Laboratory diagnosis of viral myocarditis. A review

Analysis of formalin-fixed and frozen myocardial autopsy samples for viral genome in childhood myocarditis and dilated cardiomyopathy with endocardial fibroelastosis using polymerase chain reaction (PCR)

Viral infection of the myocardium is implicated in the pathogenesis of myocarditis and dilated cardiomyopathy (DCM). Enteroviruses have been considered the most common viral etiologic agents, based on peripheral culture and serologic methods. Recently, polymerase chain reaction (PCR) has been shown to be useful in the detection of viral genomes from various infected organs and body fluids. In this study, myocardial samples from autopsy specimens (formalin fixed and fresh frozen) were examined for enteroviral and DNA viral (adenovirus, herpes simplex virus [HSV], and cytomegalovirus (CMV]) genome by PCR. The specimens studied were from 58 patients with myocarditis, 28 patients with DCM and endocardial fibroelastosis [EFE], and 22 controls. Viral genome was detectable in 34 of the 58 (59%) autopsy-proven myocarditis samples (18 adenovirus, 12 enterovirus, 2 CMV, 2 HSV) and 6 of the 28 samples from patients with DCM and EFE (6 adenovirus). We conclude that PCR is effective in the rapid amplification of virus from frozen and formalin-fixed myocardial samples and that adenovirus is an important etiologic agent in viral myocarditis as well as DCM with EFE.

Increased virulence of coxsackievirus B3 in mice due to vitamin E or selenium deficiency

Nutrition has long been known to affect the ability of the host to respond to infectious disease. Widespread famines are often accompanied by increased morbidity and mortality due to infectious diseases. The currently accepted view of the relationship between nutrition of the host and its susceptibility to infectious disease is one of a direct relationship with host immune status. That is, if the nutritional status of the host is poor-due to either single or multiple nutrient deficiencies-then the functioning of the host immune system is compromised. This impairment of the immune response will lead to an increased susceptibility to infectious disease. Clearly, the immune response has been shown to be weakened by inadequate nutrition in many model systems and in human studies. However, what about the effect of host nutrition on the pathogen itself? Our laboratory has shown, using a mouse model of coxsackievirus-induced myocarditis, that a host deficiency in either selenium or vitamin E leads to a change in viral phenotype, such that an avirulent strain of the virus becomes virulent and a virulent strain becomes more virulent. The change in phenotype was shown to be due to point mutations in the viral genome. Once the mutations occur, the phenotype change is stable and can now be expressed even in mice of normal nutriture. Our results suggest that nutrition can affect not only the host, but the pathogen as well, and demonstrate a new model of relating host nutritional effects to viral pathogenesis.

Rhabdomyolysis with pericardial tamponade

A young man developed an acute illness and presented to the hospital in shock. On admission, both severe rhabdomyolysis and pericardial tamponade were present, the tamponade occurring as a complication of pericarditis. Echocardiography was required for rapid diagnosis of the cardiac tamponade. The etiology of this severe, life-threatening illness is discussed.

The incidence of myocarditis in endomyocardial biopsy samples from patients with congestive heart failure

We present the combined experience of three Yugoslavian cardiovascular centers in the application of endomyocardial biopsy for the diagnosis of myocarditis in patients who present clinically with congestive heart failure. The study group comprised 107 patients (mean age, 40.8 years; range, 19 to 61 years). On the basis of patient history and diagnostic tests, the following clinical diagnoses were established: dilated cardiomyopathy (85), myocarditis (16), and alcohol-induced heart disease (6). EMB samples were taken from the left ventricle (95) or both ventricles (12) by use of a King's College bioptome, with a mean of 3.2 samples per patient. Histologic evidence of myocarditis was noted in 10 of 85 patients (12%) with a clinical diagnosis of dilated cardiomyopathy, in 2 of 6 patients (33%) with alcohol-induced heart disease, and in 12 of 16 patients (75%) with a clinical diagnosis of myocarditis. There was confirmation of the clinically suspected diagnosis in 63% of cases, a change of diagnosis based on histology in 15% of cases, and nonspecific findings in 22%. However, useful information was obtained in 78% of the cases, and there was a 22% incidence of histologically proven myocarditis for the entire group. Our results indicate that endomyocardial biopsy is beneficial in determining the true incidence of myocarditis in patients with a clinical presentation of dilated cardiomyopathy.