Microvascular spasm in the cardiomyopathic Syrian hamster: a preventable cause of focal myocardial necrosis

Coronary Artery Spasm-Related Heart Failure Syndrome: Literature Review

Although heart failure (HF) is a clinical syndrome that becomes worse over time, certain cases can be reversed with appropriate treatments. While coronary artery spasm (CAS) is still underappreciated and may be misdiagnosed, ischemia due to coronary artery disease and CAS is becoming the single most frequent cause of HF worldwide. CAS could lead to syncope, HF, arrhythmias, and myocardial ischemic syndromes such as asymptomatic ischemia, rest and/or effort angina, myocardial infarction, and sudden death. Albeit the clinical significance of asymptomatic CAS has been undervalued, affected individuals compared with those with classic Heberden's angina pectoris are at higher risk of syncope, life-threatening arrhythmias, and sudden death. As a result, a prompt diagnosis implements appropriate treatment strategies, which have significant life-changing consequences to prevent CAS-related complications, such as HF. Although an accurate diagnosis depends mainly on coronary angiography and provocative testing, clinical characteristics may help decision-making. Because the majority of CAS-related HF (CASHF) patients present with less severe phenotypes than overt HF, it underscores the importance of understanding risk factors correlated with CAS to prevent the future burden of HF. This narrative literature review summarises and discusses separately the epidemiology, clinical features, pathophysiology, and management of patients with CASHF.

Prognostic value of summed motion score assessed by gated SPECT myocardial perfusion imaging in patients with dilated cardiomyopathy

Background

The prognosis of patients with dilated cardiomyopathy (DCM) is poor and new indicators are urgently needed to predict lethal cardiac events. This study aimed to investigate the value of summed motion score (SMS) in predicting cardiac death of DCM patients using gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI).

Methods and results

Eighty-one patients with DCM who underwent 99mTc-MIBI gated SPECT MPI were retrospectively enrolled and were divided into cardiac death and survivor groups. The functional parameters of left ventricle including SMS were measured using quantitative gated SPECT software. During the follow-up period of 44 (25, 54) months, 14 (17.28%) cardiac deaths were observed. Compared with the survivor group, SMS was significantly higher in the cardiac death group. Multivariate cox regression analysis showed that SMS was an independent predictor for cardiac death (HR 1.34, 95% CI 1.02–1.77, P = 0.034). SMS also provided incremental prognostic value over other variables in the multivariate model as determined by likelihood ratio global chi-squared test. In the Kaplan-Meier survival analysis, the event-free survival rate was significantly lower in the high-SMS (HSMS) group than the low-SMS (LSMS) (log-rank P < 0.001). Furthermore, the area under curve (AUC) of SMS was larger than that of LVEF at the 12th month of follow-up (0.85 vs. 0.80, P = 0.045).

Conclusion

SMS is an independent predictor of cardiac death in DCM patients and provides incremental prognostic value. SMS might have higher predictive value than LVEF for early cardiac death.

Hypotension in hereditary cardiomyopathy

It is well accepted that hypertension may lead to the development of heart failure (HF). However, little is known about the development of hypotension that may contribute to the onset of hereditary cardiomyopathy (HCM), thus promoting heart failure and early death. The purpose of this study is to verify whether a decrease in blood pressure takes place during different phases of HCM (asymptomatic, necrosis, hypertrophy, and heart failure). Using the well-known animal model, the UM-X7.1 hamster strain of HCM (HCMH), our results showed the absence of a change in mean arterial pressure (MAP) during the asymptomatic phase preceding the development of necrosis in HCMHs when compared to age-matched normal hamster (NH). However, there was a progressive decrease in MAP that reached its lowest level during the heart failure phase. The MAP during the development of the necrosis phase of HCM was accompanied by a significant increase in the level of the sodium-hydrogen exchanger, NHE1. Treatments with the potent NHE1 inhibitor, EMD 87580 (rimeporide), did not affect MAP of NH. However, treatments with EMD 87580 during the three phases of the development of HCM significantly reversed the hypotension associated with HCM.Our results showed that the development of HCM is associated with hypotension. These results suggest that a decrease in blood pressure could be a biomarker signal for HCM leading to HF and early death. Since the blockade of NHE1 significantly but partially prevented the reduction in MAP, this suggests that other mechanisms can contribute to the development of hypotension in HCM.

Clinical trial in a dish using iPSCs shows lovastatin improves endothelial dysfunction and cellular cross-talk in LMNA cardiomyopathy

Mutations in LMNA, the gene that encodes lamin A and C, causes LMNA-related dilated cardiomyopathy (DCM) or cardiolaminopathy. LMNA is expressed in endothelial cells (ECs); however, little is known about the EC-specific phenotype of LMNA-related DCM. Here, we studied a family affected by DCM due to a frameshift variant in LMNA Human induced pluripotent stem cell (iPSC)-derived ECs were generated from patients with LMNA-related DCM and phenotypically characterized. Patients with LMNA-related DCM exhibited clinical endothelial dysfunction, and their iPSC-ECs showed decreased functionality as seen by impaired angiogenesis and nitric oxide (NO) production. Moreover, genome-edited isogenic iPSC lines recapitulated the EC disease phenotype in which LMNA-corrected iPSC-ECs showed restoration of EC function. Simultaneous profiling of chromatin accessibility and gene expression dynamics by combining assay for transposase-accessible chromatin using sequencing (ATAC-seq) and RNA sequencing (RNA-seq) as well as loss-of-function studies identified Krüppel-like factor 2 (KLF2) as a potential transcription factor responsible for the EC dysfunction. Gain-of-function studies showed that treatment of LMNA iPSC-ECs with KLF2 agonists, including lovastatin, rescued the EC dysfunction. Patients with LMNA-related DCM treated with lovastatin showed improvements in clinical endothelial dysfunction as indicated by increased reactive hyperemia index. Furthermore, iPSC-derived cardiomyocytes (iPSC-CMs) from patients exhibiting the DCM phenotype showed improvement in CM function when cocultured with iPSC-ECs and lovastatin. These results suggest that impaired cross-talk between ECs and CMs can contribute to the pathogenesis of LMNA-related DCM, and statin may be an effective therapy for vascular dysfunction in patients with cardiolaminopathy.

Myocardial Ischemic Syndromes, Heart Failure Syndromes, Electrocardiographic Abnormalities, Arrhythmic Syndromes and Angiographic Diagnosis of Coronary Artery Spasm: Literature Review

In coronary artery spasm (CAS), an excess coronary vasoconstriction causing total or subtotal vessel occlusion could lead to syncope, heart failure syndromes, arrhythmic syndromes, and myocardial ischemic syndromes including asymptomatic myocardial ischemia, stable and unstable angina, acute myocardial infarction, and sudden cardiac death. Although the clinical significance of CAS has been underrated because of the frequent absence of symptoms, affected patients appear to be at higher risk of syncope, serious arrhythmias, and sudden death than those with classic Heberden's angina pectoris. Therefore, a prompt diagnosis has important therapeutic implications, and is needed to avoid CAS-related complications. While a definitive diagnosis is based mainly on coronary angiography and provocative testing, clinical features may help guide decision-making. We perform a literature review to assess the past and current state of knowledge regarding the clinical features, electrocardiographic abnormalities and angiographic diagnosis of CAS, while a discussion of mechanisms is beyond the scope of this review.

