Multidetector computed tomography predictors of late ventricular remodeling and function after acute myocardial infarction

BACKGROUND

Despite advent of rapid arterial revascularization as 1st line treatment for acute myocardial infarction (AMI), incomplete restoral of flow at the microvascular level remains a problem and is associated with adverse prognosis, including pathological ventricular remodeling. We aimed to study the association between multidetector row computed tomography (MDCT) perfusion defects and ventricular remodeling post-AMI.

METHODS

In a prospective study, 20 patients with ST-elevation AMI, treated by primary angioplasty, underwent arterial and late phase MDCT as well as radionuclide scans to study presence, size and severity of myocardial perfusion defects. Contrast echocardiography was performed at baseline and at 4 months follow-up to evaluate changes in myocardial function and remodeling.

RESULTS

Early defects (ED), late defects (LD) and late enhancement (LE) were detected in 15, 7 and 16 patients, respectively and radionuclide defects in 15 patients. The ED area (r=0.74), and LD area (r=0.72), and to a lesser extent LE area (r=0.62) correlated moderately well with SPECT summed rest score. By univariate analysis, follow-up end-systolic volume index and ejection fraction were both significantly related to ED and LD size and severity, but not to LE size or severity. By multivariate analysis, end-systolic volume index was best predicted by LD area (p<0.05) and ejection fraction by LD enhancement ratio.

CONCLUSIONS

LD size and severity on MDCT are most closely associated with pathological ventricular remodeling after AMI and may thus play a role in early identification and treatment of this condition.

Macrophage LRP1 suppresses neo-intima formation during vascular remodeling by modulating the TGF-β signaling pathway

BACKGROUND

Vascular remodeling in response to alterations in blood flow has been shown to modulate the formation of neo-intima. This process results from a proliferative response of vascular smooth muscle cells and is influenced by macrophages, which potentiate the development of the intima. The LDL receptor-related protein 1 (LRP1) is a large endocytic and signaling receptor that recognizes a number of ligands including apoE-containing lipoproteins, proteases and protease-inhibitor complexes. Macrophage LRP1 is known to influence the development of atherosclerosis, but its role in vascular remodeling has not been investigated.

METHODOLOGY/PRINCIPAL FINDINGS

To define the contribution of macrophage LRP1 to vascular remodeling, we generated macrophage specific LRP1-deficient mice (macLRP1-/-) on an LDL receptor (LDLr) knock-out background. Using a carotid ligation model, we detected a 2-fold increase in neointimal thickening and a 2-fold increase in the intima/media ratio in macLRP1-/- mice. Quantitative RT-PCR arrays of the remodeled vessel wall identified increases in mRNA levels of the TGF-β2 gene as well as the Pdgfa gene in macLRP1-/- mice which could account for the alterations in vascular remodeling. Immunohistochemistry analysis revealed increased activation of the TGF-β signaling pathway in macLRP1-/- mice. Further, we observed that LRP1 binds TGF-β2 and macrophages lacking LRP1 accumulate twice as much TGF-β2 in conditioned media. Finally, TNF-α modulation of the TGF-β2 gene in macrophages is attenuated when LRP1 is expressed. Together, the data reveal that LRP1 modulates both the expression and protein levels of TGF-β2 in macrophages.

CONCLUSIONS/SIGNIFICANCE

Our data demonstrate that macrophage LRP1 protects the vasculature by limiting remodeling events associated with flow. This appears to occur by the ability of macrophage LRP1 to reduce TGF-β2 protein levels and to attenuate expression of the TGF-β2 gene resulting in suppression of the TGF-β signaling pathway.

Concise review: the role of clinical trials in deciphering mechanisms of action of cardiac cell-based therapy

Although the initial promise of cardiac cell-based therapy was based on the concept that stem cells engraft into diseased tissue and differentiate into beating cardiomyocytes, it is now clear that successful cell-based tissue repair involves a more complex orchestration of cellular and molecular events. Many lessons about successful tissue repair can be gleaned from the results of early-stage clinical trials. This body of work shows that cell-based therapy (with various cell sources and delivery methods) effectively prevents and reverses the remodeling process, the sine qua non of the myocardial injury reaction and anatomic substrate for subsequent clinical events. The potentially favorable remodeling responses to cell therapy have prompted a search for mechanisms of action beyond cell repopulation and guided future clinical trial design by providing more clear focus on pathophysiological endpoints signifying favorable responses to cell-based therapy. Perhaps the most important mechanistic insight is that endogenous stem/precursor cells have the potential to participate in tissue healing. With regard to the phenotype of cellular response, it is clear that parameters of remodeling, such as infarct size and ventricular dimensions, should be directly measured, thereby necessitating the use of sophisticated imaging modalities, such as cardiac magnetic resonance imaging or multidetector computed tomography. These new insights offer an optimistic outlook on the state of cell-based therapeutics for cardiac disease and suggest that pivotal clinical trials are warranted. Here, we review lessons learned from clinical trials and evaluate the choice and assessment of endpoints to best predict efficacy of cell therapy.

