| Background and Objective:Dengue fever is a common human diseases caused by the dengue virus infection,mainly prevalent in tropical and subtropical areas.Each year,about 100 million worldwide patients infected with dengue,dengue seriously threated more than 100 countries and approximately 2.5 billion people's health.With the changing climate and modern modes of transportation,Dengue epidemic spread showed geographical and seasonal trend,the expansion of the situation made it a major public health problem in humans.In China,the recent dengue epidemic showed an upward trend.Guangzhou has a dengue epidemic in almost every year,once a pandemic occurs every 3?5 years,the cumulative number of cases currently account for about 70 percent of Guangdong Province's number.In 2009,World Health Organization divided dengue fever into a total of three categories:non-severe dengue without warning signs,non-severe dengue with warning signs and severe dengue.Most patients showed ordinary dengue and common symptoms,such as fever,significant fatigue,headache,muscle,bone and joint pain,decreased white blood cell and platelet counts,and many of them can be self-healing.In the first three to six days,the majority of patients were found to have a large number of rash in the limbs or head,face(congestive or hemorrhagic rash),can also be found to have varying degrees of bleeding.Few patients with severe dengue will have increased capillary permeability which resulted in significant plasma leakage,and further causing a serious lack of plasma volume.The patient may therefore shock.Prolonged shock in patients can cause metabolic acidosis,and multiple organ dysfunction.Severe dengue often was accompanied by poor prognosis due to myocarditis,toxic hepatitis,electrolyte and acid-base unbalance,acute intravascular hemolysis and other complications.Viral myocarditis is myocardium inflammation caused by viral infection,it is characterized with myocardial degeneration,necrosis,accompanied with interstitial edema,fibrosis and other clinical pathological features.Dengue virus is a widely recognized pathogen that can cause viral myocarditis.According to reports,about 1%to 5%of viral-infected cases involved the heart in general population,myocarditis prevalence ranged 9?15%in patients with dengue virus infection.As one of the major complications of dengue patients,myocarditis often leads to arising of various clinical symptoms,such as chest tightness,palpitations,dizziness,shortness of breath.Myocarditis is a common cause of death in patients with severe dengue.Pathophysiology of the development of viral myocarditis is more complex.Some researchers believe that viral replication directly damage the structure and function of cardiac myocytes in the host,while some other scholars believe that the immune response in viral myocarditis pathology plays an important role.On this issue,the researchers are quite controversial.This is due to two reasons,One reason is due to the diverse clinical manifestations of viral myocarditis.Symptoms of viral myocarditis vary from asymtom to acute hemodynamic disfunction or death.Viral myocarditis patients may exhibit a variety of clinical manifestations,including tachycardia,diastolic gallop,enlarged heart,congestive heart failure.Another reason is that the diagnostic criteria need to be further improved.Endomyocardial biopsy is the gold standard for the diagnosis of myocarditis,but it is difficult to be popularized because of operational risk.Currently,the guidelines recommend the use of a variety of complementary diagnostics,including electrocardiogram,cardiac imaging and cardiac enzyme tests,as an alternative to endomyocardial biopsy,comprehensively applied to the diagnosis of myocarditis.With a low incidence of dengue infection and overall prevalence,and this disease has seasonal and regional characteristics,cases for dengue viral myocarditis research are obviously even more scare.So far,there was still no any domestic or foreign data available from large-scale research about the incidence of dengue viral myocarditis.As far as we know,most of the previous studies were focused on the sporadic cases of myocarditis in reported dengue patients.In other countries,only three cross-sectional studies or cohort studies have been finished on dengue viral myocarditis.However,these data do not accurately reflect the clinical features of myocarditis due to small sample size.These studies did not further clarify the distribution of symptoms,laboratory abnormalities of dengue viral myocarditis,and its relevance to the pathogenesis of severe dengue.To clarify the clinical pathogenic and diagnostic