IL-1β reduces cardiac lymphatic muscle contraction via COX-2 and PGE2 induction: Potential role in myocarditis

The role of lymphatic vessels in myocarditis is largely unknown, while it has been shown to play a key role in other inflammatory diseases. We aimed to investigate the role of lymphatic vessels in myocarditis using in vivo model induced with Theiler's murine encephalomyelitis virus (TMEV) and in vitro model with rat cardiac lymphatic muscle cells (RCLMC). In the TMEV model, we found that upregulation of a set of inflammatory mediator genes, including interleukin (IL)-1β, tumor necrosis factor (TNF)-αand COX-2 were associated with disease activity. Thus, using in vitro collagen gel contraction assays, we decided to clarify the role(s) of these mediators by testing contractility of RCLMC in response to IL-1β and TNF-α individually and in combination, in the presence or absence of: IL-1 receptor antagonist (Anakinra); cyclooxygenase (COX) inhibitors inhibitors (TFAP, diclofenac and DuP-697). IL-1β impaired RCLMC contractility dose-dependently, while co-incubation with both IL-1β and TNF-α exhibited synergistic effects in decreasing RCLMC contractility with increased COX-2 expression. Anakinra maintained RCLMC contractility; Anakinra blocked the mobilization of COX-2 induced by IL-1β with or without TNF-α. COX-2 inhibition blocked the IL-1β-mediated decrease in RCLMC contractility. Mechanistically, we found that IL-1β increased prostaglandin (PG) E₂ release dose-dependently, while Anakinra blocked IL-1β mediated PGE₂ release. Using prostaglandin E receptor 4 (EP4) receptor antagonist, we demonstrated that EP4 receptor blockade maintained RCLMC contractility following IL-1β exposure. Our results indicate that IL-1β reduces RCLMC contractility via COX-2/PGE₂ signaling with synergistic cooperation by TNF-α. These pathways may help provoke inflammatory mediator accumulation within the heart, driving progression from acute myocarditis into dilated cardiomyopathy.

Sarcospan Regulates Cardiac Isoproterenol Response and Prevents Duchenne Muscular Dystrophy-Associated Cardiomyopathy

Background

Duchenne muscular dystrophy is a fatal cardiac and skeletal muscle disease resulting from mutations in the dystrophin gene. We have previously demonstrated that a dystrophin‐associated protein, sarcospan (SSPN), ameliorated Duchenne muscular dystrophy skeletal muscle degeneration by activating compensatory pathways that regulate muscle cell adhesion (laminin‐binding) to the extracellular matrix. Conversely, loss of SSPN destabilized skeletal muscle adhesion, hampered muscle regeneration, and reduced force properties. Given the importance of SSPN to skeletal muscle, we investigated the consequences of SSPN ablation in cardiac muscle and determined whether overexpression of SSPN into mdx mice ameliorates cardiac disease symptoms associated with Duchenne muscular dystrophy cardiomyopathy.

Methods and Results

SSPN‐null mice exhibited cardiac enlargement, exacerbated cardiomyocyte hypertrophy, and increased fibrosis in response to β‐adrenergic challenge (isoproterenol; 0.8 mg/day per 2 weeks). Biochemical analysis of SSPN‐null cardiac muscle revealed reduced sarcolemma localization of many proteins with a known role in cardiomyopathy pathogenesis: dystrophin, the sarcoglycans (α‐, δ‐, and γ‐subunits), and β1D integrin. Transgenic overexpression of SSPN in Duchenne muscular dystrophy mice (mdx^TG) improved cardiomyofiber cell adhesion, sarcolemma integrity, cardiac functional parameters, as well as increased expression of compensatory transmembrane proteins that mediate attachment to the extracellular matrix.

Conclusions

SSPN regulates sarcolemmal expression of laminin‐binding complexes that are critical to cardiac muscle function and protects against transient and chronic injury, including inherited cardiomyopathy.

Pathogenesis of chronic Chagas' myocarditis: An overview

The evidence provided by both human and animal studies on chronic Chagas' heart disease suggests that the development of the chronic fibrosing myocarditis is related to progressive and additive focal cellular necrosis with associated inflammatory lymphomononuclear infiltrate, reactive and reparative myocardial fibrosis, surrounding myocyte hypertrophy. These processes may be initiated and perpetuated by alterations in the myocardial microcirculation and by autoimmune factors. These findings could foster future therapeutic strategies in the management of chronic chagasic patients to optimize the medical treatment and hopefully to improve prognosis.

Protective effects of aspirin from cardiac hypertrophy and oxidative stress in cardiomyopathic hamsters

Objective. To evaluate the capacity of chronic ASA therapy to prevent cardiac alterations and increased oxidative stress in cardiomyopathic hamsters. Methods and Results. Male Syrian cardiomyopathic and age-matched inbred control hamsters received ASA orally from the age of 60 days. Animals were sacrificed at the age of 150, 250, and 350 days to evaluate the time course of cardiac hypertrophy and cardiovascular tissue superoxide anion (O₂⁻) production. At the age of 150 days, the ventricular weight over body weight ratio, resting heart rate, and cardiovascular O₂⁻ production were much higher in cardiomyopathic hamsters than those in control. At the age of 250 days, in addition to the continual deterioration of these parameters with age, the blood pressure started to fall and the signs of heart failure appeared. In these cardiomyopathic hamsters, chronic ASA treatment (a) completely prevented elevated O₂⁻ production and the NAD(P)H oxidase activity, (b) significantly slowed down the development of the cardiac hypertrophy and fibrosis. Conclusions. Chronic ASA treatment significantly prevents the deterioration of cardiac function and structure as well as the increased oxidative stress in the cardiomyopathic hamster. Our findings suggest that ASA presents a therapeutic potential to prevent cardiac dysfunction.

δ-Sarcoglycan-deficient muscular dystrophy: from discovery to therapeutic approaches

Mutations in the δ-sarcoglycan gene cause limb-girdle muscular dystrophy 2F (LGMD2F), an autosomal recessive disease that causes progressive weakness and wasting of the proximal limb muscles and often has cardiac involvement. Here we review the clinical implications of LGMD2F and discuss the current understanding of the putative mechanisms underlying its pathogenesis. Preclinical research has benefited enormously from various animal models of δ-sarcoglycan deficiency, which have helped researchers to explore therapeutic approaches for both muscular dystrophy and cardiomyopathy.

Effect of Waon therapy on oxidative stress in chronic heart failure

BACKGROUND

A previous report by our team showed that Waon therapy, using a far infrared-ray dry sauna at 60°C, improves cardiac and vascular function in patients with chronic heart failure (CHF). The purpose of the present study was to clarify the effect of Waon therapy on oxidative stress in CHF patients and investigate its mechanism by animal experiments.

METHODS AND RESULTS

Forty patients with CHF were divided into control (n=20) and Waon therapy (n=20) groups. All patients received standard optimal medications for CHF. Waon therapy group was treated with Waon therapy daily for 4 weeks. After 4 weeks of Waon therapy, concentrations of hydroperoxide and brain natriuretic peptide (BNP) decreased significantly (hydroperoxide, 422±116 to 327±88U.CARR, P<0.001; BNP, 402±221 to 225±137pg/ml, P<0.001), and the nitric oxide metabolites increased (71.2±35.4 to 92.0±40.5mmol/L, P<0.05). In contrast, none of these variables changed over the 4-week interval in the control group. Furthermore, animal experiments were performed using TO-2 cardiomyopathic hamsters. On immunohistochemistry, cardiac expression of 4-hydroxy-2-nonenal, a marker of oxidative stress, was decreased in the 4-week Waon therapy compared to untreated hamsters. On Western blotting, cardiac expressions of heat shock protein (HSP) 27, manganese superoxide dismutase and HSP32, which reduce oxidative stress, were significantly upregulated in the 4-week Waon therapy compared to untreated hamsters.

CONCLUSIONS

Waon therapy decreases oxidative stress in patients and hamsters with heart failure.

