scholarly journals Heart Rate Influence on the QT Variability Risk Factors

Diagnostics ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1096
Author(s):  
Irena Andršová ◽  
Katerina Hnatkova ◽  
Martina Šišáková ◽  
Ondřej Toman ◽  
Peter Smetana ◽  
...  
Keyword(s):  
Heart Rate ◽  
Standard Deviation ◽  
Qt Interval ◽  
Healthy Subjects ◽  
Sequential Analysis ◽  
Rr Intervals ◽  
Qt Variability Index ◽  
Qt Variability ◽  
Variability Index ◽  
Qt Interval Variability

QT interval variability, mostly expressed by QT variability index (QTVi), has repeatedly been used in risk diagnostics. Physiologic correlates of QT variability expressions have been little researched especially when measured in short 10-second electrocardiograms (ECGs). This study investigated different QT variability indices, including QTVi and the standard deviation of QT interval durations (SDQT) in 657,287 10-second ECGs recorded in 523 healthy subjects (259 females). The indices were related to the underlying heart rate and to the 10-second standard deviation of RR intervals (SDRR). The analyses showed that both QTVi and SDQT (as well as other QT variability indices) were highly statistically significantly (p < 0.00001) influenced by heart rate and that QTVi showed poor intra-subject reproducibility (coefficient of variance approaching 200%). Furthermore, sequential analysis of regression variance showed that SDQT was more strongly related to the underlying heart rate than to SDRR, and that QTVi was influenced by the underlying heart rate and SDRR more strongly than by SDQT (p < 0.00001 for these comparisons of regression dependency). The study concludes that instead of QTVi, simpler expressions of QT interval variability, such as SDQT, appear preferable for future applications especially if multivariable combination with the underlying heart rate is used.

Influence of age, the autonomic nervous system and anxiety on QT-interval variability

2001 ◽  
Vol 101 (4) ◽  
pp. 429-438 ◽  
Author(s):  
Gianfranco PICCIRILLO ◽  
Mauro CACCIAFESTA ◽  
Marco LIONETTI ◽  
Marialuce NOCCO ◽  
Vincenza DI GIUSEPPE ◽  
...  
Keyword(s):  
Heart Rate ◽  
Qt Interval ◽  
Spectral Power ◽  
Low Frequency ◽  
Elderly Subjects ◽  
Rr Interval ◽  
T Wave ◽  
Qt Variability ◽  
Qt Interval Variability ◽  
Sympathetic Stress

As QT variability increases and heart rate variability diminishes, the QT variability index (QTVI)-a non-invasive measure of beat-to-beat fluctuations in QT interval on a single ECG lead-shows a trend towards positive values. Increased QT variability is a risk factor for sudden death. Aging lengthens the QT interval and reduces RR-interval variability. In the present study we investigated the influence of aging and the autonomic nervous system on QT-interval variability in healthy subjects. We studied 143healthy subjects, and divided them into two age ranges (younger and older than 65 years). For each subject we measured two QTVIs: from the q wave to the end of the T wave (QTeVI) and to the apex of the T wave (QTaVI). Both indexes were calculated at baseline and after sympathetic stress. In 10 non-elderly subjects, both QTVIs were determined after β-adrenoreceptor blockade induced by intravenous infusion of propranolol or sotalol. The QTVI was higher in elderly than in younger subjects (P < 0.001). QTVIs obtained during sympathetic stress remained unchanged in the elderly, but became more negative in the younger group (P < 0.05). QTeVI and QTaVI at baseline were correlated positively with age (P < 0.01) and anxiety scores (P < 0.05), but inversely with the low-frequency spectral power of RR-interval variability (P < 0.001). QTVIs were higher in subjects with higher anxiety scores. In younger subjects, sotalol infusion increased both QTVIs significantly, whereas propranolol infusion did not. In conclusion, aging increases QT-interval variability. Whether this change is associated with an increased risk of sudden death remains unclear. The association of abnormal QT-interval variability with anxiety and with reduced low-frequency spectral power of heart rate variability merits specific investigation. In healthy non-elderly subjects, acute sympathetic stress (tilt) decreases the QTVI. β-Adrenoreceptor blockade inhibits this negative trend, thus showing its sympathetic origin. Because a negative trend in QTVI induced by sympathetic stress increases only in younger subjects, it could represent a protective mechanism that is lost with aging.

