The PR interval–fetal heart rate relationship during repetitive umbilical cord occlusions in immature fetal sheep

Keunen, Han; Wijngaarden, Willem J. van; Sahota, Daljit Singh; Hasaart, T. H. M.

doi:10.1016/s0301-2115(99)00160-8

Cited by 10 publications

(9 citation statements)

References 19 publications

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“…AV delay was generally increased during UCO (Supplementary Figure S4 online). Others have reported a decrease in AV delay due to hypoxia (8,10). It is tempting to postulate that the different duration and number of hypoxic events are responsible for the observed differences.…”

Section: Discussionmentioning

confidence: 93%

“…Other ECG markers for hypoxia detection have been suggested, namely, atrioventricular (AV) conduction delay (PR) (7,8), the relationship of AV delay and HR (PR/RR and PR-HR) (9,10) and ventricular activation and repolarization (QT) (11) and HR-corrected QT (QT c,Bazett and Qt c,Hodges ), as well as heart rate variability (HRV) in the temporal and frequency domain. These markers are all interval-based, i.e., they use time intervals between characteristic points in the ECG.…”

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confidence: 99%

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Comparison of ECG-based physiological markers for hypoxia in a preterm ovine model

et al. 2016

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Background: Current methods for assessing perinatal hypoxic conditions did not improve infant outcomes. Various waveform-based and interval-based ECG markers have been suggested, but not directly compared. We compare performance of ECG markers in a standardized ovine model for fetal hypoxia. Methods: Sixty-nine fetal sheep of 0.7 gestation had ECG recorded 4 h before, during, and 4 h after a 25-min period of umbilical cord occlusion (UCO), leading to severe hypoxia. Various ECG markers were calculated, among which were heart rate (HR), HR-corrected ventricular depolarization/ repolarization interval (QT c ), and ST-segment analysis (STAN) episodic and baseline rise markers, analogue to clinical STAN device alarms. Performance of interval-and waveform-based ECG markers was assessed by correlating predicted and actual hypoxic/normoxic state. results: Of the markers studied, HR and QT c demonstrated high sensitivity (≥86%), specificity (≥96%), and positive predictive value (PPV) (≥86%) and detected hypoxia in ≥90% of fetuses at 4 min after UCO. In contrast, STAN episodic and baseline rise markers displayed low sensitivity (≤20%) and could not detect severe fetal hypoxia in 65 and 28% of the animals, respectively. conclusion: Interval-based HR and QT c markers could assess the presence of severe hypoxia. Waveform-based STAN episodic and baseline rise markers were ineffective as markers for hypoxia. c ontinuous monitoring of the fetal heart rate (HR) is assumed to provide clinical information about the wellbeing of the fetus (1). Cardiotocography (CTG) allows noninvasive real-time assessment of fetal HR and its response to uterine contractions and is nowadays used in clinics worldwide. However, HR patterns in CTG are often not predictive for hypoxia (2). Introduction of CTG in clinics did not significantly reduce occurrences of neonatal death or cerebral palsy but did lead to an increase in caesarean sections (1). Consequently, analysis of the ECG ST waveform (STAN) was proposed as an additional analysis method. STAN assesses hypoxia-induced changes in the ST waveform of the ECG (3) and operates in conjunction with CTG. Implementation of STAN in clinical practice was initially associated with a beneficial reduction in hypoxia-induced outcomes (metabolic acidosis and moderate/ severe neonatal encephalopathy) compared to CTG alone (4). However, recent meta-analyses of clinical trials demonstrated no clear advantage of STAN with CTG over CTG alone with respect to primary outcomes (5,6).STAN markers are based on the shape of the ECG waveform. Other ECG markers for hypoxia detection have been suggested, namely, atrioventricular (AV) conduction delay (PR) (7,8), the relationship of AV delay and HR (PR/RR and PR-HR) (9,10) and ventricular activation and repolarization (QT) (11) and HR-corrected QT (QT c,Bazett and Qt c,Hodges ), as well as heart rate variability (HRV) in the temporal and frequency domain. These markers are all interval-based, i.e., they use time intervals between characteristic points in the ECG. A major di...

