Influenza A1 myocarditis in conscripts

Influenza vaccination and risk of atrial fibrillation in patients with gout: A nationwide population-based cohort study

Objective: Although influenza vaccination reduces the risk of atrial fibrillation (AF), its protective effect in patients with gout remains unclear. The present study aimed to evaluate the protective effect of influenza vaccination in patients with gout.

Methods: A total of 26,243 patients with gout, aged 55 and older, were enrolled from the National Health Insurance Research Database (NHIRD) between 1 January 2001, and 31 December 2012. The patients were divided into vaccinated (n = 13,201) and unvaccinated groups (n = 13,042). After adjusting comorbidities, medications, sociodemographic characteristics, the risk of AF during follow-up period was analyzed.

Results: In influenza, non-influenza seasons and all seasons, the risk of AF was significantly lower in vaccinated than in unvaccinated patients (Adjust hazard ratio [aHR]: 0.59, 95% confidence interval [CI]: 0.50–0.68; aHR: 0.50, 95% CI: 0.42–0.63; aHR: 0.55, 95% CI: 0.49–0.62, respectively). In addition, the risk of AF significantly decreased with increased influenza vaccination (aHR: 0.85, 95% CI: 0.69–1.04; aHR: 0.72, 95% CI: 0.60–0.87; aHR: 0.40, 95% CI: 0.33–0.49, after first, 2–3 times, and ≥4 times of vaccination, respectively). Furthermore, sensitivity analysis indicated that the risk of AF significantly decreased after influenza vaccination for patients with different sexes, medication histories, and comorbidities.

Conclusions: Influenza vaccination is associated with a lower risk of AF in patients with gout. This potentially protective effect seems to depend on the dose administered.

Influenza virus replication in cardiomyocytes drives heart dysfunction and fibrosis

Cardiac dysfunction is a common complication of severe influenza virus infection, but whether this occurs due to direct infection of cardiac tissue or indirectly through systemic lung inflammation remains unclear. To test the etiology of this aspect of influenza disease, we generated a novel recombinant heart-attenuated influenza virus via genome incorporation of target sequences for miRNAs expressed in cardiomyocytes. Compared with control virus, mice infected with miR-targeted virus had significantly reduced heart viral titers, confirming cardiac attenuation of viral replication. However, this virus was fully replicative in the lungs and induced similar systemic inflammation and weight loss compared to control virus. The miR-targeted virus induced fewer cardiac conduction irregularities and significantly less fibrosis in mice lacking interferon-induced transmembrane protein 3 (IFITM3), which serve as a model for influenza-associated cardiac pathology. We conclude that robust virus replication in the heart is required for pathology, even when lung inflammation is severe.

Influenza Vaccination and the Risk of Ventricular Arrhythmias in Patients With Chronic Obstructive Pulmonary Disease: A Population-Based Longitudinal Study

Backgrounds: Influenza vaccination could decrease the risk of major cardiac events in patients with chronic obstructive pulmonary disease (COPD). However, the effects of the vaccine on decreasing the risk of ventricular arrhythmia (VA) development in such patients remain unclear. Methods: We retrospectively analyzed the data of 18,658 patients with COPD (≥55 years old) from the National Health Insurance Research Database from January 1, 2001, to December 31, 2012. After a 1:1 propensity score matching by the year of diagnosis, we divided the patients into vaccinated and unvaccinated groups. Time-varying Cox proportional hazards regression was applied to assess the time to event hazards of influenza vaccination exposure. Results: The risk of VA occurrence was significantly lower in the vaccinated group during influenza season and all seasons [adjusted hazard ratio (aHR): 0.62, 95% CI: 0.41-0.95; aHR: 0.69, 95% CI: 0.44-1.08; and aHR: 0.65, 95% CI: 0.48-0.89, in the influenza season, non-influenza season, and all seasons, respectively]. Among patients with CHA₂DS₂-VASc scores (conditions and characteristics included congestive heart failure, hypertension, diabetes, stroke, vascular disease, age, and sex) of 2-3, receiving one time and two to three times of influenza vaccination were associated with lower risk of VA occurrence in all seasons (aHR: 0.28, 95% CI: 0.10-0.80; aHR: 0.27, 95% CI: 0.10-0.68, respectively). Among patients without stroke, peripheral vascular disease, and diabetes, a lower risk of VA occurrence after receiving one and two to three times vaccination was observed in all seasons. Among patients with a history of asthma and patients without a history of heart failure, ischemic heart disease, angina hypertension, or renal failure, a significantly lower risk of VA occurrence was observed after the first time of vaccination in all seasons. Conclusions: Influenza vaccination may be associated with lower risks of VA among patients with COPD aged 55-74. Further investigation is still needed to resolve this clinical question.

Association of influenza infection and vaccination with cardiac biomarkers and left ventricular ejection fraction in patients with acute myocardial infarction

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We examined the association of influenza infection and vaccination with cardiac biomarkers and LVEF .

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Mean and median CK-MB levels were significantly higher among unvaccinated cases .

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Large size infarcts were more frequent in influenza positive cases and less frequent in vaccinated cases.

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Influenza vaccine may have a protective effect against large infarcts .

Aims

The aim of this study was to examine the association of influenza infection and vaccination with extent of cardiac damage during acute myocardial infarctions (AMIs) as measured by serum biomarkers and left ventricular ejection function (LVEF) in patients.

Methods

Post-hoc analysis was performed on data from a prospective case-control study of influenza and AMI, conducted in a tertiary care hospital in Sydney, Australia. We included 275 cases of AMI, aged ≥ 40 years admitted to the cardiology during the study period.

