The impacts of age and frailty on heart rate and sinoatrial node function

Abstract

Sinoatrial node (SAN) dysfunction increases with age, although not all older adults are affected in the same way. This is because people age at different rates and individuals of the same chronological age vary in health status from very fit to very frail. Our objective was to determine the impacts of age and frailty on heart rate (HR) and SAN function using a new model of frailty in ageing mice. Frailty, which was quantified in young and aged mice using a frailty index (FI), was greater in aged vs. young mice. Intracardiac electrophysiology demonstrated that HR was reduced whereas SAN recovery time (SNRT) was prolonged in aged mice; however, both parameters showed heteroscedasticity suggesting differences in health status among mice of similar chronological age. Consistent with this, HR and corrected SNRT were correlated with, and graded by, FI score. Optical mapping of the SAN demonstrated that conduction velocity (CV) was reduced in aged hearts in association with reductions in diastolic depolarization (DD) slope and action potential (AP) duration. In agreement with in vivo results, SAN CV, DD slope and AP durations all correlated with FI score. Finally, SAN dysfunction in aged mice was associated with increased interstitial fibrosis and alterations in expression of matrix metalloproteinases, which also correlated with frailty. These findings demonstrate that age-related SAN dysfunction occurs in association with electrical and structural remodelling and that frailty is a critical determinant of health status of similarly aged animals that correlates with changes in HR and SAN function.

Heart rate and early progression of cardiac allograft vasculopathy: A prospective study using highly automated 3‐D optical coherence tomography analysis

“…The association we observed between younger donor age and higher HR at M1 after HTx is in agreement with previous studies . A likely explanation for such a finding is sinus node dysfunction, which increases in prevalence during aging and commonly occurs in older adults, as demonstrated by the decline in intrinsic HR …”

“…9,10 A likely explanation for such a finding is sinus node dysfunction, which increases in prevalence during aging and commonly occurs in older adults, as demonstrated by the decline in intrinsic HR. 29 Despite its detrimental effect on the exercise capacity of HTx patients, 30 beta-blocker treatment might be of benefit. Compared to other studies, 5,26 a relatively high proportion of patients in our cohort were prescribed beta blockers (51.7% at M1, 66.4% at M12).…”

Aging Modulates the Substrate and Triggers Remodeling in Atrial Fibrillation

“…71 HR is reduced whereas SAN recovery time, a direct measure of SAN function, is prolonged in the aged human or animal. 35, 72 Animal studies reveal downregulation of hyperpolarization-activated cyclic nucleotide gated potassium channel 4 (HCN4), diminished expression of the Cav1.2 protein, and loss of Cx43 with increased distance travelled by the impulse generated at the center of the aged SAN to …”

Alpinate Oxyphyllae extracts enhance the longevity and homing of mesenchymal stem cells and augment their protection against senescence in H9c2 cells

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