Electrocardiographic changes following rabbit coronavirus-induced myocarditis and dilated cardiomyopathy

Rabbit Coronavirus (RbCV) infection was divided into two phases based upon day of death and pathologic findings. During the acute phase (days 2-5) heart weights (HW) and heart weight-to-body weight (HW/BW) ratios were increased with striking dilation of the right ventricle. These changes as well as increased dilation of the left ventricle were especially pronounced during the subacute phase (days 6-12). Myocytolysis, pulmonary edema, and degeneration and necrosis of myocytes, were seen during both phases. Myocarditis, pleural effusion, calcification of myocytes, and congestion in the liver and lungs were seen in the subacute phase. Electrocardiograms (ECGs) exhibited low voltage, nonspecific ST-T wave changes, sinus tachycardia, occasional ventricular and supraventricular premature complexes and 2(0) AV block consistent with myocarditis and heart failure. Forty-one percent of the survivors exhibited increased HW and HW/BW ratios, biventricular dilation, interstitial and replacement fibrosis, myocyte hypertrophy and myocarditis. ECGs exhibited nonspecific ST-T wave changes, sinus arrhythmia, occasional ventricular and supraventricular premature complexes and 2(0) AV block. These data suggest that RbCV infection may result in viral myocarditis and heart failure with a proportion of survivors progressing into DCM.

Group F beta-hemolytic streptococcus, tonsillitis and myocarditis

A case of tonsillitis and myocarditis is reported, where the only positive microbiological finding was a throat swab growing group F beta-hemolytic streptococci. The patient made an uneventful recovery after treatment with benzylpenicillin and clindamycin.

Indium 111-monoclonal antimyosin antibody and magnetic resonance imaging in the diagnosis of acute Lyme myopericarditis

BACKGROUND

Lyme borreliosis is a tick-borne multisystem disorder that may present as self-limiting early or persistent chronic diseases of the skin, nervous system, joints, heart, and other organs. Cardiac involvement has mainly been reported as acute atrioventricular conduction disturbances or transient ventricular dysfunction.

METHODS AND RESULTS

We treated a patient with clinical signs of acute myopericarditis and serologic evidence of Lyme borreliosis confirmed by silver staining of endomyocardial biopsy specimens and indium 111-monoclonal antimyosin antibody scan, which we believe has not been reported previously. Additionally, magnetic resonance imaging revealed epicardial and myocardial areas of increased intensity.

CONCLUSION

Indium 111-monoclonal antimyosin antibody scanning and magnetic resonance imaging might play an additional important role in assessing and confirming the diagnosis of Lyme carditis in the presence of clinical symptoms and positive serologic findings.

[Acute Staphylococcus aureus myocarditis in AIDS. 2 cases]

The authors report two cases of acute myocarditis due to Staphylococcus aureus in patients with AIDS. There was no history of opportunist infections in either case but the CD4 lymphocyte levels were very low. The myocarditis caused acute cardiac failure and death. Histological examination showed microabscesses filled with Gram positive cocci throughout the myocardium. Bacteriological studies identified the Staphylococcus aureus. Staphylococcus aureus myocarditis without endocardial or pericardial involvement is very rare. It is the result of septic emboli in the cardiac microcirculation. Bacterial myocarditis has rarely been diagnosed in HIV positive patients. Both our cases featured severe cell-mediated immunodeficiency without associated neutropaenia. The decreased bactericidal activity of the neutrophil polynuclears and/or a deficit in the immunity mediated by the B-cell lymphocytes in AIDS could explain the lethal septic complications observed in our two cases.

[Cardiac lesions in bacterial endocarditis: from findings of pathology to possibilities and limits of surgery]

Infective endocarditis remains a common condition for pathologists interested in cardiology who fortunately examine more infected valves excised surgically (66 in 1992) than observed at autopsy after death from this condition (2 in 1992). The authors discuss the elementary valvular lesions (ulceration and vegetations), the severity of which affects the prognosis, and the special aspects of these ulcerating vegetations with respect to their location (aortic, mitral, pulmonary and tricuspid), to the type of underlying valvular disease (rheumatic, myxoid or calcific) and infecting organism. The extravalvular complications are then reviewed: annular abscess (and possible extensions), purulent pericarditis, parietal endocarditis, myocarditis and coronary embolism. The authors attempt to answer questions about infective endocarditis from the pathologist's viewpoint: the difference between acute and subacute endocarditis, the reality of infective lesions of "healthy hearts", the role of the pathologist in the detection of pathogenic organisms, the evolution of lesions after sterilisation. The particular situation of prosthetic valve (biological or mechanical) endocarditis is treated in detail. The role and possibilities of surgery, the value of which is now universally accepted (the mortality of severe infective endocarditis has been lowered from 50-60% to 10-20% by a good operative strategy) are emphasised throughout.