Results

Mean and median CK-MB levels were significantly higher among unvaccinated group compared to vaccinated group (p value < 0.05). Troponin levels were also higher among unvaccinated group compared to vaccinated group; although not statistically significant. Troponin and CKMB values were not statistically different among influenza positive cases and influenza negative cases. Large size infarcts were less frequent among vaccinated cases compared to unvaccinated cases (25% vs 35.5%) and were more frequent among influenza positive cases compared to influenza negative cases (35.3% vs 31.5%), however differences were not statistically significant. LVEF was lower among vaccinated cases compared to unvaccinated cases (62.5% vs. 52.8%) and influenza positive cases compared to influenza negative cases (58.8% vs 55.4), however differences were not significant.

Conclusion

Lower CKMB levels among vaccinated groups showed that influenza vaccine may have a protective effect against large infarcts, therefore influenza vaccination should be recommended for high risk groups. The study suggests an association of larger infarcts with influenza infection, but larger studies are required to confirm this.

Diminished immune responses with aging predispose older adults to common and uncommon influenza complications

Influenza (flu) is a serious disease for older adults, with increased severity of infection and greater risk for hospitalization and death. Flu infection is limited to pulmonary epithelial cells, yet there are many systemic symptoms and older adults are more susceptible to flu-related complications. In older adults, flu rarely comes without additional complications and there is a perfect storm for enhanced disease due to multiple factors including existing co-morbidities, plus impaired lung function and dysregulated immune responses that occur with even healthy aging. Commonly, opportunistic secondary bacterial infections prosper in damaged lungs. Intensified systemic inflammation with aging can cause dysfunction in extra-pulmonary organs and tissues such as cardiovascular, musculoskeletal, neuropathologic, hepatic, and renal complications. Often overlooked is the underappreciated connections between many of these conditions, which exacerbate one another when in parallel. This review focuses on flu infection and the numerous complications in older adults associated with diminished immune responses.

IFITM3 protects the heart during influenza virus infection

Influenza virus can disseminate from the lungs to the heart in severe infections and can induce cardiac pathology, but this has been difficult to study due to a lack of small animal models. In humans, polymorphisms in the gene encoding the antiviral restriction factor IFN-induced transmembrane protein 3 (IFITM3) are associated with susceptibility to severe influenza, but whether IFITM3 deficiencies contribute to cardiac dysfunction during infection is unclear. We show that IFITM3 deficiency in a new knockout (KO) mouse model increases weight loss and mortality following influenza virus infections. We investigated this enhanced pathogenesis with the A/PR/8/34 (H1N1) (PR8) influenza virus strain, which is lethal in KO mice even at low doses, and observed increased replication of virus in the lungs, spleens, and hearts of KO mice compared with wild-type (WT) mice. Infected IFITM3 KO mice developed aberrant cardiac electrical activity, including decreased heart rate and irregular, arrhythmic RR (interbeat) intervals, whereas WT mice exhibited a mild decrease in heart rate without irregular RR intervals. Cardiac electrical dysfunction in PR8-infected KO mice was accompanied by increased activation of fibrotic pathways and fibrotic lesions in the heart. Infection with a sublethal dose of a less virulent influenza virus strain (A/WSN/33 [H1N1]) resulted in a milder cardiac electrical dysfunction in KO mice that subsided as the mice recovered. Our findings reveal an essential role for IFITM3 in limiting influenza virus replication and pathogenesis in heart tissue and establish IFITM3 KO mice as a powerful model for studying mild and severe influenza virus-induced cardiac dysfunction.

Transient depression of myocardial function after influenza virus infection: A study of echocardiographic tissue imaging

Background

Influenza virus infection (IVI) was reported to be associated with minor cardiac changes, mostly those detected on electrocardiogram with and without elevated blood markers of myocardial injury; however, the characteristics of myocardial involvement in association with IVI are poorly understood. This study used echocardiographic tissue imaging (tissue Doppler, strain, and strain rate) to evaluate changes in left atrial (LA) and left ventricular (LV) myocardial function after IVI.

Methods and results

We examined 20 adult individuals (mean age, 43 years) at 2 and 4 weeks after diagnosis of IVI. For myocardial functional variables, we obtained LV global longitudinal strain (GLS), LV early diastolic strain rate (e'sr), LA strain, and LA stiffness (E/e’/LA strain), in addition to data on tissue Doppler (s’, e’, and a’) and myocardial performance index. Blood markers of myocardial injury were also examined. During follow-up, there were no significant changes in global chamber function such as LV ejection fraction, E/e’, and LA volume. However, significant changes in myocardial function were observed, namely, in s’ (8.0 ± 1.6 cm/s to 9.3 ± 1.5 cm/s; p = 0.01), e’ (10.2 ± 2.8 cm/s to 11.4 ± 3.0 cm/s; p < 0.001), e’sr (1.43 ± 0.44 1/s to 1.59 ± 0.43 1/s; p = 0.005), and LA strain (35 ± 8% to 40 ± 12%; p = 0.025), and the myocardial performance index (0.52 ± 0.20 to 0.38 ± 0.09; p = 0.009), but not in a’, LA stiffness, or GLS. Cardiac troponin T and creatinine kinase isoenzyme MB were not elevated significantly at any examination.

Conclusions

Myocardial dysfunction during IVI recovery appeared to be transient particularly in the absence of myocardial injury. Echocardiographic tissue imaging may be useful to detect subclinical cardiac changes in association with IVI.

H1N1 Influenza Causing Fulminant Myocarditis Requiring Extracorporeal Membrane Oxygenation

Influenza infection is a known cause of global morbidity and mortality. Most cases of influenza A (H1N1) influenza infection are mild and do not require hospitalization. Although the most common presentation is with upper respiratory tract symptoms, hemodynamic instability requiring vasoactive drugs and ventilatory support use is unusual. We present a case of acute fulminant myocarditis that presented with dyspnea, which was confirmed with laboratory tests, chest X-ray, and echocardiogram. The test for H1N1 in nasopharyngeal secretions was positive. The patient evolved to refractory cardiogenic shock despite the clinical measures applied.

