In patients with an acute myocardial infarction, disrupted circadian rhythms during the initial days in the cardiac intensive care unit, caused by factors such as noise, excessive night-time light and frequent patient–staff interactions, can have devastating effects on cardiac repair and long-term prognosis. Providing care that aligns with the patient’s natural circadian rhythms is critical for optimum long-term recovery. Incorporating ‘circadian medicine’ into clinical practice will provide important health-care benefits.

This chapter presents epidemiologic data on the incidence of myocarditis and dilated cardiomyopathy (DCM) and their associations with enteroviruses. The pathogenesis of enterovirus-induced heart disease is comprehensively reviewed, with particular attention given to experimental studies elucidating the viral and immunologic mechanisms of the disease process. The chapter gives an overview of pathology, and talks about viral replication in the heart, host defense mechanisms, cell-mediated destruction of myofibers, virus participation in chronic heart disease, autoimmunity, viral infection and cardiac dysfunction, and factors affecting disease severity. Next, it reviews the detection of enteroviral infection in patients with myocarditis and DCM. It also describes the clinical features of myocarditis and DCM, and discusses evidence that these diseases are two ends of the same disease spectrum. Finally, the chapter reviews conventional treatments for patients with myocarditis and DCM. In addition, the role of immunosuppression and future avenues of therapy are also examined.

RATIONALE:Patients in intensive care units are disconnected from their natural environment. Synchrony between environmental diurnal rhythms and intracellular circadian rhythms is essential for normal organ biology; disruption causes pathology. Whether disturbing rhythms after myocardial infarction (MI) exacerbates long-term myocardial dysfunction is not known.OBJECTIVE:Short-term diurnal rhythm disruption immediately after MI impairs remodeling and adversely affects long-term cardiac structure and function in a murine model.METHODS AND RESULTS:Mice were infarcted by left anterior descending coronary artery ligation (MI model) within a 3-hour time window, randomized to either a normal diurnal or disrupted environment for 5 days, and then maintained under normal diurnal conditions. Initial infarct size was identical. Short-term diurnal disruption adversely affected body metabolism and altered early innate immune responses. In the first 5 days, crucial for scar formation, there were significant differences in cardiac myeloperoxidase, cytokines, neutrophil, and macrophage infiltration. Homozygous clock mutant mice exhibited altered infiltration after MI, consistent with circadian mechanisms underlying innate immune responses crucial for scar formation. In the proliferative phase, 1 week after MI, this led to significantly less blood vessel formation in the infarct region of disrupted mice; by day 14, echocardiography showed increased left ventricular dilation and infarct expansion. These differences continued to evolve with worse cardiac structure and function by 8 weeks after MI.CONCLUSIONS:Diurnal rhythm disruption immediately after MI impaired healing and exacerbated maladaptive cardiac remodeling. These preclinical findings suggest that disrupted diurnal rhythms such as found in modern intensive care unit environments may adversely affect long-term patient outcome.

There is critical demand in contemporary medicine for gene expression markers in all areas of human disease, for early detection of disease, classification, prognosis, and response to therapy. The integrity of circadian gene expression underlies cardiovascular health and disease; however time-of-day profiling in heart disease has never been examined. We hypothesized that a time-of-day chronomic approach using samples collected across 24-h cycles and analyzed by microarrays and bioinformatics advances contemporary approaches, because it includes sleep-time and/or wake-time molecular responses. As proof of concept, we demonstrate the value of this approach in cardiovascular disease using a murine Transverse Aortic Constriction (TAC) model of pressure overload-induced cardiac hypertrophy in mice. First, microarrays and a novel algorithm termed DeltaGene were used to identify time-of-day differences in gene expression in cardiac hypertrophy 8 wks post-TAC. The top 300 candidates were further analyzed using knowledge-based platforms, paring the list to 20 candidates, which were then validated by real-time polymerase chain reaction (RTPCR). Next, we tested whether the time-of-day gene expression profiles could be indicative of disease progression by comparing the 1- vs. 8-wk TAC. Lastly, since protein expression is functionally relevant, we monitored time-of-day cycling for the analogous cardiac proteins. This approach is generally applicable and can lead to new understanding of disease.

