14th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 2000

Jan. 29 - Feb. 5, 2000
Marilleva, Trento, Italy

RT-20

Hypertrophic cardiomyopathy and sudden death in the young

Cristina Basso, Domenico Corrado, Gaetano Thiene.
Department of Pathology, University of Padua Medical School, Padua, Italy

Pathology

Left ventricular concentric hypertrophy, whether asymmetric or symmetric, with increased heart weight not explained by any cause of overload, is the usual finding^2,3. Septal asymmetric hypertrophy, located either in the basal portion or in the mid septum, and bulging into the left ventricular outflow tract, is by far the most frequent variety. Other localised forms of asymmetric hypertrophy at the apex and free wall have been reported. The septal asymmetric variety almost regularly shows an endocardial plaque, mirror image to the septal leaflet of the mitral valve, which is pushed against the bulging hypertrophy during the systolic anterior motion. The symmetric form of HCM is less frequent (nearly 10-20%) and usually does not exhibit subaortic endocardial plaque. It seems less severe than the asymmetric one, since it has been observed mostly in old patients with HCM. Congenital coronary artery anomalies, either in the origin or along with the epicardial course (myo-cardial bridging) have been reported in association with HCM; they may contribute to precipitate cardiac arrest through an ischemic event.

Structural disorganisation of myocardial fascicles and myocytes in the forms of myocardial disarray, involving at least 5% of septal tissue section, is considered to be the pathognomonic histologic feature of HCM⁴. Myocyte hypertrophy, bizzare nuclei and various degree of interstitial and replacement-type fibrosis are accompanying microscopic features. Small vessel disease, in the form of intimal hyperplasia, medial hypertrophy and fragmentation of internal elastic membrane of intramural arteries, is a frequent observation⁵, but rarely accounts for significant lumen size reduction.