Effect of beta-blockers on the relation between QT-interval and heart rate in exercise ECG

1987 ◽  
Vol 8 (suppl D) ◽  
pp. 71-74 ◽  
Author(s):  
A. Algra ◽  
J. R. T. C. Roelandt ◽  
J. G. P. Tussen ◽  
M. L. Simoons ◽  
J. Pool
Keyword(s):  
Heart Rate ◽  
Qt Interval ◽  
Beta Blockers ◽  
Exercise Ecg

QT-Zeit – Was fange ich eigentlich damit an?

2020 ◽  
Vol 145 (08) ◽  
pp. 536-542
Author(s):  
Alessandro Castiglione ◽  
Katja Odening
Keyword(s):  
Heart Rate ◽  
Qt Interval ◽  
Beta Blockers ◽  
Clinical History ◽  
Interval Methods ◽  
Qt Intervals ◽  
Surface Ecg ◽  
Tangent Method ◽  
Clinical Consequences ◽  
Genetically Determined

AbstractThe assessment of the QT interval has been an integral part of ECG interpretation since the first descriptions of long QT syndrome by Wolff in 1950 and by Jervell and Lange-Nielsen in 1957. The correct measurement of the QT interval as well as a correct interpretation of the causes and of the clinical consequences of a QT prolongation, however, may be difficult even for trained internists and cardiologists. In this review, we give an overview on physiological determinants of cardiac repolarization, its marker in the surface ECG – the QT interval –, methods to correctly assess QT interval duration, causes for pathologically prolonged QT intervals, and resulting clinical consequences. A correct measurement of the QT interval should be performed by using the „tangent method“, excluding possible U waves. A heart rate correction formula should be employed to determine the heart rate corrected QT interval (QTc).Many factors, which may prolong the QT interval, should be checked whenever a QTc prolongation is observed. These include drugs, electrolyte imbalances, hormonal influence, and comorbidities. The correct management of a patient with (genetically determined) LQTS starts with a risk stratification based on genotype, ECG phenotype, clinical history, age, sex, concomitant diseases, drug therapies, and family history for syncope or sudden cardiac death. The therapeutic approaches for LQTS are multimodal. Prevention is the basis of the therapy and includes avoiding known risk factors / and potentially QT-prolonging drugs, and a pharmacological treatment with non-selective beta blockers. According to the risk profile and to the patient’s lifestyle the implantation of an ICD or a pacemaker should be considered.

Heart Rate and QT Interval in Streptozotocin-induced Diabetic Rat

2009 ◽  
Vol 2 (3) ◽  
pp. 108-118 ◽  
Author(s):  
F. C. Howarth ◽  
E. Adeghate ◽  
M. Jacobson
Keyword(s):  
Heart Rate ◽  
Qt Interval ◽  
Diabetic Rat

scholarly journals Changes in left ventricular electromechanical relations during targeted hypothermia

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Kristin Wisløff-Aase ◽  
Viesturs Kerans ◽  
Kristina Haugaa ◽  
Per Steinar Halvorsen ◽  
Helge Skulstad ◽  
...  
Keyword(s):  
Heart Rate ◽  
Qt Interval ◽  
Clinical Importance ◽  
Left Ventricular ◽  
Peak Strain ◽  
Time To Peak ◽  
Mechanical Dispersion ◽  
Dispersion Of Repolarization ◽  
Aortic Valve Closure ◽  
Prolonged Qt Interval