The Prevalence and Findings of Subclinical Influenza-associated Cardiac Abnormalities among Japanese Patients

Objective Although life-threatening cardiac complications in influenza infection are rare, subclinical influenza-associated cardiac abnormalities may occur more frequently. We investigated the prevalence of subclinical cardiac findings. Methods After obtaining their written informed consent, 102 subjects were enrolled in the present study. The study subjects underwent a first set of examinations, which included electrocardiography (ECG), echocardiography, and the measurement of their cardiac enzyme levels. Those with one or more abnormal findings among these examinations were encouraged to undergo a repeat examination 2 weeks later. Results Among the 102 subjects enrolled, 22 (21.6%) were judged to have cardiac findings, including ST-T abnormalities, pericardial effusion, diastolic dysfunction, and cardiac enzyme elevation. Eighteen of these 20 subjects underwent a second screening at a median of 14 days later, and it was found that 11 of the 18 subjects were free from cardiac findings on this second examination. This suggested that the abnormalities were only transient and they therefore might have been associated with influenza. Approximately 20% of the influenza patients enrolled had cardiac findings, including ST-T segment abnormalities, pericardial effusion, and cardiac enzyme elevation. Conclusion Among the 102 patients who were studied, the cardiac findings were only mild and transient; however, physicians should be aware of influenza infection-associated cardiac abnormalities because such abnormalities may not be rare.

Fatal Influenza B Myocarditis in a 34-Year-Old Female

A 34-year-old female reported to the emergency department with a chief complaint of epigastric pain. Initial rapid screening was negative for both influenza A and B. The patient eventually developed myocarditis that led to pulseless ventricular tachycardia and death within 24 hours of admission. Viral smear was positive for influenza B postmortem despite the initial negative rapid screen. This case demonstrates the need for a new diagnostic criteria and treatment strategy for viral myocarditis due to influenza while concisely illustrating how the disease can progress in adults despite commonly presenting as a disease in adolescents.

The hidden burden of influenza: A review of the extra-pulmonary complications of influenza infection

Severe influenza infection represents a leading cause of global morbidity and mortality. Although influenza is primarily considered a viral infection that results in pathology limited to the respiratory system, clinical reports suggest that influenza infection is frequently associated with a number of clinical syndromes that involve organ systems outside the respiratory tract. A comprehensive MEDLINE literature review of articles pertaining to extra‐pulmonary complications of influenza infection, using organ‐specific search terms, yielded 218 articles including case reports, epidemiologic investigations, and autopsy studies that were reviewed to determine the clinical involvement of other organs. The most frequently described clinical entities were viral myocarditis and viral encephalitis. Recognition of these extra‐pulmonary complications is critical to determining the true burden of influenza infection and initiating organ‐specific supportive care.

Cardiac complications associated with the influenza viruses A subtype H7N9 or pandemic H1N1 in critically ill patients under intensive care

BACKGROUND AND OBJECTIVE

The clinical presentations and disease courses of patients hospitalized with either influenza A virus subtype H7N9 (H7N9) or 2009 pandemic H1N1 influenza virus were compared in a recent report, but associated cardiac complications remain unclear. The present retrospective study investigated whether cardiac complications in critically ill patients with H7N9 infections differed from those infected with the pandemic H1N1 influenza virus strain.

METHODS

Suspect cases were confirmed by reverse transcription polymerase chain reaction assays with specific confirmation of the pandemic H1N1 strain at the Centers for Disease Control and Prevention. Comparisons were conducted at the individual-level data of critically ill patients hospitalized with H7N9 (n=24) or pandemic H1N1 influenza virus (n=22) infections in Suzhou, China. Changes in cardiac biochemical markers, echocardiography, and electrocardiography during hospitalization in the intensive care unit were considered signs of cardiac complications.

RESULTS

The following findings were more common among the H7N9 group relative to the pandemic H1N1 influenza virus group: greater tricuspid regurgitation pressure gradient, sinus tachycardia (heartbeat≥130bpm), ST segment depression, right ventricular dysfunction, and elevated cardiac biochemical markers. Pericardial effusion was more often found among pandemic H1N1 influenza virus patients than in the H7N9 group. In both groups, most of the cardiac complications were detected from day 6 to 14 after the onset of influenza symptoms. Those who developed cardiac complications were especially vulnerable during the first four days after initiation of mechanical ventilation. Cardiac complications were reversible in the vast majority of discharged H7N9 patients.

CONCLUSIONS

Critically ill hospitalized H7N9 patients experienced a higher rate of cardiac complications than did patients with 2009 pandemic H1N1 influenza virus infections, with the exception of pericardial effusion. This study may help in the prevention, identification, and treatment of influenza-induced cardiac complications in both pandemic H1N1 influenza virus and H7N9 infections.

The use of extracorporeal life support in the treatment of influenza-associated myositis/rhabdomyolysis

A 13-year-old girl presented to the emergency department with fatigue, headaches and muscle stiffness after returning from a family camping trip. Within 24 h, she was transferred to ICU with general oedema and low saturations, where she had a cardio-respiratory arrest and was placed on veno-arterial extracorporeal membrane oxygenation (ECMO). The patient was successfully supported with ECMO for profound myocardial dysfunction and haemofiltration for rhabdomyolysis and acute renal failure.

Patients who present with profound myocardial dysfunction and myoglobinuria as a consequence of viral infection can be successfully supported with ECMO.