Coronary microvascular disease in chronic Chagas cardiomyopathy including an overview on history, pathology, and other proposed pathogenic mechanisms

This review focuses on the short and bewildered history of Brazilian scientist Carlos Chagas's discovery and subsequent developments, the anatomopathological features of chronic Chagas cardiomyopathy (CCC), an overview on the controversies surrounding theories concerning its pathogenesis, and studies that support the microvascular hypothesis to further explain the pathological features and clinical course of CCC. It is our belief that knowledge of this particular and remarkable cardiomyopathy will shed light not only on the microvascular involvement of its pathogenesis, but also on the pathogenetic processes of other cardiomyopathies, which will hopefully provide a better understanding of the various changes that may lead to an end-stage heart disease with similar features. This review is written to celebrate the 100th anniversary of the discovery of Chagas disease.

Hemodynamic alterations in the coronary circulation of cardiomyopathic hamsters: age and Ang II-dependent mechanisms

BACKGROUND

Coronary vasospasms have been reported in the early stages of cardiomyopathy in the Syrian cardiomyopathic hamster (CM; BIO-TO2 strain). It has been proposed these alterations could lead to ischemic heart disease and heart failure. However, the cause of these coronary abnormalities has not been established. In this study, we evaluated coronary hemodynamic to assess the role of Ang-II, reactive oxygen species, and nitric oxide (NO) in the development of these alterations in CM of 1, 2, and 6 months of age.

METHODS AND RESULTS

Excised hearts from control (CT) and CM were retroperfused with Krebs-Ringer bicarbonate solution (KRB), and coronary resistance (CR) was determined. The experimental protocol involved sequential infusions of the thromboxane analog U46619 (THX, 0.1micromol/L), bradykinin (BKN, 10micromol/L), and sodium nitroprusside (SNP, 10micromol/L). Similar experiments were conducted after treatment of hearts with N(omega)-nitro-L-arginine methyl ester (L-NAME, 10micromol/L). Basal CR increased with age, but no significant differences were observed between CT and CM. Reactivity to THX was increased (69%, P < .05) in 2-month-old CM when compared with CT. This effect was observed concomitantly with a significant reduction (53%, P < .05) in BKN-induced relaxation. The reduction in BKN-dependent relaxation was prevented by treatment for 1 month with the antioxidant N-acetylcysteine (1 g.kg.day), or losartan, an Ang II type 1 receptor blocker (10 mg.kg.day). Losartan also prevented the THX-induced increased reactivity in 2-month-old CM. The BKN-induced relaxation occurred through an L-NAME-sensitive pathway that was impaired with age. SNP dilation was preserved in all animal groups.

CONCLUSIONS

Our results strongly implicate vascular renin-angiotensin-system (RAS) and oxidative stress in endothelial dysfunction and increased reactivity in the early stages of cardiomyopathy in CM. These findings could be relevant to understand the etiology of cardiovascular disorders, in particular, in patients with sarcoglycanopathies.

Mutation of delta-sarcoglycan is associated with Ca(2+) -dependent vascular remodeling in the Syrian hamster

We examined whether mutation of the delta-sarcoglycan gene, which causes dilated cardiomyopathy, also alters the vascular smooth muscle cell (VSMC) phenotype and arterial function in the Syrian hamster CHF 147. Thoracic aorta media thickness showed marked variability in diseased hamsters with zones of atrophy and hypertrophied segments. CHF-147 VSMCs displayed a proliferating/"synthetic" phenotype characterized by the absence of the smooth muscle myosin heavy chain SM2, dystrophin, and Ca(2+)-handling proteins, and the presence of cyclin D1. In freshly isolated VSMCs from CHF 147 hamsters, voltage-independent basal Ca(2+) channels showed enhanced activity similar to that in proliferating wild-type (WT) cells. The transcription factor NFAT (nuclear factor of activated T cells) was spontaneously active in freshly isolated CHF 147 VSMCs, as in proliferating VSMCs from WT hamsters. Mibefradil inhibited B-type channels, NFAT activity, and VSMC proliferation. CHF 147 hamsters had abundant apoptotic cells distributed in patches along the aorta, and clusters of inactive mitochondria were observed in 25% of isolated CHF 147 cells, whereas no such clusters were seen in WT cells. In conclusion, mutation of the delta-sarcoglycan gene increases plasma membrane permeability to Ca(2+), activates the Ca(2+)-regulated transcription factor NFAT, and leads to spontaneous mitochondrial aggregation, causing abnormal VSMC proliferation and apoptosis.

New approaches in the therapy of cardiomyopathy in muscular dystrophy

Cardiomyopathy is a frequent occurrence in muscular dystrophy, and heart disease in muscular dystrophy can contribute to both morbidity and mortality. A number of novel therapies are being developed for muscular dystrophy, and the efficacy of these therapies for heart disease is unknown. The most common X-linked recessive disease is Duchenne muscular dystrophy (DMD), which arises from defects in the dystrophin gene. Therapy specifically aimed at DMD is reviewed in the context of its projected effect on cardiomyopathy associated with DMD. Additionally, novel therapies are being pursued to treat specifically the cardiomyopathy of DMD. There is substantial genetic heterogeneity underlying the muscular dystrophies, and not all muscular dystrophy patients develop cardiomyopathy. A subset of muscular dystrophies may place patients at significantly greater risk of developing cardiomyopathy and cardiac rhythm disturbances. These disorders are discussed, highlighting recent studies and recommendations for therapy.

Differential myolysis of myocardium and skeletal muscle in hamsters with dilated cardiomyopathy: beneficial protective effect of diltiazem

BACKGROUND

Although dilated cardiomyopathic hamsters (TO-2) with mutation of the delta-sarcoglycan gene exhibit histological features of muscular dystrophy, it remains to be elucidated whether both myocardium and skeletal muscle are injured in a similar manner.

METHODS AND RESULTS

The progression of myolysis in both myocardium and skeletal muscle were assessed biochemically and pathologically in TO-2 and F1B control hamsters. Left ventricular (LV) function was assessed by echocardiography and cardiac catheterization. Both the plasma concentration of cardiac troponin T and the plasma activity of alpha-hydroxybutyrate dehydrogenase (HBD) peaked at 8 weeks of age, and thereafter reduced greatly in TO-2 hamsters. Activity of creatine kinase (CK) in TO-2 hamsters was significantly greater than in controls throughout the observation period. Pathological findings of both nuclear chain and central nuclei in skeletal muscles were observed in TO-2 hamsters throughout the observation period, suggesting regeneration. LV dysfunction was first evident at 8 weeks of age and deteriorated thereafter in TO-2 hamsters. Treatment of TO-2 hamsters with diltiazem from 5 to 8 weeks of age could avert the LV functional deterioration and the increment in alpha-HBD activity, but CK activity was unchanged.

CONCLUSIONS

Despite myolysis in skeletal muscle occurring consistently throughout the observation period, cardiac myolysis occurred predominantly in the early phase. These initial cardiac events might involve coronary spasm and/or calcium overload in the myocardium.

Micronutrients and their supplementation in chronic cardiac failure. An update beyond theoretical perspectives

Physicians' use of micronutrients to improve symptoms or outcomes in chronic illness has until recently been guided by limited data on the actions of individual agents in vitro or in animal studies. However several recently published clinical trials have provided information about which groups of patients are likely to benefit from which combination of micronutrients. Patients with chronic cardiac failure (CCF), particularly elderly individuals, have several reasons to be deficient in micronutrients including reduced intake, impaired gastrointestinal absorption and increased losses on the background of increased utilisation due for example to increased oxidative stress. Studies of nutritional supplementation in CCF patients have usually concentrated on specific agents. However given that many micronutrients have synergistic influences upon metabolic processes this strategy might merely lead to a shifting of a limiting step. Rather, a strategy of increasing the availability of multiple agents at once might be more logical. The aim of this article is to briefly review the experimental rationale for each of the micronutrients of potential benefit in chronic heart failure and examine the current clinical trial evidence supporting their use.