Abstract Background Targeted hypothermia, as used after cardiac arrest, increases electrical and mechanical systolic duration. Differences in duration of electrical and mechanical systole are correlated to ventricular arrhythmias. The electromechanical window (EMW) becomes negative when the electrical systole outlasts the mechanical systole. Prolonged electrical systole corresponds to prolonged QT interval, and is associated with increased dispersion of repolarization and mechanical dispersion. These three factors predispose for arrhythmias. The electromechanical relations during targeted hypothermia are unknown. We wanted to explore the electromechanical relations during hypothermia at 33 °C. We hypothesized that targeted hypothermia would increase electrical and mechanical systolic duration without more profound EMW negativity, nor an increase in dispersion of repolarization and mechanical dispersion. Methods In a porcine model (n = 14), we registered electrocardiogram (ECG) and echocardiographic recordings during 38 °C and 33 °C, at spontaneous and atrial paced heart rate 100 beats/min. EMW was calculated by subtracting electrical systole; QT interval, from the corresponding mechanical systole; QRS onset to aortic valve closure. Dispersion of repolarization was measured as time from peak to end of the ECG T wave. Mechanical dispersion was calculated by strain echocardiography as standard deviation of time to peak strain. Results Electrical systole increased during hypothermia at spontaneous heart rate (p < 0.001) and heart rate 100 beats/min (p = 0.005). Mechanical systolic duration was prolonged and outlasted electrical systole independently of heart rate (p < 0.001). EMW changed from negative to positive value (− 20 ± 19 to 27 ± 34 ms, p = 0.001). The positivity was even more pronounced at heart rate 100 beats/min (− 25 ± 26 to 41 ± 18 ms, p < 0.001). Dispersion of repolarization decreased (p = 0.027 and p = 0.003), while mechanical dispersion did not differ (p = 0.078 and p = 0.297). Conclusion Targeted hypothermia increased electrical and mechanical systolic duration, the electromechanical window became positive, dispersion of repolarization was slightly reduced and mechanical dispersion was unchanged. These alterations may have clinical importance. Further clinical studies are required to clarify whether corresponding electromechanical alterations are accommodating in humans.

Discharge heart rate and clinical outcomes in hospitalized heart failure patients with coexisted atrial fibrillation

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
F Xing ◽  
X Bai ◽  
J Li
Keyword(s):  
Heart Failure ◽  
Atrial Fibrillation ◽  
Heart Rate ◽  
Clinical Outcome ◽  
Confidence Interval ◽  
Clinical Outcomes ◽  
Beta Blockers ◽  
Funding Source ◽  
Proportional Hazard ◽  
Cox Proportional Hazard

Abstract Background Whether discharge heart rate for hospitalized heart failure (HF) patients with coexisted atrial fibrillation (AF) is associated with long-term clinical outcomes and whether this association differs between patients with and without beta-blockers have not been well studied. Purpose We investigated the associations between discharge heart rate and clinical outcomes in hospitalized HF patients with coexisted AF, while stratified to beta-blockers at discharge. Methods The study cohort included 1631 HF patients hospitalized primarily with AF, which was from the China PEACE Prospective Heart Failure Study. Clinical outcome was 1-year combined all-cause mortality and HF hospitalization after discharge. We analyzed association between outcome and heart rate at discharge with restricted cubic spline and Cox proportional hazard ratios (HR). Results The median age was 68 (IQR: 60- 77) years, 41.9% were women, discharge heart rate was (median (IQR)) 75 (69- 84) beats per minute (bpm), and 60.2% received beta-blockers at discharge. According to the result of restricted cubic spline plot, the relationship between discharge heart rate and clinical outcome may be nonlinear (P&lt;0.01). Based on above result, these patients were divided into 3 groups: lowest &lt;65 bpm, middle 65–86 bpm and highest ≥87 bpm, clinical outcomes occurred in 128 (64.32%), 624 (53.42%) and 156 (59.32%) patients in the lowest, middle, and highest groups respectively. In the Cox proportional hazard analysis, the lowest and highest groups were associated with increased risks of clinical outcome compared with the middle group (HR: 1.289, 95% confidence interval (CI): 1.056 - 1.573, p=0.013; HR: 1.276, 95% CI: 1.06 - 1.537, p=0.01, respectively). And a significant interaction between discharge heart rate and beta-blocker use was observed (P&lt;0.001 for interaction). Stratified analysis showed the lowest group was associated with increased risks of clinical outcomes in patients with beta-blockers (HR: 1.584, 95% confidence interval (CI): 1.215–2.066, p=0.001). Conclusion There may be a U-curve relationship between discharge heart rate and clinical outcomes in hospitalized HF patients with coexisted AF. They may have the best clinical outcomes with heart rates of 65 - 86 bpm. And strict heart rate control (&lt;65 bpm) may be avoided for patients who discharge with beta-blockers. Figure 1 Funding Acknowledgement Type of funding source: Other. Main funding source(s): This work was supported by the National Key Research and Development Program (2017YFC1310803) from the Ministry of Science and Technology of China; the CAMS Innovation Fund for Medical Science (2017-I2M-B&R-02); the 111 Project from the Ministry of Education of China (B16005).

