PR and QT intervals short on the same electrocardiogram

Breijo-Márquez Francisco R

doi:10.29328/journal.avm.1001010

PR and QT intervals short on the same electrocardiogram

Mapping Intimacies ◽

10.29328/journal.avm.1001010 ◽

2020 ◽

Vol 4 (1) ◽

pp. 001-004

Author(s):

Breijo-Márquez Francisco R

Keyword(s):

Qt Interval ◽

Qt Intervals ◽

Pr Interval

In 2007, Professor Breijo-Márquez described an electrocardiographic pattern, consisting of the presence of a short PR interval (or PQ) together with a short QT interval in the same individual. It was published with the headline “Decrease in cardiac electrical systole” in International Journal of Cardiology (IJC) [1].

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Electrocardiographic patterns of Mangalarga Marchador horses before and after implementation of the marcha gait

Ciência Rural ◽

10.1590/0103-8478cr20150873 ◽

2016 ◽

Vol 46 (5) ◽

pp. 915-920 ◽

Cited By ~ 4

Author(s):

Clarisse Simões Coelho ◽

Gabriella Agra de Omena e Silva ◽

Luiz Antonio Trindade Oliveira Junior ◽

Vanessa Sartor Moraes ◽

Laura Monteiro de Castro Conti ◽

...

Keyword(s):

Qt Interval ◽

P Wave ◽

Qrs Complex ◽

Sinus Arrhythmia ◽

Qt Intervals ◽

Pr Interval ◽

Before And After ◽

Kolmogorov Smirnov ◽

Electrocardiographic Parameters ◽

T Waves

ABSTRACT: The aim of this study was to evaluate the electrocardiographic parameters in Mangalarga Marchador horses submitted to marcha exercise. Twenty-four Mangalarga Marchador horses, thirteen females and eleven males, 6.4±2.7 years old with a mean weight of 428.3±24.7kg, were used. Electrocardiograms were recorded in two different moments: rest and immediately after exercise (40 minutes of aerobic exercise, marcha gait). The electrocardiographic variables analyzed were cardiac rhythm, heart rate (HR), duration of P wave, QRS complex, PR and QT intervals, amplitudes of P, R and T waves, and analysis of QT corrected (QTc) according to Bazett's formula (QT/√RR). Variables were analyzed for normality with Kolmogorov-Smirnov test and paired t-test, considering P<0.05. Rhythm analysis revealed 91.7% of sinus rhythm and 8.3% of sinus arrhythmia in rest, with mean HR of 45.7±12.7 beats minute-1, and 100% of sinus tachycardia, with mean HR of 77.3±13.5 beats minute-1 after exercise (P<0.0001). In post-exercise, it was possible to observe decreases in P wave duration (P=0.0121), PR interval (P=0.0007) and QT interval (P<0.0001) and increase of QTc (P=0.0039) and R wave amplitude (P=0.0033). There were no significant differences for amplitude of P and T waves and QRS complex related to atrioventricular enlargement. Although QT interval decreased after exercise, there was an increase on QTc after exercise, indicating changes in ventricular repolarization. It was possible to conclude that the imposed exercise (marcha gait) led to electrocardiographic alterations without causing pathological arrhythmias.

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Abstract 14311: Qt Interval Correlation Between Telemetry and 12-lead Electrocardiogram

Circulation ◽

10.1161/circ.142.suppl_3.14311 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Mohamed Farhan Nasser ◽

Ahmad Jabri ◽

Saima Karim ◽

Elizabeth Kaufman

Keyword(s):