Global burden of influenza as a cause of cardiopulmonary morbidity and mortality

Severe acute respiratory infections, including influenza, are a leading cause of cardiopulmonary morbidity and mortality worldwide. Until recently, the epidemiology of influenza was limited to resource-rich countries. Emerging epidemiological reports characterizing the 2009 H1N1 pandemic, however, suggest that influenza exerts an even greater toll in low-income, resource-constrained environments where it is the cause of 5% to 27% of all severe acute respiratory infections. The increased burden of disease in this setting is multifactorial and likely is the result of higher rates of comorbidities such as human immunodeficiency virus, decreased access to health care, including vaccinations and antiviral medications, and limited healthcare infrastructure, including oxygen therapy or critical care support. Improved global epidemiology of influenza is desperately needed to guide allocation of life-saving resources, including vaccines, antiviral medications, and direct the improvement of basic health care to mitigate the impact of influenza infection on the most vulnerable populations.

Neurologic aspects of influenza viruses

Although influenza A and B viruses are primarily known as respiratory viruses and mainly infected only the upper respiratory tract in humans, patients with influenza often develop signs and symptoms that are not due to the respiratory system. Frequently individuals with influenza develop headaches, meningismus, and even seizures in addition to their typical respiratory symptoms. In the past decades, influenza viruses have also been associated with serious non-respiratory signs. The famous 1918 strain of influenza was associated with von Economo's encephalitis lethargica and postencephalitic parkinsonism. In the 1960s influenza virus infections in children were associated with Reye's syndrome characterized often by fatty non-inflammatory hepatic disease and an encephalopathy with marked non-inflammatory cerebral edema. Intermittently children with influenza develop focal myalgia and myositis. Guillain–Barré syndrome was epidemiologically associated with the 1978 killed influenza vaccine but not subsequent vaccines. Although occasional children with influenza have developed encephalopathy, from 2000 through 2004 there was an increase in the number of serious cases of acute necrotizing encephalopathy accompanying infection with the influenza A 2009 strain. The current H5N1 strain of bird influenza occasionally infects humans with a high mortality rate and some appear to have central nervous signs. This chapter explores what is known about these influenza neurologic associations.

Myocardial dysfunction during H1N1 influenza infection

PURPOSE

The purpose of the study is to evaluate the incidence and hemodynamic consequences of right ventricular (RV) and left ventricular (LV) dysfunction in critically ill patients with H1N1 infection.

PATIENTS AND METHODS

This is a retrospective analysis of all patients admitted to the intensive care unit of an academic hospital between October 2009 and March 2011 with severe H1N1 infection. Hemodynamic measurements and respiratory conditions were noted daily during the intensive care unit stay.

RESULTS

Forty-six patients were admitted with severe H1N1 infection. Echocardiography was obtained in 39 patients on admission: 28 (72%) had abnormal ventricular function, of whom 13 (46%) had isolated LV abnormalities, 11 (39%) had isolated RV dysfunction, and 4 (14%) had biventricular dysfunction. Echocardiography was repeated in 19 of the 39 patients during their hospitalization: RV function tended to worsen with time, but LV function tended to normalize. The ventricular abnormalities were not associated with history, severity of the respiratory failure, or hemodynamic status. However, patients with ventricular dysfunction needed more aggressive therapy, including more frequent use of vasopressor and inotropic agents and of rescue ventilatory strategies, such as inhaled nitric oxide, prone positioning, and extracorporeal membrane oxygenation.

CONCLUSIONS

These observations emphasize the high incidence of cardiac dysfunction in patients with H1N1 influenza infections.

Myocarditis Associated with Influenza A H1N1pdm2009

Acute myocarditis is a well-known complication of influenza infection. The frequency of myocardial involvement in influenza infection varies widely, with the clinical severity ranging from asymptomatic to fulminant varieties. The worst cases can result in death due to impaired cardiac function, although such fulminant myocarditis associated with influenza infection is rare, as shown by previous papers. Following the 2009 influenza pandemic, we reported on the clinical features of a cohort of 15 patients in Japan with H1N1pdm2009 myocarditis. In our subsequent survey of the literature for case reports or series of patients with myocarditis associated with H1N1pdm2009, we identified 58 detailed cases. We discuss here the high prevalence of fulminant myocarditis (36/58, 62%) among patients reported to have myocarditis associated with H1N1pdm2009. Mechanical circulatory support was required in 17 of the patients with fulminant myocarditis, 13 of whom recovered. We stress the need for increased awareness of influenza-associated myocarditis; such knowledge will facilitate earlier diagnosis and treatment of this fatal complication during future influenza pandemics.

Electrocardiographic abnormalities in patients with novel H1N1 influenza virus infection

The cardiac effects imposed by the novel H1N1 influenza strain have not been elucidated until now. Electrocardiographic (ECG) abnormalities were evaluated in a series of 50 patients with confirmed novel H1N1 influenza infection. Epidemiologic and clinical characteristics, laboratory correlations, and the effect ECG abnormalities may exert on disease outcomes were prospectively studied. Of the 50 patients, 14 (28%) exhibited ECG changes on admission. Nine patients presented with T-wave inversions, while ST-segment depression was observed on the electrocardiograms of 6 patients. The presence of ECG changes did not correlate with age, gender, co-morbidities, the laboratory profiles of the patients, or the coexistence of lower respiratory tract involvement. None of the patients exhibited alterations in cardiac-specific biochemistry or cardiac ultrasonography. All ECG changes were transient and reversed during disease regression. Two patients with ECG changes and 1 with normal ECG findings required intensive care, the former 2 eventually dying. Among the remainder, the duration of hospitalization did not exhibit a significant difference between the 2 groups, although there was a trend toward fewer days of hospitalization in the patients with ECG changes. In conclusion, ECG abnormalities are frequently encountered during novel H1N1 influenza infection, but their presence does not indicate a direct pathogen effect to the myocardium; these alterations may necessitate admission in the first place but are transient and not correlated with preexisting patient characteristics or with outcomes.

