Myocardial Disease: Difference between revisions

The identification of the genetic background of HCM resulted in the hypothesis that HCM is a disease of the sarcomere; the contractile unit of the cell. First, mutations were found in the cardiac B-myosin heavy chain gene, while later on other sarcomeric proteins were found to play a role in HCM (Table 1).

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! Table 1. Sarcomeric genes associated with HCM

Two-dimensional echocardiography is the easiest diagnostic modality for detection of HCM, (Table 2) but cardiac magnetic resonance imaging (CMR) may be used when echocardiography is inconclusive, acoustic windows are insufficient, or when more detailed anatomic information is needed for clinical decision making. Echocardiographic characteristics include thickening of the left ventricular wall without cavity dilatation, and a normal or hyperdynamic left ventricle. Left ventricular outflow tract obstruction is not mandatory for the diagnosis of HCM. Moreover, as mentioned previously, although the diagnosis of HCM is based on a cut-off value for maximal wall thickness of 15 mm in the overall population, multiple HCM-linked mutations are associated with only minor LVH, but represent a high risk of sudden cardiac death.  

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!Table 2. Echocardiographic diagnostic criteria for HCM in first-degree relatives of index cases with HCM :

Electrocardiographic signs of HCM are typical as the increase in myocardial tissue increases the size of the QRS complexes. Therefore, a typical ECG characteristic of HCM is that it meets voltage criteria for LVH, and shows changes in repolarization (Table 3).

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!Table 3. Electrocardiographic diagnostic criteria for HCM in first-degree relatives of index cases with HCM :

An important differentiation is that between RCM and constrictive pericarditis. Constrictive pericarditis is similarly characterized by impaired ventricular filling with preserved systolic function, but may be adequately treated by pericardiectomy, which makes this distinction of major clinical importance.

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!Table 5 - Classification of Restrictive Cardiomyopathy  

ARVC is a difficult diagnosis to make. Therefore, the European Society of Cardiology has created a list of diagnostic criteria for the diagnosis of ARVC, which were updated in 2009 (Table 6). An [http://www.arvc.ca/pdg/public.php?rep=arvc_cri online calculator] can help in assessing the risk in an individual patient.  

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! Table 6. The Revised Task Force Criteria for ARVD / ARVC Revised Task Force Criteria