P3517Failure to achieve adequate heart rate control in women during therapy optimization

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
V Kutyifa ◽  
J W Erath ◽  
A Burch ◽  
B Assmus ◽  
D Bondermann ◽  
...  
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Beta Blocker ◽  
Rate Control ◽  
Beta Blockers ◽  
Heart Rate Control ◽  
Blocker Therapy ◽  
Cardioverter Defibrillator ◽  
Beta Blocker Therapy ◽  
The Mean

Abstract Background Previous studies highlighted the importance of adequate heart rate control in heart failure patients, and suggested under-treatment with beta-blockers especially in women. However, data on women achieving effective heart rate control during beta-blocker therapy optimization are lacking. Methods The wearable cardioverter defibrillator (WCD) allows continuous monitoring of heart rate (HR) trends during WCD use. In the current study, we assessed resting HR trends (nighttime: midnight-7am) in women, both at the beginning of WCD use and at the end of WCD use to assess the adequacy of beta-blockade following a typical 3 months of therapy optimization with beta-blockers. An adequate heart rate control was defined as having a nighttime HR <70 bpm at the end of the 3 months. Results There were a total of 21,453 women with at least 30 days of WCD use (>140 hours WCD use on the first and last week). The mean age was 67 years (IQR 58–75). The mean nighttime heart rate was 72 bpm (IQR 65–81) at the beginning of WCD use, that decreased to 68 bpm (IQR 61–76) at the end of WCD use with therapy optimization. Women had an insufficient heart rate control with resting heart rate ≥70 bpm in 59% at the beginning of WCD use that decreased to 44% at the end of WCD use, but still remained surprisingly high. Interestingly, there were 21% of the women starting with HR ≥70 bpm at the beginning of use (BOU) who achieved adequate heart rate control by the end of use (EOU). Interestingly, 6% of women with adequate heart rate control at the start of therapy optimization ended up having higher heart rates >70 bpm at the end of the therapy optimization time period (Figure). Figure 1 Conclusions A significant proportion of women with heart failure and low ejection fraction do not reach an adequate heart rate control during the time of beta blocker initiation/titration. The wearble cardioverter defibrillator is a monitoring device that has been demonstrated in this study to appropriately identify patients with inadequate heart rate control at the end of the therapy optimization period. The WCD could be utilized to improve management of beta-blocker therapy in women and improve the achievement of adequate heart rate control in women.

Electrocardiographic characteristics and associated outcomes in patients with Takotsubo syndrome. Insights from the RETAKO registry

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
I Martin-Demiguel ◽  
I Nunez-Gil ◽  
A Perez-Castellanos ◽  
O Vedia ◽  
A Uribarri ◽  
...  
Keyword(s):  
Heart Rate ◽  
Primary Endpoint ◽  
Qt Interval ◽  
Protective Factor ◽  
Independent Predictor ◽  
Prognostic Significance ◽  
Takotsubo Syndrome ◽  
St Segment Elevation ◽  
Corrected Qt Interval ◽  
St Segment

Abstract Background Our aim was to describe the prevalence and prognostic significance of electrocardiographic features in patients with Takotsubo syndrome (TTS). Methods Our data come from the Spanish Multicenter REgistry of TAKOtsubo syndrome (RETAKO). All patients with complete electrocardiogram were included. Results 246 patients were studied, mean age was 71.3±11.5 and 215 (87.4%) were women. ST-segment elevation was seen in 143 patients (59.1%) and was present in ≥2 wall leads in 97 (39.8%). Exclusive elevation in inferior leads was infrequent (5 - 2.0%). After 48 hours, 198 patients (88.0%) developed negative T-waves in a median of 8 leads with a mean amplitude of 0.7±0.5 mV. Mean corrected QT interval was 520±72 ms and it was independently associated with the primary endpoint of all-cause death and nonfatal cardiovascular events (p=0.002) and all-cause death (p=0.008). A higher heart rate at admission was also an independent predictor of the primary endpoint (p=0.001) and of developing acute pulmonary edema (p=0.04). ST-segment elevation with reciprocal depression was an independent predictor of all-cause death (p=0.04). Absence of ST-segment deviation was a protective factor (p=0.005) for the primary endpoint. Arrhythmias were independently associated with cardiogenic shock (p&lt;0.001). Conclusion Prolonged corrected QT interval, arrhythmia, heart rate at admission and broader repolarization alterations are associated with a poor outcome in TTS. Typical ECG at admission and after 48h. Funding Acknowledgement Type of funding source: None

scholarly journals Safety and effectiveness of drug therapy for the acutely agitated patient (Part I)