Right and left heart failure in severe H1N1 influenza A infection

Influenza infection can affect cardiac function. The recent pandemic of H1N1 influenza A provided an opportunity to study echocardiographic findings in critically ill infected patients. We hypothesised that critically ill patients with H1N1 infection would have a higher incidence of right and left heart failure than is seen in unselected populations of patients with septic shock and/or acute respiratory distress syndrome (ARDS). We retrospectively studied all patients admitted to four intensive care units at three hospitals in Salt Lake County, UT, USA, with laboratory-confirmed H1N1 infection in whom a clinical echocardiogram was available. 23 out of 48 patients had qualifying echocardiograms. Right ventricular (RV) dilatation (50-80%) and at least moderate systolic impairment (23%) were common, higher than the range described in general populations with ARDS. Left ventricular systolic dysfunction was present in 17% of patients. No single echocardiographic parameter was associated with 28-day mortality or ventilator-free days to 28 days. Critically ill patients with H1N1 infection frequently exhibit right heart dilatation and failure. RV basal dilatation was extremely common. These patients have less left heart failure than expected on the basis of prior descriptions of influenza myopericarditis or of general populations of septic patients.

Cardiac tamponade and heart failure due to myopericarditis as a presentation of infection with the pandemic H1N1 2009 influenza A virus

We describe a fatal case of myopericarditis presenting with cardiac tamponade in a previously healthy 11-year-old child. Pandemic H1N1 2009 influenza A virus sequences were identified in throat and myocardial tissues and pericardial fluid, suggesting damage of myocardial cells directly caused by the virus.

Reversible cardiac dysfunction associated with pandemic 2009 influenza A(H1N1)

Historical influenza A epidemics have carried elevated rates of cardiovascular disease, including transient cardiac dysfunction. Whether such an association holds for the novel influenza A strain, pandemic 2009 influenza A(H1N1) [A(H1N1)], remains unknown. We report an index case of transient cardiac dysfunction associated with A(H1N1) infection. Next, we reviewed 123 sequential cases of patients hospitalized with pandemic A(H1N1) at a single academic medical center in the United States from April 1, 2009, through October 31, 2009. We identified that 4.9% (6/123) of patients had either new or worsened left ventricular dysfunction. These cases ranged in age from 23 to 51 years, and all had preexisting medical conditions. ICU level care was required in 83% (5/6) of the cases. Sixty-seven percent (4/6) of the cases had follow-up echocardiograms, and left ventricular function improved in all four. We conclude that potentially reversible cardiac dysfunction is a relatively common complication associated with hospitalized pandemic A(H1N1) influenza.

Cardiac troponin-I as a screening tool for myocarditis in children hospitalized for viral infection

AIM

The incidence of myocarditis in children is uncertain because patients with minor symptoms can remain undiagnosed. We hypothesized that screening all children who are hospitalized for an acute infection with troponin-I (TnI) would reveal myocarditis cases and performed a prospective screening study.

METHODS

Between October 2005 and July 2008, a blood sample for TnI measurement was taken every time a sample for C-reactive protein measurement was drawn. If TnI value was above the screening limit (0.06 microg/L), electrocardiogram (ECG) and cardiac ultrasound were performed. TnI measurements were repeated until at normal level.

RESULTS

Altogether, 1009 children were screened during the 33 months. TnI was above the screening limit (0.06 microg/L) in six children. None of them had any signs of myocarditis in ECG or cardiac ultrasound. Five of those six children were younger than 30 days. All had a respiratory infection as a cause for hospitalization, three of which was caused by RSV. In four children, all younger than 30 days, TnI levels remained high (>0.37 microg/L) for two months, but decreased after that to normal levels.

CONCLUSION

The incidence of myocarditis during viral infections is low and a routine TnI screening for asymptomatic myocarditis is not useful.

Myocarditis mimicking acute coronary syndrome following influenza B virus infection: a case report

We present a notable case of a 15-year-old male infected with influenza B virus who showed the clinical manifestations of myocardial ischemia. He was admitted to our hospital with sudden chest pain. He had febrile illness for the past 2 days. Rapid antigen test for influenza revealed positive influenza B virus antigen. The initial electrocardiogram showed elevation of the ST-segments in leads II, II, aVF and reciprocal depression in leads V1 and V2. Serum test showed elevation of creatine kinase and troponin T. Gadlinium-enchanced magnetic resonance imaging, Tl-201 and I-123 beta-methyl-p-iodephenyl-pentadecanoic acid scintigram, coronary angiography revealed no abnormality. Follow-up electrocardiogram showed ST-segment change improvement over the course. Myocarditis associated with influenza B virus seemed to be caused by endothelial impairment and disturbance of microcirculation rather than direct injury to cardiac myocytes.

Fatal influenza A myocarditis with isolation of virus from the myocardium

A previously healthy 27-year-old woman developed an acute cardiac failure one week after onset of influenza-like respiratory infection, and died on her fourth day in hospital. Intravital differential diagnosis included myocardial infarction because of ECG changes and massive elevation of myocardial enzymes. Autopsy revealed severe myocarditis and intact coronary arteries. At microscopic examination the myocardium was heavily infiltrated with lymphocytes, and there was a marked myocytolysis. Influenza A virus was isolated from the myocardial tissue. An immunological mechanism of myocardial damage is suggested.