Objectives Our objective was to test the hypothesis that there is a significant diurnal variation for the therapeutic benefit of angiotensin-converting enzyme (ACE) inhibitors on pressure-overload cardiovascular hypertrophy.Background Physiological and molecular processes exhibit diurnal rhythms that may affect efficacy of disease treatment (chronotherapy). Evidence suggests that the heart primarily remodels during sleep. Although a growing body of clinical and epidemiological evidence suggests that the timing of therapy, such as ACE inhibition, alters diurnal blood pressure patterns in patients with hypertension, the benefits of chronotherapy on myocardial and vascular remodeling have not been studied.Methods We examined the effects of the short-acting ACE inhibitor, captopril, on the structure and function of cardiovascular tissue subjected to pressure overload by transverse aortic constriction (TAC) in mice. Captopril (15 mg/kg intraperitoneally) or placebo was administered at either murine sleep time or wake time for 8 weeks starting 1 week after surgery.Results TAC mice given captopril at sleep time had improved cardiac function and significantly decreased heart: body weight ratios, myocyte cross-sectional areas, intramyocardial vascular medial wall thickness, and perivascular collagen versus TAC mice given captopril or placebo during wake time. Captopril induced similar drops in blood pressure at sleep or wake time, suggesting that time-of-day differences were not attributable to blood pressure changes. These beneficial effects of captopril were correlated with diurnal changes in ACE mRNA expression in the heart.Conclusions The ACE inhibitor captopril benefited cardiovascular remodeling only when administered during sleep; wake-time captopril ACE inhibition was identical to that of placebo. These studies support the hypothesis that the heart (and vessels) remodel during sleep time and also illustrate the importance of diurnal timing for some cardiovascular therapies. (J Am Coll Cardiol 2011; 57:2020-8) (C) 2011 by the American College of Cardiology Foundation

Abstract: Diurnal rhythms influence cardiovascular physiology such as heart rate and blood pressure and the incidence of adverse cardiac events such as heart attack and stroke. For example, shift workers and patients with sleep disturbances, such as obstructive sleep apnea, have an increased risk of heart attack, stroke, and sudden death. Diurnal variation is also evident at the molecular level, as gene expression in the heart and blood vessels is remarkably different in the day as compared to the night. Much of the evidence presented here indicates that growth and renewal (structural remodeling) are highly dependent on processes that occur during the subjective night. Myocardial metabolism is also dynamic with substrate preference also differing day from night. The risk/benefit ratio of some therapeutic strategies and the appearance of biomarkers also vary across the 24-hour diurnal cycle. Synchrony between external and internal diurnal rhythms and harmony among the molecular rhythms within the cell is essential for normal organ biology. Cell physiology is 4 dimensional; the substrate and enzymatic components of a given metabolic pathway must be present not only in the right compartmental space within the cell but also at the right time. As a corollary, we show disrupting this integral relationship has devastating effects on cardiovascular, renal and possibly other organ systems. Harmony between our biology and our environment is vital to good health.

Diurnal rhythms influence cardiovascular physiology such as heart rate and blood pressure and the incidence of adverse cardiac events such as heart attack and stroke. For example, shift workers and patients with sleep disturbances, such as obstructive sleep apnea, have an increased risk of heart attack, stroke, and sudden death. Diurnal variation is also evident at the molecular level, as gene expression in the heart and blood vessels is remarkably different in the day as compared to the night. Much of the evidence presented here indicates that growth and renewal (structural remodeling) are highly dependent on processes that occur during the subjective night. Myocardial metabolism is also dynamic with substrate preference also differing day from night. The risk/benefit ratio of some therapeutic strategies and the appearance of biomarkers also vary across the 24-hour diurnal cycle. Synchrony between external and internal diurnal rhythms and harmony among the molecular rhythms within the cell is essential for normal organ biology. Cell physiology is 4 dimensional; the substrate and enzymatic components of a given metabolic pathway must be present not only in the right compartmental space within the cell but also at the right time. As a corollary, we show disrupting this integral relationship has devastating effects on cardiovascular, renal and possibly other organ systems. Harmony between our biology and our environment is vital to good health.

