Pathophysiologic aspects of end-stage heart failure

Hyaluronidase-2 Regulates RhoA Signaling, Myofibroblast Contractility, and Other Key Profibrotic Myofibroblast Functions

Hyaluronidase (HYAL)-2 is a weak, acid-active, hyaluronan-degrading enzyme broadly expressed in somatic tissues. Aberrant HYAL2 expression is implicated in diverse pathology. However, a significant proportion of HYAL2 is enzymatically inactive; thus the mechanisms through which HYAL2 dysregulation influences pathobiology are unclear. Recently, nonenzymatic HYAL2 functions have been described, and nuclear HYAL2 has been shown to influence mRNA splicing to prevent myofibroblast differentiation. Myofibroblasts drive fibrosis, thereby promoting progressive tissue damage and leading to multimorbidity. This study identifies a novel HYAL2 cytoplasmic function in myofibroblasts that is unrelated to its enzymatic activity. In fibroblasts and myofibroblasts, HYAL2 interacts with the GTPase-signaling small molecule ras homolog family member A (RhoA). Transforming growth factor beta 1–driven fibroblast-to-myofibroblast differentiation promotes HYAL2 cytoplasmic relocalization to bind to the actin cytoskeleton. Cytoskeletal-bound HYAL2 functions as a key regulator of downstream RhoA signaling and influences profibrotic myofibroblast functions, including myosin light-chain kinase–mediated myofibroblast contractility, myofibroblast migration, myofibroblast collagen/fibronectin deposition, as well as connective tissue growth factor and matrix metalloproteinase-2 expression. These data demonstrate that, in certain biological contexts, the nonenzymatic effects of HYAL2 are crucial in orchestrating RhoA signaling and downstream pathways that are important for full profibrotic myofibroblast functionality. In conjunction with previous data demonstrating the influence of HYAL2 on RNA splicing, these findings begin to explain the broad biological effects of HYAL2.

H2O 2 induces myocardial hypertrophy in H9c2 cells: a potential role of Ube3a

Myocardial hypertrophy that often leads to eventual heart failure is a leading cause of mortality worldwide. While both apoptosis and cell proliferation have been reported to play an important part in heart failure, its exact triggering mechanism is still unclear. Reports have shown that low concentrations of H2O2 (10-30 µM) can induce myocardial hypertrophy without affecting survival. The ubiquitin ligase Ube3a has been reported to have a close affiliation with Angelman syndrome; but many ubiquitin ligases have been reported in a variety of cardiovascular conditions including myocardial hypertrophy. However, the relationship between Ube3a and myocardial hypertrophy has never been reported in literature. The rat cardiac myoblast cell line H9c2 and primary neonatal cardiomyocytes showed similar hypertrophic responses in vitro. In this report, we utilized H2O2 treatment on H9c2 cells to induce myocardial hypertrophy and determined the relationship between Ube3a and myocardial hypertrophy. Our results showed that 10-20 μM H2O2 can induce myocardial hypertrophy without affecting cell viability and inducing cell apoptosis, while the corresponding transcription and translation levels of Ube3a are significantly increased during the process. Therefore, these findings underline that Ube3a may play an important role in myocardial hypertrophy.

Evaluation of patients with heart failure

Heart failure is one of the most prevalent cardiovascular diseases in the United States, and is associated with significant morbidity, mortality, and costs. Prompt diagnosis may help decrease mortality, hospital stay, and costs related to treatment. A complete heart failure evaluation comprises a comprehensive history and physical examination, echocardiogram, and diagnostic tools that provide information regarding the etiology of heart failure, related complications, and prognosis in order to prescribe appropriate therapy, monitor response to therapy, and transition expeditiously to advanced therapies when needed. Emerging technologies and biomarkers may provide better risk stratification and more accurate determination of cause and progression.

Hyaluronan facilitates transforming growth factor-β1-dependent proliferation via CD44 and epidermal growth factor receptor interaction

Fibroblast proliferation is an early feature of progressive tissue fibrosis and is largely regulated by the cytokine transforming growth factor-β1 (TGF-β1). In the oral mucosa, fibroblasts have a unique phenotype and demonstrate healing with no fibrosis/scarring. Our previous studies show that whereas dermal fibroblasts proliferate in response to TGF-β1, oral fibroblasts have an antiproliferative response to this cytokine. Hyaluronan (HA) was directly linked to this TGF-β1-dependent response. The aim of this study was to understand the underlying mechanism through which HA regulates TGF-β-dependent responses. Using patient-matched oral and dermal fibroblasts, we show that TGF-β1-dependent proliferation is mediated through the HA receptor CD44, whereas the TGF-β1-mediated antiproliferative response is CD44-independent. Furthermore, overexpression of HAS2 (HA synthase-2) in oral cells modifies their response, and they subsequently demonstrate a proliferative, CD44-dependent response to TGF-β1. We also show that epidermal growth factor (EGF) and its receptor (EGFR) are essential for TGF-β1/HA/CD44-dependent proliferation. Increased HA levels promote EGFR and CD44 coupling, potentiating signal transduction through the MAPK/ERK pathway. Thus, in a HA-rich environment, late ERK1/2 activation results from EGFR/CD44 coupling and leads to a proliferative response to TGF-β1. In comparison, in a non-HA-rich environment, only early ERK1/2 activation occurs, and this is associated with an antiproliferative response to TGF-β1. In summary, HA facilitates TGF-β1-dependent fibroblast proliferation through promoting interaction between CD44 and EGFR, which then promotes specific MAPK/ERK activation, inducing cellular proliferation.