Myocardium-targeted delivery of endothelial progenitor cells by ultrasound-mediated microbubble destruction improves cardiac function via an angiogenic response

Application of ultrasound-mediated destruction of microbubbles (US + Bubble) to skeletal muscle creates capillary ruptures leading to leakage of the cell components. We studied whether US + Bubble combined with bone-marrow-derived mononuclear cells (BM-MNCs) infusion enables the targeted delivery of endothelial-lineage cells into the myocardium and improves cardiac function of the cardiomyopathy model due to the paucity of neocapillary formation. Pulsed US was applied to the anterior chest of BIOTO2 cardiomyopathy hamsters for 90 s after the intravenous injection of microbubble (Optison) followed by infusion of BM-MNCs. Cardiac samples from US + microbubble + BM-MNCs (US + Bubble + BM), US + Bubble, US + BM without Bubble, and saline infusion control groups were analyzed 12 weeks after treatment. Labeled BM-MNCs transplanted by US + Bubble were found to be mainly localized in the microvessels, but not by US stimulation without microbubble (121.2 +/- 24.5 vs. 2.80 +/- 1.30 cells/mm2, P < 0.001). Capillary densities in US + Bubble + BM group were increased 1.7-fold (P < 0.05) over the control, and neither US + Bubble nor US + BM enhanced neocapillary formation. 99mTc-Tetrofosmin scintigraphy revealed that blood perfusion area in the US + Bubble + BM group was 48% greater than the control (P < 0.01). US + Bubble stimulation induces the expression of adhesion molecules (VCAM-1 and ICAM-1) in capillaries, and the US + Bubble-mediated supply of BM-MNCs increased the myocardial content of VEGF and bFGF. The left ventricular wt/body wt, area of cardiac fibrosis, and apoptotic cell numbers in the US + Bubble + BM group significantly (P < 0.05) decreased by 82%, 73%, and 64% relative to the control, respectively. The cardiac function in myopathic hamsters (assessed by fractional shortening) was markedly improved 36% (P < 0.05) by US + Bubble + BM treatment. Targeted delivery of BM-MNCs by US + Bubble to the myocardium of the cardiomyopathic hamster increased the capillary densities and regional blood flow and inhibited cardiac remodeling, resulting in the prevention of heart failure. This non-invasive cell delivery system may be useful as a novel efficient approach for angiogenic cell therapy to the myocardium.

Assessment of left ventricular function and volumes for patients with dilated cardiomyopathy using gated myocardial perfusion SPECT and comparison with echocardiography

AIM

Left ventricular function, volumes and regional wall motion provide valuable diagnostic information and are of long-term prognostic importance in patients with dilated cardiomyopathy (DCM). This study was designed to compare the effectiveness of two-dimensional echocardiography and gated single photon emission computed tomography (SPECT) to evaluate these parameters in patients with DCM.

METHODS

Gated SPECT and two-dimensional echocardiography were performed in 45 patients with DCM, and in 10 normal subjects as the control group. Patients were divided into two groups according to the aetiology of DCM: group I, ischaemic DCM (n=30); group II, non-ischaemic DCM (n=15). All patients and the control group underwent resting myocardial gated SPECT, 45 min after injection of 555 MBq of Tc-methoxyisobutyl-isonitrile (Tc-MIBI). Gated SPECT data, including left ventricular volumes and left ventricular ejection fraction (LVEF), were processed using an automated algorithm. Simpson's method was used to evaluate these parameters. Regional wall motion was evaluated using both modalities and scored using a 16-segment model with a five-point scoring system. Perfusion defects were expressed as a percentage of the whole myocardium planimetered by a bull's-eye polar map of composite non-gated SPECT. Myocardial perfusion was scored using a 16-segment model with a four-point scoring system.

RESULTS

Mean perfusion defects and perfusion defect scores were 25+/-13% and 1.12+/-0.36 in group I and 4+/-8% and 0.76+/-0.26 in group II (P<0.01). The overall agreement between the two imaging modalities for the assessment of regional wall motion was 57% (403/720 segments: 269/480 segments in group I and 134/240 segments in group II). With gated SPECT, LVEF was 27+/-9%, the end-diastolic volume (EDV) was 212+/-71 ml and the end-systolic volume (ESV) was 160+/-67 ml. With echocardiography, these values were 29+/-8%, 197+/-56 ml and 139+/-47 ml, respectively. The correlation between gated SPECT and two-dimensional echocardiography was good (r=0.72, P<0.01) for the assessment of LVEF. The correlation was also good for EDV and ESV, but with wider limits of agreement (r= 0.71, P<0.01 and r=0.71, P<0.01, respectively) and with significantly higher values with gated SPECT (P<0.01). For patients with a perfusion defect of <20% or low myocardial perfusion scores, a higher correlation was found between the two methods for the assessment of LVEF, EDV and ESV. On the other hand, the correlation was lower for the assessment of wall motion.

CONCLUSIONS

Gated SPECT and two-dimensional echocardiography correlate well for the assessment of left ventricular function and volumes. Gated SPECT has the advantage of providing information about left ventricular function, dimensions and perfusion.

A novel paradigm for therapeutic basis of advanced heart failure--assessment by gene therapy

The precise mechanism(s) of the progression of advanced heart failure (HF) should be determined to establish strategies for its treatment or prevention. Based on pathological, molecular, and physiological findings in 3 animal models and human cases, we propose a novel scheme that a vicious cycle formed by increased sarcolemma (SL) permeability, preferential activation of calpain over calpastatin, and translocation and cleavage of dystrophin (Dys) commonly lead to advanced HF. The aim of this article was to assess our recent paradigm that disruption of myocardial Dys is a final common pathway to advanced HF, irrespective of its hereditary or acquired origin, but not intended to provide a comprehensive overview of the various factors that may be involved in the course of HF in different clinical settings. In addition, each component of Dys-associated proteins (DAP) was heterogeneously degraded in vivo and in vitro, i.e. Dys and alpha-sarcoglycan (SG) were markedly destroyed using isolated calpain 2, while delta-SG was not degraded at all. The up-regulation of calpain 2 was confirmed through previously published data that remain insufficient for precise evaluation, supporting our new scheme that the activation of calpain(s) is involved in the steady process of Dys cleavage. In addition, somatic gene therapy is discussed as a potential option to ameliorate the physiological/metabolic indices and to improve the prognosis.

Oscillatory transient inward currents in ventricular myocytes of healthy versus myopathic Syrian hamster

The present experiments were performed in order to study abnormal action potential configuration and ion channel activity in ventricular myocytes obtained from 23 male myopathic Syrian hamsters (Biobreeders strain 14.6, 32-52 weeks old) compared with 10 age-matched healthy control hamsters (Biobreeders F1B) by means of whole-cell patch-clamp techniques. The results show that the myopathic myocytes had a longer action potential duration, a reduced transient outward K(+) current on depolarization and a smaller transient inward current on repolarization after prolonged depolarizing pulses (> 500 msec). However, the L-type Ca(2+) current and the inwardly rectifing K(+) current were not significantly different from those of healthy myocytes. The oscillatory transient inward currents could be diminished by treatment with ryanodine (0.01-1 micromol/L), a sarcoplasmic reticulum (SR) Ca(2+) release channel blocker, or with Na(+)-free superfusate. We conclude that the hereditary myopathic hamsters are less likely to develop delayed after depolarization-related transient inward currents and triggered arrhythmias owing to a smaller SR Ca(2+) content.