Does endomyocardial biopsy aid in the diagnosis of active rheumatic carditis?

BACKGROUND

Carditis is the only component of rheumatic fever that leads to permanent disability. The diagnosis of carditis is presently made by using composite clinical criteria based on the revised Jones' criteria. Since myocardial involvement is an important component of rheumatic carditis, right ventricular endomyocardial biopsies were performed in 54 patients with clinical acute rheumatic fever and quiescent rheumatic heart disease to evaluate the role of biopsy for the diagnosis of rheumatic carditis.

METHODS AND RESULTS

In 11 of the 54 patients, clinical consensus was certain about rheumatic fever and carditis based on the revised Jones' criteria (group 1). Histomorphological abnormalities in these patients were scarce. The diagnostic features of rheumatic myocarditis including Aschoff nodules or histiocytic aggregates were encountered in 3 patients (27%). Lymphocytic infiltration was sparse. A majority of patients demonstrated myocyte degeneration, interstitial degeneration, or occasional interstitial mononuclear cell infiltration, but since these histopathological lesions may occur in other conditions also, they were considered nondiagnostic. In 33 of the 54 patients with preexisting rheumatic heart disease, the diagnosis of carditis was suspected based on varied clinical presentations. Since previous cardiac findings were not available in these patients, the clinical diagnosis of carditis could not be made without equivocation (group 2). Twenty-three patients presented with unexplained acute onset of congestive heart failure and evidence of recent streptococcal infection (group 2A). While 13 of them had one or more other major manifestations, 10 patients had only minor manifestations. Mimetic carditis was suspected in the remaining 10 of 33 patients based on carditis having occurred in previous episodes of rheumatic fever (group 2B). The endomyocardial biopsy provided confirmatory evidence of rheumatic myocarditis in 9 patients of group 2A but in none of the 10 patients with suspected mimetic carditis. Nondiagnostic myocyte or interstitial alterations were frequently observed in group 2. Ten of the 54 patients had no clinical evidence of active carditis (group 3). No histological alterations diagnostic of rheumatic carditis were noted in these patients. Twenty-two follow-up biopsies were performed in the first 10 consecutive patients. Diagnostic histiocytic aggregates or Aschoff nodules were observed in initial biopsies in 4 of 10 patients, and nonspecific myocyte or interstitial alterations were observed in 9. All patients with diagnostic changes in initial biopsy demonstrated fibrohistiocytic nodules in 6- or 12-week biopsy samples. Nondiagnostic alterations, similar to those seen in acute cases, were present in 5 of 8 patients at 6 weeks, 5 of 8 patients at 12 weeks, and 3 of the 6 patients at 24 weeks despite the presumed adequate immunosuppressive therapy. No complications related to biopsy were encountered.

CONCLUSIONS

The present study highlights the low frequency of diagnostic features in the biopsy specimens of patients with definite clinical rheumatic carditis. Although such alterations are not observed in patients with chronic rheumatic heart disease, endomyocardial biopsy does not appear to provide additional diagnostic information where clinical consensus is certain about diagnosis of rheumatic carditis. Our study, however, substantiates the concept of carditis underlying unexplained congestive heart failure of acute onset in patients with preexisting rheumatic heart disease and elevated antistreptolysin-O titers.

Use of the polymerase chain reaction with a murine model of picornavirus-induced myocarditis

Enteroviruses are common pathogens responsible for a wide spectrum of systemic infections. Conventional diagnosis of these infections relies on the isolation of viruses in cell culture and their identification by seroneutralization with polyclonal or monoclonal antibodies. Among enteroviruses, coxsackieviruses B have been involved as causative agents for viral myocarditis. Most of the time, in the case of cardiac pathologies, viral isolation is negative. Molecular biology techniques appear to be an alternative to conventional diagnosis and could supply evidence for the direct implication of enteroviruses in these severe pathologies. In this paper, we describe a murine experimental model of infection with the presumed highly cardiopathogenic coxsackie-virus B type 3. A kinetics of infection was observed for a period of 31 days, and the classical virological markers (viral isolation from feces and heart biopsies, seroconversion) were monitored and compared by means of molecular techniques (molecular hybridization, polymerase chain reaction [PCR]). In this 31-day period, the detection of coxsackievirus B type 3 RNA in the heart was possible only by using two successive seminested PCRs. After 9 to 11 days of active viral replication, when all other virological markers were negative, positive PCR signals were obtained, which supports the hypothesis of a shift to persistent enteroviral infection.