Age-related changes in pericellular hyaluronan organization leads to impaired dermal fibroblast to myofibroblast differentiation

We have previously demonstrated that transforming growth factor-beta1 (TGF-beta1)-mediated fibroblast-myofibroblast differentiation is associated with accumulation of a hyaluronan (HA) pericellular coat. The current study demonstrates failure of fibroblast-myofibroblast differentiation associated with in vitro aging. This is associated with attenuation of numerous TGF-beta1-dependent responses, including HA synthesis and induction of the HA synthase enzyme HAS2 and the hyaladherin tumor necrosis factor-alpha-stimulated gene 6 (TSG-6), which led to an age-related defect in pericellular HA coat assembly. Inhibition of HAS2-dependent HA synthesis by gene silencing, removal of the HA coat by hyaluronidase digestion, or gene silencing of TSG-6 or cell surface receptor CD44 led to abrogation of TGF-beta1-dependent induction of alpha-smooth muscle actin in "young" cells. This result supports the importance of HAS2-dependent HA synthesis and the HA coat during phenotypic activation. Interleukin-1beta stimulation, however, failed to promote phenotypic conversion despite coat formation. A return to basal levels of HA synthesis in aged cells by HAS2 overexpression restored TGF-beta1-dependent induction of TSG-6 and pericellular HA coat assembly. However, this did not lead to the acquisition of a myofibroblast phenotype. Coordinated induction of HAS2 and TSG-6 facilitation of pericellular HA coat assembly is necessary for TGF-beta1-dependent activation of fibroblasts, and both components of this response are impaired with in vitro aging. In conclusion, the HA pericellular coat is integral but not sufficient to correct for the age-dependent defect in phenotypic conversion.

Chemokines and cardiac fibrosis

Several members of the chemokine family play an important role in reparative fibrosis and are involved in the pathogenesis of remodeling following myocardial infarction. Chemokines may regulate the fibrotic process through recruitment and activation of mononuclear cell subsets and fibroblast progenitors (fibrocytes), by exerting direct effects on resident fibroblasts, and by modulating angiogenesis. Monocyte Chemoattractant Protein (MCP)-1/CCL2 is the best studied chemokine in cardiac fibrosis. Disruption of the MCP-1 axis reduces fibrosis attenuating dilation of the infarcted ventricle. In addition, MCP-1 signaling is activated in response to insults that do not cause cardiomyocyte death, such as brief ischemia or pressure overload and regulates fibrous tissue deposition in experimental models of fibrotic non-infarctive cardiomyopathy. Understanding the role of chemokine-mediated interactions in the development of cardiac fibrosis may identify novel therapeutic targets for treatment of patients with heart failure.

Contemporary management of pediatric heart failure

The spectrum of causes of pediatric heart failure is broad and differs significantly from that seen in most adult patients. Left-to-right shunts and outflow obstruction lesions are responsible for a large number of pediatric cases of heart failure. Most of these are now treated successfully with surgery or catheter intervention. Medical therapy is the mainstay of care for myocardial disorders with diuretics, angiotensin-converting enzyme inhibitors, beta-blockade and cardiac glycosides. There are few prospective trials of these agents in a pediatric population, but extrapolated data support their use in children. In addition to medical therapy, interventions such as automatic implantable cardioverter defibrillators and resynchronization therapy have become increasingly common in pediatric heart disease, as well as in adult patients with congenital heart disease.

Cardiac oxidative stress and remodeling following infarction: role of NADPH oxidase

BACKGROUND

There is growing recognition that oxidative stress plays a role in the pathogeneses of myocardial repair/remodeling following myocardial infarction (MI). Nicotinamide adenine denucleotide phosphate (NADPH) oxidase is a major source for cardiac reactive oxygen species production. Herein, we studied the importance of NADPH oxidase in development of cardiac oxidative stress and its induced molecular and cellular changes related to myocardial repair/remodeling.

METHODS

MI was created by coronary artery ligation in C57/BL (wild type) and NADPH oxidase (gp91(phox)) knockout mice. Cardiac oxidative stress, inflammatory/fibrogenic responses, apoptosis, and hypertrophy were detected by in situ hybridization, immunohistochemistry, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL), picrosirius red staining, and image analysis, respectively, at different stages post MI.

RESULTS

In wild-type mice with MI, and compared to sham-operated animals, we observed significantly increased gp91(phox) and 3-nitrotyrosine, a marker of oxidative stress, in the infarcted myocardium; accumulated macrophages and myofibroblasts at the infarct site; abundant apoptotic myocytes primarily at border zones on Day 3; and numerous apoptotic inflammatory/myofibroblasts in the later stages. In addition, we detected significantly increased transforming growth factor beta1, tissue inhibitor of metalloprotease 2, and type 1 collagen gene expression; continuously increasing collagen volume in the infarcted myocardium; and hypertrophy in noninfarcted myocardium. Compared to wild-type mice with MI, we did not observe significant difference in infarct size/thickness, cardiac hypertrophy, myocyte apoptosis, inflammatory/fibrogenic responses, as well as cardiac oxidative stress in gp91(phox) knockout mice.

CONCLUSION

Our findings indicate that during NADPH oxidase deficiency, superoxide production can be compensated by other sources, which leads to cardiac oxidative stress and its related molecular/cellular events in the infarcted heart.

Hyaluronan facilitates transforming growth factor-beta1-mediated fibroblast proliferation

This study aims to understand the role of the matrix polysaccharide hyaluronan (HA) in influencing fibroblast proliferation and thereby affecting wound healing outcomes. To determine mechanisms that underlie scarred versus scar-free healing, patient-matched dermal and oral mucosal fibroblasts were used as models of scarring and non-scarring fibroblast phenotypes. Specifically, differences in HA generation between these distinct fibroblast populations have been examined and related to differences in transforming growth factor-beta(1) (TGF-beta(1))-dependent proliferative responses and Smad signaling. There was a differential growth response to TGF-beta(1), with it inducing proliferation in dermal fibroblasts but an anti-proliferative response in oral fibroblasts. Both responses were Smad3-dependent. Furthermore, the two fibroblast populations also demonstrated differences in their HA regulation, with dermal fibroblasts generating increased levels of HA, compared with oral fibroblasts. Inhibition of HA synthesis in dermal fibroblasts was shown to abrogate the TGF-beta(1)-mediated induction of proliferation. Inhibition of HA synthesis also led to an attenuation of Smad3 signaling in dermal fibroblasts. Microarray analysis demonstrated no difference in the genes involved in TGF-beta(1) signaling between dermal and oral fibroblasts, whereas there was a distinct difference in the pattern of genes involved in HA regulation. In conclusion, these two distinct fibroblast populations demonstrate a differential proliferative response to TGF-beta(1), which is associated with differences in HA generation. TGF-beta(1) regulates proliferation through Smad3 signaling in both fibroblast populations; however, it is the levels of HA generated by the cells that influence the outcome of this response.