Transplanted hematopoietic stem cells demonstrate impaired sarcoglycan expression after engraftment into cardiac and skeletal muscle

Pluripotent bone marrow-derived side population (BM-SP) stem cells have been shown to repopulate the hematopoietic system and to contribute to skeletal and cardiac muscle regeneration after transplantation. We tested BM-SP cells for their ability to regenerate heart and skeletal muscle using a model of cardiomyopathy and muscular dystrophy that lacks delta-sarcoglycan. The absence of delta-sarcoglycan produces microinfarcts in heart and skeletal muscle that should recruit regenerative stem cells. Additionally, sarcoglycan expression after transplantation should mark successful stem cell maturation into cardiac and skeletal muscle lineages. BM-SP cells from normal male mice were transplanted into female delta-sarcoglycan-null mice. We detected engraftment of donor-derived stem cells into skeletal muscle, with the majority of donor-derived cells incorporated within myofibers. In the heart, donor-derived nuclei were detected inside cardiomyocytes. Skeletal muscle myofibers containing donor-derived nuclei generally failed to express sarcoglycan, with only 2 sarcoglycan-positive fibers detected in the quadriceps muscle from all 14 mice analyzed. Moreover, all cardiomyocytes with donor-derived nuclei were sarcoglycan-negative. The absence of sarcoglycan expression in cardiomyocytes and skeletal myofibers after transplantation indicates impaired differentiation and/or maturation of bone marrow-derived stem cells. The inability of BM-SP cells to express this protein severely limits their utility for cardiac and skeletal muscle regeneration.

Serial alterations of beta-adrenergic signaling in dilated cardiomyopathic hamsters: possible role of myocardial oxidative stress

BACKGROUND

The relationship between enhanced myocardial oxidative stress and impaired beta-adrenergic signaling remains to be characterized during the development of dilated cardiomyopathy.

METHODS AND RESULTS

Alterations in myocardial oxidative stress and beta-adrenergic signaling, as well as left ventricular (LV) functional and structural changes, were evaluated during the development of cardiomyopathy in TO-2 hamsters; F1B hamsters served as controls. LV dysfunction was first apparent at 8 weeks of age and deteriorated thereafter in the TO-2 hamsters. At 32 weeks, the animals exhibited heart failure with an increased plasma norepinephrine concentration. Cardiac myolysis, as demonstrated by elevated plasma concentration of cardiac troponin T, peaked at 8 weeks. The glutathione redox ratio revealed increased oxidative stress in the LV myocardium in TO-2 hamsters even at 4 weeks and became manifest after 8 weeks. The hearts of TO-2 hamsters had significantly reduced superoxide dismutase activity from 8 weeks onward compared with control hamsters. However, glutathione peroxidase activity was unchanged at any time point. The LV functional response to isoproterenol was markedly reduced at 8 weeks, without any apparent changes in the amount of beta-adrenergic signaling molecules, and it deteriorated thereafter. Adenylyl cyclase activity was significantly decreased, despite increased amounts of both G(s) alpha mRNA and protein, in the LV myocardium at 18 weeks.

CONCLUSIONS

Myocardial oxidative stress is actually enhanced in the initial development of LV dysfunction. Both activation of myocardial oxidative stress and impairment of beta-adrenergic signaling become prominent at the stage of severe LV dysfunction. Myocardial oxidative stress may be involved in the development of beta-adrenergic desensitization.

Myocardial blood flow in patients with dilated cardiomyopathy: Quantitative assessment with velocity-encoded cine magnetic resonance imaging of the coronary sinus

PURPOSE

To quantify global myocardial perfusion using magnetic resonance imaging (MRI) in patients with heart failure due to idiopathic dilated cardiomyopathy (IDC) and to compare myocardial perfusion and microvascular reactivity with healthy subjects.

MATERIALS AND METHODS

A total of 19 subjects (healthy volunteers (N = 12) and IDC patients (N = 7)) were studied using cine MRI to measure left ventricular (LV) mass and a velocity-encoded cine MRI technique to measure coronary sinus flow at rest and after dipyridamole-induced hyperemia. Absolute values of total myocardial blood flow (MBF) were calculated from coronary sinus flow and LV mass.

RESULTS

At baseline, MBF was not significantly different in patients with IDC (0.48 +/- 0.07 mL/minute/g) and healthy subjects (0.55 +/- 0.19 mL/minute/g, P= 0.41). After dipyridamole administration, MBF in IDC patients increased to a level significantly less than that in normal volunteers (1.05 +/- 0.35 mL/minute/g vs. 1.99 +/- 1.05 mL/minute/g, P < 0.05). Consequently, MBF reserve was impaired in patients with IDC (2.19 +/- 0.77) compared to that in healthy subjects (3.51 +/- 1.29, P < 0.05). A moderate correlation was found between MBF reserve and LV ejection fraction (r = 0.48, P < 0.05).

CONCLUSION

MBF reserve is reduced in patients with IDC, indicating that coronary microcirculatory flow is impaired. This integrated MRI approach allows quantitative measurement of global MBF in humans and may have the potential to study the effects of pharmacological interventions on myocardial perfusion.

Repeated Sauna Therapy Increases Arterial Endothelial Nitric Oxide Synthase Expression and Nitric Oxide Production in Cardiomyopathic Hamsters

BACKGROUND

Vascular endothelial dysfunction is involved in the pathophysiology of chronic heart failure (CHF). It has been reported that sauna therapy, which allows thermal vasodilation, improves vascular endothelial dysfunction in patients with CHF. The present study investigates the mechanisms through which sauna therapy improves endothelial dysfunction induced by CHF.

METHODS AND RESULTS

Normal control and male TO-2 cardiomyopathic hamsters were used. Thirty-week-old TO-2 hamsters were treated daily with an experimental far infrared-ray dry sauna system for 15 min at 39 degrees C followed by 20 min at 30 degrees C. This procedure raised the rectal temperatures by about 1 degrees C. Arterial endothelial nitric oxide (NO) synthase (eNOS) mRNA and protein expressions were examined, and serum concentrations of nitrate were measured. The expression of eNOS mRNA in the aortas of normal controls did not change, whereas those of the TO-2 hamsters decreased with age. Four weeks of sauna therapy significantly increased eNOS mRNA expression in the aortas of TO-2 hamsters compared with those that did not undergo sauna therapy. Sauna therapy also upregulated aortic eNOS protein expression. Serum nitrate concentrations of the TO-2 hamsters were increased by 4 weeks of sauna therapy compared with those that did not undergo sauna.

CONCLUSION

Repeated sauna therapy increases eNOS expression and NO production in cardiomyopathic hamsters with heart failure.

Molecular and cell biology of the sarcoglycan complex

The original sarcoglycan (SG) complex has four subunits and comprises a subcomplex of the dystrophin-dystrophin-associated protein complex. Each SG gene has been shown to be responsible for limb-girdle muscular dystrophy, called sarcoglycanopathy (SGP). In this review, we detail the characteristics of the SG subunits, and the mechanism of the formation of the SG complex and various molecules associated with this complex. We discuss the molecular mechanisms of SGP based on studies mostly using SGP animal models. In addition, we describe other SG molecules, epsilon- and zeta-SGs, with special reference to their expression and roles in vascular smooth muscle, which are currently in dispute. We further consider the maternally imprinted nature of the epsilon-SG gene. Finally, we stress that the SG complex cannot work by itself and works in a larger complex system, called the transverse fixation system, which forms an array of molecules responsible for various muscular dystrophies.

Effect of left ventricular assist device combination therapy on myocardial blood flow in patients with end-stage dilated cardiomyopathy

BACKGROUND

Changes in myocardial blood flow (MBF) and coronary flow reserve (CFR) are independent prognostic risk factors in idiopathic dilated cardiomyopathy (DCM). The aim of this study was to assess the impact of left ventricular unloading using left ventricular assist device (LVAD) combination therapy on resting MBF and CFR in patients with end-stage heart disease.