Qt Interval ◽

Ventricular Arrhythmias ◽

Qt Prolongation ◽

T Wave ◽

Qt Intervals ◽

Increased Risk ◽

Tangent Method ◽

Wave Morphology ◽

Monitoring Service ◽

Inpatient Units

Introduction: QT prolongation is associated with increased risk of ventricular arrhythmias.As many patients with COVID19 may be started on QT prolonging drugs, measuring and monitoring QT is imperative to prevent fatal ventricular arrhythmias. However, we need to limit exposure of staff to patients with confirmed COVID19 and judiciously use personal protective equipment. Thus, it is important to find alternatives to doing frequent 12-lead ECGs. Hypothesis: We hypothesize that the QT interval measured from telemetry is similar to the QT interval on 12-lead ECG. Methods: Telemetry recordings and 12-lead ECGs were obtained from 15 patients at the same time and identical heart rates. Patients were from two different inpatient units with the same telemetry monitoring service. QT intervals were measured manually using calipers with the tangent method, excluding U waves. Telemetry recordings included lead I and II or a precordial lead. QT from telemetry was compared to the corresponding leads and to the longest QT on the 12-lead ECG. In cases of atrial fibrillation (AF), the QT from all the complexes was averaged. Results: Of 15 patients, 2 were in AF and 2 had RBBB. One patient had abnormal T-wave morphology and QT prolongation (abnormal repolarization). In all patients, QT intervals from the same leads as telemetry matched the QT measured from 12-lead. In 14 of 15 patients, telemetry QT matched the longest QT on the 12-lead ECG. However, in the patient with abnormal repolarization, maximum QT on 12-lead ECG was substantially longer than telemetry QT (Figure 1). Conclusion: When using the same lead, QT intervals were identical on telemetry and 12-lead ECG. However, in the patient with abnormal repolarization, the longest QT on 12-lead ECG was not represented on telemetry. In patients with abnormal repolarization on 12-lead ECG, we recommend serial 12-lead ECGs while on QT-prolonging drugs. Telemetry may suffice as a surrogate for 12-lead ECG to follow QT intervals in most patients.

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Influence of estrous stages on electrocardiography, clinical pathology and ovarian weight of experimental beagle dogs: a retrospective analysis

Interdisciplinary Toxicology ◽

10.2478/intox-2019-0018 ◽

2019 ◽

Vol 12 (3) ◽

pp. 149-156 ◽

Cited By ~ 1

Author(s):

Chitrang Shah ◽

Laxit Bhatt ◽

B.V. Ravichandra ◽

Viren Kothule ◽

Shekhar Kadam ◽

...

Keyword(s):

Retrospective Analysis ◽

Estrous Cycle ◽

Clinical Pathology ◽

Mammary Glands ◽

Beagle Dogs ◽

Ovarian Weight ◽

Qt Intervals ◽

Pr Interval ◽

Reproductive Life ◽

Erroneous Interpretation

Abstract Estrous cycle is a repetitive phenomenon occurring during the reproductive life of a female dog. The duration of the canine estrous cycle is considerably longer than one in the most of the other animals and is broadly grouped into follicular phase (proestrus and estrus), luteal phase (diestrus) and non-seasonal anestrus. Dogs in the same stage of cycle can be inadvertently assigned to same group during routine safety and metabolic studies leading to possible erroneous interpretation of test-item related effects. This retrospective analysis was conducted by analyzing data of 86 female beagle dogs from control/placebo treated groups to correlate any possible effect of estrous stages with electrocardiography, clinical pathology and ovarian weight. Different estrous cycle stages of beagles were confirmed histologically by evaluating ovary, uterus, vagina and mammary glands. The incidence of beagles in diestrus was the highest, followed by anestrus, proestrus and estrus. No significant effect was noticed on heart rate, P–A, P–D, RR, QRS and QT intervals across different stages of estrous cycle. However, significantly higher PQ (PR) interval in dogs in proestrus stage was observed compared to dogs in anestrus and estrus. Marginally higher WBCs, neutrophils, lymphocytes, RBCs, hemoglobin, AST and lower hematocrit, lipid profile (total cholesterol, HDL, LDL, triglycerides), ALP level was evident in estrous period. Relative ovary weight was significantly higher in dogs in diestrus stage. Considering these results, one may need to exercise caution while interpreting experimental data from female beagle dogs.

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Changes in ECG among patients with drug induced poisoning in a tertiary care hospital

Bangladesh Medical Research Council Bulletin ◽

10.3329/bmrcb.v44i3.39943 ◽

2019 ◽

Vol 44 (3) ◽

pp. 160-167 ◽

Cited By ~ 1

Author(s):

Ashraf Ur Rahman ◽

AW Chowdhury ◽

S Jabeen

Keyword(s):

