Primary and secondary cardioneuropathies and their functional significance

For most functions of the heart its nerves are as important as its coronary arteries, but this is particularly true concerning cardiac rhythm, conduction and repolarization. It is thus paradoxical that postmortem correlative studies of sudden death virtually always include careful scrutiny of the coronary arteries but only rarely of the cardiac nerves or ganglia. In this review, abnormalities of the cardiac nerves and ganglia, collectively termed cardioneuropathies, are examined from the dual standpoint of their structural appearance and functional significance. Some cardioneuropathies are found in the absence of any other significant structural abnormality detectable in the heart and these are designated as primary cardioneuropathies. A viral etiology or some heritable disorder must rank high among possible causes. Secondary cardioneuropathies are those observed in association with almost every disease that can affect the heart; examples include myocardial infarction, infections, amyloidosis and cancer, but there are many others. Because abnormalities of the heart's nerves and ganglia not only have their own unstabilizing influence on cardiac electrical activity but can also profoundly alter a patient's responses to pharmacologic treatment, it is hoped that future clinicopathologic examinations will more often include their careful study and thereby add to our meager knowledge about these important structures.