The inflammasome promotes adverse cardiac remodeling following acute myocardial infarction in the mouse

Acute myocardial infarction (AMI) initiates an intense inflammatory response that promotes cardiac dysfunction, cell death, and ventricular remodeling. The molecular events underlying this inflammatory response, however, are incompletely understood. In experimental models of sterile inflammation, ATP released from dying cells triggers, through activation of the purinergic P2X7 receptor, the formation of the inflammasome, a multiprotein complex necessary for caspase-1 activation and amplification of the inflammatory response. Here we describe the presence of the inflammasome in the heart in an experimental mouse model of AMI as evidenced by increased caspase-1 activity and cytoplasmic aggregates of the three components of the inflammasome--apoptosis speck-like protein containing a caspase-recruitment domain (ASC), cryopyrin, and caspase-1, localized to the granulation tissue and cardiomyocytes bordering the infarct. Cultured adult murine cardiomyocytes also showed the inducible formation of the inflammasome associated with increased cell death. P2X7 and cryopyrin inhibition (using silencing RNA or a pharmacologic inhibitor) prevented the formation of the inflammasome and limited infarct size and cardiac enlargement after AMI. The formation of the inflammasome in the mouse heart during AMI causes additional loss of functional myocardium, leading to heart failure. Modulation of the inflammasome may therefore represent a unique therapeutic strategy to limit cell death and prevent heart failure after AMI.

Depression is associated with increased occurrence of left ventricle concentric geometry in older subjects independently of blood pressure levels

BACKGROUND AND AIM

Depression is emerging as an independent risk factor for CV events, though mechanisms underlying this association are unknown. We investigated the relation between depression and LV hypertrophy (LVH) and LV structure in a group of elderly subjects.

METHODS AND RESULTS

Three hundred seventy patients (mean age 79 ± 6 years) were enrolled. CV risk factors were assessed. Depression was defined as a score ≥ 6 on the 15-item Geriatric Depression Scale. On the basis of the presence of LVH and of LV relative wall thickness (RWT) 4 echocardiographic patterns of LV adaptation were defined: concentric LVH (LVH with increased RWT); eccentric LVH (LVH with normal RWT); concentric LV remodeling (no LVH with increased RWT); normal LV (no LVH with normal RWT). Prevalence of hypertension was approximately 86% and 24.7% had diabetes (n.s. depressed vs not depressed subjects). BP was comparable in these two groups (134.7 ± 1.4 vs 135.3 ± 1.8 mmHg, 77.1 ± 0.8 vs 76.3 ± 1.0 mmHg for SBP and DBP respectively). Depressed subjects (n = 165) showed a significantly higher occurrence of concentric LVH than not depressed, after adjustment for age, sex, and hypertension. Depression was associated with a 2.1 fold higher risk of showing a LV concentric, either remodeling or LVH, pattern after adjustment for age, sex, and traditional CV risk factors.

CONCLUSIONS

Depression is accompanied by a higher occurrence of concentric LVH in elderly subjects, independently of BP levels.

[Intima-media thickness and left ventricle remodeling in patients with prehypertension and impaired glucose tolerance]

OBJECTIVE

To investigate the intima-media thickness and cardiac remodeling in patients with prehypertension and impaired glucose tolerance.

METHOD

Three-hundred patients were divided into four groups: normal control (NC, n = 61), prehypertension (PH, n = 83), impaired glucose tolerance (IGT, n = 91), prehypertension and impaired glucose tolerance (PH + IGT, n = 65). Intima-media thickness (IMT) was measured by doppler ultrasonography. Left ventricle mess (LVMI), midwall fractional shortening (mFS), peakE/peakA (E/A) were measured by echocardiography.

RESULTS

(1) IMT was significantly increased in PH, IGT and PH + IGT groups than in NC group [(0.7 ± 0.1) mm, (0.7 ± 0.1) mm and (1.0 ± 0.1) mm vs.(0.6 ± 0.1) mm, all P < 0.01], which was significantly high in PH + IGT group than in PH or IGT group. Regression analysis demonstrated that high-sensitivity C-reactive protein (hs-CRP), 2-hour postprandial blood glucose (2hPBG), systolic pressure (SBP), diastolic blood pressure (DBP) were independent predictors to increased IMT. (2) LVMI was higher in PH and PH + IGT groups than in NC group [(97.0 ± 3.3) g/m(2), (97.1 ± 2.8) g/m(2) vs.(87.0 ± 2.0) g/m(2), (87.9 ± 1.5) g/m(2), all P < 0.01], and positively related with SBP, DBP. (3) mFS was lower in PH and PH + IGT groups [(14.0 ± 0.8)%, (14.0 ± 0.8)% vs. (18.3 ± 1.0)%, (18.2 ± 0.5)%, P < 0.01], negatively related with SBP and DBP. E/A was similar among groups and lower E/A was associated with higher SBP.