Cardiac Troponin T as a Prognostic Marker in Patients With Heart Failure : A 3-Year Outcome Study

Cardiac troponin T (cTnT), a highly sensitive and specific indicator of myocardial cell death, may be elevated in congestive heart failure (CHF). The aims of this study were to test the hypothesis that decompensated CHF may be associated with an increase in cTnT release and to correlate between cTnT levels and patient outcomes. The authors studied 55 patients aged between 38 and 86 years (30 women and 25 men) who were hospitalized for CHF. Left ventricular ejection fraction (EF) was calculated by using modified Simpson's rule by echocardiography. cTnT levels were assessed. Troponin T ≥0.1 ng/mL was considered as positive. All patients were contacted by phone annually during the next 3 years, and their history of subsequent hospital admissions and current health status were recorded. cTnT was negative in 44 (80%) and positive in 11 (20%) patients. EF was significantly lower and NYHA was higher in cTnT-positive patients. During the 3-year follow-up period, 25 patients died from CHF. The mortality rate was 8/11 (72.7%) among cTnT-positive patients, whereas the mortality rate was 17/44 (38.6%) among cTnT-negative patients. There were significant relationships among positivity of cTnT, NYHA, EF, and mortality rate. Multivariate regression analysis yielded an independent relationship between positivity of cTnT, NYHA classification, and mortality rate. The percent of hospital admissions due to CHF was also higher in patients with cTnT positive (63.6% versus, 27.3%, p <0.05). In conclusion, this study shows that cTnT positivity is an independent risk factor in predicting the long-term mortality and morbidity rate in patients with CHF. Patients with worsening CHF may possibly be identified early on the basis of their elevated serum cTnT levels.

Oxidative Stress and Cardiac Repair/Remodeling Following Infarction

Extensive cardiac remodeling after myocardial infarction (MI) contributes significantly to ventricular dysfunction. Factors regulating left ventricular remodeling at different stages after MI are under investigation. There is growing recognition and experimental evidence that oxidative stress mediated by reactive oxygen species plays a role in the pathogeneses of myocardial repair/remodeling in various cardiac diseases. After acute MI, oxidative stress is developed in both infarcted and noninfarcted myocardium. Accumulating evidence has demonstrated that oxidative stress participates in several aspects of cardiac repair/remodeling after infarction that include cardiomyocyte apoptosis, inflammatory/fibrogenic responses, and hypertrophy. The exact pathways on reactive oxygen species-mediated myocardial remodeling are under investigation. The therapeutic potential of oxidative stress-directed drugs in myocardial remodeling after infarction has not been fully realized.

Involvement of hyaluronan in regulation of fibroblast phenotype

This study aimed to understand the role of the matrix polysaccharide, hyaluronan (HA), in influencing the scarring process by assessing its impact on regulating fibroblast behavior. Donor-matched human oral and dermal fibroblasts were used as models of nonscarring and scarring fibroblast phenotypes, respectively. Phenotypic differences in these two fibroblast populations were assessed and related to differences in HA synthesis and assembly. The two fibroblast populations showed intrinsic differences in their response to the profibrotic cytokine, transforming growth factor-beta1 (TGFbeta1), in that oral fibroblasts were resistant to TGFbeta1-driven myofibroblastic differentiation. In dermal fibroblasts, differentiation was associated with an induction of HA synthase (HAS1 and HAS2) transcription and assembly of pericellular HA coats. In comparison, resistance to differentiation in oral fibroblasts was associated with failure of induction of HAS1 and HAS2 transcription and failure of pericellular coat assembly. Furthermore, inhibition of HA synthesis in dermal fibroblasts significantly attenuated TGFbeta1-mediated differentiation. Interleukin-1beta stimulation resulted in induction of HAS1 and HAS2 transcription but did not induce phenotypic differentiation or induce HA coat assembly. In addition, neither overexpression nor down-regulation of HAS1 (the isoform uniquely deficient in nonscarring oral fibroblasts) influenced phenotypic differentiation. In conclusion, inhibiting HA synthesis modulates TGFbeta1-dependent responses in these cells preventing fibroblast to myofibroblast differentiation. Moreover, HA pericellular coat assembly, rather than HAS isoform expression, appears to be associated with phenotypic differentiation.

Cardiac dysfunction in the R6/2 mouse model of Huntington's disease

Recent evidence suggests that mutant huntingtin protein-induced energetic perturbations contribute to neuronal dysfunction in Huntington's disease (HD). Given the ubiquitous expression of huntingtin, other cell types with high energetic burden may be at risk for HD-related dysfunction. Early-onset cardiovascular disease is the second leading cause of death in HD patients; a direct role for mutant huntingtin in this phenomenon remains unevaluated. Here we tested the hypothesis that expression of mutant huntingtin is sufficient to induce cardiac dysfunction, using a well-described transgenic model of HD (line R6/2). R6/2 mice developed cardiac dysfunction by 8 weeks of age, progressing to severe failure at 12 weeks, assessed by echocardiography. Limited evidence of cardiac remodeling (e.g. hypertrophy, fibrosis, apoptosis, beta(1) adrenergic receptor downregulation) was observed. Immunogold electron microscopy demonstrated significant elevations in nuclear and mitochondrial polyglutamine presence in the R6/2 myocyte. Significant alterations in mitochondrial ultrastructure were seen, consistent with metabolic stress. Increased cardiac lysine acetylation and protein nitration were observed and were each significantly associated with impairments in cardiac performance. These data demonstrate that mutant huntingtin expression has potent cardiotoxic effects; cardiac failure may be a significant complication of this important experimental model of HD. Investigation of the potential cardiotropic effects of mutant huntingtin in humans may be warranted.

