Clinical impact of repolarization changes in supine versus upright body position

Markendorf, Susanne; Lüscher, Thomas F.; Gerds‐Li, Jin‐Hong; Schönrath, Felix; Schmied, Christian

doi:10.5603/cj.a2017.0138

Cited by 8 publications

(9 citation statements)

References 13 publications

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“…Our finding of the association of beat-to-beat QT variability with the morphological instability (which, for simplicity's sake, we call "noise") of the source ECG tracing should not be interpreted as a suggestion that there are no beat-to-beat QT changes and that only morphology changes influence the beatto-beat measurements. Morphological ECG changes might also have valid biological basis [e.g., related to respiration (Noriega et al, 2012;Sadiq et al, 2021), posture (Markendorf et al, 2018), food intake (Täubel et al, 2019), mental stress (Hwang et al, 2018), and other external inputs and physiologic reflexes]. While some of these mechanisms might not be fast enough to contribute beat-to-beat changes in QT interval measurements, it seems clear that the measurement of the differences between individual beats and the global representative waveform is not FIGURE 14 | The residual reductions shown in this figure (A-D) are defined as values of relative decrease of intra-subject residuals of linear regressions SDQT calculated as proportions of intra-subject standard deviations of SDQT.…”

Section: Discussionmentioning

confidence: 99%

Short-Term Beat-to-Beat QT Variability Appears Influenced More Strongly by Recording Quality Than by Beat-to-Beat RR Variability

et al. 2022

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Increases in beat-to-beat variability of electrocardiographic QT interval duration have repeatedly been associated with increased risk of cardiovascular events and complications. The measurements of QT variability are frequently normalized for the underlying RR interval variability. Such normalization supports the concept of the so-called immediate RR effect which relates each QT interval to the preceding RR interval. The validity of this concept was investigated in the present study together with the analysis of the influence of electrocardiographic morphological stability on QT variability measurements. The analyses involved QT and RR measurements in 6,114,562 individual beats of 642,708 separate 10-s ECG samples recorded in 523 healthy volunteers (259 females). Only beats with high morphology correlation (r > 0.99) with representative waveforms of the 10-s ECG samples were analyzed, assuring that only good quality recordings were included. In addition to these high correlations, SDs of the ECG signal difference between representative waveforms and individual beats expressed morphological instability and ECG noise. In the intra-subject analyses of both individual beats and of 10-s averages, QT interval variability was substantially more strongly related to the ECG noise than to the underlying RR variability. In approximately one-third of the analyzed ECG beats, the prolongation or shortening of the preceding RR interval was followed by the opposite change of the QT interval. In linear regression analyses, underlying RR variability within each 10-s ECG sample explained only 5.7 and 11.1% of QT interval variability in females and males, respectively. On the contrary, the underlying ECG noise contents of the 10-s samples explained 56.5 and 60.1% of the QT interval variability in females and males, respectively. The study concludes that the concept of stable and uniform immediate RR interval effect on the duration of subsequent QT interval duration is highly questionable. Even if only stable beat-to-beat measurements of QT interval are used, the QT interval variability is still substantially influenced by morphological variability and noise pollution of the source ECG recordings. Even when good quality recordings are used, noise contents of the electrocardiograms should be objectively examined in future studies of QT interval variability.

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Section: Discussionmentioning

confidence: 99%

Short-Term Beat-to-Beat QT Variability Appears Influenced More Strongly by Recording Quality Than by Beat-to-Beat RR Variability

et al. 2022

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“…Excitement, panic, worry, and posture change can all cause sympathetic excitement. Markendorf et al ( 31 ) reported that when the supine position was turned to the orthostatic position, the heart rate and the rate of T-wave inversion increased. Obata et al ( 32 ) reported that the QT interval was lower in orthostatic ECG than supine ECG (366.40 ± 35.00 ms vs. 382.30 ± 33.90 ms, P < 0.05).…”

Section: Discussionmentioning

confidence: 99%

The Changes of T-Wave Amplitude and QT Interval Between the Supine and Orthostatic Electrocardiogram in Children With Dilated Cardiomyopathy

Tan

Chen

et al. 2021

Front. Pediatr.