CONCLUSION

Vascular and left ventricular structure remodeling and systolic dysfunction could be detected in prehypertension patients. Impaired glucose tolerance could enhance vascular remodeling in prehypertension patients.

[Metal stress-induced arrhythmia and thoracic spinal cord 1-5 nerve remodeling and myocardial electrophysiological remodeling in rats]

OBJECTIVE

The study aimed to investigate the relationship between arrhythmia occurrence and nerve remodeling of thoracic spinal cord 1-5 nerves as well as myocardial electrophysiological remodeling in a metal stress rat model.

METHODS

Thirty SD rats (weight 180-250 g) were randomly divided into control group (n = 10), stress group (n = 10) and fluoxetine group (n = 10, 10 mg/kg i.p. for 3 weeks). Stress model (given by unpredicted chronic mild stress) was established according to Cronli's protocol. Following parameters were observed:(1) ECG waveform change and arrhythmias;(2) tissue field action potential duration (FAPD) of thoracic spinal cord 1-5 and cardiac tissue mapped by microelectrode arrays (MEA) technique;(3) myocardial growth-associated protein (GAP-43), tyrosine hydroxylase (TH), choline acetyltransferase (CHAT) distribution observed by immunofluorescence and confocal laser scanning microscope (LSCM).

RESULTS

Three weeks later: (1) The body weight, food intake, consumption of sugar water, the horizontal and vertical movement score, cleaning action of rats were significantly decreased, and fecal grains significantly increased, P-wave, P-R interval, QRS-wave and Q-T interval were significantly prolonged and heart rate was significantly reduced in stress group compared with control group (all P < 0.05). Incidence of ventricular premature beat was 80% in stress group and 0% in control group (P < 0.05). The FAPD of thoracic spinal cord 1-5 nerves [(144.25 ± 12.63)ms vs (79.56 ± 8.01)ms] and of cardiac tissue [LA(122.43 ± 19.34)ms vs (92.59 ± 7.61)ms, RA(149.89 ± 14.68)ms vs (105.18 ± 15.94)ms, LV(162.62 ± 7.04)ms vs (110.45 ± 6.92)ms, RV(152.21 ± 30.49)ms vs (131.06 ± 12.04)ms] were significantly prolonged, FAPD dispersion (FAPDd) significantly increased [thoracic spinal cord 1-5(13.3 ± 9.11)ms vs (9.36 ± 7.01)ms] in stress group compared with the control group. Disarrangement of myocardial cells, proliferation of collagen fiber, infiltration of neutrophil and lymphocytes in the cardiac tissue were also observed and distribution of GAP-43, TH and CHAT was significantly increased in stress group. (2) All these changes could be partly reversed by the treatment with fluoxetine.

CONCLUSION

Metal stress induced cardiac autonomic nerve and myocardial electrophysiological remodeling and ventricular arrhythmia in rats which could be significantly attenuated by fluoxetine in this model.

Influence of injectable hyaluronic acid hydrogel degradation behavior on infarction-induced ventricular remodeling

Increased myocardial wall stress after myocardial infarction (MI) initiates the process of adverse left ventricular (LV) remodeling that is manifest as progressive LV dilatation, loss of global contractile function, and symptomatic heart failure, and recent work has shown that reduction in wall stress through injectable bulking agents attenuates these outcomes. In this study, hyaluronic acid (HA) was functionalized to exhibit controlled and tunable mechanics and degradation once cross-linked, in an attempt to assess the temporal dependency of mechanical stabilization in LV remodeling. Specifically, two hydrolytically degrading (low and high HeMA-HA, degrading in ~3 and 10 weeks, respectively) and two stable (low and high MeHA, little mass loss even after 8 weeks) hydrogels with similar initial mechanics (low: ~7 kPa; high: ~35-40 kPa) were evaluated in an ovine model of MI. Generally, the more stable hydrogels maintained myocardial wall thickness in the apical and basilar regions more efficiently (low MeHA: apical: 6.5 mm, basilar: 7 mm, high MeHA: apical: 7.0 mm basilar: 7.2 mm) than the hydrolytically degrading hydrogels (low HeMA-HA: apical: 3.5 mm, basilar: 6.0 mm, high HeMA-HA: apical: 4.1 mm, basilar: 6.1 mm); however, all hydrogel groups were improved compared to infarct controls (IC) (apical: 2.2 mm, basilar: 4.6 mm). Histological analysis at 8 weeks demonstrated that although both degradable hydrogels resulted in increased inflammation, all treatments resulted in increased vessel formation compared to IC. Further evaluation revealed that while high HeMA-HA and high MeHA maintained reduced LV volumes at 2 weeks, high MeHA was more effective at 8 weeks, implying that longer wall stabilization is needed for volume maintenance. All hydrogel groups resulted in better cardiac output (CO) values than IC.