Activities of Home-Based Heart Failure Nurse Specialists: A Modified Narrative Analysis

• Background Heart failure nurse specialists strive to optimize patients’ outcomes in home-based settings.

• Objective To document the activities of home-based heart failure nurse specialists.

• Method A modified narrative analysis of clinical notes of home-based heart failure nurse specialists during a 12-month period was used.

• Results Data analysis revealed 7 key activities of home-based heart failure nurse specialists: (1) monitoring signs and symptoms and reinforcing patients’ self-management: identifying trends and appropriate action; (2) organization, liaison, and consultation with other health professionals to deal with changes in clinical status; (3) clarifying and reinforcing patients’ self-care strategies; (4) assisting patients in their desire to avoid institutionalized care; (5) identifying patients’ psychosocial issues: dealing with social isolation; (6) providing support: journeying with patients and patients’ families; and (7) helping patients and patients’ families deal with death and dying.

• Conclusions A major proportion of the activities of home-based heart failure nurse specialists are related to facilitating communication between health professionals and providing information and support to patients and patients’ families.

When all else has failed: Nurses' perception of factors influencing palliative care for patients with end-stage heart failure

The purpose of this study was to describe registered nurses' (RNs') perceptions of factors influencing care for patients in the palliative phase of end-stage heart failure (ESHF). Seventeen senior RNs across 3 acute care and 5 community centres in metropolitan Adelaide, Australia, participated in the study. In this descriptive, exploratory research project, we analyzed audiotaped indepth, semistructured interviews, using a computer-assisted (NVIVO) thematic procedure. According to participants, the care of patients with ESHF is dominated by a focus on symptom management and optimal pharmacologic therapies, with a perceived deficit in other aspects of palliative management. Key mitigating factors against quality palliative care for this population included the difficulty in recognising ESHF and reluctance by physicians to negotiate end-of-life decisions. In the acute care sector, nurses believed ESHF was medicalized and characterized by paternalistic care, with treatment generally curative to the last breath. Nursing care and patient advocacy were also negatively influenced by a lack of awareness in patients and families concerning the inevitability of death in ESHF until the last few days or hours before death. Involvement of the palliative care team was often an afterthought rather than an integral component of care. Nurses in acute care settings embraced the concept of a multidisciplinary team approach, but stressed the need for the cardiac team to be the overall coordinator of care for the ESHF population. Care of patients with ESHF should promote the amalgamation of technological and pharmaceutical advances in the treatment of heart failure with more timely end-of-life care. All involved parties must work toward advancing a common middle ground for appropriate end-of-life care for patients with ESHF. Recommendations for practice include the need for greater education for patients and their families and greater collaboration between the members of the multidisciplinary healthcare team to assist patients with ESHF and their families prepare more timely for the final trajectory of the illness.

c-Fos phosphorylation induced by H2O2 prevents proteasomal degradation of c-Fos in cardiomyocytes

Oxidants cause activation of the AP-1 transcription factor in cardiomyocytes. c-Fos, a component of the AP-1 transcription factor, is transiently induced by H2O2 and the induction is sensitive to the protein synthesis inhibitor cycloheximide. With high percentage gel electrophoresis, multiple c-Fos bands were resolved by Western blot analyses, indicating post-translational modification of newly synthesized c-Fos protein after H2O2 exposure. Treatment of immunoprecipitated c-Fos protein with the type 2 serine/threonine phosphatase A (PP2A) and immunoblotting of c-Fos protein with antibodies against phosphorylated serine or threonine demonstrated that c-Fos was phosphorylated at serine residues. A pharmacological inhibitor of JNKs inhibited the formation of multiple c-Fos bands without affecting c-fos transcription. The proteasomal inhibitor MG132 and Proteasome Inhibitor I extended the time course of c-Fos protein elevation. An increase in ubiquitin was detectable in c-Fos protein from H2O2-treated cells. Interestingly, treating the whole cell lysates with PP2A, but not calcineurin (i.e. PP2B), resulted in disappearance of c-Fos protein and MG132 was able to prevent this loss. H2O2 caused an elevation of PP2B and total phosphatase activity. The phosphatase inhibitor okadaic acid, but not PP2B inhibiter cypermethrin, extended the time course of c-Fos protein elevation after H2O2 exposure. These data suggest that JNK-mediated phosphorylation of newly synthesized c-Fos protects the protein from being degraded by the proteasome. PP2B independent dephosphorylation contributes to degradation of c-Fos protein during oxidative stress response of cardiomyocytes.

Selective microembolization of the circumflex coronary artery in an ovine model: dilated, ischemic cardiomyopathy and left ventricular dysfunction

BACKGROUND

Ventricular remodeling often occurs after myocardial infarction, yet the natural history remains unpredictable because of the chronicity of the process and therapeutic interventions involved. We induced cardiac dysfunction in an ovine model via selective microembolization of the circumflex coronary artery (LCx) to test the hypothesis that ventricular remodeling progresses following coronary microembolization for up to 24 months. Methods and results Sheep underwent weekly selective microembolization of the LCx until left ventricular ejection fraction stabilized <35% for 2 consecutive weeks. In a subgroup carried out to 4 months, the end-systolic pressure-volume relationship slope decreased from 2.3+/-0.6 (baseline) to 1.3+/-0.5 at month 4 (P<.05). In a second group, echocardiography at 24 months, the ejection fraction decreased from 51+/-3% (baseline) to 25+/-2% (month 5) (P<.05) and stabilized through month 24 (23+/-5%, P<.05), whereas left ventricular end-systolic area and left ventricular end-diastolic area increased by 222% and 98%, respectively, through month 24.

CONCLUSIONS

Selective microembolization of the LCx induces left ventricular dysfunction followed by dilated, ischemic cardiomyopathy, which continues to progress for up to 2 years despite stabilization of left ventricular ejection fraction. This model of ventricular remodeling secondary to microinfarction may be a useful experimental platform for large animal heart failure investigations.