The impact of heart failure and its treatment on specific nutrient requirements is unknown. Furthermore, depletion of water-soluble B vitamins that play key roles in the production of cellular energy in patients with heart failure can contribute to depletion of energy reserves observed in the failing heart. A cross-sectional study recently reported that approximately one third of hospitalized patients with heart failure had tissue levels suggestive of thiamin deficiency (vitamin B-1). Riboflavin (vitamin B-2) and pyridoxine (vitamin B-6) are similar to thiamin in that they are water-soluble, subject to renal excretion, have limited tissue storage, and are dependent on intake. Therefore, it was hypothesized that the status of these B vitamins may also be adversely affected by heart failure. As a result, the prevalence of patients at risk of vitamin B-2 (erythrocyte glutathione reductase activity coefficient > or = 1.2) and B-6 deficiency (plasma B-6 < or = 20 nmol/L) was determined in a cross-section of 100 patients hospitalized with heart failure between April 2001 and June 2002 as well as in a group of volunteers without heart failure. Twenty-seven percent of patients with heart failure had biochemical evidence of vitamin B-2 deficiency, while 38% had evidence of B-6 deficiency. These prevalence rates were significantly higher than those observed in the volunteers without heart failure (2% and 19%, respectively; P < or = 0.02). Use of common B-vitamin-containing supplements by patients with heart failure did not significantly reduce deficiency rates in comparison with those who did not use supplements (B-2 P=0.38 or B-6 P=0.18)). Finally, while 80% of patients with heart failure took diuretics, neither the dose nor the duration of furosemide use was related to the presence of either B-2 or B-6 deficiency. Given the physiologic importance of these vitamins, further investigations aimed at determining the effect of heart failure on specific nutrient requirements as well as the safety and efficacy of B-vitamin supplementation are warranted.

Heart failure (HF) is a common, disabling, and costly disease. Despite major advances in medical therapy, morbidity and mortality remain high, in part because current pharmacological regimens may not fully address some unique requirements of the heart for energy. The heart requires a continuous supply of energy-providing substrates and amino acids in order to maintain its function. In HF, defects in substrate metabolism and cardiac energy and substrate utilization may contribute to contractile dysfunction. HF is often accompanied by a deficiency in key micronutrients required for unimpeded energy transfer. Correcting these deficits has been proposed as a method to limit or even reverse the progressive myocyte dysfunction and/or necrosis in HF. This review summarizes the existing HF literature with respect to supplementation trials of key micronutrients involved in cardiac metabolism: coenzyme Q10, L-carnitine, thiamine, and amino acids, including taurine. Studies using a broader approach to supplementation are also considered. Although some of the results are promising, none are conclusive. There is a need for a prospective trial to examine the effects of micronutrient supplementation on morbidity and mortality in patients with HF. (J Am Coll Cardiol 2009; 54: 1660-73) (c) 2009 by the American College of Cardiology Foundation

Long-term follow-up studies ofpatients withsus- pected viral myocarditis reveal progression todilated cardio- myopathy (DCM)inasignificant numberofcases. Thus, an underlying viral etiology hasbeenhypothesized inthepatho- genesis ofongoing heart disease that leads toDCM.Recent application ofmolecular biology inclinical diagnosis has strengthened this hypothesis. Byuseofprobe hybridization andpolymerase chainreaction, enteroviral RNA hasbeen detected inthemyocardium ofpatients atallstages ofthe disease process: myocarditis, chronic heart disease, andDCM. Acutemyocarditis anditschronic complement, \ dilated cardiomyopathy (DCM),havegone .LXkthrough anevolutionary cycle inconcept. His- torically, itwasrecognized asaviral disease. However, thesubsequent inability toconsistently culture thevirus ortodetect viral antigens andtheimmunologic and pathological resemblance totransplant rejection openedthenexteraoftheautoimmune etiology of myocarditis. Unfortunately, disappointment setinwhen immunemodulation failed toalter thecourse ofthe disease, andsomerecent immunodeficient models chal- lenged theimmunetheory. Withcurrently available molecular techniques, wearenowagain onthethresh- oldofrediscovering therole ofthevirus andelucidating its interaction withtheimmunesystem andthecells of themyocardium. Thepresent review will putinperspec- tiveclinical andexperimental evidence ontheviral etiology ofmyocarditis andDCM.