Relation between left ventricular morphology and reduction in functional mitral regurgitation by cardiac resynchronization therapy in patients with idiopathic dilated cardiomyopathy

The presence of functional mitral regurgitation (MR) is considered a significant risk factor for poor clinical prognosis in patients with idiopathic dilated cardiomyopathy (IDC). The objectives of this study were to test the hypothesis that not only global but also local left ventricular (LV) remodeling, including the position of the papillary muscles, may contribute to the development of MR in patients with IDC and wide QRS durations and can be reversed with cardiac resynchronization therapy (CRT). Eighty-four subjects were studied, 44 patients with IDC who underwent CRT and 40 age- and gender-matched controls. The position of the posteromedial papillary muscle was similar in the 2 groups, whereas the position of the anterolateral papillary muscle in patients with IDC was displaced more posteriorly than in controls. Multivariate analysis revealed that reduction in coaptation height (β = 0.44, p <0.001) and LV dyssynchrony by speckle-tracking radial strain (β = 0.303, p <0.01) were independent determinants of reduction in MR 5 ± 2 days after CRT; in contrast, restoration of the position of the posteriorly displaced anterolateral papillary muscle (β = 0.50, p <0.001) and the increase in sphericity index (β = 0.440, p <0.001) were identified as independent determinants of reduction in MR 6 ± 1 months after CRT. In conclusion, asymmetric local LV remodeling was observed at baseline, and asymmetric local LV reverse remodeling was observed at long-term follow-up after CRT in patients with IDC. Furthermore, different parameters contribute to the reduction in MR observed at short- and long-term follow-up after CRT.

Interleukin-17A stimulates cardiac fibroblast proliferation and migration via negative regulation of the dual-specificity phosphatase MKP-1/DUSP-1

The dual-specificity mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) inactivates MAP kinases by dephosphorylation. Here we show that the proinflammatory cytokine interleukin (IL)-17A induces adult mouse primary cardiac fibroblast (CF) proliferation and migration via IL-17 receptor A//IL-17 receptor C-dependent MKP-1 suppression, and activation of p38 MAPK and ERK1/2. IL-17A mediated p38 MAPK and ERK1/2 activation is inhibited by MKP-1 overexpression, but prolonged by MKP-1 knockdown. IL-17A induced miR-101 expression via PI3K/Akt, and miR-101 inhibitor reversed MKP-1 down regulation. Importantly, MKP-1 knockdown, pharmacological inhibition of p38 MAPK and ERK1/2, or overexpression of dominant negative MEK1, each markedly attenuated IL-17A-mediated CF proliferation and migration. Similarly, IL-17F and IL-17A/F heterodimer that also signal via IL-17RA/IL-17RC, stimulated CF proliferation and migration. These results indicate that IL-17A stimulates CF proliferation and migration via Akt/miR-101/MKP-1-dependent p38 MAPK and ERK1/2 activation. These studies support a potential role for IL-17 in cardiac fibrosis and adverse myocardial remodeling.

Geometric assessment of regional left ventricular remodeling by three-dimensional echocardiographic shape analysis correlates with left ventricular function

BACKGROUND

Left ventricular (LV) volumes and ejection fraction derived from two-dimensional echocardiography are two measures of adverse LV remodeling, which predict survival in patients with systolic heart failure. However, the geometric assumptions and image foreshortening that can occur with two-dimensional echocardiography reduces measurement accuracy and thus predictive value. By its nature, three-dimensional (3D) echocardiography allows the entire LV shape to be studied, providing a methodology to examine LV remodeling through LV curvature on a global and regional scale. The aim of this study was to correlate changes in global and regional LV shape to LV ejection fraction.

METHODS

Full-volume, 3D transthoracic echocardiographic studies of the left ventricle were performed in 106 consecutive patients with either normal left ventricles (n = 59) or cardiomyopathies (n = 47). Customized software (QLAB) was used to extract segmented 3D LV endocardial shells at end-systole and end-diastole and to analyze these shells to determine global and regional LV shape analysis. Independent t tests were used for intergroup comparisons, and linear regression was used to correlate regional shape changes with systolic performance.

RESULTS

Derivation and analysis of the 3D LV shells was possible in all patients. Patients with dilated cardiomyopathy had significantly smaller curvature values, indicating rounder global LV shape throughout the cardiac cycle. Regional analysis identified a loss of septal and apical curvatures in these patients. Systolic apical mean curvature was well correlated with LV ejection fraction (r = 0.89).

CONCLUSIONS

This is the first study to demonstrate that regional remodeling measured by regional 3D LV curvature correlates well with LV function. As well, this methodology is independent of the geometric assumptions that limit the predictive value of two-dimensional echocardiographic measures of LV remodeling. Overall, this is a novel tool that may have applications in the assessment and prediction of outcomes of different forms of dilated cardiomyopathy.

Cardiac structure and function, remodeling, and clinical outcomes among patients with diabetes after myocardial infarction complicated by left ventricular systolic dysfunction, heart failure, or both

AIMS

The mechanisms responsible for the increased risk of heart failure (HF) post-myocardial infarction (MI) may differ between patients with versus without diabetes. We hypothesized that after high-risk MI, patients with diabetes would demonstrate patterns of remodeling that are suggestive of reduced ventricular compliance and that are associated with an increased risk of death or HF.