2013 ◽  
pp. 127-136
Author(s):  
Gianluca Airoldi
Keyword(s):  
Heart Rate ◽  
Qt Interval ◽  
Physical Restraint ◽  
Safety Data ◽  
Surrogate Marker ◽  
Diagnostic Procedures ◽  
Torsades De Pointes ◽  
Long Qt ◽  
Drug Induced ◽  
Qt Interval Prolongation

Acute agitation occurs in a variety of medical and psychiatric conditions, and the management of agitated, abusive, or violent patients is a common problem in the emergency department. Rapid control of potentially dangerous behaviors by physical restraint and pharmacologic tranquillization is crucial to ensure the safety of the patient and health-care personnel and to allow diagnostic procedures and treatment of the underlying condition. The purpose of this article (the first in a 2-part series) is to review the extensive safety data published on the antipsychotic medications currently available for managing situations of this type, including older neuroleptics like haloperidol, chlorpromazine, and pimozide as well as a number of the newer atypical antipsychotics (olanzapine, risperidone, ziprasidone). Particular attention is focused on the ability of these drugs to lengthen the QT interval in surface electrocardiograms. This adverse effect is of major concern, especially in light of the reported relation between QT interval and the risk of sudden death. In patients with the congenital long-QT syndrome, a long QT interval is associated with a fatal paroxysmal ventricular arrhythmia knownas torsades de pointes. Therefore, careful evaluation of the QT-prolonging properties and arrhythmogenic potential of antipsychotic drugs is urgently needed. Clinical assessment of drug-induced QT-interval prolongation is strictly dependent on the quality of electrocardiographic data and the appropriateness of electrocardiographic analyses. Unfortunately, measurement imprecision and natural variability preclude a simple use of the actually measured QT interval as a surrogate marker of drug-induced proarrhythmia. Because the QT interval changes with heart rate, a rate-corrected QT interval (QTc) is commonly used when evaluating a drug’s effect. In clinical settings, themost widely used formulas for rate-correction are those of Bazett (QTc=QT/RR^0.5) and Fridericia (QTc=QT/RR^0.33), both of which standardize themeasuredQTinterval to an RRinterval of 1 s (heart rate of 60 bpm).However, QT variability can also be influenced by other factors that are more difficult to measure, including body fat, meals, psycho-physical distress, and circadian and seasonal fluctuations.

Relation between heart rate and QT interval in exercise-induced myocardial ischemia

1985 ◽  
Vol 56 (13) ◽  
pp. 861-862 ◽  
Author(s):  
Massimo Romano ◽  
Teresa Di Maro ◽  
Giovanni Carella ◽  
Maria Rosaria Cotecchia ◽  
Giuseppe Ferro ◽  
...  
Keyword(s):  
Heart Rate ◽  
Myocardial Ischemia ◽  
Qt Interval ◽  
Exercise Induced

Haemodynamic Effects of Different Beta Blockers in Angina Pectoris

1977 ◽  
Vol 22 (1) ◽  
pp. 64-68 ◽  
Author(s):  
H. Åström ◽  
B. Jonsson
Keyword(s):  
Heart Rate ◽  
Angina Pectoris ◽  
Stroke Volume ◽  
Partial Agonist ◽  
Beta Blockers ◽  
Haemodynamic Effects ◽  
Agonist Activity ◽  
Peripheral Vascular ◽  
Reduce Heart Rate ◽  
Beta Blocking

Beta-blocking agents with partial agonist activity seem to reduce heart rate at rest slightly less than those without this property. Cardio-selective drugs have no effect on stroke volume at rest contrary to the non-selective ones which will reduce it somewhat. This difference is abolished during exercise. The only difference seen during work between different beta-blockers is the effect on the peripheral vascular resistance. The selective drugs lower the arterial pressure with unchanged resistance.

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