Qt Interval ◽

Atrial Tachycardia ◽

Tertiary Care Hospital ◽

Tertiary Care ◽

Channel Blockers ◽

Care Hospital ◽

Ecg Changes ◽

Drug Induced ◽

Female Ratio ◽

Pr Interval

Background: A wide variety of ECG changes can be seen with cardiac and noncardiac agents and may occur at therapeutic or toxic levels. Wide QRS and QT prolongation may be seen in poisoning cases; are potentially dangerous and indicate the necessity of continuous cardiac monitoring.The objective of this study was to determine the changes in ECG among patients admitted with pharmaceutical drug induced poisoning in a tertiary care hospital in Dhaka. Methods: This cross sectional study was carried out at the Department of Medicine, Dhaka Medical College Hospital (DMCH) during July-December, 2013. Detailed information were obtained; clinical examination and relevant investigations including ECG were done in each case according to protocol. Results: Among 66 cases mean age was 22.9 (±6.47) years and male to female ratio was 1: 2.14 (21 Vs 45). Common drug groups taken by the study population were benzodiazepines in 31(47.0%) and tricyclic antidepressants (TCA) in 18(27.3%) cases.Normal ECG findings were found in 28 (42.4%) cases, 18 (27.3%) cases revealed sinus tachycardia, 11(16.7%) showed prolong QT Interval, 6(9.1%) had atrial tachycardia, 5(7.6%) showed wide QRS and 3(4.6%) cases revealed prolong PR interval. Patients withTCA poisoning developedsinus tachycardia in 11(61.1%), prolong QT Interval in 6(33.3%), wide QRS in 5(27.8%),atrial tachycardia in 5(27.8%), prolong PR Interval in 2(11.1%), and Tall R in aVRin 2(11.1%) cases. Prolong QT Interval were found among 3 (75.0%) patients with K+ efflux channel blockers (chlorpromazine, chlorpheniramine and quetiapine) overdose.Patients with beta blocker overdose developed sinus bradycardia in 4 (100.0%) and prolong PR Interval in 1(25.0%) cases. Conclusion: Common drugs taken by the patients were amitriptyline sedatives. Wide QRS, prolong QT interval and some other ECG changes were observed by TCA poisoning in higher doses. TCA, benzodiazepines and K channel blockers induced prolong QT Interval in higher doses.Careful interpretation of ECG findings can provide key information to guide management of the poisoned patients. Bangladesh Med Res Counc Bull 2018; 44: 160-167

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The Short QTc Is a Marker for the Development of Atrial Flutter and Atrial Fibrillation

Cardiology Research and Practice ◽

10.1155/2020/2858149 ◽

2020 ◽

Vol 2020 ◽

pp. 1-8

Author(s):

Simon W. Rabkin ◽

Jacky K. K. Tang

Keyword(s):

Atrial Fibrillation ◽

Atrial Flutter ◽

Qt Interval ◽

Atrial Arrhythmias ◽

Exclusion Criteria ◽

Bundle Branch Block ◽

Qt Intervals ◽

Ecg Database ◽

Age And Sex ◽

Important Marker

A short QT interval has been difficult to define, and there is debate whether it exists outside of an extremely small group of individuals with inherited channelopathies and whether it predicts cardiac arrhythmias. The objective was to identify cases with short QT and their consequences. Our hospital ECG database was screened for cases with a QTc based on the Bazett formula (QTcBZT) of less than 340 ms. The QTc was recalculated using the spline (QTcRBK) formula, which more accurately adjusts for the heart rate and identifies cases based on percentile distribution of the QT interval. The exclusion criteria were presence of bundle branch block, arrhythmias, or electronic pacemakers. An age- and sex-matched cohort was obtained from individuals with normal QT intervals with the same exclusion criteria. There were 28 cases with a short QTc (QTcRBK < 380 ms). The age was 69.6 ± 14.6 years (mean ± SD) (50% males). The QT interval was 305.7 ± 61.1 ms with QTcRBK 308.4 ± 31.4 ms. Subsequent ECGs showed atrial flutter in 21%, atrial fibrillation in 18%, and atrial tachycardia in 4% of cases. Thus, atrial arrhythmias occurred in 43% of cases. This incidence was significantly ( p < 0.0001 ) greater than the incidence of atrial arrhythmias in age- and sex-matched controls. In conclusion, a short QT interval can be readily identified based on the first percentile of the new QTc formula. A short QTc is an important marker for the development of atrial arrhythmias, including atrial flutter and atrial fibrillation, with the former predominating. It should be part of patient assessment and warrants consideration to develop strategies for detection and prevention of atrial arrhythmias.

