Beat‐to‐Beat QT Interval Variability Is Primarily Affected by the Autonomic Nervous System

Mine, Takanao; Shimizu, Hiroki; Hiromoto, Kenji; Furukawa, Yoichi; Kanemori, Tetsuzou; Nakamura, Hiroaki; Masuyama, Tohru; Ohyanagi, Mitsumasa

doi:10.1111/j.1542-474x.2008.00225.x

Cited by 22 publications

(24 citation statements)

References 18 publications

(13 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…groups with tetraplegia and high paraplegia). Our report corroborates previous findings on the effect of autonomic modulation and age on QTVI [12], but is in stark contrast to others, in that the primary autonomic dysfunction in SCI is the result of a traumatic neurological injury (presumed) and not a byproduct of an end-organ disease process or burden [15,16,17,18,19]. …”

Section: Discussionsupporting

confidence: 79%

The QT Variability Index and Cardiac Autonomic Modulation: Perspectives from Apparently Healthy Men with Spinal Cord Injury

Fountaine¹,

Wecht²,

Rosado-Rivera

et al. 2010

Cardiology

View full text Add to dashboard Cite

Objective: To describe the effect of spinal cord injury (SCI) on the QT variability index (QTVI). Methods: Digital electrocardiograms from 113 age-matched men (40 with tetraplegia, 26 with high paraplegia, 17 low paraplegia and 31 controls) were analyzed. RR interval, heart rate (HR) variability [total power (TP_RR), low frequency (LF_RR) and high frequency (HF_RR)], QT interval duration, Bazett HR-corrected QT (QTc), QT interval variance (QTVN) and QTVI were compared. Results: Significant group main effects were present for RR, QTc, TP_RR and LF_RR, but not QT duration, QTVN or HF_RR. Post hoc comparisons revealed the following: (1) longer RR in controls versus subjects with high paraplegia and low paraplegia, and in subjects with tetraplegia versus high paraplegia and low paraplegia; (2) QTc was longer in subjects with low paraplegia versus controls and shorter in subjects with tetraplegia versus high paraplegia, and (3) TP_RR and LF_RR were different in controls and subjects with high paraplegia compared to those with low paraplegia. QTVI was significantly elevated in all SCI groups compared to controls. Significant negative correlations between QTVI and HF_RR were observed in all SCI groups, and TP_RR and LF_RR in subjects with tetraplegia and high paraplegia only. Age was negatively correlated in controls. Conclusions: QTVI is negatively affected in otherwise healthy SCI men compared to age-matched controls. This observation appears to reflect the attenuation of vagal modulation, sympathetic impairment above the sixth thoracic vertebra and/or a heightened degree of cardiovascular disease risk.

show abstract

Section: Discussionsupporting

confidence: 79%

The QT Variability Index and Cardiac Autonomic Modulation: Perspectives from Apparently Healthy Men with Spinal Cord Injury

Fountaine¹,

Wecht²,

Rosado-Rivera

et al. 2010

Cardiology

View full text Add to dashboard Cite

show abstract

“…In support of this view, patients with autonomic failure and heterogeneous autonomic denervation showed prolonged QT intervals and increased spatial QT dispersion (8). ␤-Adrenoceptor activation by isoprotenerol has been shown to increase beat-to-beat QT variability in healthy subjects during sinus rhythm (35), and ␤-adrenoceptor blockade with propranolol decreased QT variability during atrial pacing in patients without structural heart disease, observations suggestive that QT variability is modulated by the sympathetic nervous system (23). However, a study of left stellate-ganglion activity in healthy dogs showed no correlation with QT variability (28), indicating that spontaneous QT variability in the normal heart is not notably affected by the sympathetic outflow to the ventricular myocardium.…”

Section: Discussionmentioning

confidence: 84%

“…A recent study in dogs showed that QT variability was related to left stellate-ganglion activity, but only after the dogs had developed heart failure (28). In healthy humans, pharmacological activation or blockade of ␤-adrenoreceptors augmented and reduced QT variability, respectively (23,35). Cardiac norepinephrine (NE) spillover, the most direct index of cardiac sympathetic activity, had no association with QT variability in patients with panic disorder and depression, patients who were free of current underlying cardiovascular disease (2).…”

mentioning

confidence: 99%

Relation between QT interval variability and cardiac sympathetic activity in hypertension