Elevated temporal QT variability index in patients with chronic renal failure

2004 ◽  
Vol 107 (6) ◽  
pp. 583-588 ◽  
Author(s):  
Mats JOHANSSON ◽  
Sinsia A. GAO ◽  
Peter FRIBERG ◽  
Marita ANNERSTEDT ◽  
Göran BERGSTRÖM ◽  
...  
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Conservative Treatment ◽  
Sudden Death ◽  
Ventricular Arrhythmia ◽  
Healthy Subjects ◽  
Increased Risk ◽  
Qt Variability Index ◽  
Qt Variability ◽  
Variability Index

Patients with CRF (chronic renal failure) are at increased risk of cardiovascular diseases, and 60% of cardiovascular mortality in CRF is attributed to sudden death. Various abnormalities in myocardial repolarization are associated with the risk of ventricular arrhythmia. The aim of this study was to evaluate an index of temporal myocardial repolarization lability, the temporal QTVI (QT variability index), in patients with CRF. ECGs were recorded in 153 patients with CRF on haemodialysis (n=67), continuous ambulatory peritoneal dialysis (n=43) or conservative treatment (n=43) during 30 min of rest. QTVI was calculated as the logarithm of the ratio between the variances of the normalized QT and RR intervals. Age-matched healthy subjects (n=39) were examined for comparison. QTVI was increased by 47% in CRF patients compared with healthy subjects (−0.82±0.56 compared with −1.54±0.27 respectively; P<0.01). QTVI did not differ among patients on dialysis or conservative treatment, whereas QTVI was elevated further in patients with diabetes compared with non-diabetic CRF patients (−0.56±0.54 compared with −0.94±0.52 respectively; P<0.01). In a multiple linear regression analysis, diabetes and a history of coronary artery disease were the only independent predictors of QTVI in the CRF population. The present study demonstrates that elevated QTVI in patients with CRF is associated with diabetes and coronary disease. The present findings are important given that repolarization instability may predispose to ventricular arrhythmia and sudden death, events that occur frequently in CRF patients.

scholarly journals Transcranial direct current stimulation improves the QT variability index and autonomic cardiac control in healthy subjects older than 60 years

2016 ◽  
Vol Volume 11 ◽  
pp. 1687-1695 ◽  
Author(s):  
Gianfranco Piccirillo ◽  
Cristina Ottaviani ◽  
Claudia Fiorucci ◽  
Nicola Petrocchi ◽  
Federica Moscucci ◽  
...  
Keyword(s):  
Direct Current ◽  
Transcranial Direct Current Stimulation ◽  
Healthy Subjects ◽  
Direct Current Stimulation ◽  
Cardiac Control ◽  
Qt Variability Index ◽  
Qt Variability ◽  
Variability Index

Relation between QT interval variability and cardiac sympathetic activity in hypertension

2011 ◽  
Vol 300 (4) ◽  
pp. H1412-H1417 ◽  
Author(s):  
Mathias Baumert ◽  
Markus P. Schlaich ◽  
Eugene Nalivaiko ◽  
Elisabeth Lambert ◽  
Carolina Ika Sari ◽  
...  
Keyword(s):  
Essential Hypertension ◽  
Qt Interval ◽  
Sympathetic Activity ◽  
Linear Regression Analysis ◽  
Cardiac Sympathetic Activity ◽  
Surface Ecg ◽  
Qt Variability Index ◽  
Qt Variability ◽  
Underlying Mechanisms ◽  
Qt Interval Variability

Elevated 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 ± 6.5 vs. 20.7 ± 14.7, P = 0.03) and QTVi (−1.75 ± 0.36 vs. −1.42 ± 0.50, P = 0.05) were significantly increased in hypertensive patients compared with normotensive subjects. QTVN was significantly correlated with cardiac NE spillover ( r2 = 0.31, P = 0.001), with RR variability ( r2 = 0.20, P = 0.008), and with systolic blood pressure ( r2 = 0.16, P = 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.