METHODS AND RESULTS

We performed quantitative echocardiographic analysis in 153 patients with diabetes and 451 patients without diabetes enrolled in the VALIANT Echo study. Diabetes was associated with a higher risk of death or HF in age-adjusted models (hazard ratio 1.44, 95% CI 1.04-2.00, P = .028). Diabetic patients were similar to nondiabetic patients with respect to left ventricular (LV) volume and ejection fraction but had higher LV mass index (104.1 ± 27.5 vs 97.1 ± 28.6 g/m(2), P = .009), relative wall thickness (0.41 ± 0.08 vs 0.38 ± 0.07, P < .0001), and left atrial volume index (LAVi) (26.2 ± 8.1 vs 24.0 ± 8.2 mL/m(2), P = .008)-all parameters that were significantly related to the risk of death or HF hospitalization. Changes in LV volume and ejection fraction from baseline to 20 months were not different, although diabetic patients demonstrated greater increase in LAVi (4.4 ± 7.7 vs 2.2 ± 6.7 mL/m(2), P = .01).

CONCLUSIONS

After high-risk MI, diabetic patients were at higher risk of death or HF and demonstrated greater baseline LV mass index, relative wall thickness, and LAVi as well as greater left atrial enlargement at 20-month follow-up. These findings suggest greater baseline concentric remodeling and long-term elevation in LV diastolic pressure post-MI among diabetic patients, which may partially mediate this risk.

[Myocardial geometry and function in overweight and obese adolescents]

114 obese (BMI > 97th age-sex percentile) and 27 overweight (BMI 85-97th age-sex percentile) adolescents (10-18 years) were studied using tissue Doppler echocardiography for the assessment of the geometry of the left ventricle and it's systolic and diastolic functions. Subjects were age and sex matched and grouped according to BMI: + 1-2 SD (Group 1); + 2-3 SD (Group 2) and + > 3 SD (Group 3). It was established that the process of cardiac remodeling in adolescents begins with an initial thickening of the interventricular septum (IVS) at the background of normal values of the myocardial mass index (MMI). The obesity was associated with eccentric myocardial hypertrophy. There were significantly increased stroke and minute volume as a result of increasing end diastolic Ieft ventricular volume without significant changes of the intracardiac kinetics, which contributes to the preservation of ejection fraction within reference values. The IVS kinetic properties were increased and posterior wall's were decreased. The central hemodynamic is hypokinetic in all groups due to enlarged body surface area. Revealed a progressive decrease in the number of subjects with normal diastolic left ventricular function and increase ones with pseudonormal and restrictive types. There is a tendency to increasing the late diastolic filling and decreasing the isovolumetric relaxation time both absolute and relative to the cardiac cycle.

Relation of growth-differentiation factor 15 to left ventricular remodeling in ST-segment elevation myocardial infarction

The development of left ventricular remodeling (LVR) after myocardial infarction is associated with a high risk of heart failure and death. LVR is difficult to predict, and limited information is available on the association of cardiac biomarkers and LVR. Growth-differentiation factor-15 (GDF-15) is induced during heart failure development and, in animals models, might influence the different processes involved in cardiac remodeling. The aim of the present investigation was to assess the association between the serum levels of GDF-15 within the first 24 hours of ST-segment elevation myocardial infarction and the development of subsequent LVR at 12 months of follow-up. This prospective study included 97 patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention. Echocardiography was performed in all patients within the first 96 hours of admission and at 12 months of follow-up. LVR was defined as a >20% increase in the left ventricular end-diastolic volume at 12 months of follow-up compared to baseline. Blood samples for the determination of GDF-15 and brain natriuretic peptide were obtained within the first 24 hours after symptom onset. According to the pre-established criteria, 21 patients (22%) had LVR. Patients with LVR had greater levels of GDF-15 at study entry (median 3,439 pg/ml, interquartile range 2,391 to 6,168 vs median 1998 pg/ml, interquartile range 1,204 to 3,067, respectively; p <0.001). Multivariate analysis showed that GDF-15 (odds ratio 10.1, 95% confidence interval 2.5 to 40.1, p <0.001) and treatment with angiotensin-converting enzyme inhibitors (odds ratio 3.9, 95% confidence interval 1.2 to 12.3, p <0.01) were independents predictors of LVR. Receiving operating characteristics analysis showed an area under the curve of 0.77 for GDF-15 (95% confidence interval 0.67 to 0.84, p <0.001). In conclusion, the results of the present study have identified GDF-15 as an independent marker of LVR in patients with ST-segment elevation myocardial infarction.

The impairment of ILK related angiogenesis involved in cardiac maladaptation after infarction

Background

Integrin linked kinase (ILK), as an important component of mechanical stretch sensor, can initiate cellular signaling response in the heart when cardiac preload increases. Previous work demonstrated increased ILK expression could induce angiogenesis to improved heart function after MI. However the patholo-physiological role of ILK in cardiac remodeling after MI is not clear.