METHODS

We studied 11 patients with deteriorating end-stage DCM (New York Heart Association Class 4) treated with LVAD support combined with pharmacologic therapy in a recovery program. Absolute MBF was measured using oxygen-15-labeled water (H(2)(15)O) positron emission tomography (PET) at rest during LVAD support and 15 minutes after the LVAD was switched off. Data were corrected for rate pressure product (RPP) when appropriate. Hyperemic MBF (intravenous adenosine, 140 mug/kg . min) was also measured in 6 patients with the LVAD switched off. CFR was calculated as the ratio MBF adenosine/MBF LVAD off (corrected). Data are expressed as mean +/- SD.

RESULTS

At 317 +/- 193 days after device implantation, resting MBF was 0.95 +/- 0.29 (LVAD on) and 1.46 +/- 0.62 (LVAD off, corrected) ml/min . g (p = 0.01). MBF (LVAD on) was comparable with that of 11 age- and gender-matched normal controls (1.09 +/- 0.22 ml/min . g). CFR in the LVAD group was 1.49 +/- 0.99 compared with 3.56 +/- 1.42 in normal controls (p < 0.01).

CONCLUSIONS

During LVAD support, resting MBF (LVAD on) was comparable to MBF in normal controls and increased when the LVAD was switched off. However, CFR was significantly impaired, even though all patients studied showed varying degrees of myocardial recovery. The implications of these findings, particularly in the long term, require further study.

Smooth muscle cell-extrinsic vascular spasm arises from cardiomyocyte degeneration in sarcoglycan-deficient cardiomyopathy

Vascular spasm is a poorly understood but critical biomedical process because it can acutely reduce blood supply and tissue oxygenation. Cardiomyopathy in mice lacking gamma-sarcoglycan or delta-sarcoglycan is characterized by focal damage. In the heart, sarcoglycan gene mutations produce regional defects in membrane permeability and focal degeneration, and it was hypothesized that vascular spasm was responsible for this focal necrosis. Supporting this notion, vascular spasm was noted in coronary arteries, and disruption of the sarcoglycan complex was observed in vascular smooth muscle providing a molecular mechanism for spasm. Using a transgene rescue strategy in the background of sarcoglycan-null mice, we replaced cardiomyocyte sarcoglycan expression. Cardiomyocyte-specific sarcoglycan expression was sufficient to correct cardiac focal degeneration. Intriguingly, successful restoration of the cardiomyocyte sarcoglycan complex also eliminated coronary artery vascular spasm, while restoration of smooth muscle sarcoglycan in the background of sarcoglycan-null alleles did not. This mechanism, whereby tissue damage leads to vascular spasm, can be partially corrected by NO synthase inhibitors. Therefore, we propose that cytokine release from damaged cardiomyocytes can feed back to produce vascular spasm. Moreover, vascular spasm feeds forward to produce additional cardiac damage.

Coxsackievirus B3 infection compromises endothelial-dependent vasodilation of coronary resistance arteries

The mechanisms of coronary artery dysfunction in coxsackievirus B3 (CVB3)-mediated viral myocarditis are poorly understood. We used pressure myography of mouse septal coronary arteries to determine the early and late effects of CVB3 infection on vascular function. Male CD-1 mice (age 6-7 weeks) were infected with CVB3 (1.75 x 10(10) pfu, i.p.). Control mice were injected with PBS. Mice were killed at 3, 7, and 42 days post infection, and the ventricular septal artery was dissected and mounted on a pressure myograph. Pressure-induced myogenic tone was similar in CVB3-infected and sham-infected mice at 3 and 7 days post infection. However, at 42 days post infection constriction of septal arteries to pressures equal to or less than 60 mm Hg was enhanced in CVB3-infected mice compared with sham controls. Agonist-induced vasodilation, as assessed by response to acetylcholine (1 nM-3 microM), was unaltered at early time points (days 3 and 7) in CVB3-infected mice. At later time points (day 42), there was a significant decrease in ACh-induced vasodilation in CVB3-infected mice. Bosentan, an ET-1 (ETA and ETB) receptor antagonist, did not completely ameliorate the reduced ACh-induced vasodilation in 42-day infected mice, indicating that ET-1 does not contribute to vascular dysfunction. Smooth muscle function, as measured by constriction to KCl or dilation to sodium nitroprusside, was unchanged in infected mice at early and late time points. Immunohistochemistry and ET-1 immunoassay were then performed to assess ET-1 levels in CVB3- and sham-infected hearts. There were no differences in ET-1 protein localization or levels at 42 days post infection in sham- and CVB3-infected animals. Finally, in situ hybridization and TUNEL staining were performed to assess viral localization and cell death in CVB3-infected hearts. There was no detectable CVB3 or TUNEL positivity in the endothelium of coronary arteries. Therefore, late impairment of endothelial-dependent vasorelaxation of coronary resistance vessels in CVB3-induced myocarditis does not appear to involve altered ET-1 expression but may be secondary to decreased stimulated NO secretion by the endothelium.

Smooth muscle cell-extrinsic vascular spasm arises from cardiomyocyte degeneration in sarcoglycan-deficient cardiomyopathy

Vascular spasm is a poorly understood but critical biomedical process because it can acutely reduce blood supply and tissue oxygenation. Cardiomyopathy in mice lacking gamma-sarcoglycan or delta-sarcoglycan is characterized by focal damage. In the heart, sarcoglycan gene mutations produce regional defects in membrane permeability and focal degeneration, and it was hypothesized that vascular spasm was responsible for this focal necrosis. Supporting this notion, vascular spasm was noted in coronary arteries, and disruption of the sarcoglycan complex was observed in vascular smooth muscle providing a molecular mechanism for spasm. Using a transgene rescue strategy in the background of sarcoglycan-null mice, we replaced cardiomyocyte sarcoglycan expression. Cardiomyocyte-specific sarcoglycan expression was sufficient to correct cardiac focal degeneration. Intriguingly, successful restoration of the cardiomyocyte sarcoglycan complex also eliminated coronary artery vascular spasm, while restoration of smooth muscle sarcoglycan in the background of sarcoglycan-null alleles did not. This mechanism, whereby tissue damage leads to vascular spasm, can be partially corrected by NO synthase inhibitors. Therefore, we propose that cytokine release from damaged cardiomyocytes can feed back to produce vascular spasm. Moreover, vascular spasm feeds forward to produce additional cardiac damage.

The oxygen stress index and levels of circulating interleukin-10 and interleukin-6 in patients with chronic heart failure

OBJECTIVES

We sought to study circulating levels of pro- and anti-inflammatory cytokines together with the oxygen stress index in patients with chronic heart failure (CHF).

BACKGROUND

Patients with CHF exhibit elevated levels of inflammatory and anti-inflammatory cytokines but the relative level of these cytokines with the oxygen stress index have not been reported.

METHODS

Twenty-two patients with CHF and 10 control subjects were studied. Plasma levels of IL-6 and IL-10 were determined and the oxygen stress index was evaluated by urine 8-iso-PGF2alpha estimations.

RESULTS

Plasma levels of IL-6 and IL-10 in CHF patients were significantly higher than those observed in the control subjects. Patients with more advanced disease (higher NYHA class) showed higher concentrations of IL-10 and IL-6 than those with less serious disease. 8-iso-PGF2alpha urine concentration (and therefore the oxygen stress index) was significantly higher in patients with CHF in comparison with control subjects. IL-6 plasma levels, but not IL-10 concentrations, correlated significantly with 8-iso-PGF2alpha levels in urine.

CONCLUSIONS

Inflammatory and anti-inflammatory cytokine levels, as well as the oxidative stress index, are increased in patients with chronic heart failure. Inflammatory cytokine IL-6, but not anti-inflammatory cytokine Il-10, levels correlated significantly with the oxygen stress index.

