Stretch-induced changes in heart rate and rhythm: clinical observations, experiments and mathematical models

Clinical and research data indicate that active and passive changes in the mechanical environment of the heart are capable of influencing both the ini tiation and the spread of cardiac excitation via pathways that are intrinsi c to the heart. This direction of the cross-talk between cardiac electrical and mechanical activity is referred to as mechano-electric feedback (MEF). MEF is thought to be involved in the adjustment of heart rate to changes i n mechanical load and would help to explain the precise beat-to-beat regula tion of cardiac performance as it occurs even in the recently transplanted (and, thus, denervated) heart. Furthermore, there is clinical evidence that MEF may be involved in mechanical initiation of arrhythmias and fibrillati on, as well as in the re-setting of disturbed heart rhythm by 'mechanical' first aid procedures. This review will outline the clinical relevance of ca rdiac MEF, describe cellular correlates to the responses observed in situ, and discuss the role that quantitative mathematical models may play in iden tifying the involvement of cardiac MEF in the regulation of heart rate and rhythm. (C) 1998 Elsevier Science Ltd. All rights reserved.