Method and Results

Hearts were induced to cardiac remodeling by infarction and studied in Sprague-Dawley rats. Until 4 weeks after infarction, ILK expression was increased in non-ischemic tissue in parallel with myocytes hypertrophy and compensatory cardiac function. 8 weeks later, when decompensation of heart function occurred, ILK level returned to baseline. Followed ILK alternation, vascular endothelial growth factor (VEGF) expression and phosphorylation of endothelial nitric oxide synthase (eNOS) was significantly decreased 8 weeks after MI. Histology study also showed significantly microvessel decreased and myocytes loss 8 weeks paralleled with ILK down-regualtion. While ILK expression was maintained by gene delivery, tissue angiogenesis and cardiac function was preserved during cardiac remodeling.

Conclusion

Temporally up-regulation of ILK level in non-ischemic myocytes by increased external load is associated with beneficial angiogenesis to maintain infarction-induced cardiac hypertrophy. When ILK expression returns to normal, this cardiac adaptive response for infarction is weaken. Understanding the ILK related mechanism of cardiac maladaptation leads to a new strategy for treatment of heart failure after infarction.

Left ventricular remodeling, hemodynamics and early clinical outcomes after aortic valve replacement with the Pericarbon Freedom stentless bioprosthesis: results from the Italian Prospective Multicenter Trial

BACKGROUND AND AIM OF THE STUDY

The aims of this multicenter prospective observational trial were to evaluate: (i) the left ventricular remodeling, hemodynamics and early clinical outcomes of patients undergoing aortic valve replacement (AVR) with the Pericarbon Freedom (PF) stentless bioprosthesis; and (ii) the impact of the two suture techniques--continuous and interrupted--on the hemodynamic performance of the bioprosthesis.

METHODS

Between November 2001 and April 2004, a total of 226 patients (131 females, 95 males; mean age 73.2 +/- 8.8 years) underwent AVR with the PF valve (Sorin Group, Saluggia, Italy) at eight Italian cardiac surgery centers. Associated surgery was performed in 73 patients (32%); of these operations, 54 were coronary artery bypass grafting. A continuous-suture technique was used in 132 patients (58%), and an interrupted-suture in 90 (40%). The suture technique was not available for four patients. All patients underwent clinical and echocardiographic evaluation immediately before surgery, and at one, six, and 12 months thereafter. The median follow up was 380 days (Q1: 363 days; Q3: 410 days), and the total cumulative follow up 236.9 patient-years (pt-yr).

RESULTS

The overall 30-day mortality was 3.5% (n = 8). Late deaths occurred in 10 patients (4%/pt-yr), of which three were valve-related (1%/pt-yr). The overall and valve-related survivals at one year were 92 +/- 2% and 98 +/- 1%, respectively. Freedom from structural valve deterioration, endocarditis, reoperation and thromboembolic events was 100%, 93 +/- 1%, 98 +/- 1% and 99 +/- 1% at one year, respectively. The peak and mean transprosthetic gradients at one year were: 19.7 +/- 12.27 and 8.7 +/- 6.0 mmHg, respectively. After 12 months, significant reductions (compared to preoperative) were observed in the left ventricular mass (148.5 +/- 48.8 versus 194.4 +/- 54.6 g/m2; p < 0.001) and mean wall thickness (1.08 +/- 0.19 versus 1.32 +/- 0.23 cm; p < 0.001). The continuous-suture technique showed a trend towards lower postoperative gradients than did the interrupted-suture technique.

CONCLUSION

The data obtained indicated that the PF bioprosthesis provided excellent results in terms of left ventricular mass regression, hemodynamics, and early clinical outcome. Although a trend towards a better hemodynamic performance of the continuous-suture technique was observed, this aspect requires further evaluation.

[Dural modulation effects of mesenchymal stem cells implantation on myocardial collagen remodeling in a rat model of myocardial infarction]

OBJECTIVE

To investigate the modulation effects of mesenchymal stem cells (MSCs) implantation on the collagen remodeling in myocardial infarction.

METHODS

Acute myocardial infarction (AMI) was induced in SD rats by left anterior descending coronary artery ligation, and the animals were assigned randomly into the Sham group, MI + PBS group and MI + MSCs group. Echocardiography and hemodynamic examinations were performed to evaluate the cardiac function. HE staining and Masson trichrome staining were used to evaluate the myocardial infarction size. Infarcted area and infarcted expansion index were calculated. The expression of collagens in infarcted hearts was evaluated by immunohistochemistry, RT-PCR and Western blot.

