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. Author manuscript; available in PMC: 2024 Mar 1.
Published in final edited form as: JACC Clin Electrophysiol. 2022 Nov 30;9(3):359–370. doi: 10.1016/j.jacep.2022.10.010

Figure 4. Central Illustration.

Figure 4.

Summary heart rate variability (HRV) findings with graphical explanation of inferred underlying cellular processes. Prospective cross-sectional study of Williams-Beuren Syndrome subjects(n=18) and age/sex matched controls(n=18) reveal autonomic abnormalities that suggest increased sudden death risk: increased sympathetic activity, diminished parasympathetic activity and diminished HRV. Cardiomyocyte firing rate and contractility are modulated by sympathetic and parasympathetic inputs via PKA phosphorylation of calcium handling proteins (L-type Ca2+channel(LTCC), ryanodine receptor (RYR), and phospholamban’s (PLB) effects on smooth ER Ca2+ ATPase (SERCA) that can significantly increase arrhythmia and sudden death risk. Heart rate variability (HRV) analysis enables quantification of sympathetic and parasympathetic activity for subsequent risk stratification.