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Objectives: Electrocardiogram (ECG) can be affected by autonomic nerves with body position changes. The study aims to explore the ECG changes of children with dilated cardiomyopathy (DCM) when their posture changes.Materials and methods: Sixty-four children diagnosed with DCM were recruited as research group and 55 healthy children as control group. T-wave amplitude and QT interval in ECG were recorded, and their differences between supine and orthostatic ECG were compared in both groups. Subsequently, the children with DCM were followed up and the differences before and after treatment compared.Results: ① Comparisons in differences: Differences of T-wave amplitude in lead II and III, aVF, and V5 and differences of QT interval in lead II, aVL, aVF, and V5 were lower in the research group than in the control group. ② Logistic regression analysis and diagnostic test evaluation: The differences of T-wave amplitude in lead III and QT interval in lead aVL may have predictive value for DCM diagnosis. When their values were 0.00 mV and 30 ms, respectively, the sensitivity and specificity of the combined index were 37.5 and 83.6%. ③ Follow-up: In the response group, the T-wave amplitude difference in lead aVR increased and the difference of QT interval in lead V6 decreased after treatment. In the non-response group, there was no difference before and after treatment. When the combined index of the differences of T-wave amplitude difference in lead aVR and QT interval difference in lead V6, respectively, were −0.05 mV and 5 ms, the sensitivity and specificity of estimating the prognosis of DCM were 44.4 and 83.3%.Conclusions: The differences of T-wave amplitude and QT interval may have a certain value to estimate DCM diagnosis and prognosis.

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“…В самое крупное исследование в этом области, проведенное среди 1 028 человек старше 18 лет, в том числе вошли пациенты, страдающие различными сердечно-сосудистыми заболеваниями, но не имеющие СУИQT, продолжительность интервала QTс в вертикальном положении была несколько ниже, чем в нашем исследовании (440 ± 28 мс), но здесь за вертикальное положение принималось положение сидя, что, возможно, обусловливает более низкие значения этого показателя. Авторы исследования сделали противоречивые выводы о том, E-mail: medalfavit@mail.ru что интервал QT можно быть оценен только в положении лежа, так как в вертикальном положении этот показатель удлиняется [13]. В работе, выполненной нами ранее по оценке изменений интервалов QT и QT с в ранний период ортостаза у юных элитных атлетов, мы не отметили достоверной разницы в продолжительности интервала QTс в ортостазе у детей, занимающихся и не занимающихся спортом [14].…”

Section: Discussionunclassified

Changing QT interval in orthostasis — new diagnostic marker of syndrome of extended QT interval

Комолятова¹,

Макаров²,

Киселева³

et al. 2019

Medicinskij alfavit

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Long QT interval syndrome (LQTS) is a disease that causes life-threatening arrhythmias and sudden death syndrome. Recently, it has been shown that about half of patients with LQTS have normal QTc interval values on an ECG. The purpose of this study was to assess changes in the QT interval in patients with LQTS in orthostasis to identify additional criteria for the disease. Surveyed 64 patients from 4 to 47 years old (13.3 ± 10.0) with LQTIS. The control group consisted of 87 healthy people of 4–20 years (11.0 ± 3.5). An ECG was performed in a lying and standing position. HR, QT and QTc interrvals in both positions and the difference between these indicators were evaluated. In both groups, we noted an increase in heart rate and QTc and a shortening of the QT interval in orthostasis. Distinctions between all parameters were revealed reliably, except for the increase in the QTc interval (∆QTc) in the main and control groups. ROC analysis revealed that the optimal point for identifying patients with LQTS is QTc interval in orthostasis –500 ms with Se 73 % and Sp 93 %. Conclusions. In the early period of orthostasis, an increase in the heart rate, a shortening of the QT interval and a prolongation of the QTc interval occur; lengthening the QTc interval in the early period of orthostasis over 500 ms is highly sensitive and highly specific in identifying patients with the syndrome of prolonged QT-interval.

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Clinical impact of repolarization changes in supine versus upright body position

Abstract: Background: The impact of postural changes on various electrocardiography (ECG) charac-

Cited by 8 publications

References 13 publications

Short-Term Beat-to-Beat QT Variability Appears Influenced More Strongly by Recording Quality Than by Beat-to-Beat RR Variability

Short-Term Beat-to-Beat QT Variability Appears Influenced More Strongly by Recording Quality Than by Beat-to-Beat RR Variability

The Changes of T-Wave Amplitude and QT Interval Between the Supine and Orthostatic Electrocardiogram in Children With Dilated Cardiomyopathy

Changing QT interval in orthostasis — new diagnostic marker of syndrome of extended QT interval

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