Etiology of mild acute infectious myocarditis. Relation to clinical features

The etiology of mild myocarditis, diagnosed on the basis of serial ECG changes during an acute infection, was studied in 126 consecutive conscripts. A fourfold rise in the antibody titers in the paired serum samples was required for a positive etiologic diagnosis. An etiologic diagnosis was made probable in 47% of the patients. Adenovirus was incriminated in 19 patients, vaccinia in 12, influenza A in eight, beta-hemolytic Streptococcus in six, mononucleosis in five and Mycoplasma in three. Chlamydia, influenza B and Coxsackie B4 were each found in two patients; parainfluenza, mumps and adult Still's disease were each found in one patient. The incidence of vaccinia myocarditis was 1/10000 smallpox vaccinations. Clear-cut myopericarditis was usually noted during vaccinia, mononucleosis, Mycoplasma, Chlamydia and Coxsackie B4 infections. Adenovirus and influenza A myocarditis was most often subclinical, being mostly detected only because of ECG screening of patients without cardiac symptoms. Frequent recent ventricular extrasystoles were most often triggered by a beta-hemolytic Streptococcus infection. The etiology of infectious myocarditis seems to reflect the overall profile of viruses and other infective agents in the study population at that particular time. Cardiotrophic viruses such as Coxsackie B only rarely cause myocarditis outside epidemics.

2009 update in prevention, evaluation, and outpatient treatment of influenza

BACKGROUND

Influenza A and B virus infections account for substantial morbidity and mortality and adversely affect quality of life and productivity in millions of Americans every year. Because of antigenic drifts and shifts, influenza is difficult to manage, presenting primary care clinicians with two major challenges every year: 'Who should be vaccinated?' and 'How should patients who present with symptoms of influenza be managed?'

METHODS

A search from 1995 to 2008 of the National Library of Medicine, the Cochrane Database of Systematic Reviews, the US Centers for Disease Control and Prevention (CDC) website, and the reference lists of retrieved articles was conducted to identify the most current and relevant information to address these two major challenges and the questions they generate in primary care. Emphasis was placed on influenza vaccination and antiviral agents.

FINDINGS

In all, 275 articles met the search criteria. Emphasis was placed on recommendations developed by the Advisory Committee on Immunization Practices for 2008-2009, as well as several advisories issued by the US Food and Drug Administration and the US CDC.

DISCUSSION

Eighty-five percent of the US population is eligible for influenza vaccination. Several measures have been demonstrated to improve vaccination rates. Diagnosis of influenza should be confirmed with testing such as a rapid viral test. Management of persons with influenza includes treatment with neuraminidase inhibitors and symptom-specific therapy.

CONCLUSION

The implementation of more aggressive measures is needed in the primary care setting to prevent and treat influenza.

Influenza

OBJECTIVE

Influenza is a major concern for intensivists in all communities in the U.S. While there is considerable concern whether or not the country will be ready for a pandemic influenza, even seasonal influenza poses a major challenge to hospitals. The objective of this review is to summarize current knowledge of influenza with emphasis on the issues that intensivist will encounter.

SETTING

Intensive care unit in a 450-bed, tertiary care, teaching hospital.

METHODS

Source data were obtained from a PubMed search of the medical literature. PubMed "related articles" search strategies were likewise employed frequently.

SUMMARY AND CONCLUSIONS

Seasonal influenza causes more than 200,000 hospitalizations and 41,000 deaths in the U.S. every year, and is the seventh leading cause of death in the U.S. Despite this impact there is a shortcoming in knowledge of influenza among many health care workers, and a paucity of clinical data and studies to guide therapy. Intensivists need to recognize the importance of seasonal influenza as a cause of severe morbidity and mortality. This review summarizes current knowledge of the diagnosis, complications, therapy, and infection control measures associated with influenza.

Sudden death in competitive athletes

Sudden death in athletes is an extremely rare event yet no less tragic for its infrequency. Up to 90% of these deaths are due to underlying cardiovascular diseases and therefore categorized as sudden cardiac death (SCD). The causes of SCD among athletes are strongly correlated with age. In young athletes (<35 years), the leading causes are congenital cardiac diseases, particularly hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and congenital coronary artery anomalies. By contrast, most of deaths in older athletes (<35 years) are due to coronary artery disease. This review focuses on the cardiac causes of SCD and provides a brief summary of the principal noncardiac causes. Current pre-participation screening strategies are also discussed, with particular emphasis on the Italian experience.

Low Voltage ECG in Myocarditis: Peripheral Edema as a Plausible Contributing Mechanism

A 24-year-old woman was hospitalized with acute myocarditis that led to multiple organ, including heart, failure, with fluid retention. An echocardiogram showed left ventricular ejection fraction approximately 10%, and her electrocardiogram (ECG) revealed low voltage. She rapidly recovered and was discharged 15 days after admission. On evaluation at 1, 10, and 22 weeks after discharge, she was asymptomatic, with unlimited exercise tolerance. An echocardiogram 11 weeks after discharge from the hospital showed left ventricular ejection fraction of approximately 60%. Correlations of weights with ECG QRS voltage parameters in the hospital revealed r = 0.80 and 0.83, with P = 0.021 and 0.029, suggesting that >or=64% of the attenuation of the QRS potentials could be accounted for by the corresponding gain in weight.

Influenza A virus infection and cardiac arrhythmia during the neonatal period

Influenza virus infection during pregnancy increases the risk of spontaneous abortion, preterm contractions, fetal compromise and early neonatal mortality. We describe a case of fetal and neonatal cardiac arrhythmia coinciding with an influenza A virus infection. Viral RNA was detected in the neonate's nasopharyngeal secretions and also in its serum, indicating influenza viremia. The cardiac arrhythmia resolved spontaneously without antiarrhythmic treatment.