Cytopathogenic effect in cardiac myocytes but not in cardiac fibroblasts is correlated with reovirus-induced acute myocarditis

A panel of reovirus strains was used to compare myocarditic potential with induction of cytopathic effect in primary cardiac myocyte and cardiac fibroblast cultures. The results suggest that viral cytopathogenicity in cardiac myocytes, but not in cardiac fibroblasts, is a determinant of reoviral myocarditis.

Attenuation of a reactivated cardiovirulent coxsackievirus B3: The 5'-nontranslated region does not contain major attenuation determinants

To investigate the molecular basis of pathogenicity of Coxsackieviruses, a virus was reactivated by transfection from a full-length cDNA clone derived from cardiovirulent Coxsackievirus B3 (CVB3). The reactivated virus, rCVB3, was passaged serially in human dermatofibroblasts (HDF). No cytopathic effect was observed up to 12 days after inoculation with rCVB3 or early-passage virus, although disintegration of the monolayers was observed with late-passage virus (10th to 14th passages). Approximately 10% of HDF inoculated with rCVB3 were positive for viral antigens by immunofluorescence using enterovirus- or CVB3-specific monoclonal antibodies. These observations, together with the low infectivity titre of rCVB3 in HDF, suggests that HDF initially support only carrier state infection. After the 14th passage, the cardiovirulence of passaged virus (p14V) in mice was attenuated by a factor of > 10(4). Phenotypic changes of plaque size were also noticed in p14V: An attenuated variant (p14V-1) that produced larger plaques than rCVB3 in Vero cells has been plaque purified. The 5'-terminus of the genome of attenuant p14V-1 was amplified by polymerase chain reaction (PCR) and its sequence determined. Only one point mutation was found within the 5'-nontranslated region (5'NTR) at position 690 (A to U) compared to the viral RNA sequence obtained for rCVB3. An intertypic chimeric virus was reactivated from a cDNA clone after replacing the 5'-terminal 891 nucleotides of the wild-type genome with the corresponding region of the attenuant p14V-1. This chimeric virus, CB3/p14V-1/1, produced wild-type plaques in Vero cells and showed cardiovirulence similar to that of rCVB3 in mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Variant responses of mice to Borrelia burgdorferi depending on the site of intradermal inoculation

C3H/He mice inoculated intradermally at one of two sites with Borrelia burgdorferi responded differently to infection. Shoulder-inoculated mice developed spirochetemia, B. burgdorferi-specific antibody, and arthritis earlier than foot-inoculated mice. Lymphocyte populations derived from spleen tissue were elevated in the shoulder- but not the foot-inoculated mice, and those from lymph nodes were increased in both groups. Lymphocytes derived from blood and spleen tissue showed impaired proliferative responses to all mitogens for shoulder-inoculated mice only, whereas proliferation of lymph node cells was not affected, regardless of route. These results demonstrate that the site of initial B. burgdorferi inoculation is an important determinant in the pathogenesis of B. burgdorferi infection.

[Myocarditis of pseudo-infarctoid onset]

The authors report two cases of myocarditis in young individuals in whom clinical and electrocardiographic findings during the acute phase could have led to an erroneous diagnosis of myocardial infarction. The problem in such cases is that of a differential diagnosis with infarction with normal coronary arteries. Few clinical or paraclinical arguments are of diagnostic value, endomyocardial biopsy remaining the reference investigation. Proof of viral infection is not always obtained. It is often the retrospective argument of "complete return to normal" which supports the clinical impression. This usual benign outcome is not always the case, since cases of cardiogenic shock have been reported. The dual nature of the pathogenesis ("myositis" and/or "vasculitis" with thrombus and actual MI) is stressed.