Growth hormone induces myocardial expression of creatine transporter and decreases plasma levels of IL-1beta in rats during early postinfarct cardiac remodeling

Growth hormone has been proposed as a potential new therapeutic agent for treatment of myocardial infarction (MI) and congestive heart failure (CHF). The purpose of this study was to evaluate the effects of GH on: (a) myocardial expression of creatine transporter (CreaT) during early postinfarct remodeling, (b) myocardial levels of total creatine (TCr) and adenine pool (TAN) and (c) plasma levels of inflammatory cytokines interleukin-1beta (IL-1beta), tumor-necrosis-factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in rat model of postinfarct cardiac remodeling. Myocardial infarction (MI) was induced by ligation of the left coronary artery in male Sprague-Dawley rats (200-250 g). Three different groups were studied: MI rats treated with GH (n=11) (3 mg/kg/day), MI rats treated with saline (n=10), and sham operated rats (n=7). In the myocardium from GH treated rats the level of mRNA CreaT expression was significantly increased (p<0.01). There was no difference in TCr between the rats with MI and sham-operated rats. Treatment with GH had no effect on TCr. GH had no effect on TAN in left ventricle. All three groups had similar levels of IL-6 and TNF-alpha in plasma. In the rats with MI, treatment with GH normalized the levels of IL-1beta (p<0.05). In conclusion GH increased the expression of CreaT and decreased levels of plasma IL-1beta during postinfarct remodeling in rats. These mechanisms may be responsible for the previously reported beneficial effects of GH on myocardial energy metabolism and preservation of cardiac function in the settings of postinfarct remodeling and CHF.

Requirement of intracellular free thiols for hydrogen peroxide-induced hypertrophy in cardiomyocytes

Reactive oxygen species (ROS) are by-products of aerobic metabolism and are implicated in the pathogenesis of several diseases. H(2)O(2) produces oxidative stress and acts as a second messenger in several cell types. We tested whether the effect of H(2)O(2) on cellular events could be altered by changes in the intracellular redox status in a cardiomyocyte cell line. Using flow cytometric measurements, we found that adding H(2)O(2) induced hypertrophy in control cells in a time-dependent manner. Pre-incubation of the cells with buthionine sulfoximine (BSO), an inhibitor of de novo GSH synthesis, induced increase in the number of cells of small sizes by the addition of H(2)O(2) as compared to non-BSO pre-incubated control cells, and exacerbated the decrease in viability. Total thiol and GSH levels in H9c2 cells pre-incubated with BSO were about 75 and 30% of control, respectively, and GSH levels fell to below the limitation of detection after the addition of H(2)O(2), although total thiol levels were not markedly decreased. In the cells pre-incubated with BSO, hypertrophy was not observed by the addition of H(2)O(2) at any level of concentration. N-acetyl-L-cysteine and cysteine not only prevented increase in the number of cells of small sizes caused by H(2)O(2) but also induced hypertrophy in cells pre-incubated with BSO. These results suggest that the intracellular free thiol levels determine whether cell death or hypertrophy occurs in cardiomyocytes in the presence of H(2)O(2). On the other hand, the hypertrophied cells did not become larger by adding H(2)O(2), but had high levels of cellular GSH, suggesting the possibility that the hypertrophied cells have tolerance to oxidative stress.

Synergizing acute care and palliative care to optimise nursing care in end-stage cardiorespiratory disease

Advances in the practice of medicine and nursing science have increased survival for patients with chronic cardiorespiratory disease. Parallel to this positive outcome is a societal expectation of longevity and cure of disease. Chronic disease and the inevitability of death creates a dilemma, more than ever before, for the health care professional, who is committed to the delivery of quality care to patients and their families. The appropriate time for broaching the issue of dying and determining when palliative care is required is problematic. Dilemmas occur with a perceived dissonance between acute and palliative care and difficulties in determining prognosis. Palliative care must be integrated within the health care continuum, rather than being a discrete entity at the end of life, in order to achieve optimal patient outcomes. Anecdotally, acute and critical care nurses experience frustration from the tensions that arise between acute and palliative care philosophies. Many clinicians are concerned that patients are denied a good death and yet the moment when care should be oriented toward palliation rather than aggressive management is usually unclear. Clearly this has implications for the type and quality of care that patients receive. This paper provides a review of the extant literature and identifies issues in the end of life care for patients with chronic cardiorespiratory diseases within acute and critical care environments. Issues for refinement of acute and critical care nursing practice and research priorities are identified to create a synergy between these philosophical perspectives.

Reductive annuloplasty of double orifices in patients with primary dilated cardiomyopathy

BACKGROUND

Patients with primary dilated cardiomyopathy exhibit extensive remodeling of the left ventricle, mitral and tricuspid annular dilation and both mitral and tricuspid regurgitation. These factors significantly contribute to heart failure, and are predictors of early lethal outcome. The aim of this study is to show hemodynamic and clinical improvement after reductive annuloplasty of both mitral and tricuspid orifices in primary dilated cardiomyopathy.

METHODS

There were 76 patients with primary dilated cardiomyopathy. Mitral annuloplasty using a Carpentier-Edwards sizer was performed on 9 patients, and posterior semicircular reductive annuloplasty was performed on 67 patients. Modified De Vega's tricuspid annuloplasty was performed on all patients.

RESULTS

Immediate and long-term results showed significant improvement in hemodynamic values and myocardial contractility after operation.

CONCLUSIONS

Reductive annuloplasty of both mitral and tricuspid orifices corrects remodeling of the left ventricle of the heart, changes sphericity and geometry of the left ventricle, improves hemodynamic action of the left and right ventricle, and slows down progression of heart failure. We recommend reductive annuloplasty of both mitral and tricuspid orifices before or soon after the first decompensation.