characteristics of dengue viral myocarditis,it is necessary to perform a large scale,systematic study on dengue viral myocarditis,which is crucial for the better prevention and treatment of severe dengue and the reducing of mortality in severe dengue patients.In 2014,China's most serious outbreak of dengue fever over the past 20 years has occurred in Guangzhou City and its surrounding areas.A large number of dengue cases of viral myocarditis were available for research,providing a rare opportunity for this study,Based on the latest viral diagnostic criteria of myocarditis(2013 ESC),this study systematically researched on the myocarditis of the hospitalized dengue patients.Dengue viral myocarditis patients were screened from 1782 cases of hospitalized dengue patients,and we clarified the characteristics of dengue viral myocarditis in many aspects,including symptoms distribution,the type of laboratory abnormalities,arrhythmias and heart failure,clinical characteristics,prognostic features and the relationship between the condition of myocarditis and the condition of dengue in patients.We further revealed the possible pathophysiological mechanisms of this disease,providing the scientific basis for better prevention and treatment.Part ?:Studies on basic clinical characteristics of dengue viral myocarditis patients1.ObjectivesAs a complication of dengue patients,myocarditis is a particularly common cause of death in patients with severe dengue.However,study of dengue viral myocarditis is still very lacking,there was still no data available from large-scale research about the incidence of dengue viral myocarditis.Previously,most studies were focused on the sporadic cases of myocarditis in reported dengue patients.In 2014,China's most serious outbreak of dengue fever in the past two decades happened in Guangzhou City and its surrounding areas.Ended at 0:00 on December 15,2014,there were at least 45,171 cases of confirmed dengue infection in Guangdong Province in the year,nearly 17 times of the number of annual total number of dengue cases in 2013(there are a total of 2776 cases throughout the year of 2013,ended at 0:00 on November 27,2013),of which 82.69%is the patients from Guangzhou.To further reveal the basic clinical characteristics of dengue patients with myocarditis,this study enrolled hospitalized dengue patients in Guangzhou No.8 People's Hospital from August to October 2014,Combined with the latest diagnostic guidelines of myocarditis,clarified the composition of myocarditis,analysed the advantage of each diagnosis method.2.Materials and methods:(1)All the data in this study are from dengue patients admitted in Guangzhou No.8 People's Hospital between August to October 2014.All patients were subjected to blood collection,then followed with every morning fasting blood collection,every other day,respectively,blood routine test and blood biochemistry test.(2)Diagnostic criteria and methods for dengue feverAll patients who has the clinical manifestations of dengue,epidemiological history(patients have been to endemic areas 15 days before the onset of dengue fever,or resident of dengue area),or neutropenia and thrombocytopenia,were defined as suspected cases of dengue fever.Secondary infections were defined as the presence of positive RT-PCR and/or positive NS 1 associated with positive IgG during the acute phase(<7 days' disease duration)and an IgM/IgG ratio of<1.2 during the convalescent phase(?7 days'disease duration).According to the classification method reported by WHO(2009),dengue can be divided into 3 groups,NSD(WS-):non-severe dengue without warning signs;NSD(WS+):non-severe dengue with warning signs;SD:severe dengue.The latter two are more danger and need more medical attention compared to the NSD(WS-)as a whole group.(3)Diagnostic criteria and methods for myocarditis:Collecting complaints,signs and symptoms of patients on the day admitted,vital signs(temperature,respiration,pulse,blood pressure,oxygen saturation)wered collected per day.Regardless of whether patients have symptoms of myocarditis or not,all dengue patients enrolled were subjected to examinations including electrocardiogram(ECG),?ltrasound cardiogram(UCG)and cardiac enzyme test(CET).According to the diagnostic criteria from European Society of Cardiology(2013),myocarditis was diagnosed if?1 clinical presentation and ?1 diagnostic criteria,?2 diagnostic criteria should be met if the patient is asymptomatic.Clinical symptoms includes chest pain,dysponea at rest or exercise,palpitation,syncope,cardiac shock and sudden cardiac death.