THE Q‐II INTERVAL. III. A STUDY OF THE SECOND HEART SOUND IN OLD AGE*

A bstract A study of the intervals between the onset of QRS and the aortic (IIA and pulmonic (IIP) components of the second heart sound was made in 16 subjects between 70 and 92 years of age. A group tendency toward prolongation of both Q‐IIA and Q‐IIP was found. The relatively greater prolongation of left over right ventricular systole or vice versa gave rise to reverse‐type splitting (25 per cent) or a single second sound (38 per cent) respectively; normal splitting was found in 37 per cent of the cases. The various possible causes of prolongation of these intervals are discussed. As neither diastolic hypertension nor severe ischemic heart disease was present in the group with reverse splitting, this manifestation would seem to be the result of the process of aging. Prolongation of the pre‐ejection period was an important contributory factor in some cases. On the basis of these findings, new formulas were developed for prediction of Q‐IIA and Q‐IIP which would be applicable to elderly persons.