidence of advanced disease. In conclusion, therapeutic clinical trials are strongly indicated because practice variation is substantial and medical outcomes in these children have not improved in the previous several decades.

C-KIT Receptor Maintains Cardiac Function in Aging Mice Post MI

Introduction: Recent findings report the potential for bone marrow- (BM) or cardiac-derived stem and progenitor cell mobilization and differentiation to repair the infarcted myocardium. Following myocardial infarction (MI), there is an influx of inflammatory cells and secretion of cytokines, leading to cardiomyocyte death and ventricular remodeling. Mobilized c-Kit+ progenitor cells, either from the BM or cardiac niches, play a key role in maintenance of the number of myocytes in aging or post-MI. We focused on determining the role of the c-Kit receptor in long term remodeling post-MI. Methods and Results: Functional repair in c-kit mutant (W/Wv) and littermate wild type (WT) mice post-MI was compared by evaluating in vivo left ventricular (LV) pressure-volume performance and pathology at 5 and 24 weeks post-MI. Evaluation of LV end-systolic and diastolic volume (ESV and EDV) showed a significant worsening of heart function and greater left ventricular dilatation at 5 and 24 weeks post-MI in W/Wv mice compared to WT (Figure 1). Similarly, the W/Wv sham and MI operated groups developed greater LV dilatation at 24 weeks when compared to W/Wv sham and MI mice at 5 weeks. Interestingly, WT sham and MI mice did not demonstrate any significant worsening of heart function at 24 weeks when compared to 5 weeks post-MI. Conclusion: This demonstrates the importance of c-Kit receptors in maintaining heart function post-MI and in aging. These findings provide further evidence indicating the presence of BM- or cardiac resident- derived stem progenitor cells in maintenance of myocardial health with age and post-injury.

Transcription Profiles of Failing and Non-Failing Hearts after Two-Cycle RNA Amplification from Biopsy-Sized Samples

Introduction: Recent findings report the potential for bone marrow(BM) or cardiac-derived stem and progenitor cell mobilization and differentiation to repair the infarcted myocardium. Following myocardial infarction (MI), there is an influx of inflammatory cells and secretion of cytokines, leading to cardiomyocyte death and ventricular remodeling. Mobilized c-Kitþ progenitor cells, either from the BM or cardiac niches, play a key role in maintenance of the number of myocytes in aging or postMI. We focused on determining the role of the c-Kit receptor in long term remodeling post-MI. Methods and Results: Functional repair in c-kit mutant (W/W) and littermate wild type (WT) mice post-MI was compared by evaluating in vivo left ventricular (LV) pressure-volume performance and pathology at 5 and 24 weeks post-MI. Evaluation of LV end-systolic and diastolic volume (ESV and EDV) showed a significant worsening of heart function and greater left ventricular dilatation at 5 and 24 weeks post-MI in W/W mice compared to WT (Figure 1). Similarly, the W/W sham and MI operated groups developed greater LV dilatation at 24 weeks when compared to W/W sham and MI mice at 5 weeks. Interestingly, WT sham and MI mice did not demonstrate any significant worsening of heart function at 24 weeks when compared to 5 weeks post-MI. Conclusion: This demonstrates the importance of c-Kit receptors in maintaining heart function post-MI and in aging. These findings provide further evidence indicating the presence of BMor cardiac residentderived stem progenitor cells in maintenance of myocardial health with age and post-injury. 133

Comparison of clinical findings in idiopathic dilated cardiomyopathy in women versus men

Clinical and laboratory findings were compared in 65 women and 238 men with invasively documented idiopathic dilated cardiomyopathy. Women had more severe symptoms (New York Heart Association class ≥III in 48 vs 39%; p < 0.05), presented more frequently with heart failure signs (63 vs 41%; p < 0.01), and had a higher cardiothoracic ratio (0.56 ± 0.06 vs 0.53 ± 0.06; p < 0.05) and higher frequency of left bundle branch block (41 vs 29%; p < 0.05). Echocardiographic measurements in women showed significantly greater left ventricular (LV) end-diastolic (42 ± 7 vs 39 ± 6 mm/m 2; p < 0.0001) and end-systolic (36 ± 7 vs 33 ± 6 mm/m 2; p < 0.001) diameters, and mean myocardial thickness (11 ± 2 vs 10 ± 2 mm; p < 0.05). Exercise duration was shorter in women than in men (7 ± 3 vs 10 ± 4 minutes; p < 0.001). After 18 ± 16 months, 9 women and 27 men died, and 7 and 17, respectively, received transplants. Transplant-free survival was not significantly different according to gender. By Cox multivariate analysis, LV ejection fraction was a significant independent predictor of cardiac death or heart transplantation in both sexes (p < 0.05 in men, and p < 0.005 in women), together with left atrial diameter index (p < 0.01) in women, and mean pulmonary artery pressure (p < 0.001) in men. In conclusion, women with idiopathic dilated cardiomyopathy present a more advanced phase of the disease with greater LV dilation, but do not have a different prognosis.

Effects of severity of the residual stenosis of the infarct-related coronary artery on left ventricular dilation and function after acute myocardial infarction

Objectives. This study was designed to evaluate the relation between the severity of the residual stenosis of the infarct-related artery and changes in left ventricular volume and function after a first anterior myocardial infarction.Background. Although thrombolytic therapy improves clinical outcome after acute myocardial infarction, the relations between the severity of the residual stenosis of the infarct-related artery and postinfarction left ventricular remodeling and function are unclear.Methods. Fifty-eight patients with a first anterior myocardial infarction and significant disease only in the left anterior descending coronary artery on arteriography performed after 7 to 10 days were evaluated. All patients received thrombolytic therapy. Residual stenosis of the infarct-related artery was measured with quantitative coronary arteriography. Left ventricular volumes and ejection fraction were measured by echocardiography and radionuclide angiography, respectively, 7 to 10 days, 6 months and 1 year after infarction. End-diastolic and end-systolic left ventricular volumes were measured by two-dimensional echocardiography and normalized to body surface area. Patients were classified into three groups according to baseline residual stenosis severity: total occlusion (Group I), minimal lesion diameter <15 mm (Group II) and minimal diameter ≥1.5 mm (Group III).Results. Group I patients had significantly greater left ventricular end-diastolic and end-systolic volumes at 6 months and 1 year than did the other groups. Group II patients had greater end diastolic and end-systolic volumes than did Group III patients at 1 year. In addition, Group 1 patients had a lower ejection fraction at 1 year than that of the other groups. The minimal lesion diameter was significantly correlated with percent change in end-diastolic volume at 1 year.Conclusions. The severity of the baseline residual stenosis of the infarct-related artery is an important predictor of change in left ventricular volumes in the 1st year after infarction. Tolal occlusion of the infarct-related artery is associated with greater left ventricular dilation and functional impairment.