Secondary coronary artery vasospasm promotes cardiomyopathy progression

Genetic defects in the plasma membrane-associated sarcoglycan complex produce cardiomyopathy characterized by focal degeneration. The infarct-like pattern of cardiac degeneration has led to the hypothesis that coronary artery vasospasm underlies cardiomyopathy in this disorder. We evaluated the coronary vasculature of gamma-sarcoglycan mutant mice and found microvascular filling defects consistent with arterial vasospasm. However, the vascular smooth muscle sarcoglycan complex was intact in the coronary arteries of gamma-sarcoglycan hearts with perturbation of the sarcoglycan complex only within the adjacent myocytes. Thus, in this model, coronary artery vasospasm derives from a vascular smooth muscle-cell extrinsic process. To reduce this secondary vasospasm, we treated gamma-sarcoglycan-deficient mice with the calcium channel antagonist verapamil. Verapamil treatment eliminated evidence of vasospasm and ameliorated histological and functional evidence of cardiomyopathic progression. Echocardiography of verapamil-treated, gamma-sarcoglycan-null mice showed an improvement in left ventricular fractional shortening (44.3 +/- 13.3% treated versus 37.4 +/- 15.3% untreated), maximal velocity at the aortic outflow tract (114.9 +/- 27.9 cm/second versus 92.8 +/- 22.7 cm/second), and cardiac index (1.06 +/- 0.30 ml/minute/g versus 0.67 +/- 0.16 ml/minute/g, P < 0.05). These data indicate that secondary vasospasm contributes to the development of cardiomyopathy and is an important therapeutic target to limit cardiomyopathy progression.

A nitric oxide‐releasing derivative of enalapril, NCX 899, prevents progressive cardiac dysfunction and remodeling in hamsters with heart failure

Nitric oxide (NO) production is known to be impaired in heart failure. A new compound (NCX 899), a NO-releasing derivative of enalapril was characterized, and its actions were evaluated in Bio 14.6 cardiomyopathic (CM) hamsters with heart failure. The hamsters were randomized to oral treatment for 4 weeks with vehicle (n=11), NCX 899 (NCX, 25 mg/kg, n=10), or enalapril (25 mg/kg, n=10). In the vehicle group, fractional shortening by echocardiography decreased (-23.6+/-2.0%) and LV end-diastolic dimension) increased (+10.9+/-1.0%), whereas fractional shortening increased (+17.5+/-4.4%) in NCX and was unchanged in the enalapril group (both P<0.01 vs. vehicle). End-diastolic dimension decreased only in NCX. LV contractility (LVdP/dt max and Emax) was significantly greater in NCX than in enalapril or vehicle, while relaxation (Tau) was shortened in both NCX and enalapril vs. vehicle. ACE activity was inhibited equally by NCX and enalapril in the CM hamster, and plasma nitrate levels were increased only in NCX (P<0.05 vs. enalapril and vehicle). In aortic strips endothelium-independent relaxation occurred only with NCX. The superior effects of NO-releasing enalapril (NCX) vs. enalapril alone to enhance vascular effects, increase LV contractility and prevent unfavorable remodeling and are consistent with vascular delivery of exogenous NO. NCX 899 may hold promise for the future treatment of heart failure.

Abnormal coronary microvascular endothelial function in humans with asymptomatic left ventricular dysfunction

BACKGROUND

Coronary endothelial dysfunction may potentially lead to myocardial ischemia and to the progression of heart failure. Though endothelial dysfunction is associated with advanced heart failure in humans, relatively little is known regarding their temporal relationship. Thus, the current study was designed to test the hypothesis that coronary endothelial dysfunction is present in patients with asymptomatic left ventricular dysfunction.

METHODS AND RESULTS

Three hundred patients without symptoms of heart failure, with normal or mildly diseased coronary arteries at angiography underwent coronary vascular reactivity evaluation using intracoronary adenosine, acetylcholine (ACH) and nitroglycerin. Patients were divided into 2 groups based on the left ventricular ejection fraction (EF): patients with asymptomatic left ventricular dysfunction (ALVD), EF <45% (n = 11); and patients with EF > or =45% (n = 289, controls). Except for a lower high-density lipoprotein level in patients with ALVD, there were no significant differences between the groups in regards to conventional cardiovascular risk factors. There was no difference in the change (mean +/- SE) in epicardial diameter in response to ACH (-21.7% +/- 7.2% vs -13.8% +/- 1.5%, P =.3). The change in coronary blood flow in response to ACH was significantly attenuated in the patients with ALVD when compared to the controls (-18.5% +/- 14.9% vs 74.0% +/- 7.2%, P <.013). By multivariate analysis, EF was an independent predictor of coronary microvascular dilation with ACH (P <.001).

CONCLUSION

The current study demonstrates that coronary microvascular endothelial dysfunction is present in ALVD. Thus, coronary endothelial dysfunction may be an early event in the pathophysiology of heart failure.

Effects of first and second generation calcium channel blockers on diastolic function of the failing hamster heart: relationship with coronary flow changes

Calcium channel blockers (CCBs) have variable efficacy in the treatment of heart failure. We hypothesized that modulation of left ventricular diastolic pressure (LVDP) may play a role in the variable efficacy of CCBs in this condition. Isolated perfused hearts from 200- to 250-day-old UM-X7.1 cardiomyopathic hamsters (failing hearts) and age-matched Syrian hamsters (normal hearts) were studied. After recording of heart rate, coronary flow (CF), LVDP and left ventricular systolic pressure (LVSP), hearts were exposed either to verapamil or diltiazem (1 nM-10 microM), mibefradil (1 nM-1 microM) or clentiazem (1 nM-10 microM). Mechanical increase in CF (+2 to +10 ml/min) was carried out using a roller pump. Mechanically-augmented flow led to an increase in coronary perfusion pressure (+40 to +90 mm Hg), LVSP (+5 to +40 mm Hg) and LVDP (+5 to +25 mm Hg). CCBs-induced increment of coronary flow led to a difference in their cardiac response. In normal hearts, the negative inotropic response was more important with diltiazem and verapamil. Failing hearts did not demonstrate increased inotropic sensitivity to first-generation CCBs. On the contrary, at clinically relevant concentrations, verapamil resulted in the most pronounced impairment of LVDP followed by diltiazem while mibefradil and clentiazem, at clinically relevant concentrations, preserved LVDP. Such findings provide an additional explanation for the variable efficacy of CCBs in heart failure.

Risks versus Benefits of NSAIDs Including Aspirin in Myocarditis

NSAIDs, including aspirin (acetylsalicylic acid), are frequently used and effective in a broad variety of inflammatory diseases, i.e. rheumatic carditis and pericarditis. Myocarditis may constitute another suitable indication for NSAIDs in order to relieve the symptoms of the presumed viral infection or because pericardial effusion is often associated with this condition. However, concerns have been raised about their indiscriminate use in myocarditis. To clarify this issue, we conducted a systematic review of the literature concerning myocarditis, aspirin and NSAIDs. We examined five animal studies of NSAIDs (indomethacin and ibuprofen) and aspirin in coxsackievirus B3- and B4-induced myocarditis. These studies indicated a deleterious effect of NSAIDs and aspirin in this setting, demonstrating a 2- to 3-fold increase in inflammation, myocytes necrosis and even mortality when compared with placebo. This possible deleterious effect was more predominant when NSAIDs or aspirin were administered during the acute and subacute phases of myocarditis; however, it was still noted when NSAIDs were administered during the late phase of the disease (the effect of aspirin was not evaluated in late phase studies). According to these animal studies, such effect might be attributed to decreased viral clearance (possibly via interferon inhibition) and/or exaggerated cytotoxic response (via interleukin-2 or inhibition of suppressor cells factors) and/or coronary artery spasm. We found one animal study looking at autoimmune myocarditis and it did not demonstrate any beneficial or detrimental effect of aspirin. Moreover, recent data suggest that aspirin and NSAIDs may counteract part of the efficacy of ACE inhibitors and be deleterious in chronic heart failure. Taken together, these studies point to a possible deleterious effect of aspirin and NSAIDs in human myocarditis. In view of these animal studies and in the absence of controlled studies of aspirin or NSAIDs in human myocarditis, we do not recommend indiscriminate treatment with NSAIDs or high-dose aspirin in patients with myocarditis where there is no or minimal associated pericarditis.