Myocarditis in infants and children: A review for the paediatrician

Clinical myocarditis is uncommon in infants and children. The most common pathogen is Coxsackievirus B. The offending agent triggers an immune response, which results in myocardial edema with subsequent impairment of systolic and diastolic function. Newborns and infants are more severely affected because the immature myocardium has limited ways of adapting to an acute insult. Children typically present with sinus tachycardia and gallop on auscultation, cardiomegaly on chest x-ray and small voltages on electrocardiogram. The echocardiogram shows reduced ventricular function. Viral studies can isolate the pathogen. Myocardial biopsy is useful diagnostically, but carries a significant risk for the sick infant. The first line of treatment includes measures such as rest, oxygen and diuretics. Inotropic agents are useful in moderate to severe heart failure. The role of immunosuppressive therapy is not yet clearly established in the paediatric age group. Prognosis is guarded in newborns but more favourable in older children.

Viral myocarditis and dilated cardiomyopathy: mechanisms, manifestations, and management

Viral infection of the heart is relatively common and usually of little consequence. It can, however, lead to substantial cardiac damage and severe acute heart failure. It can also evolve into the progressive syndrome of chronic heart failure. Recent studies have gone some way towards unravelling the complex mechanisms underlying the heart muscle damage that occurs after viral infection. These studies have lent support to both immune and viral mediated (independent of an immune response) cardiac damage. Acute myocarditis can present in various ways, and it may be a cause of sudden death in an otherwise healthy young adult. New treatments for viral heart disease are awaited. In the meanwhile, the haemodynamic support of patients with acute left ventricular failure caused by myocarditis should be aggressive, to allow for the possibility of spontaneous recovery. Contemporary trials of treatment in chronic heart failure secondary to dilated cardiomyopathy support the use of angiotensin converting enzyme inhibitors, beta adrenoceptor blockers, and spironolactone in such patients.

Influenza

Influenza is an acute respiratory illness of global importance that causes considerable morbidity and mortality every year. At the beginning of the millennium, influenza will still be an emergent or re-emergent infection because of the viral ability to mutate. Global influenza surveillance indicates that influenza viruses may vary within a country and between countries and continents during an influenza season. Virologic surveillance is of critical importance in monitoring antigenic shift and drift. Disease surveillance is important in assessing the impact of the epidemics. Both types of information provide the basis of vaccine composition and the correct use of antivirals. Laboratory diagnosis is of critical importance for the global surveillance of influenza and may allow the timely use of antiviral drugs. Viral isolation remains the gold standard for laboratory diagnosis; however, several new rapid diagnostic tests are available or in development. The clinical spectrum of the disease varies from asymptomatic infection to the classic flu syndrome, and respiratory and nonrespiratory complications are observed particularly in high-risk groups. Current inactivated influenza vaccines have shown efficacy and effectiveness in preventing influenzalike illness, hospitalization for pneumonia, and death and in reducing health care costs. Because of the annual administration of the vaccine and the short period of time where it can be administered, strategies directed at improving vaccine coverage are of critical importance. In this sense, experiences obtained in different countries, such as with the National Immunization Campaigns developed in Argentina, provide one model of massive vaccine administration. In addition to current vaccines, new live attenuated vaccines will permit a most effective prevention of influenza in the community in the near future. A new type of antiviral, neuraminidase inhibitors, offers valuable benefits in the prevention and treatment of influenza A and B. A future pandemic of influenza seems inevitable. There is wide recognition that preparation for the next pandemic requires that infrastructure be in place during interpandemic periods for implementing preventive and therapeutic measures. The WHO has established a pandemic influenza task force, and a number of countries in Latin America have developed formal pandemic plans. These national and international efforts are essential to reduce the mortality and morbidity in the next influenza pandemic.

Acute tonsillitis in young men: etiological agents and their differentiation

Group A beta-hemolytic streptococci were found in 38% of 257 young men in military service with acute tonsillitis. Of the 108 patients tested also for viral antibodies, 42% showed a 4-fold rise in antibody titers. Adenovirus was the most frequent (31%) nonstreptococcal agent, followed by Epstein-Barr virus (6%), and influenza virus (5%). Non-group A streptococci were isolated in about the same proportion (18%) as in healthy control subjects. Other data also suggested that these bacteria were carried and not true infecting organisms. Group A streptococci and adenovirus occurred in mixed infection in 9% of the 108 cases. In group A streptococcal tonsillitis compared to others, white blood cell counts were higher (13.3 vs. 8.3 x 10(9)/l, p less than 0.01), C-reactive protein was higher (70 vs. 48 mg/l, p less than 0.01), tonsillitis was more often non-exudative (p less than 0.05), and the duration of fever was shorter (2.2 vs. 3.5 days, p less than 0.01), while there was no difference in the height of the fever or erythrocyte sedimentation rate.

Cardiac effects of common viral illnesses

We compared the clinical, electrocardiographic and echocardiographic findings of 32 patients during the acute and recuperative phases of viral illness with similar data from a healthy age- and sex-matched normal control group. During the acute phase, no patient had cardiac symptoms and none had clinical evidence of left ventricular or valvular dysfunction, nor pericarditis. Electrocardiograms revealed no differences in mean sinus rate or ectopic dysrhythm between the two groups. Spatial 12- and 120-lead body surface electrocardiographic patterns were normal in 30 patients; two others had nonspecific T wave abnormalities. There were no differences in echo-determined left ventricular cavity size or systolic shortening fraction between the two groups. Three patients had segmental ventricular hypokinesis; 17 patients had small pericardial effusions. Data herein suggest effects on myocardial electrical and mechanical function in patients with viral illness. It may be prudent for such patients to minimize cardiac stress during illness.