Sole MJ, Martino TA. Diurnal physiology: core principles with application to the pathogenesis, diagnosis, prevention, and treatment of myocardial hypertrophy and failure. J Appl Physiol 107: 1318-1327, 2009. First published June 25, 2009; doi:10.1152/japplphysiol.00426.2009.-The circadian system has been shown to be fundamentally important in human health and disease. Recently, there have been major advances in our understanding of daily rhythmicity, and its relevance to human physiology, and to the pathogenesis and treatment of cardiac hypertrophy and heart failure. Cardiovascular tissues, such as heart and blood vessels, show remarkable daily variation in gene expression, metabolism, growth, and remodeling. Moreover, synchrony of daily molecular and physiological rhythms is integral to healthy organ growth and renewal. Disruption of these rhythms adversely affects normal growth, also the remodeling mechanisms in disease, leading to gross abnormalities in heart and vessels. These observations provide new insights into the pathogenesis, diagnosis, treatment, and prevention of heart disease. In this review, we focus on the recent advances in circadian biology and cardiovascular function, with particular emphasis on how this applies to human myocardial hypertrophy and heart failure, and the implications and importance for translational medicine.

Heart failure (HF) is a common, disabling, and costly disease. Despite major advances in medical therapy, morbidityand mortality remain high, in part because current pharmacological regimens may not fully address some uniquerequirements of the heart for energy. The heart requires a continuous supply of energy-providing substrates andamino acids in order to maintain its function. In HF, defects in substrate metabolism and cardiac energy and sub-strate utilization may contribute to contractile dysfunction. HF is often accompanied by a deficiency in key micronutri-ents required for unimpeded energy transfer. Correcting these deficits has been proposed as a method to limit oreven reverse the progressive myocyte dysfunction and/or necrosis in HF. This review summarizes the existing HF liter-ature with respect to supplementation trials of key micronutrients involved in cardiac metabolism: coenzyme Q10,

Sleep deprivation, shift work, and jet lag all disrupt normal biological rhythms and have major impacts on health; however, circadian disorganization has never been shown as a causal risk factor in organ disease. We now demonstrate devastating effects of rhythm disorganization on cardiovascular and renal integrity and that interventions based on circadian principles prevent disease pathology caused by a short-period mutation (tau) of the circadian system in hamsters. The point mutation in the circadian regulatory gene, casein kinase-1epsilon, produces early onset circadian entrainment with fragmented patterns of behavior in +/tau heterozygotes. Animals die at a younger age with cardiomyopathy, extensive fibrosis, and severely impaired contractility; they also have severe renal disease with proteinuria, tubular dilation, and cellular apoptosis. On light cycles appropriate for their genotype (22 h), cyclic behavioral patterns are normalized, cardiorenal phenotype is reversed, and hearts and kidneys show normal structure and function. Moreover, hypertrophy does not develop in animals whose suprachiasmatic nucleus was ablated as young adults. Circadian organization therefore is critical for normal health and longevity, whereas chronic global asynchrony is implicated in the etiology of cardiac and renal disease.

Neuroendocrine peptides express biologic activity relevant to the cardiovascular system, including regulating heart rate and blood pressure, though little is known about the mechanisms involved. Here, we investigated neuroendocrine gene expression underlying diurnal physiology of the heart. We first used microarray and RT-PCR analysis and demonstrate the simultaneous expression of neuroendocrine genes in normal murine heart, including POMC, GnRH, neuropeptide Y, leptin receptor, GH-releasing hormone, cocaine- and amphetamine-regulated transcript, proglucagon, and galanin. We examined diurnal gene expression profiles, with cosinar bioinformatics to evaluate statistically significant rhythms. The POMC gene exhibits a day/night, circadian or diurnal, pattern of expression in heart, and we postulated that this may be important to cardiac growth and renewal. POMC diurnal gene rhythmicity is altered in pressure-overload cardiac hypertrophy, when compared with control heart, and levels increased at the dark-to-light transition times. These findings are also consistent with the proposal that neuropeptides mediate adverse remodeling processes, such as occur in pathologic hypertrophy. To investigate cellular responses, we screened three cell lines representing fibroblasts, cardiac myocytes, and vascular smooth muscle cells (NIH3T3, heart line 1, and mouse vascular smooth muscle cell line 1 (Movas-1) respectively). POMC mRNA expression is the most notable in Movas-1 cells and, furthermore, exhibits rhythmicity with culture synchronization. Taken together, these results highlight the diverse neuroendocrine mRNA expression profiles in cardiovasculature, and provide a novel model vascular culture system to research the role these neuropeptides play in organ health, integrity, and disease.