(4)Exclusion criteria:We excluded patients with previous history of myocarditis,myocardial ischemia,myocardial infarction,heart failure,coronary heart disease,rheumatic heart disease,cardiac neurosis,valvular heart disease and congenital heart disease,autoimmune diseases patients and pregnant women were excluded.(5)Statistical AnalysisFor all the four parts of the whole thesis,analyses were carried out using SPSS 19.0.1 for Windows.Qualitative variables are defined by number of cases and percentage.Quantitative variables are expressed as means±SD.Comparisons of means were done using unpaired Student's t-test for variables with Gaussian distribution,and Mann-Whitney for non-Gaussian variables.Comparison of categorical variables was made using Fisher exact test.A P value of<0.05 was considered to be significant in all analyses.3.Results:From August to October2014,a total of 1782 cases of confirmed dengue patients according to WHO(2009)diagnostic criteria were admitted.Among them,we found a total of 449 cases of ECG abnormalities,247 cases of abnormal CET,139 cases of UCG abnormalities.According to the European Society of Cardiology(2013)diagnostic criteria,this study confirmed a total of 201 cases of dengue viral myocarditis,The incidence of myocarditis in domestic hospitalized dengue patients was 11.28%(201/1782).In all 201 cases of dengue viral myocarditis patients,ECG abnormalities,CET abnormalities and UCG abnormalities in patients were 153 cases,83 cases and 130 cases respectively.In these three kinds of auxiliary diagnostic methods(ECG,UCG and CET),ECG is the most sensitive method for the diagnosis of myocarditis,it'sensitivity was 76.12%(153/201),while for UCG is 64.68%(130/201),for CET 41.29%(83/201)respectively.In all 201 cases of dengue viral myocarditis in patients who have symptoms of myocarditis,number of patients with only one abnormal of ECG,UCG and CET were 19 cases,4 cases and 39 cases respectively;number of patients with two abnormals of ECG plus UCG,ECG plus CET,CET plus UCG were 74 cases,86 cases and 31 cases respectively;number of patients with three abnormals ECG,UCG and CET for 26 cases.The ratio of NSD(WS+)/SD is 11.11%(17/153)in dengue myocarditis patients with ECG abnormalities,6.02%(5/83)with UCG abnormalities,20.77%(27/130)with CET abnormalities.We analysed the percentage of patients with cardiac symptoms in the different dengue patients group with different combinations of myocarditis auxiliary diagnosis abnormals(single,double or three).We found that population of symptoms of myocarditis have the highest percentages(23.89%)in the group of dengue patients with CET abnormal among all the group,followed with other groups of dengue patients with CET abnormal.However,in other group without abnormal CET,the proportion of patients who have symptoms of myocarditis decreased to below 10%.It was indicated that patients with CET abnormalities are prone to have some cardiac symptoms such as chest discomfort4.Discussion and Conclusion76.12%of dengue viral myocarditis patients showed abnormal ECG.ECG has higher sensitivity.Therefore,patients with suspected myocarditis should firstly be subjected to the ECG examination.We can clearly find that the group dengue patients with CET abnormal have the biggest possibility of myocarditis symptoms,suggesting the importance of CET in dengue diagnosis of viral myocarditis?According to our results,the prevalence of myocarditis is 11.28%(201/1782)in the domestic epidemic hospealized dengue patients population,this results is consistent with previously reported result(9?15%).The study found that the proportion of patients with ECG abnormalities was accounted for 25.20%(449/1782)of the whole dengue patients.It was much higher than the previously reported data,suggesting that there is a higher proportion of abnormal ECG in this dengue outbreak in Guangdong in 2014.The study included 1782 cases of dengue patients,among them,we conformed 201 cases of myocarditis according to the 2013 ESC myocarditis diagnostic criteria,and carefully analysed the composition of ECG,UCG,CET as well as the proportion of severe dengue,analyzed the correlation between three different methods of diagnosis and symptoms,provided a more accurate and detailed data for the clinical diagnosis of dengue viral myocarditis.Part ?:Studies on the effects of myocarditis on the progression of dengue patients1.Objectives:For severe dengue patients,myocarditis is a common complication leading to increased mortality.Currently,it is still need further study which dengue related indicators are important factors affected by myocarditis in dengue patients.Data from previous studies can not clarify if there are some more severe performance in the clinical manifestations,signs and biochemical examination in dengue patients with myocarditis than dengue patients without myocarditis.The study included 201 cases of dengue patients with myocarditis and 150 cases of dengue patients without myocarditis,Comparing the general information,the difference between clinical symptoms and laboratory examinations between the two groups of patients,to explore whether these factors are related with myocarditis.2.Materials and methods:(1)Diagnostic criteria and methods for dengue fever are the same as Part 1.