Peroxisome proliferator-activated receptor alpha (PPAR alpha) agonist, WY-14,643, increased transcription of myosin light chain-2 in cardiomyocytes

Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that can be activated by xenobiotics and natural fatty acids. To assess the potential physiological activity of PPAR ligands on cardiac muscular cells, the effects of PPAR alpha agonist, WY-14,643, on both rat hearts and a rat cardiomyocyte cell line (H9c2 cells) were investigated. Male F344 rats were fed a diet containing WY-14,643 at a concentration of 100 ppm for 26 weeks. Cardiac muscular hypertrophy was revealed by morphometric analysis in which the diameter of the muscular fibers in WY-14,643-treated rats was larger than those of control rats. Using H9c2 cells in vitro, the protein content per cell was increased in a dose-dependent manner with the treatment of WY-14,643. The transcription of myosin light chain-2 (MLC-2), a parameter of myocardial hypertrophy, was increased in H9c2 cells transfected with the rat MLC-2/luciferase fusion gene by WY-14,643 as well as other peroxisome proliferators, clofibrate and di(2-ethylhexyl) phthalate. In addition, accumulation of myosin light chain protein was confirmed in H9c2 cells treated with WY-14,643 at 10 micrograms/ml for 7 days or more by immunohistochemistry. These results suggest that PPAR alpha ligands have a potential to regulate MLC-2, which is a contractile protein in cardiomyocytes and may play a part of role in the pathogenesis of cardiac hypertrophy.

Biventricular systolic function in young lambs subject to chronic systemic right ventricular pressure overload

In various clinical situations of congenital heart disease, the right ventricle (RV) is subject to a chronic systemic pressure overload which affects biventricular function and may progress to the development of RV failure. Young lambs (2-3 wk old) underwent adjustable pulmonary artery banding (PAB) at systemic (aortic) level for 8 wk. Biventricular function was determined by using load-independent indexes of global ventricular contractile performance by the end-systolic pressure-volume relationship (ESPVR) using the conductance catheter at baseline and during dobutamine infusion. PAB resulted in a significant fivefold increase in RV end-systolic pressure (12-64 mmHg) and a doubling of the RV-to-left ventricular (LV) wall thickness ratio (P < 0.01). RV global contractile performance increased significantly, as indicated by an increased slope of the ESPVR. Compared with age-matched control lambs, cardiac output decreased from 2.6 to 1.6 l/min (P < 0.05) whereas heart rates were equal. In contrast with RV volume, LV volume decreased significantly after PAB (P < 0.01), whereas the LV-ESPVR slope was unchanged. In the PAB group, the RV, but not the LV, showed a reduced response to dobutamine. We concluded that chronic RV pressure overload for 8 wk results in diminished pump function despite compensatory increased RV global contractile performance.

Addressing the burden of heart failure in Australia: the scope for home-based interventions

The growing burden of heart failure (HF) challenges health practitioners to implement and evaluate models of care to facilitate optimal health related outcomes. Australia supports a publicly funded universal health insurance system with a strong emphasis on primary care provided by general practitioners. The burden of chronic HF, and a social and political framework favoring community-based, noninstitutionalized care, represents an ideal environment in which home-based HF programs can be implemented successfully. Cardiovascular nurses are well positioned to champion and mentor implementation of evidence-based, patient-centered programs in Australian communities. This paper describes the facilitators and barriers to implementation of best practice models in the Australian context. These include the challenge of providing care in a diverse, multicultural society and the need for clinical governance structures to ensure equal access to the most effective models of care.

Transgenic mice with cardiac-specific expression of activating transcription factor 3, a stress-inducible gene, have conduction abnormalities and contractile dysfunction

Activating transcription factor 3 (ATF3) is a member of the CREB/ATF family of transcription factors. Previously, we demonstrated that the expression of the ATF3 gene is induced by many stress signals. In this report, we demonstrate that expression of ATF3 is induced by cardiac ischemia coupled with reperfusion (ischemia-reperfusion) in both cultured cells and an animal model. Transgenic mice expressing ATF3 under the control of the alpha-myosin heavy chain promoter have atrial enlargement, and atrial and ventricular hypertrophy. Microscopic examination showed myocyte degeneration and fibrosis. Functionally, the transgenic heart has reduced contractility and aberrant conduction. Interestingly, expression of sorcin, a gene whose product inhibits the release of calcium from sarcoplasmic reticulum, is increased in these transgenic hearts. Taken together, our results indicate that expression of ATF3, a stress-inducible gene, in the heart leads to altered gene expression and impaired cardiac function.

Cardiac troponin I as diagnostic and prognostic marker in severe heart failure

BACKGROUND

Cardiac cell death has been shown to occur in heart failure and has been implicated as one of the mechanisms responsible for progression of the disease. Cardiac Troponin I (cTnI) represents a highly sensitive marker for myocardial cell death. Based on previous studies reporting that cTnI may be detected in patients with heart failure, we evaluated the clinical correlates and prognostic implications of detectable cTnI in a consecutive series of patients with severe heart failure.

METHODS

Thirty-four patients were examined. Upon admission, we measured serum levels of cTnI by conventional immunoenzymatic assay (Stratus Dade II). According to the results of this assay, patients were divided into 2 groups, based on the presence (cTnI+) or absence (cTnI-) of detectable cTnI. These 2 groups were compared by non-parametric analysis for their clinical characteristics, instrumental findings, and short-term outcome.

RESULTS

The cTnI+ group included 10 patients (29%) with a mean serum cTnI of 0.7 +/- 0.3 ng/ml. Compared with the cTnI- group, these patients had significantly lower left ventricular ejection fractions (20% +/- 5% vs 26% +/- 7%, p = 0.023) and a trend for higher systolic pulmonary artery pressure (59 +/- 17 mm Hg vs 49 +/- 13 mm Hg, p = 0.08). In cTnI+ patients, the correlation between cTnI levels upon admission and ejection fraction was r = -0.530 (p = 0.11). We found ischemic etiology was equally present in the 2 groups, whereas we never found histologic signs of acute myocarditis. Other clinical characteristics (functional class, daily diuretic dose, need for intravenous inotropes) were not statistically different in the 2 groups. In cTnI+ patients who improved after admission, cTnI became undetectable after a few days; in patients with refractory heart failure who were hospitalized until death, cTnI persisted in detectable levels throughout the observation period. Using the Cox proportional hazard model, a positive cTnI was the most powerful predictor of mortality at 3 months (p = 0.013; hazard ratio 6.86; 95% confidence interval 1.32 to 35.4).

