A 3-dimensional analysis of modes of cardiovascular adaptation: concepts, methods and preliminary findings

Objective: To present a 3-dimensional approach to displaying and interpreti ng processes of cardiovascular adaptation. Design: Laboratory study of blood pressure changes in response to a protoco l set in advance. The authors plotted the coordinates of 3711 cardiovascula r change events (CVCEs) in 3-dimensional space defined by changes in systol ic blood pressure, diastolic blood pressure and heart rate. This was follow ed by cluster analyses and preliminary estimates of reliability and constru ct validity. Setting: The teaching hospitals of a large southwestern US medical centre. Participants: Approximately 100 female nursing personnel aged 25 to 50 year s. Interventions: Medical history, self-administered questionnaires, laborator y protocol of presser challenges, rest periods. Results: Nine distinct clusters ("species of response") were identified and replicated in randomly chosen halves of the sample. Postural, isomorphic a nd psychologic challenges generated several distinctive profiles of "rising " responses, and were also followed by distinctive "declining" responses. T he frequencies of various cardiovascular reactions ("clusters") to the same protocol were correlated with psychosocial characteristics and hypertensio n risk indicators. Conclusions: The 3-dimensional approach reveals many features of cardiovasc ular adaptation not discernible from traditional univariate displays and an alyses. This paradigm might prove useful for matching patients with hyperte nsion by their cluster patterns to their most suitable medication, but it r equires further validation by direct hemodynamic measurements.