(2)Diagnostic criteria and methods for myocarditis are the same as Part 1.(3)Inclusion criteria:According to the diagnostic criteria guidelines,this study has a total of 201 confirmed cases of dengue viral myocarditis as the test group,150 cases of hospitalized patients with dengue fever without myocarditis during the same period were selected as control group.(4)Exclusion criteria are the same as Part 1.(5)Statistical analysis:please refer to the methods mentioned in Part 1.3.Results:There was no significant difference in age,gender and positive rate of dengue virus between the 201 cases of dengue patients with myocarditis and 150 cases of dengue patients without myocarditis.And,the difference on whether the proportion of secondary infection between two groups was not statistically significant,suggesting myocarditis susceptibility is not related to secondary infections.Proportion of NSD(WS +)/SD is significantly higher(17.41%vs.2%,?2=21.137,P<0.001)in dengue patients with myocarditis compared with the control patients,suggesting myocarditis patients were more likely to have serious dengue type.The incidence of shock was significantly higher in dengue patients with myocarditis than in the control group(14%vs.1%,?2=8.330,P=0.004).In addition,the incidence of bleeding,convulsions,coma and aphasia was higher in dengue patients with myocarditis than in the dengue patients without myocarditis,but the difference was not statistically significant.No significant difference in other dengue symptoms,including fever,extreme fatigue,rash,headache,muscle and joint pain,vomiting,abdominal pain,diarrhea,jaundice,and hepatomegaly,etc.,was found between the two groups.Compared with dengue patients without myocarditis,a significant increase in AST(399.71 ± 1064.56vs.163,12±122.31,t=3.123,P=0.002)and AST/ALT(1.95±1.10 vs.1.64±0.95,t=2.812,P=0.005)was observed in dengue patients with myocarditis.Low hemoglobin(115.29±22.996 vs.127.61±14.95,t=-6.106,P<0.01)and hematocrit(39.01±5.61 vs.41.20±8.23,t=-2.810,P<0.050),as well as higher levels of systolic blood pressure(115.98±18.01 vs.109.43±14.30,t=3.668,P<0.010)and creatinine levels(103.05±67.65 vs.84.44±25.12,t=3.582,P<0.010)can be found in dengue patients with myocarditis.There was no significant difference in the heart rate,ALT,white blood cells and platelets,etc.between the two groups.4.Discussion and ConclusionThere was no significant difference in age,gender,positive rate of dengue virus and the proportion of secondary infection between the dengue patients with myocardits and the patients with myocardits.The proportion of NSD(WS +)/SD or shock patients in the dengue patients with myocarditis was significantly higher than the control group.In this part of study,AST were found significantly higher in dengue patients with myocarditis group,which suggested more myocardial cell injury and necrosis in this group than in the control group.Compared with dengue patients without myocarditis,dengue patients with myocarditis had lower hemoglobin and hematocrit,higher systolic blood pressure and creatinine levels.Part ?:A comparative study of myocarditis in patients with varying degrees of dengue1.Objectives:In this part,we compared several aspects such as symptom distribution,arrhythmia and heart failure rate,to find out the similarities and differences in myocarditis index change between dengue myocarditis patients with different severity.2.Materials and methods:This study has a total of 201 confirmed cases of dengue viral myocarditis as a whole,according to the diagnostic criteria guidelines of severe dengue WHO(2009),the study can be divided into two groups:166 cases in NSD(WS-)group,35 cases in NSD(WS +)/SD group.3.Results:(1)Myocarditis indications Incidence of shortness of breath,palpitations,amaurosis,shock,aborted sudden cardiac death was significantly higher in NSD(WS +)/SD group than NSD(WS-)group.But no significant difference of ECG abnormalities and enzyme abnormalities was found between the two groups.There existed more cases of valvular regurgitation(n= 58,34.94%)in NSD(WS-)group of patients than SD/NSD(WS +)patients(n=2,5.71%).There was no other difference of echocardiographic manifestations between these two patient groups with different severity of dengue.