QT Adaptation and Intrinsic QT Variability in Congenital Long QT Syndrome

Seethala, Srikanth; Singh, Prabhpreet; Shusterman, Vladimir; Ribe, Margareth; Haugaa, Kristina H.; Němec, Jan

doi:10.1161/jaha.115.002395

Cited by 9 publications

(7 citation statements)

References 41 publications

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“…The slow QT response to HR changes during AF appears to be quite similar to SR as described in Holter data in normal subjects [11] and congenital LQTS patients [12]. In those papers, the exponential weight function with time constant of 60 s provided the best data fit, but longer time-constants were not studied.…”

Section: Discussionmentioning

confidence: 84%

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Recent heart rate history affects QT interval duration in atrial fibrillation

et al. 2017

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QT interval prolongation is associated with a risk of polymorphic ventricular tachycardia. QT interval shortens with increasing heart rate and correction for this effect is necessary for meaningful QT interval assessment. We aim to improve current methods of correcting the QT interval during atrial fibrillation (AF). Digitized Holter recordings were analyzed from patients with AF. Models of QT interval dependence on RR intervals were tested by sorting the beats into 20 bins based on corrected RR interval and assessing ST-T variability within the bins. Signal-averaging within bins was performed to determine QT/RR dependence. Data from 30 patients (29 men, 69.3±7.3 years) were evaluated. QT behavior in AF is well described by a linear function (slope ~0.19) of steady-state corrected RR interval. Corrected RR is calculated as a combination of an exponential weight function with time-constant of 2 minutes and a smaller “immediate response” component (weight ~ 0.18). This model performs significantly (p<0.0001) better than models based on instantaneous RR interval only including Bazett and Fridericia. It also outperforms models based on shorter time-constants and other previously proposed models. This model may improve detection of repolarization delay in AF. QT response to heart rate changes in AF is similar to previously published QT dynamics during atrial pacing and in sinus rhythm.

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Section: Discussionmentioning

confidence: 84%

“…When the beat-to-beat RR interval changes are large, an “immediate response,” which occurs without delay and accounts for approximately 20% of overall QT response, can also be resolved. QT interval accommodation during sinus rhythm (SR) exhibits similar dynamics [ 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

Recent heart rate history affects QT interval duration in atrial fibrillation

et al. 2017

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“…However, removing the trend using the EMD method may have some influence on this result. We expect the opposite—greater QT regularity in the group of LQTS1 patients ( Seethala et al, 2015 ; DeMaria et al, 2020 ). Moreover, for a regularity parameter, such as SE, the sequential order of data is very important in contrast to variability measures ( Pincus and Goldberger, 1994 ).…”

Section: Discussionmentioning

confidence: 89%

Information Flow Between Heart Rhythm, Repolarization, and the Diastolic Interval Series for Healthy Individuals and LQTS1 Patients

2021

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Using information theoretic measures, relations between heart rhythm, repolarization in the tissue of the heart, and the diastolic interval time series are analyzed. These processes are a fragment of the cardiovascular physiological network. A comparison is made between the results for 84 (42 women) healthy individuals and 65 (45 women) long QT syndrome type 1 (LQTS1) patients. Self-entropy, transfer entropy, and joint transfer entropy are calculated for the three time series and their combinations. The results for self-entropy indicate the well-known result that regularity of heart rhythm for healthy individuals is larger than that of QT interval series. The flow of information depends on the direction with the flow from the heart rhythm to QT dominating. In LQTS1 patients, however, our results indicate that information flow in the opposite direction may occur—a new result. The information flow from the heart rhythm to QT dominates, which verifies the asymmetry seen by Porta et al. in the variable tilt angle experiment. The amount of new information and self-entropy for LQTS1 patients is smaller than that for healthy individuals. However, information transfers from RR to QT and from DI to QT are larger in the case of LQTS1 patients.

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“…Therefore, QT variability was considered to be a better predictor of TdP than traditional QT interval assessment. Previously, QT variability has been shown to be elevated in long QT syndrome, ischemia, and congestive heart failure (CHF) ( Dobson et al, 2011 ; Badran et al, 2012 ; Seethala et al, 2015 ; Yao et al, 2019 ). Piccirillo et al (2009) reported that during CHF, the activation of sympathetic is related to the increase in QT interval and QT variability.…”

Section: Discussionmentioning

confidence: 99%

Absence of Rgs5 Influences the Spatial and Temporal Fluctuation of Cardiac Repolarization in Mice

Song

Liu

et al. 2021

Front. Physiol.

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AimsThis study investigated the contribution of the regulator of G-protein signaling 5 (Rgs5) knockout to the alteration of the action potential duration (APD) restitution and repolarizing dispersion in ventricle.Methods and ResultsThe effects of Rgs5–/– were investigated by QT variance (QTv) and heart rate variability analysis of Rgs5–/– mice. Monophasic action potential analysis was investigated in isolated Rgs5–/– heart. Rgs5–/– did not promote ventricular remodeling. The 24-h QTv and QT variability index (QTVI) of the Rgs5–/– mice were higher than those of wild-type (WT) mice (P < 0.01). In WT mice, a positive correlation was found between QTv and the standard deviation of all NN intervals (r = 0.62; P < 0.01), but not in Rgs5–/– mice (R = 0.01; P > 0.05). The absence of Rgs5 resulted in a significant prolongation of effective refractory period and APD in isolated ventricle. In addition, compared with WT mice, the knockout of Rgs5 significantly deepened the slope of the APD recovery curve at all 10 sites of the heart (P < 0.01) and increased the spatial dispersions of Smax (COV-Smax) (WT: 0.28 ± 0.03, Rgs5–/–: 0.53 ± 0.08, P < 0.01). Compared with WT heart, Rgs5–/– increased the induced S1–S2 interval at all sites of heart and widened the window of vulnerability of ventricular tachyarrhythmia (P < 0.05).ConclusionOur findings indicate that Rgs5–/– is an important regulator of ventricular tachyarrhythmia in mice by prolonging ventricular repolarization and increasing spatial dispersion in ventricle.

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QT Adaptation and Intrinsic QT Variability in Congenital Long QT Syndrome

Cited by 9 publications

References 41 publications

Recent heart rate history affects QT interval duration in atrial fibrillation

Recent heart rate history affects QT interval duration in atrial fibrillation

Information Flow Between Heart Rhythm, Repolarization, and the Diastolic Interval Series for Healthy Individuals and LQTS1 Patients

Absence of Rgs5 Influences the Spatial and Temporal Fluctuation of Cardiac Repolarization in Mice

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