Lymphocytes protect against and are not required for reovirus-induced myocarditis

Many studies suggest that host lymphocytes are damaging, rather than protective, in virally induced myocarditis. We have investigated the role of lymphocyte-based immunity in murine myocarditis by using a myocarditic reovirus (reovirus serotype 3 8B), nonmyocarditic reoviruses, adoptive transfer experiments, and mice with severe combined immunodeficiency (SCID mice). Prior to infection, passive transfer of monoclonal antibodies specific for 8B capsid proteins protected neonatal mice against 8B-induced myocarditis, indicating that humoral immunity can protect against myocarditis. Some monoclonal antibodies acted by blocking viral spread to and/or replication in the heart. Passive transfer of reovirus-immune, but not naive, spleen cells prior to infection protected neonatal mice from 8B-induced myocarditis. Depletion of either CD4 or CD8 T cells resulted in increased viral titer in the heart but did not abrogate immune cell-mediated protection against myocardial injury. This shows that both CD4 and CD8 T cells can act independently to protect myocardial tissue from reovirus infection. In addition, reovirus 8B caused extensive myocarditis in SCID mice. This confirms a prior report (B. Sherry, F. J. Schoen, E. Wenske, and B. N. Fields, J. Virol. 63:4840-4849, 1989) that T cells are not required for reovirus-induced myocarditis and demonstrates for the first time that B cells are not required for reovirus-induced myocarditis. We used SCID mice and a panel of reoviruses to assess (i) the relationship between growth in the heart and myocardial damage and (ii) the possibility that nonmyocarditic reoviruses exhibit a myocarditic phenotype in the absence of functional lymphocytes. Growth in the heart was not the sole determinant of myocarditic potential in SCID mice. Although 8B induced myocarditis in SCID mice, no or minimal myocarditis was found in SCID mice infected with four reovirus strains previously shown (B. Sherry and B. N. Fields, J. Virol. 63:4850-4856, 1989) to be nonmyocarditic or poorly myocarditic in normal neonatal mice. We conclude that (i) humoral immunity and cellular immunity are protective against, and not required for, reovirus-induced myocarditis and (ii) the potential to induce cardiac damage is a property of the virus independent of lymphocyte-based immunity.

[Cardiac manifestations of Borrelia burgdorferi infection (Lyme-borreliosis)]

Lyme borreliosis, caused by the tick-borne spirochete Borrelia burgdorferi, has been found to cause a variety of clinical syndromes including cardiomyopathy, dermatopathy, neuropathy, and arthropathy. Lyme carditis was originally described as a mild self-limited carditis, primarily involving the conduction system. However, recent reports suggest that cardiac involvement may be more serious than previously suspected, and may cause heart failure and probably congestive cardiomyopathy.

A report of human parvovirus B19 infection in hydrops fetalis. First Australian cases confirmed by serology and immunohistology

OBJECTIVE

To present the first Australian cases of fetal hydrops induced by parvovirus B19.

CLINICAL FEATURES

Autopsies on two cases of intrauterine fetal death with hydrops fetalis and pallor revealed evidence of myocarditis and widespread characteristic inclusion-bearing cells, predominantly erythroblasts. The diagnosis of hydrops fetalis induced by parvovirus B19 was confirmed in both cases by immunohistological localisation of the viral inclusions by means of a monoclonal antibody to the VP1 and VP2 proteins of parvovirus B19. A low level of parvovirus B19 IgM antibodies was detected in the second case.

CONCLUSIONS

It is possible that our relatively small population and lack of familiarity with the histopathological features may have led to underdiagnosis rather than a true absence of fetal parvovirus B19 infection in Australia. The condition can be diagnosed and treated antenatally and therefore should be included in the differential diagnosis of causes of hydrops fetalis.

Immunological status and pathology of coxsackie B viral myocarditis and dilated cardiomyopathy

The changes in 15 cases of viral myocarditis and 28 cases of dilated cardiomyopathy were reported and compared, which were the pathological changes of endomyocardial biopsy; NK cells activity; % of peripheral T lymphocytes and its subsets determined by using OKT3,4,8 (OKT3-peripheral total lymphocytes; OKT4-helper cells; OKT8-suppressive cells) monoclonal antibody; values of immunoglobulin IgG, IgA, IgM; titer of coxsackie B antibody neutralization test. And a discussion on their relationship was included.

[Serious arrhythmias in Borrelia infections]

Carditis is seen in about 4-10% of cases of Lyme's disease. It is usually dominated by varying degrees of atrioventricular block, and implantation of a temporary pacemaker may be necessary. Ventricular and supraventricular tachycardias seem to be less frequent than block, and as far as we know ventricular tachycardia provoked by bradycardia has not been reported previously. Third degree AV-block after oral penicillin treatment of erythema migrans is unusual in Europe. When an atrioventricular block of unknown origin is diagnosed, Lyme carditis must be considered, especially among young patients.