(2)arrhythmia indications In all 201 cases of dengue viral myocarditis patients,patients with arrhythmia is 113 cases,patients with heart failure is 51 cases,which account for 56.22%,25.37%of 201 myocarditis patients respectively.In both groups of patients,we found many types of arrhythmias,including sinus arrhythmia,ventricular arrhythmia,supraventricular arrhythmias and conduction blockage.Compared with the NSD(WS-)group,the incidence of atrial fibrillation and supraventricular tachycardia was significantly increased in the NSD(WS +)/SD group,and the difference was statistically significant.(3)heart failure indications Most heart failure index,for example,respiratory rate,cardiogenic shock,gallop,bilateral pulmonary rales,blood oxygen,pulmonary congestion,was significantly increased with the aggravation of the dengue fever.However,the difference of left ventricular ejection fraction,end-diastolic diameter,AVB(? and ?),QRS width between the different dengue patient groups with different severity was not statistically significant.4.ConclusionIn all 201 cases of dengue viral myocarditis patients,patients with arrhythmia is 113 cases,patients with heart failure is 51 cases,which account for 56.22%,25.37%of 201 myocarditis patients respectively.In all dengue patients with viral myocarditis,the NSD(WS +)/SD group experienced more symptoms than the NSD(WS-)group.Several indices of heart failure,including respiratory rate,bilateral pulmonary rales,gallop,pulmonary congestion in chest X-ray,were significantly higher in NSD(WS+)/SD patients than NSD(WS-)patients,indicating that dengue-induced myocardial injury significantly increased with the aggravating dengue disease.In patients with different types of arrhythmias,there are more supraventricular tachycardia and atrial fibrillation in NSD(WS +)/SD patient population than NSD(WS-)patient population.Part ?:Preliminary pathological studies on dengue viral myocarditis 1.Objectives:Dengue virus is a widely recognized pathogen that can cause viral myocarditis.Myocarditis is a common cause of death in patients with severe dengue.However,becasuse the myocarditis research is still very lacking so far,scientists have poor knowledge of the specific mechanism of dengue viral myocarditis,To better understand clinical pathophysiology of the pathogenesis of dengue viral myocarditis,We tried to reveal the possible pathophysiological mechanisms of the genesis and development of this disease with the histopathological analysis of autopsy tissue and the determination of the plasma inflammatory cytokines using the ELISA method,2.Materials and methods:(1)Measurement of cytokines Early in the morning,fasting venous blood was collected from the quietly lying patient.Levels of IL-2(Interleukin-2),IL-6(Interleukin-6),IL-10(Interleukin-10)and TNF-a(necrotic factor-a)were detected with radioimmunoassay method,levels of other cytokines were detected by enzyme-linked immunosorbent assay(ELISA)method.(2)histopathological analysis The histopathological examination was performed in one case died from cardiac shock.Wash bloody tissue with PBS,fixed with conventional 4%paraformaldehyde,dehydrated,sliced sections after paraffin-embeding.After HE staining,myocardial tissue lesions were observed with ordinary optical microscope.3.Results:(1)Pathological analysis of myocardial tissue in patients with severe dengue We found the apparent degeneration of myocardial cells,and the emergence of significant interstitial edema.HE staining showing the presence of perivascular inflammatory cell infiltration of mononuclear cells.(2)Multiple cytokines in patients with dengue viral myocarditisTNF-?,MCP-1 and MMP-9 levels in the serum of dengue patients with myocarditis were significantly higher.The level of interleukins,such as IL-2,IL-6,IL-8 and IL-10,between the two groups was not statistically significant.4.ConclusionThe pathological analysis showed the apparent degeneration of myocardial cells and the emergence of significant interstitial edema,perivascular inflammatory cell infiltration.It was suggested that the main mechanism of dengue myocardial injury may be the release and activation of inflammatory mediators,not just because the virus directly attacks cardiomyocytes.A significantly elevated level of TNF-?,MCP-1 and MMP-9 was found in the serum of dengue patients with myocarditis,suggesting that thes cytokines may be involved in the pathological injury of myocardium cells in dengue patients. |
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