RMSSD, a measure of vagus-mediated heart rate variability, is associated with risk factors for SUDEP: The SUDEP-7 Inventory

Abstract

Objective To determine if specific measures of heart rate variability (HRV) are associated with the total score on a seven-item inventory for Sudden Unexplained Death in Epilepsy (SUDEP). Methods Nineteen subjects with intractable partial seizures, at least three per month, were enrolled in a randomized clinical trial of omega-3 fatty acids in epilepsy. At study entry, subjects underwent a 1-hour ECG recording for the determination of HRV. To estimate the risk of SUDEP, we assembled a seven-item inventory (The SUDEP-7 Inventory) from risk factors prospectively validated by Walczak al. [6] The SUDEP-7 score was then correlated with measures of HRV using the Pearson Correlation and other parametric and non-parametric methods. Results Subjects were highly refractory, with a mean seizure frequency of 22.8 seizures per month. Scores on the SUDEP-7 inventory ranged from 1 – 7 of a maximum possible score of 12. RMSSD, a measure of high frequency HRV was inversely correlated with the SUDEP-7 score, r = −0.64, p =0.004. Subjects with higher SUDEP-7 scores had reduced levels of HRV (RMSSD). Other time-dependent measures of HRV (SDNN, SDANN) were not significantly correlated with SUDEP risk scores. Conclusions RMSSD, a measure of HRV, which reflects the integrity of vagus nerve-mediated autonomic control of the heart, is highly associated with the total score on a new 7-item SUDEP risk inventory. Lower RMSSD values were associated with higher risk scores on a new SUDEP risk inventory. This provides new evidence that HRV (specifically RMSSD) is a marker of SUDEP risk.

Severe peri-ictal respiratory dysfunction is common in Dravet syndrome

“…A variety of mechanisms have been proposed for SUDEP (1,2,(4)(5)(6), including cardiac arrhythmias (7)(8)(9)(10), dysfunction of autonomic control (11)(12)(13)(14)(15), apnea/hypoventilation (3,(16)(17)(18)(19)(20)(21), airway obstruction (22), pulmonary edema (23), brain stem spreading depolarization (BSD) (24), and postictal generalized EEG suppression (PGES) (25). Many investigators have focused on cardiac tachyarrhythmias as the cause of death, in part because of an association between SUDEP and mutations of genes expressed in the heart, such as those that underlie long QT syndrome (10,(26)(27)(28).…”

Can natural ways to stimulate the vagus nerve improve seizure control?

“…RMSSD was then correlated with SUDEP-7 inventory, which is a measure that reflects the severity of epilepsy -the number of seizures, the duration of epilepsy and the number of AEDs used. The study found a significant inverse correlation between RMSSD and SUDEP-7 scores, suggesting that more severe epilepsy is associated with poorer parasympathetic autonomic function [20]. In another study of 61 subjects, those with intractable epilepsy had greater sympathetic and lower parasympathetic tone compared to those with well-controlled epilepsy [15].…”

Energy expenditure in frontotemporal dementia: a behavioural and imaging study

“…Resting and stressed heart rates and measures of autonomic function were obtained after entering the beat-to-beat RR interval data obtained by the Actiheart into Kubios HRV, an advanced and easy to use software for heart rate variability (HRV) analysis (Tarvainen et al, 2014). The following measurements were obtained: the root mean squared of successive differences (RMSSD), which is a measure of vagal control of the heart (DeGiorgio et al, 2010); the low frequency (LF), which corresponds to the 0.10 Hz slow fluctuations of arterial pressure and reflects sympathetic and parasympathetic tone; the high frequency (HF), which corresponds to $0.25 Hz fluctuations and is a measure of respiratory sinus arrhythmias and can be considered an index of vagal modulation; and the LF/HF ratio, which is used to indicate balance between sympathetic and parasympathetic tone.…”