Dilated cardiomyopathy and myocarditis: natural history, etiology, clinical manifestations, and management

This monograph begins and ends with a statement of uncertainty regarding many aspects of dilated cardiomyopathy. Natural history studies identify patients with widely differing outcomes. A host of prognostic factors have emerged, yet it would appear that the major determinants of survival are as yet unrecognized. The diagnosis remains primarily one of exclusion, and management is largely nonspecific and supportive. The frequency of sudden cardiac death is well documented, but the ability to accurately identify patients at risk and the efficacy of antiarrhythmic therapy is unestablished. The emerging success of cardiac transplantation is a source of encouragement. The causes of dilated cardiomyopathy remain a source of intense investigation. Accumulating evidence (much of it circumstantial) does, however, implicate a viral etiology and perhaps altered function of the immunoregulatory system. However, the disparity between the severity of functional disturbance with the relative lack of histologic markers of cellular necrosis implies a disturbance at a cellular level. The etiology or etiologies remain elusive. Future investigation directed at fundamental aspects of cardiac cellular biology may provide the answers.

Infection and infarction. Acute viral (and other) infection in the onset, pathogenesis, and mimicry of acute myocardial infarction

Because a prospective controlled investigation showed a highly significant association of the onset of acute myocardial infarction with signs of preceding respiratory infection, the clinical, laboratory, experimental, and epidemiologic evidence more directly supporting this association was analyzed. Inflammation--specifically of infectious, usually viral, origin--has been shown by several lines of evidence to be capable of precipitating or mimicking clinical myocardial infarction. Myocardial biopsy is producing rapidly increasing confirmation that myocarditis can perfectly mimic clinical acute myocardial infarction. Coronary arteritis, with implications for vasospasm and thrombosis, is being increasingly demonstrated when deliberately sought in necropsy and biopsy material. Effects of blood-borne infectious agents, particularly viremia, on platelets in vivo and in vitro--aggregation and lysis with release of vasoactive substances--have even more serious potential for coronary thrombosis and vasospasm. It is not clear whether such mechanisms operate entirely independently or are more potent in high-risk patients, particularly in view of the demonstrable hypercoagulable state in many patients with coronary disease. Because of the great importance of confirming precipitating mechanisms for acute myocardial infarction (as well as its frequent mimic, myocarditis), intensive investigation of the relation between infection and infarction has important preventive and therapeutic implications.

Cardiovascular diseases due to viruses

In acute myocardiopathy and pericardiopathy, Coxsackie virus B infections are increasingly recognized as a cause of primary myocardial disease and may cause chronic cardiovascular disease. With other viruses, such as cytomegaloviruses and rubella virus, transplacental infection during pregnancy may occur, and this can cause the congenital rubella syndrome, which involves heart abnormalities. Other viruses are now under study. Myocarditis was observed in a newborn infant infected with Coxsackie virus B3, which was isolated by tissue culture methods. Experimental infection of Coxsackie virus A and B was studied in suckling mice and the histopathologic changes in heart muscle were observed. Laboratory findings of viral infection are very useful for clinical diagnosis, however care needs to be taken with respect to the obtaining of specimens, diagnostic procedures, and the assessment of results.

Natural history of left ventricular function in neonatal Coxsackie myocarditis

Three neonates are described who had severe congestive cardiac failure following Coxsackie-B virus infection. Overall left ventricular function was depressed and accompanied by regional differences in wall motion. Recovery has been gradual, and after 40 or more months of follow-up, all three infants still have evidence of myocardial damage. This provides further evidence linking myocarditis with dilated cardiomyopathy.

Clinical aspects of virus/immune myocarditis

Although a cause-and-effect relationship between viral infection and myocarditis remains inferential, two distinct clinical syndromes can be identified. During the early viral phase, the cardiac manifestations emerge while the symptoms of active viral infection are also present. During the chronic phase, symptoms of the viral infection may be remote or nonexistent, and identification of active myocarditis is contingent upon an aggressive diagnostic approach with endomyocardial biopsy and gallium 67 imaging. The exact incidence of myocarditis in patients with heart failure of unknown cause is unclear due to lack of standardization of histologic parameters. There are no other clinical clues to the presence of myocarditis in those patients presenting with cardiomyopathy or ventricular arrhythmia. For further clarification of the incidence and various presentations of myocarditis a large multi-center trial is necessary.

Evaluation of mild acute infectious myocarditis

The diagnosis of acute mild myocarditis in vaguely defined. Therefore we studied 185 consecutive young men in military service with electrocardiographic changes arousing a suspicion of myocarditis in connection with an acute infectious disease. It was possible to classify 160 patients into seven electrocardiographic groups; definite or probable myocarditis was observed in 104 patients. The electrocardiographic patterns considered characteristic for acute myocarditis were: ST segment elevations followed by T wave inversions; gradually changing T wave inversions not corrected by beta blockade; and ventricular extrasystoles more than 10 per minute triggered by acute infection. Thirty-nine subjects without myocarditis had "functional" T wave abnormalities completely normalised by beta blockade, or stable T wave inversion. The leading symptoms in acute myocarditis were fatigue and chest pains; loud S3 gallop, paradoxical cardiac pulsation, pericardial friction rub, or enlargement of the heart were noted altogether in 50% of the patients. Echocardiography disclosed segmental wall motion abnormalities related to the T wave inversions. Serum creatine kinase MB fraction increased in 70% of the acute myopericarditis patients during the ST segment elevation stage. In the non-myocarditis groups the clinical and pertinent laboratory findings remained normal. Thus, we noted in clinically mild acute infectious myocarditis clear-cut and early signs of myocardial dysfunction, suggesting that the direct and often local viral invasion of the myocardium is the basic pathogenetic mechanism. The present electrocardiographic classification based on serial tracings and beta blockade proved useful in the evaluation of patients suspected of having mild acute myocarditis.