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Section: Discussionmentioning

confidence: 93%

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confidence: 99%

Comparison of ECG-based physiological markers for hypoxia in a preterm ovine model

et al. 2016

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“…The present study observed an increase in QT intervals, whereas the frequency decreased over the course of weeks (0.168-0.209 s). Studies with lambs from two to five months and 10 to 12 months (Tudbury and Atkinson 1950;Bright 1995;Keunen et al 2000;Mir et al 2000;Ker and Webb 2005;Hamlin 2007;O'Connor et al 2008;Mendes et al 2010;Nunes et al 2014) presented more QT intervals with lower frequencies (105 and 150 bpm), indicating a negative correlation. In adult animals, between one to two years (Atmaca et al 2014) and two to seven years (Torío et al 1997), the QT exhibits high values, with frequencies close to 100 bpm.…”

Section: Discussionmentioning

confidence: 94%

“…The results indicated the immaturity of the parasympathetic system and performance of the sinoatrial and atrioventricular nodes as sympathetic because they suffer influence (in) directly. The atrioventricular node is sensitive to changes in sympathetic activity, leading to tachycardia and increased speed of electric conduction (Keunen et al 2000). The delay in conduction of the electrical stimulation of the atria to the ventricles is also due to the lower myocardial mass in relation to adults (Chan et al 2008;O'Connor et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Electrocardiographic dynamic development and heart rate variability in lambs during the neonatal period

Chiacchio

Ulian

Gonçalves

et al. 2018

Journal of Applied Animal Research

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The cardiovascular system in newborns has unique features; the system differs from that of foetuses due to the onset of pulmonary respiration and the closure of shunts and differs from that of adults due to heart and autonomic system immaturity. Twenty Ile de France lambs were evaluated during the first 35 days of life to describe changes in the electrical conduction of the heart and in the sympathetic and parasympathetic system during the neonatal period. Electrocardiographic evaluation and the sympathovagal balance was assessed by heart rate variability (HRV) were performed, and ambulatory electrocardiography was performed with a Holter system from birth and at 7, 14, 21, 28 and 35 days of age. There was a significant difference in the duration of the PR and QT intervals and the T wave, as well as a decrease in the amplitude of the P, R and T waves for the evaluated moments. The heart rate and total QRS decreased progressively until 35 days, whereas the HRV indexes increased during the same period. The neonatal period requires care and attention, as several adaptations for neonate survival in the extrauterine environment occur during this period.Abbreviations: HRV: heart rate variability; PR, QT: electrocardiographic intervals; P, R and T: electrocardiographic waves; QRS: electrocardiographic complexes; I, II, III, aVL, aVF and aVL: electrocardiographic member derivations; FP: frontal plane of electrocardiogram; HR: heart rate; RR or NN: interval between two R waves in Holter evaluation; NNmed: the average value of all normal cycles measured during the Holter evaluation; RMSSD: square root of the average of successive differences squared between normal RR intervals measured during the Holter evaluation; pNN50: successive differences between the percentage of RR intervals greater than 50 ms in Holter evaluation ARTICLE HISTORY

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“…Therefore, this parameter serves as an important indicator of heart block and cardiac conduction abnormalities [ 19 ]. Hence, the detection of a change in the relationship between the PR interval and fetal heart rate could potentially be used to detect fetal compromise in sheep, further highlighting the importance of age-matched control data [ 46 ].…”

Section: Discussionmentioning

confidence: 99%

The normal electrocardiograms in the conscious newborn lambs in neonatal period and its progression

et al. 2015

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BackgroundVeterinary cardiology, especially electrocardiography, has shown major advancements for all animal species. Consequently, the number of ovine species used as experimental animals has increased to date. Few studies have been published on ovine systematic electrocardiography, particularly with respect to lamb physiology and neonatology. This study aimed to standardize the values of normal waves, complexes, and intervals of the electrocardiogram (ECG) in clinically Bergamasca healthy neonatal lambs, used as experimental animals. Serial computerized electrocardiography was performed in 10 male and 12 female neonates on the 1st, 7th, 14th, 21st, 28th, and 35th days of age. The following parameters were analyzed: heart rate and rhythm, duration and amplitude of waves, duration of intervals, and heart electrical axis.ResultsDuring the first 35 days of life, (1) the sinusal heart rhythm was predominant, (2) there was a progressive decrease in the heart rate and R and T wave amplitude, and (3) a progressive increase in the PR, QT, and RR intervals. Finally, we confirmed that various components of neonatal evolution were more discernible in the augmented unipolar leads (aVF), which we recommend should be preferentially used in future studies. No significant statistical alterations were observed between males and females in relation to the analyzed parameters.ConclusionsThe information assimilated in this study is anticipated to enhance the diagnosis of multiple congenital heart defects in Bergamasca lambs and could be implemented in studies that use ovine species as experimental models.

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The PR interval–fetal heart rate relationship during repetitive umbilical cord occlusions in immature fetal sheep

Cited by 10 publications

References 19 publications

Comparison of ECG-based physiological markers for hypoxia in a preterm ovine model

Comparison of ECG-based physiological markers for hypoxia in a preterm ovine model

Electrocardiographic dynamic development and heart rate variability in lambs during the neonatal period

The normal electrocardiograms in the conscious newborn lambs in neonatal period and its progression

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