RESULTS

(1) Infarct area was significantly reduced post MSCs transplantation [MI + MSCs vs. MI + PBS: (38.27 ± 2.70)% vs. (46.20 ± 3.17)%, P < 0.001]. (2) Cardiac function was significantly improved post MSCs transplantation [MI + MSCs vs. MI + PBS: FS(%): 29.98 ± 4.50 vs. 23.43 ± 3.34, P = 0.005; LVSP (mm Hg, 1 mm Hg = 0.133 kPa): 113.63 ± 10.81 vs. 99.25 ± 16.76, P < 0.05; LVEDP (mm Hg): 12.10 ± 4.28 vs. 20.08 ± 4.26, P < 0.05; +dp/dtmax (mm Hg/s): 4616.63 ± 363.34 vs. 3912.75 ± 248.79, P < 0.05; -dp/dtmax (mm Hg/s): 4254.63 ± 324.34 vs. 3530.88 ± 309.71, P < 0.05]. (3) Collagen synthesis was enhanced in infarcted area and decreased in non-infarcted area post MSCs transplantation (P < 0.05).

CONCLUSIONS

MSCs transplantation could enhance the collagen synthesis in infarcted area while decrease the deposition of collagen in non-infarcted area in this MI model. This may be one of the mechanisms by which ventricular remodeling is attenuated post MSCs transplantation.

A statistical model for quantification and prediction of cardiac remodelling: application to tetralogy of Fallot

Cardiac remodelling plays a crucial role in heart diseases. Analyzing how the heart grows and remodels over time can provide precious insights into pathological mechanisms, eventually resulting in quantitative metrics for disease evaluation and therapy planning. This study aims to quantify the regional impacts of valve regurgitation and heart growth upon the end-diastolic right ventricle (RV) in patients with tetralogy of Fallot, a severe congenital heart defect. The ultimate goal is to determine, among clinical variables, predictors for the RV shape from which a statistical model that predicts RV remodelling is built. Our approach relies on a forward model based on currents and a diffeomorphic surface registration algorithm to estimate an unbiased template. Local effects of RV regurgitation upon the RV shape were assessed with Principal Component Analysis (PCA) and cross-sectional multivariate design. A generative 3-D model of RV growth was then estimated using partial least squares (PLS) and canonical correlation analysis (CCA). Applied on a retrospective population of 49 patients, cross-effects between growth and pathology could be identified. Qualitatively, the statistical findings were found realistic by cardiologists. 10-fold cross-validation demonstrated a promising generalization and stability of the growth model. Compared to PCA regression, PLS was more compact, more precise and provided better predictions.

S100B-RAGE dependent VEGF secretion by cardiac myocytes induces myofibroblast proliferation

Post-infarct remodeling is associated with the upregulation of the receptor for advanced glycation end products (RAGE), the induction of its ligand the calcium binding protein S100B and the release of the potent endothelial-cell specific mitogen vascular endothelial growth factor (VEGF). To determine a possible functional interaction between S100B, RAGE and VEGF we stimulated rat neonatal cardiac myocyte cultures transfected with either RAGE or a dominant-negative cytoplasmic deletion mutant of RAGE with S100B for 48 h. Under baseline conditions, cardiac myocytes express low levels of RAGE and VEGF and secrete VEGF in the medium as measured by ELISA. In RAGE overexpressing myocytes, S100B (100 nM) resulted in increases in VEGF mRNA, VEGF protein, VEGF secretion, and activation of the transcription factor NF-κB. Pre-treatment of RAGE overexpressing myocytes with the NF-κB inhibitor caffeic acid phenethyl ester inhibited increases in VEGF mRNA, VEGF protein and VEGF in the medium by S100B. In myocytes expressing dominant-negative RAGE, S100B did not induce VEGF mRNA, VEGF protein, VEGF secretion or NF-κB activation. In culture, rat neonatal and adult cardiac fibroblasts undergo phenotypic transition to myofibroblasts. Treatment of neonatal and adult myofibroblasts with VEGF (10 ng/mL) induces VEGFR-2 (flk-1/KDR) tyrosine kinase phosphorylation, ERK1/2 phosphorylation and myofibroblast proliferation. Together these data demonstrate that secreted VEGF by cardiac myocytes in response to S100B via RAGE ligation induces myofibroblast proliferation potentially contributing to scar formation observed in infarcted myocardium. This article is part of a Special Issue entitled "Local Signaling in Myocytes".

[Effects of ventricular demand and dual-chamber pacing models on the long-term clinical outcome and cardiac remodeling in patients with symptomatic bradycardia]

OBJECTIVE

To assess the effects of VVI (ventricular demand) and DDD (dual-chamber) pacing models on cardiac remodeling and the long-term clinical outcome of patients with symptomatic bradycardia.

METHODS

All patients with DDD and VVI pacing models at our hospital from January 1991 to January 2003 were retrospectively analyzed.