CONCLUSIONS

These observations suggest that cTnI is detected in the blood of 25% to 33% of patients with severe heart failure; its presence may help to identify a high-risk sub-group who faces very poor short-term prognosis.

Invasive and non-invasive determinants of pulmonary hypertension in patients with chronic heart failure

BACKGROUND

In patients with chronic heart failure, pulmonary hypertension is an important predictive marker of adverse outcome. Its invasive and non-invasive determinants have not been evaluated.

OBJECTIVE

This study was performed to evaluate hemodynamic determinants of pulmonary hypertension in chronic heart failure and to compare the predictive value of Doppler indices with that of invasively measured hemodynamic indices.

METHODS

Right heart catheterization and transthoracic echo-Doppler were simultaneously performed in 259 consecutive patients with chronic heart failure (ejection fraction 24% +/- 7%) who were in sinus rhythm and receiving optimized medical therapy. Systolic pulmonary artery pressure (sPAP), cardiac index, transpulmonary gradient pressure, and pulmonary wedge pressure (PWP) were measured invasively. Left atrial and ventricular systolic and diastolic volumes, the ratio of maximal early to late diastolic filling velocities (E/A ratio), deceleration time (DT) and atrial filling fraction (AFF) of transmitral flow, systolic fraction of forward pulmonary venous flow (SFpvf), and mitral regurgitation were quantified by echo-Doppler.

RESULTS

Patients with pulmonary hypertension had greater left atrial systolic and diastolic dysfunction, more left ventricular diastolic abnormalities, and greater hemodynamic impairment. The correlations between systolic left ventricular indices, mitral regurgitation, and sPAP were generally poor. Among invasive and non-invasive measurements, PWP (r = 0.89, p < 0.0001) and SFpvf (r = -0.68, p < 0.0001) showed the strongest correlation with sPAP. When we compared all patients with those without mitral regurgitation, the correlations between E/A ratio (r = 0.56 vs r = 0. 74, p < 0.002), SFpvf (r = -0.68 vs r = -0.84, p < 0.03), and systolic pulmonary artery pressure were significantly stronger. Multivariate analysis revealed that PWP was the strongest invasive independent predictor of systolic pulmonary artery pressure in patients with (R(2) = 0.87, p < 0.0001) and without (R(2) = 0.90, p < 0.0001) mitral regurgitation. A PWP > or= 18 mm Hg (odds ratio [95% CL], 142 (41-570) was strongly associated with systolic pulmonary hypertension. Among non-invasive variables DT, SFpvf, and AFF were identified as independent predictors of sPAP in patients with (R(2) = 0.56, p < 0.0001) and without (R(2) = 0.78, p < 0.0001) mitral regurgitation. A DT < 130 (odds ratio [95% CL], 3.5 (1.3-8.5), SFfvp < 40% (odds ratio [95% CL], 333 (41-1,007), and AFF < 30% (odds ratio [95% CL], 2 (1.3-7) most strongly predicted systolic pulmonary hypertension.

CONCLUSIONS

The results of this study indicate that in patients with chronic heart failure, venous pulmonary congestion is an important determinant of systolic pulmonary artery hypertension. Hemodynamic and Doppler determinants showed similar predictive power in identifying systolic pulmonary artery hypertension.

Cardiac afferents and neurohormonal activation in congestive heart failure

Cardiac chambers have afferent connections to the brainstem and to the spinal cord. Vagal afferents mediate depressor responses and become activated by volume expansion, increased myocardial contractility and atrial natriuretic factor. Sympathetic afferents, on the contrary, are activated by metabolic mediators, myocardial ischemia and cardiac enlargement. These opposite behaviors may lead to activation or suppression of the sympathetic nervous system and of the renin-angiotensin-aldosterone system. As cardiac diseases progress, the heart dilates, plasma norepinephrine increases, atrial natriuretic factor is released and the renin-angiotensin-aldosterone system is suppressed to maintain water and sodium excretion. This dissociation of the neurohormonal profile of cardiac patients, may be explained by coactivation of sympathetic afferents, by cardiac dilatation, and of vagal afferents by atrial natriuretic factor. In more advanced stages, atrial natriuretic factor suppression of the renin-angiotensin-aldosterone system is overridden by overt sympathetic activation and sodium and water retention ensues. Digitalis, angiotensin-converting enzyme inhibitors and beta-blockers selectively decrease cardiac adrenergic drive. A common mechanism of action, to all three groups of drugs, would be attenuation of sympathetic afferents and partial normalization of vagal afferents. Consequently, heart size and cardiac afferents emerge as the key factors to understand the pathophysiology and treatment of the syndrome of congestive heart failure.

Hydrogen peroxide dose dependent induction of cell death or hypertrophy in cardiomyocytes

Cardiomyocyte hypertrophy and cell death are often observed in the end stages of heart failure. The triggers of these two cellular processes are not known under most pathological conditions. Oxidants are by-products of aerobic metabolism. The level of oxidants increases as a result of ischemic reperfusion. Using H9C2 and primary cultured neonatal rat cardiomyocytes, we found that a 2-h pulse treatment with H(2)O(2) at 250 microM or lower caused activation of DEVD sequence specific caspases. The activity of DEVD-ase peaked with 200 microM H(2)O(2) at 24 h. While a fraction of the cells detached and showed nuclear condensation, the majority of the cells (>55%) survived the treatment and appeared to enlarge when cultured for 5 days. These cells showed increases in cell surface area, cell volume, and protein content. With 200 microM H(2)O(2), treated cells appeared to be six times bigger in volume and contained three times more protein per cell than untreated cells. The enlarged cells showed enhanced actin stress fibers and disrupted myofibrils. Our data indicate that while H(2)O(2) can cause cell death, the surviving cardiomyocytes undergo hypertrophy.

Cardiac troponins in congestive heart failure

BACKGROUND

We sought to assess the release of cardiac troponins in congestive heart failure (CHF).

