Cardiac innervation, neonatal electrocardiography, and SIDS. A key for a novel preventive strategy?

The present decade is finally witnessing large and controlled prospective studies designed to test specific mechanisms proposed for SIDS. The respiratory and the cardiac mechanisms are not at all mutually exclusive, as a defect in the control of respiration may trigger a lethal cardiac arrhythmia, given the appropriate substrate (decreased cardiac electrical stability). These two mechanisms seem to be the largest contributors to the whole of SIDS, even if their respective importance still remains to be quantified. It would be logical to concentrate the research efforts on them before extensively investigating other, less likely possibilities. It is important that the idea of the multifactorial origin of SIDS, with all of its implications, be accepted by the interested investigators. One critical implication is the factor that SIDS will never be completely eliminated, because it will be impossible to deal appropriately with all its potential causes. On the other hand, important and rewarding success may be achieved by progressively removing, after appropriate identification, those factors that produce a substantial number of SIDS deaths. The concepts and data presented here indicate that the sympathetic imbalance hypothesis, although not yet proven, has gained plausibility on the basis of current knowledge. The potential for the early identification of some future SIDS victims and the likelihood, if the hypothesis is correct, of developing an effective and safe preventive strategy make even more necessary an accurate and unbiased evaluation of the cardiac hypothesis.