Baumert

Schlaich

Nalivaiko

et al. 2011

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

vated QT interval variability is a predictor of malignant ventricular arrhythmia, but the underlying mechanisms are incompletely understood. A recent study in dogs with pacing-induced heart failure suggests that QT variability is linked to cardiac sympathetic nerve activity. The aim of this study was to determine whether increased cardiac sympathetic activity is associated with increased beat-to-beat QT interval variability in patients with essential hypertension. We recorded resting norepinephrine (NE) spillover into the coronary sinus and single-lead, short-term, high-resolution, body-surface ECG in 23 patients with essential hypertension and 9 normotensive control subjects. To assess beat-to-beat QT interval variability, we calculated the overall QT variability (QTVN) as well as the QT variability index (QTVi). Cardiac NE spillover (12.2 Ϯ 6.5 vs. 20.7 Ϯ 14.7, P ϭ 0.03) and QTVi (Ϫ1.75 Ϯ 0.36 vs. Ϫ1.42 Ϯ 0.50, P ϭ 0.05) were significantly increased in hypertensive patients compared with normotensive subjects. QTVN was significantly correlated with cardiac NE spillover (r 2 ϭ 0.31, P ϭ 0.001), with RR variability (r 2 ϭ 0.20, P ϭ 0.008), and with systolic blood pressure (r 2 ϭ 0.16, P ϭ 0.02). Linear regression analysis identified the former two as independent predictors of QTVN. In conclusion, elevated repolarization lability is directly associated with sympathetic cardiac activation in patients with essential hypertension. norepinephrine spillover THE QT INTERVAL OF THE BODY surface ECG reflects global depolarization and repolarization in the ventricular myocardium and undergoes subtle beat-to-beat fluctuations (9). Elevated beat-to-beat QT interval variability has been demonstrated in various cardiac (6, 26) but also noncardiac conditions (4, 36). Importantly, QT variability has been shown to be elevated in dogs before pharmacologically induced Torsades de Pointes (32, 34) and in patients with structural heart disease before ventricular tachycardia/ventricular fibrillation events (33). Furthermore, QT variability was associated with an increased risk of ventricular tachycardia/ventricular fibrillation in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial (MADIT) II (17) and was predictive of sudden cardiac death in patients with asymptomatic chronic heart failure with mild to moderate left ventricular (LV) diastolic dysfunction (27). However, the mechanisms contributing to beat-to-beat QT interval variability are incompletely understood. Besides electrical restitution, which reflects the intrinsic adaptation of the action potential duration to changes in cycle length (14), the autonomic nervous system is thought to play a key role in the genesis of beat-to-beat QT interval variability. Previous studies addressing this issue have provided conflicting results. A recent study in dogs showed that QT variability was related to left stellate-ganglion activity, but only after the dogs had developed heart failure (28). In healthy humans, pharmacological activation or blockade of ␤-adren...

show abstract

“…Pharmacologic sympathetic activation/block and orthostatic challenge have shown to affect QT variability. 11,12 Spontaneous QTV appears to be reflective of sympathetic activation, but only when a cardiovascular morbidity exists. 13,15 In most previous studies, QTV has been reported only for a single lead.…”

mentioning

confidence: 99%

Relation between Beat‐to‐Beat QT Interval Variability and T‐Wave Amplitude in Healthy Subjects

Hasan¹,

Abbott²,

Baumert³

2012

Noninvasive Electrocardiol

View full text Add to dashboard Cite

Objectives: Elevated beat-to-beat QT interval variability (QTV) has been associated with increased cardiovascular morbidity and mortality.The aim of this study was to investigate interlead differences in beat-to-beat QTV of 12-lead ECG and its relationship with the T wave amplitude.Methods: Short-term 12-lead ECGs of 72 healthy subjects (17 f, 38 ± 14 years; 55 m, 39 ± 13 years) were studied. Beat-to-beat QT intervals were extracted separately for each lead using a template matching algorithm. We calculated the standard deviation of beat-to-beat QT intervals as a marker of QTV as well as interlead correlation coefficients. In addition, we measured the median T-wave amplitude in each lead.Results: There was a significant difference in the standard deviation of beat-to-beat QT intervals between leads (minimum: lead V 3 (2.58 ± 1.36 ms), maximum: lead III (7.2 ± 6.4 ms), ANOVA: P < 0.0001). Single measure intraclass correlation coefficients of beat-to-beat QT intervals were 0.27 ± 0.18. Interlead correlation coefficients varied between 0.08 ± 0.33 for lead III and lead V 1 and 0.88 ± 0.09 for lead II and lead aVR. QTV was negatively correlated with the T-wave amplitude (r = -0.62, P < 0.0001). There was no significant affect of mean heart rate, age or gender on QT variability (ANOVA: P > 0.05).

show abstract

Beat‐to‐Beat QT Interval Variability Is Primarily Affected by the Autonomic Nervous System

Abstract: Beat-to-beat QT interval variability is affected by drugs that modulate the autonomic nervous system.

Cited by 22 publications

References 18 publications

The QT Variability Index and Cardiac Autonomic Modulation: Perspectives from Apparently Healthy Men with Spinal Cord Injury

The QT Variability Index and Cardiac Autonomic Modulation: Perspectives from Apparently Healthy Men with Spinal Cord Injury

Relation between QT interval variability and cardiac sympathetic activity in hypertension

Relation between Beat‐to‐Beat QT Interval Variability and T‐Wave Amplitude in Healthy Subjects

Contact Info

Product

Resources

About