RESULTS

After a follow-up period of over 8 years in DDD and VVI groups (97 ± 27, 107 ± 44 months), left atrial diameter [(45 ± 12) mm vs (39 ± 12) mm, P < 0.01] and left ventricular end-diastolic diameter [(53 ± 11) mm vs (50 ± 9) mm, P = 0.01] in 57 patients with VVI pacing model were markedly enlarged than those at pre-implantation. And tricuspid regurgitation increased (42.4% vs 16.9%, P < 0.05). But in 59 patients with DDD pacing model, except for increased tricuspid regurgitation (42.1% vs 10.5%, P < 0.01), left atrial diameter [(37 ± 5) mm vs. (35 ± 5) mm, P = 0.07] and left ventricular end-diastolic diameter [(47 ± 7) mm vs (47 ± 5) mm, P = 0.32] were not significantly different. Mitral regurgitation significantly increased only in the VVI group (P < 0.01). The increases of left ventricular end-diastolic diameter (P = 0.04), mitral valve (P = 0.02) and tricuspid regurgitation (P < 0.01) were much more pronounced in the VVI group than those in the DDD group. Left ventricular ejection fraction (LVEF) showed no difference with that at pre-implantation (P = 0.11 in DDD group, P = 0.05 in VVI group). But the LVEF value was lower (P = 0.04) while the incidence of thrombosis was higher (P = 0.03) in the VVI group than those in the DDD group at post-implantation. However, the incidence of atrial fibrillation (P = 0.14), hospitalization (P = 0.08) and survival (P = 0.77) showed no significant difference between two groups.

CONCLUSION

DDD pacing offers more benefits over VVI pacing through improving cardiac functions and arresting left ventricular remodeling. However, neither groups showed any difference in decreasing mortality rate and hospitalization. Moreover, both pacing modes fail to reverse cardiac electrical and anatomical remodeling. It is imperative to explore more physiological pacing site and rational atrioventricular (AV) interval to improve the prognosis of patients.

Left atrial volume index predictive of mortality independent of left ventricular geometry in a large clinical cohort with preserved ejection fraction

OBJECTIVE

To determine the effect on mortality of the left atrial volume index (LAVI) and left ventricular (LV) geometry (normal, concentric remodeling, eccentric hypertrophy, and concentric hypertrophy).

PATIENTS AND METHODS

From January 1, 2004, through December 31, 2006, we evaluated 36,561 patients with preserved ejection fraction with an average follow-up of 1.7±1.0 years. The LAVI was categorized as normal (≤28 mL/m(2)) or increased (mild, 29-33 mL/m(2); moderate, 34-39 mL/m(2); severe, ≥40 mL/m(2)).

RESULTS

Progressive increases in LAVI and mortality were noted with abnormal LV geometry. Similarly, abnormal LV geometry and mortality were significantly higher in patients with increased LAVI. In patients who died vs surviving patients, the LAVI ± SD was significantly higher (33.0±14.8 vs 28.1±10.8 mL/m(2); P<.001) and abnormal LV geometry was significantly more prevalent (62% vs 44%; P<.001). Compared with those with a normal LAVI, patients with a severe LAVI had a 42% increased risk of mortality. In patients with normal LV geometry or concentric remodeling, a severe LAVI was a significant independent predictor of mortality, with an increased risk of 28% and 46%, respectively. Similarly, in patients with eccentric hypertrophy and concentric hypertrophy, the mortality risk in patients with a severe LAVI was twice that of patients with a normal LAVI. Comparison of area under the curve (0.565 [without LAVI] vs 0.596 [with LAVI]; P<.001] and predictive models with and without LAVI for mortality prediction were significant, indicating increased mortality prediction by the addition of LAVI to other independent predictors.

CONCLUSION

The LAVI significantly predicts mortality risk, independent of LV geometry, and adds to the overall mortality prediction in a large cohort of patients with preserved systolic function.

[Correlation of structurally-functional cardiac condition and levels of erythropoietin, tumour necrosis factor-alpha in blood in heart failure]

Structurally-functional myocardium parameters and their interconnection with erythropoietin and tumour necrosis factor-alpha levels in blood plasma of patients with heart failure were analysed. Prevalence of erythropoietin over tumour necrosis factor-alpha in blood had positive effect on myocardium-contraction ability under acute heart failure. Improvement of pumped cardiac function was not registered under prevalence of erythropoietin over tumour necrosis faetor-a in blood of patients with chronic heart failure.

Electrical vagus nerve stimulation for the treatment of chronic heart failure

Autonomic dysregulation is a feature of chronic heart failure (HF) and is characterized by a sustained increase of sympathetic drive and by withdrawal of parasympathetic activity. Both sympathetic overdrive and increased heart rate are predictors of poor long-term outcome in patients with HF. Pharmacologic agents that partially inhibit sympathetic activity, such as beta-adrenergic receptor blockers, effectively reduce mortality and morbidity in patients with chronic HF. In contrast, modulation of parasympathetic activation as a potential therapy for HF has received only limited attention because of its inherent complex cardiovascular effects. This review examines results of experimental animal studies that provide support for the possible use of electrical vagus nerve stimulation (VNS) as a long-term therapy for the treatment of chronic HF. The review also addresses the effects of VNS on potential modifiers of the HF state, including proinflammatory cytokines, nitric oxide elaboration, and myocardial expression of gap junction proteins. Finally, the safety, feasibility, and efficacy trends of VNS in patients with advanced HF are reviewed.