Is regional wall stress a stimulus for myocardial hypertrophy in hypertrophic cardiomyopathy?
To answer the question of whether regional wall stress may be a stimulus for myocardial hypertrophy in hypertrophic cardiomyopathy, we have to firstly look at the nature of dynamic outflow tract obstruction and its influence on left ventricular wall stress. We may discriminate two types of outflow tract obstruction: type A, in which peak wall stress occurs before the onset of obstruction and type B, in which it occurs afterwards. Only in type B could one expect that obstruction could have any influence on wall stress. In type B the obstruction is more severe and occurs earlier than in type A. Secondly, to say something about regional wall stress, we should look at the morphology of the left ventricular wall. We have found magnetic resonance imaging to be an accurate and comprehensive way of looking at this. We may discriminate four types of left ventricular wall morphology in hypertrophic cardiomyopathy: (a) the anteroseptal type, (b) the upper septal type, (c) the midseptal type, (d) the apicolateral type. Only in the upper septal type is outflow tract obstruction found. However, posterior wall thickness, as a measure of hypertrophy, is not different in these patients from posterior wall thickness in types c and d, in which no obstruction is found. Also, no difference is found in cross-sectional area in the long axis plane between types b, c and d. Only in type a, which seems to represent a less seriously affected group, posterior wall thickness and cross-sectional area are less than in the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)
D006332:Cardiomegaly / Q000209:etiology*; D002312:Cardiomyopathy, Hypertrophic / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D003331:Coronary Vessels / Q000473:pathology; D006321:Heart / Q000502:physiology*; D006352:Heart Ventricles; D006801:Humans; D013314:Stress, Mechanical; D014694:Ventricular Outflow Obstruction / Q000503:physiopathology