METHODS AND RESULTS

We performed a computer-assisted search of the English language literature (MEDLINE database) followed by a manual search of the reference list of pertinent articles retrieved. Studies evaluating the release of cardiac troponins (T and I) in patients with CHF were screened for review. Studies investigating cardiac troponins in patients with ischemic coronary syndromes that reported the rate of CHF were also selected. Available data on the release of cardiac troponins in ischemic and nonischemic CHF were summarized. Possible mechanisms of cell death in the progression to end-stage CHF were discussed.

CONCLUSIONS

Cardiac troponins were detected in patients with advanced CHF. These markers correlated with the severity of CHF and suggest an association with worse prognosis. Possible mechanisms for the release of cardiac troponins T and I in advanced CHF may include the following: ventricular remodeling, presence of coronary artery disease in CHF, abnormalities of coronary microcirculation, and reduced coronary reserve. Further studies will be necessary to elucidate the actual mechanism and determine the clinical significance of cardiac troponins in CHF.

Monitoring of cardiac troponin I in patients with acute heart failure

Cardiac troponin I (cTnI) and creatine kinase MB isoenzyme (CK-MB) were measured in the plasma of 37 patients with acute heart failure. Elevated plasma cTnI concentrations were found in 89% of acute heart failure patients (P < 0.001 compared with a normal population), while plasma CK-MB showed no significant difference (P = 0.09). During follow-up, serial measurements of cTnI and CK-MB were performed. In acute heart failure patients, improvement of the clinical profile was associated with declining cTnI concentrations, while deterioration of heart function was closely related to increasing cTnI. Plasma CK-MB activities remained within the normal range throughout the observation period. This preliminary study provides evidence of cardiac damage to functionally overloaded myocytes. cTnI may be a sensitive marker both for early detection of myocyte damage and for monitoring of function in patients with acute heart failure.

Cardiac compartment-specific overexpression of a modified retinoic acid receptor produces dilated cardiomyopathy and congestive heart failure in transgenic mice

Retinoids play a critical role in cardiac morphogenesis. To examine the effects of excessive retinoid signaling on myocardial development, transgenic mice that overexpress a constitutively active retinoic acid receptor (RAR) controlled by either the alpha- or beta-myosin heavy chain (MyHC) promoter were generated. Animals carrying the alpha-MyHC-RAR transgene expressed RARs in embryonic atria and in adult atria and ventricles, but developed no signs of either malformations or disease. In contrast, beta-MyHC-RAR animals, where expression was activated in fetal ventricles, developed a dilated cardiomyopathy that varied in severity with transgene copy number. Characteristic postmortem lesions included biventricular chamber dilation and left atrial thrombosis; the incidence and severity of these lesions increased with increasing copy number. Transcript analyses showed that molecular markers of hypertrophy, alpha-skeletal actin, atrial natriuretic factor and beta-MyHC, were upregulated. Cardiac performance of transgenic hearts was evaluated using the isolated perfused working heart model as well as in vivo, by transthoracic M-mode echocardiography. Both analyses showed moderate to severe impairment of left ventricular function and reduced cardiac contractility. Thus, expression of a constitutively active RAR in developing atria and/ or in postnatal ventricles is relatively benign, while ventricular expression during gestation can lead to significant cardiac dysfunction.

Determinants of pulmonary hypertension in left ventricular dysfunction

OBJECTIVES

This study sought to analyze the determinants of pulmonary hypertension in patients with left ventricular dysfunction.

BACKGROUND

Pulmonary hypertension in patients with left ventricular dysfunction is a predictor of poor outcome. The independent role of cardiac functional abnormalities in the genesis of pulmonary hypertension is unclear.

METHODS

In 102 consecutive patients with primary left ventricular dysfunction (ejection fraction < 50%), systolic pulmonary artery pressure was prospectively measured by Doppler echocardiography (using tricuspid regurgitant velocity), and left ventricular systolic and diastolic function, functional mitral regurgitation, cardiac output and left atrial volume were quantified.

RESULTS

Systolic pulmonary artery pressure was elevated in patients with left ventricular dysfunction (51 +/- 14 mm Hg [mean +/- SD]), but the range was wide (23 to 87 mm Hg). Of the numerous variables correlating significantly with systolic pulmonary artery pressure, the strongest were mitral deceleration time (r = -0.61, p = 0.0001; odds ratio of pulmonary pressure > or = 50 mm Hg [95% confidence interval] if < 150 ms, 48.8 [14.8 to 161]) and mitral effective regurgitant orifice (r = 0.50, p = 0.0001; odds ratio [95% confidence interval] if > or = 20 mm2, 5.9 [2.3 to 15.5]). In multivariate analysis, these two variables were the strongest predictors of systolic pulmonary artery pressure in association with age (p = 0.005). Ejection fraction or end-systolic volume was not an independent predictor of pulmonary artery pressure.

CONCLUSIONS

Pulmonary hypertension is frequent and highly variable in patients with left ventricular dysfunction. It is not independently related to the degree of left ventricular systolic dysfunction but is strongly associated with diastolic dysfunction (shorter mitral deceleration time) and the degree of functional mitral regurgitation (larger effective regurgitant orifice). These results emphasize the importance of assessing diastolic function and quantifying mitral regurgitation in patients with left ventricular dysfunction.

Causes of congestive heart failure. Prompt diagnosis may affect prognosis

Congestive heart failure (CHF) is a progressive disease with multiple possible causes. Systolic heart failure, defined as contractile failure of the myocardium leading to a reduced ejection fraction, is the most common type. Systolic heart failure may result from coronary artery disease, hypertension, a metabolic disorder, infection, or an infiltrative or other disease, or it may be idiopathic. Recognition of CHF can be difficult, especially in elderly patients with several medical conditions. An early clinical sign may be dyspnea on exertion. The extent of workup needed is often indicated by findings on history taking and physical examination. In all patients suspected of having new-onset CHF, a chest film, an electrocardiogram, and left ventricular ejection fraction should be obtained and a search for complicating and causative factors undertaken. Early treatment may halt the otherwise inevitable decline in cardiac function and improve prognosis.