The pathogenesis of dilated cardiomyopathy.

Using the WHO/ISFC definition and recommendations of nomenclature for cardiomyopathies, the aetiology is unknown. Over many years research has concentrated on defining pathogenetic mechanisms and owing to the widespread use of the bioptome-permitting recovery of fresh endomyocardial tissue-myocarditis has emerged as being intimately involved in the pathogenesis of dilated cardiomyopathy. In approximately 2,000 patients with a presumed diagnosis of dilated cardiomyopathy, myocarditis was found in 28% of these cases. The morphological diagnosis of myocarditis has been fraught with difficulties and, in attempt to establish criteria for its recognition, a group of cardiovascular pathologists (the author among them) met in Dallas in 1984. These criteria are detailed and categorization into acute, resolving (healing) and resolved (healed) has been emphasized because of important therapeutic implications. The cause of myocarditis has been established as being due to coxsackie B viruses. Up to recent times such findings could only be surmised by investigations such as micro-neutralization tests. It was not until the hydridization probe was employed that direct proof was provided. These studies together with immunological consequences continue to be investigated in the hope of providing a rational approach to therapy.