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Electrocardiogram screening of deaf children for long QT syndrome: are we following UK national guidelines?

The Journal of Laryngology & Otology ◽

10.1017/s0022215110002379 ◽

2010 ◽

Vol 125 (4) ◽

pp. 354-356 ◽

Cited By ~ 5

Author(s):

S L Kang ◽

C Jackson ◽

W Kelsall

Keyword(s):

Cochlear Implant ◽

Long Qt Syndrome ◽

Qt Interval ◽

Deaf Children ◽

National Guidelines ◽

Long Qt ◽

Local Practice ◽

Qt Intervals ◽

Centre Database ◽

Qt Syndrome

AbstractIntroduction:Jervell–Lange-Nielsen syndrome is characterised by congenital deafness and a long QT interval on electrocardiography.Aim:(1) To survey UK national practice regarding electrocardiography screening of deaf children referred to cochlear implant centres, performed to evaluate for prolonged QT interval as recommended by national guidelines, and (2) to review local practice.Methods:Data were collected via a questionnaire sent to all UK cochlear implant centres, and via review of the medical records of a local cochlear implant centre database.Results:Eight (42 per cent) of the 19 cochlear implant centres surveyed performed electrocardiographic screening. Thirteen cases of long QT syndrome were reported in seven centres, with two related deaths. In our local cochlear implant centre, 14 (7.1 per cent) of 193 children had abnormal electrocardiograms; one definite long QT syndrome case and 13 borderline cases were identified.Conclusion:Despite clear national guidelines for electrocardiographic screening of deaf children, there is wide variation in practice. Our local practice of performing investigations, including electrocardiography, during magnetic resonance imaging sedation has been very successful. Electrocardiograms should be reviewed by trained clinicians, and corrected QT intervals should be calculated manually.

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Serum Quinidine Concentrations and Effect on QT Dispersion and Interval

Annals of Pharmacotherapy ◽

10.1345/aph.1a472 ◽

2002 ◽

Vol 36 (7-8) ◽

pp. 1156-1161 ◽

Cited By ~ 9

Author(s):

A Scott Mathis ◽

Ashesh J Gandhi

Keyword(s):

Qt Interval ◽

Torsade De Pointes ◽

Qt Dispersion ◽

University Teaching ◽

Qt Intervals ◽

Qt Interval Dispersion ◽

Proarrhythmic Risk ◽

Post Hoc ◽

Serum Quinidine ◽

Interval Dispersion

OBJECTIVE: To establish a relationship between serum quinidine concentrations (SQCs) and QT interval dispersion, compared with corresponding QT intervals, in order to identify a reason why many reports describe torsade de pointes as occurring at subtherapeutic concentrations. DESIGN: Retrospective study. SETTING: University teaching hospital. PARTICIPANTS: Eleven patients with atrial arrhythmias managed with quinidine therapy. MAIN OUTCOME MEASURES: Patients with subtherapeutic (<2 μg/mL) and therapeutic (2–5 μg/mL) SQCs with corresponding 12-lead electrocardiograms (ECGs) (25 mm/sec) and baseline ECG were evaluated for QT interval dispersion, calculated as the maximum minus the minimum QT interval on the 12-lead ECG. RESULTS: Mean ± SD subtherapeutic and therapeutic SQCs were 1.48 ± 0.39 μg/mL and 3.78 ± 0.88 μg/mL (p < 0.001). Baseline values for QT/QTc intervals were 376.4 ± 59.2/429.5 ± 57.3 msec. At subtherapeutic and therapeutic SQCs, mean QT/QTc intervals were 403.6 ± 59.9/450.5 ± 38.5 msec and 439.1 ± 48.9/472.4 ± 44.6 msec, respectively. Mean QT dispersion was 47 ± 16.2 msec at baseline, 98.2 ± 27.5 msec at subtherapeutic SQC, and 70.9 ± 33.9 msec at therapeutic SQCs (p = 0.001 for overall analysis; p < 0.001 for baseline vs. subtherapeutic concentrations; p = NS for therapeutic vs. subtherapeutic in post hoc comparison). CONCLUSIONS: Despite QT interval lengthening with increasing SQCs, QT dispersion was numerically greatest at subtherapeutic SQCs. Further study is required to determine the value of QT dispersion as a tool for identifying proarrhythmic risk with drugs that prolong the QT interval.

