Research ArticleHeart Disease

Redundant and diverse intranodal pacemakers and conduction pathways protect the human sinoatrial node from failure

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Science Translational Medicine  26 Jul 2017:
Vol. 9, Issue 400, eaam5607
DOI: 10.1126/scitranslmed.aam5607

Keeping the beat

The human heart beats more than 100,000 times per day. Arrhythmia, or irregular heartbeat, can occur due to heart disease, changes in diet or hormones, electrolyte imbalances, or for other reasons—but these inconsistencies only infrequently lead to total loss of heart function. Li et al. uncovered how the heart is hardwired to maintain consistency. Optical and molecular mapping of human hearts ex vivo coupled with electrocardiograms and histology revealed that the sinoatrial node is home to multiple pacemakers, specialized cardiomyocytes that generate electrical heartbeat-inducing impulses. This means that multiple conduction pathways can deliver the electrical impulses required for rhythm control, so total cardiac arrest occurs only when all pacemakers and conduction pathways fail. Understanding inherent cardiac robustness may help develop treatments for arrhythmias.

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