Cardiac endothelial-myocardial signaling: its role in cardiac growth, contractile performance, and rhythmicity

Experimental work during the past 15 years has demonstrated that endothelial cells in the heart play an obligatory role in regulating and maintaining cardiac function, in particular, at the endocardium and in the myocardial capillaries where endothelial cells directly interact with adjacent cardiomyocytes. The emerging field of targeted gene manipulation has led to the contention that cardiac endothelial-cardiomyocytal interaction is a prerequisite for normal cardiac development and growth. Some of the molecular mechanisms and cellular signals governing this interaction, such as neuregulin, vascular endothelial growth factor, and angiopoietin, continue to maintain phenotype and survival of cardiomyocytes in the adult heart. Cardiac endothelial cells, like vascular endothelial cells, also express and release a variety of auto- and paracrine agents, such as nitric oxide, endothelin, prostaglandin I(2), and angiotensin II, which directly influence cardiac metabolism, growth, contractile performance, and rhythmicity of the adult heart. The synthesis, secretion, and, most importantly, the activities of these endothelium-derived substances in the heart are closely linked, interrelated, and interactive. It may therefore be simplistic to try and define their properties independently from one another. Moreover, in relation specifically to the endocardial endothelium, an active transendothelial physicochemical gradient for various ions, or blood-heart barrier, has been demonstrated. Linkage of this blood-heart barrier to the various other endothelium-mediated signaling pathways or to the putative vascular endothelium-derived hyperpolarizing factors remains to be determined. At the early stages of cardiac failure, all major cardiovascular risk factors may cause cardiac endothelial activation as an adaptive response often followed by cardiac endothelial dysfunction. Because of the interdependency of all endothelial signaling pathways, activation or disturbance of any will necessarily affect the others leading to a disturbance of their normal balance, leading to further progression of cardiac failure.

Altered microvasculature is involved in remodeling processes in cardiomyopathic hamsters

The cardiomyopathic hamster (BIO TO2) is a well-established model of heart failure. Deterioration of cardiac function in BIO TO2 is attributed to a defect in delta-sarcoglycan, whereas cardiac dysfunction in delta-sarcoglycan knockout mice is caused by microvascular abnormalities. We examined the relation between cardiac function and the microvasculature, including angiogenic factors, in BIO TO2.

METHODS AND RESULTS

At the age of 5 weeks, percent fractional shortening (%FS) and positive rate of change in left ventricular pressure over time (dP/dt max) were lower in BIO TO2 than in age-matched F1B controls. Capillary density, capillary/myocyte (CM) ratio, capillary domain area (CDA), and myocyte density were similar between BIO TO2 and F1B controls. At the ages of 13 and 20 weeks, BIO had significantly lower capillary and myocyte densities and a significantly higher CM ratio and CDA. Myocyte density positively correlated with %FS and dP/dt max. There were no significant differences in mRNA expression for VEGF, Flt-1, angiopoietin-1, or angiopoietin-2 between BIO TO2 and F1B control.

CONCLUSION

Progressive myocyte loss is responsible for deterioration of cardiac function in BIO TO2. The impaired neovascularization may be involved in the progress of cardiac remodeling in cardiomyopathic hamsters.

Caveolin-3 knock-out mice develop a progressive cardiomyopathy and show hyperactivation of the p42/44 MAPK cascade

A growing body of evidence suggests that muscle cell caveolae may function as specialized membrane micro-domains in which the dystrophin-glycoprotein complex and cellular signaling molecules reside. Caveolin-3 (Cav-3) is the only caveolin family member expressed in striated muscle cell types (cardiac and skeletal). Interestingly, skeletal muscle fibers from Cav-3 (-/-) knock-out mice show a number of myopathic changes, consistent with a mild-to-moderate muscular dystrophy phenotype. However, it remains unknown whether a loss of Cav-3 affects the phenotypic behavior cardiac myocytes in vivo. Here, we present a detailed characterization of the hearts of Cav-3 knock-out mice. We show that these mice develop a progressive cardiomyopathic phenotype. At four months of age, Cav-3 knock-out hearts display significant hypertrophy, dilation, and reduced fractional shortening, as revealed by gated cardiac MRI and transthoracic echocardiography. Histological analysis reveals marked cardiac myocyte hypertrophy, with accompanying cellular infiltrates and progressive interstitial/peri-vascular fibrosis. Interestingly, loss of Cav-3 expression in the heart does not change the expression or the membrane association of the dystrophin-glycoprotein (DG) complex. However, a marker of the DG complex, alpha-sarcoglycan, was specifically excluded from lipid raft domains in the absence of Cav-3. Because activation of the Ras-p42/44 MAPK pathway in cardiac myocytes can drive cardiac hypertrophy, we next assessed the activation state of this pathway using a phospho-specific antibody probe. We show that p42/44 MAPK (ERK1/2) is hyperactivated in hearts derived from Cav-3 knock-out mice. These results are consistent with previous in vitro data demonstrating that caveolins may function as negative regulators of the p42/44 MAPK cascade. Taken together, our data argue that loss of Cav-3 expression is sufficient to induce a molecular program leading to cardiac myocyte hypertrophy and cardiomyopathy.

Long-term combined therapy with an angiotensin type I receptor blocker and an angiotensin converting enzyme inhibitor prolongs survival in dilated cardiomyopathy

The efficacy of ACE inhibitors (ACEIs) in the treatment of chronic heart failures is well documented. However, ACEIs may provide incomplete blockade of the renin-angiotensin system (RAS) because of the alternative pathways for angiotensin II (All) production. We hypothesized that more complete blockade of RAS by adding an AT1 receptor blocker (ARB) may have greater potential to decrease mortality associated with heart failure and improve cardiac function than monotherapy with ACEIs. The objective of this study was to evaluate the effect of combined therapy on cardiac functions and survival in cardiomyopathic hamsters. Male cardiomyopathic hamsters (BIO TO2) were administered either placebo (group C), enalapril (30 mg/kg/day) (group E), or enalapril (30 mg/kg/day) + valsartan (500 mg/ kg/day) (group EV), starting at the age of 6 weeks. Kaplan-Meier analysis was performed to assess the differences in survival. Cardiac functions were evaluated by echocardiogram and cardiac catheterization. Group EV showed significant increases in fractional shortening, LV dP/dTmax, and deceleration time, and showed significant decreases in left ventricular diastolic dimension, LV dP/dTmin, and early diastolic mitral velocity/atrial systolic velocity. Treatment with enalapril resulted in longer survival compared with placebo. Moreover, life expectancy (median probability of survival: 433 days) increased significantly in group EV compared with group E (P<0.05) as well as group C (P<0.001). It is concluded that combined therapy improved cardiac function and survival compared to placebo or enalapril monotherapy.

Nutritional abnormalities contributing to cachexia in chronic illness

Cachexia is a common consequence of chronic illness. The nutritional abnormalities contributing to the clinical picture are often a composite of reduced appetite, dietary factors including protein, energy and micronutrient intake, malabsorption and increased consumption or loss of nutrients. In this article, using chronic heart failure as an example, we have reviewed the potential influences of chronic disease on each of these and how they might lead to the relentless progression of wasting and the poor prognosis associated with it.