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Quantitative Assessment of the Physiological Parameters Influencing QT Interval Response to Medication: Application of Computational Intelligence Tools

Computational and Mathematical Methods in Medicine ◽

10.1155/2018/3719703 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11

Author(s):

Sebastian Polak ◽

Barbara Wiśniowska ◽

Aleksander Mendyk ◽

Adam Pacławski ◽

Jakub Szlęk

Keyword(s):

Computational Intelligence ◽

Qt Interval ◽

Physiological Parameters ◽

Programming Technique ◽

Physiological Variables ◽

Pr Interval ◽

Wave Morphology ◽

Heart Electrophysiology ◽

Interval Response

Human heart electrophysiology is complex biological phenomenon, which is indirectly assessed by the measured ECG signal. ECG trace is further analyzed to derive interpretable surrogates including QT interval, QRS complex, PR interval, and T wave morphology. QT interval and its modification are the most commonly used surrogates of the drug triggered arrhythmia, but it is known that the QT interval itself is determined by other nondrug related parameters, physiological and pathological. In the current study, we used the computational intelligence algorithms to analyze correlations between various simulated physiological parameters and QT interval. Terfenadine given concomitantly with 8 enzymatic inhibitors was used as an example. The equation developed with the use of genetic programming technique leads to general reasoning about the changes in the prolonged QT. For small changes of the QT interval, the drug-related IKr and ICa currents inhibition potentials have major impact. The physiological parameters such as body surface area, potassium, sodium, and calcium ions concentrations are negligible. The influence of the physiological variables increases gradually with the more pronounced changes in QT. As the significant QT prolongation is associated with the drugs triggered arrhythmia risk, analysis of the role of physiological parameters influencing ECG seems to be advisable.

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Prolongation of the QT interval in heart failure occurs at low but not at high heart rates

Clinical Science ◽

10.1042/cs0980603 ◽

2000 ◽

Vol 98 (5) ◽

pp. 603-610 ◽

Cited By ~ 20

Author(s):

P. P. DAVEY ◽

C. BARLOW ◽

G. HART

Keyword(s):

Heart Failure ◽

Heart Rate ◽

Left Ventricular Hypertrophy ◽

Qt Interval ◽

Ventricular Hypertrophy ◽

Left Ventricular ◽

Qt Interval Prolongation ◽

Qt Intervals ◽

Ventricular Structure ◽

And Function

Abnormal left ventricular structure and function as in, for example, left ventricular hypertrophy or chronic heart failure, is associated with sudden cardiac death and, when the ejection fraction is depressed, with prolongation of the QT interval. The dependence on heart rate of QT interval prolongation in these conditions, and the relationship of any abnormalities either to deranged autonomic nervous system function or to an adverse prognosis, has not been well studied. We therefore investigated (1) the dependence on heart rate of the QT interval, and (2) the relationship between both QT interval and the QT/heart rate slope and markers of adverse prognosis in these two conditions. The QT interval was measured at rest and during exercise in 34 subjects with heart failure, 16 subjects with left ventricular hypertrophy and 16 age-matched controls with normal left ventricular structure and function. QTc (corrected QT) intervals at rest were significantly longer in heart failure patients (471±10 ms) than in controls (421±6 ms) or in subjects with hypertrophy (420±6 ms) (P < 0.05). At peak exercise, despite the attainment of similar heart rates, the QT intervals no longer differed from each other, being 281±7 ms for controls, 296±11 ms in hypertrophy and 303±10 ms in heart failure (no significant difference). The QT/heart rate slope was significantly increased in heart failure [2.3±0.1 ms·(beats/min)-1] compared with controls [1.55±0.06 ms·(beats/min)-1] and hypertrophy [1.66±0.1 ms·(beats/min)-1] (P < 0.001). In left ventricular hypertrophy, despite animal data suggesting that QT interval prolongation should occur, no abnormalities were found in QT intervals at rest or during exercise. The QT/heart rate slope did not relate to any markers for an adverse prognosis, except that of prolongation of QT interval. Long QT intervals were associated principally with impairment of left ventricular systolic function. Our data emphasize the dynamic nature of the QT interval abnormalities found in heart failure.

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