scholarly journals A single dose of dark chocolate increases parasympathetic modulation and heart rate variability in healthy subjects

2016 ◽  
Vol 29 (6) ◽  
pp. 765-773 ◽  
Author(s):  
Ana Amélia Machado DUARTE ◽  
Cristiano MOSTARDA ◽  
Maria Claudia IRIGOYEN ◽  
Katya RIGATTO
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Single Dose ◽  
Standard Deviation ◽  
Healthy Subjects ◽  
Frequency Component ◽  
Dark Chocolate ◽  
High Frequency Component ◽  
Rr Intervals

ABSTRACT Objective: The aim of this study was to investigate the acute effect of a single dose of dark chocolate (70% cocoa) on blood pressure and heart rate variability. Methods: Thirty-one healthy subjects (aged 18-25 years; both sexes) were divided into two groups: 10 subjects in the white chocolate (7.4 g) group and 21 in the dark chocolate (10 g) group; measurements were performed at the university's physiology lab. An electrocardiogram measured the sympathovagal balance by spectral and symbolic analysis. Results: A single dose of dark chocolate significantly reduced systolic blood pressure and heart rate. After consuming 10 g of dark chocolate, significant increases were observed for heart rate variability, standard deviation of RR intervals standard deviation of all NN intervals, square root of the mean squared differences between adjacent normal RR intervals root mean square of successive differences, and an increase in the high frequency component in absolute values, representing the parasympathetic modulation. Conclusion: In conclusion the importance of our results lies in the magnitude of the response provoked by a single dose of cocoa. Just 10 g of cocoa triggered a significant increase in parasympathetic modulation and heart rate variability. These combined effects can potentially increase life expectancy because a reduction in heart rate variability is associated with several cardiovascular diseases and higher mortality.

scholarly journals Effect of Acute Mental Stress on Heart Rate and QT Variability in Postmyocardial Infarction Patients

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Damiano Magrì ◽  
Gianfranco Piccirillo ◽  
Raffaele Quaglione ◽  
Annalaura Dell’Armi ◽  
Marilena Mitra ◽  
...  
Keyword(s):  
Acute Stress ◽  
Management Strategies ◽  
Low Frequency ◽  
Frequency Component ◽  
Postmyocardial Infarction ◽  
Increased Risk ◽  
Qt Variability Index ◽  
Qt Variability ◽  
Variability Index

Emotionally charged events are associated with an increased risk of sudden cardiac death (SCD). In this study we assessed RR and QT variability index (QTVI) at baseline during anger recall test (AR). We calculated QTVI from a 5-min ECG recording and from a 10-beats segment around the presumed maximum sympathetic activation in thirty post-myocardial infarction patients under β-blocker therapy and 10 controls underwent. In all groups, the low-frequency component of RR and SBP increased during AR. In all recordings, the QTVI calculated on a 5-min ECG recording and the were higher in patients than in controls (P < 0.05). The QTVI during AR remained unchanged from baseline within each group. Conversely, during AR, the in controls diminished significantly (P < 0.05) from baseline whereas in patients remained unchanged. The inability to buffer an acute stress-induced increase in sympathetic activity could explain why events charged with acute stress are associated with an increased risk of ventricular arrhythmias in this setting of patients and support the role of cognitive behavior stress management strategies.

scholarly journals Maturation of the QT Variability Index is Impaired in Preterm Infants

2018 ◽  
Vol 39 (5) ◽  
pp. 902-905 ◽  
Author(s):  
Arisa Kojima ◽  
Tadayoshi Hata ◽  
Tsuneaki Sadanaga ◽  
Yuri Mizutani ◽  
Hidetoshi Uchida ◽  
...  
Keyword(s):  
Preterm Infants ◽  
Qt Variability Index ◽  
Qt Variability ◽  
Variability Index
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