Heritability of cardiac autonomic balance from ambulatory re-cordings in a large-scale twin sample

G. Willemsen, N. Kupper, D.I. Boomsma and E.J.C. de Geus

Department of Biological Psychology, Vrije Universiteit, Amsterdam, The Netherlands

Cardiac disease has been associated with a distinct shift in the autonomic control over the heart; parasympathetic activity is decreased, while sympathetic activity is increased. Laboratory studies have shown individual differences in parasympathetic activation, such as respiratory sinus arrhythmia (RSA), to be partly genetically determined. Little is known however about the heritability of indices of sympathetic control over cardiac contractility, such as pre-ejection period (PEP). Moreover, the contribution of genetic and environmental factors to the variation in autonomic activation has not yet been investigated during prolonged periods of ambulatory monitoring in a naturalistic setting. Using the VU-AMS, we recorded ambulatory ECG and thorax impedance signals during 24 hours in 790 healthy twins and their singleton siblings. Average PEP and RSA was determined for four periods of the day (morning, afternoon, evening, night). Multivariate genetic analyses showed signi.cant heritability at all daily periods for PEP (48 to 62%) and RSA (40% to 55%). In conclusion, ambulatory measured indices of autonomic balance show substantial heritability at all periods of the day and during sleep..

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.

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