Varicella zoster myocarditis progressing to cardiomyopathy and cardiac transplantation

The case of a 12 year old schoolgirl with heart failure due to varicella myocarditis is reported. Heart failure and cardiogenic shock were evident 21 days after the appearance of the rash, and cardiac transplantation was performed two weeks later. Myocarditis is a serious complication of varicella zoster infection and heart failure may be fulminant. Endomyocardial biopsy changes consistent with myocarditis were documented six days after the start of heart failure. The histological changes, however, developed into those of idiopathic dilated cardiomyopathy (with anisonucleosis and fibre width variation) over a seven day period. This case provides further evidence for the link between viral myocarditis and idiopathic cardiomyopathy and underlines the value of immediate endomyocardial biopsy in heart failure of recent onset. Cardiac transplantation led to a rapid and full recovery.

Role of oxygen derived free radicals in the pathogenesis of coxsackievirus B3 myocarditis in mice

OBJECTIVE

The aim was to test the role of oxygen derived free radicals in the development of myocarditis. This involved investigating the effects of polyethylene glycol conjugated superoxide dismutase (PEG-SOD, an enzyme catalysing the conversion of O2.- to H2O2) and polyethylene glycol conjugated catalase (PEG-catalase, accelerating the reaction of H2O2 to H2O and O2) upon coxsackievirus B3 (CB3) myocarditis.

METHODS

Two week old male C3H/He mice were inoculated intraperitoneally with 10(3) plaque forming units of CB3. PEG-SOD, 1 x 10(3) U.kg-1 x d-1, and PEG-SOD, 1 x 10(3) U.kg-1 x d-1, plus PEG-catalase, 1 x 10(3) U.kg-1 x d-1, were injected subcutaneously daily on days 0 to 14. Treated groups were compared to the infected control.

RESULTS

On day 7, there were no significant differences in pathological scores among the three groups. On day 14, the cellular infiltration, myocardial necrosis, and calcification scores were significantly lower in the PEG-SOD group and the PEG-SOD plus PEG-catalase group than in the control. There were no significant differences in pathological scores between the PEG-SOD group and the PEG-SOD plus PEG-catalase group. There were no differences in the myocardial virus titres on day 7 among the three groups. On day 14, virus was not detected from the myocardium in any of the three groups.

CONCLUSIONS

The results suggest that superoxide anion is mostly responsible for myocyte injury in CB3 myocarditis in mice, and that hydrogen peroxide formed as a result of dismutation of superoxide anion may not play a significant role in the development of myocarditis. Superoxide anion is one of the most important factors in free radical mediated injury in CB3 myocarditis in mice and the administration of PEG-SOD alone has therapeutic potential in clinical CB3 myocarditis.

The effects of pre-existing coxsackievirus B4 myocardial disease on the expression of coxsackievirus B3 myocarditis

OBJECTIVE

To assess the expression of coxsackievirus B3 (CB3) myocarditis in mice with pre-existing CB4 myocardial disease.

DESIGN

Double blind comparative study of CB3 myocarditis in CD1 mice with or without prior CB4 induced cardiac damage.

INTERVENTIONS

Antecedent myocardial injury was produced by CB4 infection intraperitoneally at age two days. Two to three weeks later, when CB4 myocarditis was established, infected and control animals were inoculated intraperitoneally with CB3. They were then sacrificed over a 45-day period. Virus and neutralizing antibody titres were measured on days 3 and 13 after CB3 infection, respectively. The incidence of myocarditis and the intensity of histopathological changes (assessed according to a semiquantitative grading scale from 0 to 4) over a 45-day period were compared.

MAIN RESULTS

Among animals with prior CB4 disease, CB3 titres were lower (2.3 +/- 1.7 versus 3.6 +/- 0.8, tissue culture infective dose 50, P = 0.05) and neutralizing antibody response was slightly higher. The incidence of myocarditis was diminished (59.1 versus 89.3%, P = 0.01) and the indices of pathological changes were lower but the differences were not significant (0.68 +/- .54 versus 1.10 +/- 0.20, 1.38 +/- 0.43 versus 1.50 +/- 0.25, 0.56 +/- 0.56 versus 1.26 +/- 0.75, 0.38 +/- 0.58 versus 1.30 +/- 0.78, 0.12 +/- 0.28 versus 0.47 +/- 0.2 on days 3, 9, 13, 30 and 45 post infection, respectively, P > 0.1).

CONCLUSION

These results demonstrate that prior exposure to CB4 offers some protection from subsequent CB3 infection. Moreover, they show that antecedent CB4 myocardial damage does not predispose to a worsened expression of CB3 myocarditis.