The circadian system in mammals is a hierarchy of oscillators throughout the organism that are coordinated by the circadian clock in the hypothalamic suprachiasmatic nucleus. Peripheral clocks act to integrate time-of-day information from neural or hormonal signals, regulating gene expression, and, subsequently, organ physiology. However, the mechanisms by which the central clock communicates with peripheral oscillators are not understood and are likely tissue specific. In this study, we establish a mouse vascular cell model suitable for investigations of these mechanisms at a molecular level. Using the immortalized vascular smooth muscle cell line Movas-1, we determined that these cells express the circadian clock machinery with robust rhythms in mRNA expression over a 36-h period after serum shock synchronization. Furthermore, norepinephrine and forskolin were able to synchronize circadian rhythms in bmal1. With synchronization, we observed cycling of specific genes, including the tissue inhibitor of metalloproteinase 1 and 3 (timp1, timp3), collagen 3a1 (col3a1), transgelin 1 (sm22alpha), and calponin 1 (cnn1). Diurnal expression of these genes was also found in vivo in mouse aortic tissue, using microarray and real-time RT-PCR analysis. Both of these revealed ultradian rhythms in genes similar to the cycling observed in Movas-1 in vitro. These findings highlight the cyclical nature of structurally important genes in the vasculature that is similar both in vivo and in vitro. This study establishes the Movas-1 cells as a novel cell model from which to further investigate the molecular mechanisms of clock regulation in the vasculature.

Day/night rhythms are recognized as important to normal cardiovascular physiology and timing of adverse cardiovascular events; however, their significance in disease has not been determined. We demonstrate that day/night rhythms play a critical role in compensatory remodeling of cardiovascular tissue, and disruption exacerbates disease pathophysiology. We use a murine model of pressure overload cardiac hypertrophy (transverse aortic constriction) in a rhythm-disruptive 20-hour versus 24-hour environment. Echocardiography reveals increased left ventricular end-systolic and -diastolic dimensions and reduced contractility in rhythm-disturbed transverse aortic constriction animals. Furthermore, cardiomyocytes and vascular smooth muscle cells exhibit reduced hypertrophy, despite increased pressure load. Microarray and real-time PCR demonstrate altered gene cycling in transverse aortic constriction myocardium and hypothalamic suprachiasmatic nucleus. With rhythm disturbance, there is a consequent altered cellular clock mechanism (per2 and bmal), whereas key genes in hypertrophic pathways (ANF, BNP, ACE, and collagen) are downregulated paradoxical to the increased pressure. Phenotypic rescue, including reversal/attenuation of abnormal pathology and genes, only occurs when the external rhythm is allowed to correspond with the animals’ innate 24-hour internal rhythm. Our study establishes the importance of diurnal rhythm as a vital determinant in heart disease. Disrupted rhythms contribute to progression of organ dysfunction; restoration of normal diurnal schedules appears to be important for effective treatment of disease.

Molecular gene cycling is useful for determining body time of day (BTOD) with important applications in personalized medicine, including cardiovascular disease and cancer, our leading causes of death. However, it impractically requires repetitive invasive tissue sampling that is obviously not applicable for humans. Here we characterize diurnal protein cycling in blood using high-throughput proteomics; blood proteins are easily accessible, minimally invasive, and can importantly serve as surrogates for what is happening elsewhere in the body in health and disease. As proof of the concept, we used normal C57BL/6 mice maintained under regular 24-h light and dark cycles. First, we demonstrated fingerprint patterns in 24-h plasma, revealed using surface-enhanced laser desorption and ionization (SELDI). Second, we characterized diurnal cycling proteins in blood using chromatography and tandem electrospray ionization mass spectrometry. Importantly, we noted little association between the cycling blood proteome and tissue transcriptome, delineating the necessity to identify de novo cycling proteins in blood for measuring BTOD. Furthermore, we explored known interaction networks to identify putative functional pathways regulating protein expression patterns in blood, thus shedding new light on our understanding of integrative physiology. These studies have profound clinical significance in translating the concept of BTOD to the practical realm for molecular diagnostics and open new opportunities for clinically relevant discoveries when applied to ELISA-based molecular testing and/or point-of-care devices.

Congestive heart failure has emerged as a major health problem during the past four decades (Bourassa et al., 1993). In spite of our advances, the underlying heart disease is relentlessly progressive in almost all patients who develop symptoms of overt failure, and mortality continues to be unacceptably high—approx 40% in 5 yr (Bourassa et al., 1993). Heart transplantation appears to be the only prospect to improve long-term survival for many patients.