A case of Arrhythmogenic right ventricular cardiomyopathy without arrhythmias
© Wei et al.; licensee BioMed Central Ltd. 2012
Received: 17 April 2012
Accepted: 31 May 2012
Published: 12 June 2012
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by recurrent coma, ventricular tachycardias and the replacement of the myocardium with fatty and fibrous tissue. We described a 42-year-old female patient without clinical arrhythmias which was diagnosed as ARVC by magnetic resonance imaging (MRI), but the transvenous endomyocardial biopsy was not specific. The patient received heart transplantation due to her refractory heart failure and the pathology of explanted heart demonstrated typical replacement of fatty and fibrous tissue and piles of infiltrated lymphocytes in myocardial tissue. It is concluded that ARVC might not have any arrhythmias and inflammatory process may be involved in the mechanism of ARVC.
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Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heart muscle disease clinically characterized by life-threatening ventricular arrhythmias. It involves progressive fibrous and fatty replacement of myocardium in the inflow, apical and outflow portions of the right ventricle, resulting in ventricular tachycardia with incurrent risk of sudden death and in a proportion of cases, progressive RV dysfunction[1–5]. The ARVC without arrhythmias has not been documented and hence has been easily misdiagnosed. Consensus diagnostic criteria were developed which included MRI, echocardiography, electrocardiography and right ventricular biopsy. The right ventricular biopsy, however, often gives a false-negative result because of the segmental nature of ARVC[7, 8]. In this paper, we reported a case of ARVC without arrthymias which was initially misdiagnosed as dilated cardiomyopathy but later the MRI and pathology examination of the explanted heart have proved ARVC as correct diagnosis in this atypical case. The significance of MRI and possible mechanism of ARVC were discussed.
ARVC is a disease pathologically characterized by fibrofatty replacement of the RV myocardium. A broad range of symptoms and signs may occur including palpitations, fatigue, syncope, chest pain and all kinds of atrial and rapid ventricular arrhythmias, especially recurrent episodes of ventricular tachycardias. Few patients presented the chronic congestive cardiac failure as chief complaint which is often confused with symptoms of mildly dilated cardiomyopathy. The clinical diagnosis of ARVC without any arrhythmias is very difficult. Transvenous endomyocardial biopsy may be of great help for an in vivo morphological demonstration of fibro-fatty myocardial replacement, but recent studies have shown a high degree of interobserver variability in assessing fatty deposition, which may be observed even in normal hearts. Endomyocardial biopsy lacks sufficient sensitivity because of the segmental nature of the disease process. Many clinicians biopsy the septum rather than the free wall of the right ventricle to avoid the risk of perforation just as this case. Correct pathological interpretation requires that a sufficient amount of myocardium be obtained without crush artifact and processed for the necessary histological, immunohistological and/or molecular diagnostic tests. MRI, however, has been proved as a specific and sensitive examination technique in diagnosis of some atypical cases of ARVC[8, 12]. It can detect right ventricular dilatation and aneurysm formation as well as wall-motion abnormalities including right ventricular dyskinesia; moreover, the black blood spin-echo sequences have provided excellent anatomic detail via suppressing-fat technique in our previous studies[13, 14] and this technique has become the most important tool for the detection of fat and remnant myocardium in the right ventricular myocardium.
The etiology of ARVC is still unclear. Bowles et al found that cardiotropic viruses are more frequently identified in patients with ARVC and have been claimed to support an infective etiology of this disease. But the role of these viruses in ARVC pathogenesis remains unknown. Myocardial inflammation may be seen in up to 75% of hearts at autopsy, and probably it plays a role in triggering ventricular tachyarrhythmias. The pathology of explanted heart in this case showed massive focal inflammatory cells infiltration and this finding may be correlated with pathogenesis of myocardium loss and/or apoptosis. The positive results of anti-myocardial antibody test (M2 and MHC) revealed autoimmune mechanism may be involved in the pathogenesis of ARVC. In addition, ARVC should not be regarded as the disease only confined within right ventricle. Corrado et al reported that macroscopic or histologic involvement of the left ventricle was found in 76% of hearts with ARVC. By autopsy of fifty ARVC cases, it is suggested that ventricular distribution is typically biventricular and the most common locations of left ventricular involvement are the posterolateral walls in a subepicardial distribution. Our pathology confirmed the involvement of left ventricle and interventricular septum. Importantly, our case presented heart failure and pathologically right ventricular enlargement and replacement of myocardium by diffuse fibrofatty tissues as well as massive small lymphocytic infiltration. However, the patient has no tachyarrythmias that was defined as characterization of ARVC.
Transplantation indications for ARVC have not been defined. In some refractory congestive heart failure, cardiac transplantation is the only therapeutic option[18–20]. Our seven years follow-up has greatly proved the effectiveness of the heart transplantation for ARVC patient.
In conclusion, ARVC without arrhythmias is rare and easily misdiagnosed. Cardiac MRI has become a non-invasive imaging tool in diagnosis of ARVC with high sensitivity and specificity. Inflammatory process may be involved in the mechanism of ARVC.
Written informed consent was obtained from the patient for publication of this Case Report and any accompanying images. A copy of written consent is available for review by the Editor-in-Chief of this journal.
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