Cardiac changes implicated in chronic heart block.

Fifteen cases of chronic heart block were studied. Eight of them could be designated as idiopathic or primary heart block; the others were associated with hypertension, diabetes and ischaemic heart disease, either singly or in various combinations. In six cases, the whole heart was available for histopathological study of the conduction system. In the other 9 cases, only a portion of the heart muscle was available for examination. A V nodal fibrosis extending upto the proximal bundle of His was seen in all the six whole heart autopsy materials. Fibrosis of the adjacent myocardium was seen in five cases. In three cases, conducting system fibrosis was associated with atherosclerotic (1 case) or diabetic changes (3 cases) of the intramural vessels. In the 9 partial autopsy studies, myocardial fibrosis was seen in two cases, diabetic microangiopathy in one and atherosclerotic changes in two including an old thrombus in one. Thus, diabetic microangiopathy was seen in total four cases. These changes may be responsible for the cardiomegaly and cardiac failure associated with conduction defects observed in diabetes. In the idiopathic group also, heart block could be considered as a significant facet of a primary myocardial degenerative process.

The role of thyroid in clinical disorders of hypothalamo-pituitary adrenocortical axis--a prelminary communication.

The study of thyroid function in clinical conditions associated with the disorders of the hypothalamio-pituitary-adrenocortical axis indicated overt hypofunction of thyroid in all the three cases of Cushing's disease and subclinical hypo-or low normal function of thyroid in most of the cases of adrenogenital syndrome. It was suggested that hypo or low normal function of thyroid might facilitate excess elaboration of ACTH through CRF by swaying the balance of neurotransmitters at hypothalamus in favour of serotonin.