QA interval heart rate correction: Species comparison of an indirect ventricular contractility biomarker

The electrocardiographic (ECG) assessment of the T peak–T end (Tpe) intervals has been used in many clinical studies, but several related physiological aspects have not been reported. Specifically, the sources of the Tpe differences between different ECG leads have not been systematically researched, the relationship of Tpe duration to underlying heart rate has not been firmly established, and little is known about the mutual correspondence of Tpe intervals measured in different ECG leads. This study evaluated 796,620 10-s 12-lead ECGs obtained from long-term Holters recorded in 639 healthy subjects (311 female) aged 33.8 ± 9.4 years. For each ECG, transformation to orthogonal XYZ lead was used to measure Tpe in the orthogonal vector magnitude (used as a reference for lead-to-lead comparisons) and to construct a three-dimensional T wave loop. The loop roundness was expressed by a ratio between its circumference and length. These ratios were significantly related to the standard deviation of Tpe durations in different ECG leads. At the underlying heart rate of 60 beats per minute, Tpe intervals were shorter in female than in male individuals (82.5 ± 5.6 vs 90.0 ± 6.5 ms, p < 0.0001). When studying linear slopes between Tpe intervals measured in different leads and the underlying heart rate, we found only minimal heart rate dependency, which was not systematic across the ECG leads and/or across the population. For any ECG lead, positive Tpe/RR slope was found in some subjects (e.g., 79 and 25% of subjects for V2 and V4 measurements, respectively) and a negative Tpe/RR slope in other subjects (e.g., 40 and 65% for V6 and V5, respectively). The steepest positive and negative Tpe/RR slopes were found for measurements in lead V2 and V4, respectively. In all leads, the Tpe/RR slope values were close to zero, indicating, on average, Tpe changes well below 2 ms for RR interval changes of 100 ms. On average, longest Tpe intervals were measured in lead V2, the shortest in lead III. The study concludes that the Tpe intervals measured in different leads cannot be combined. Irrespective of the measured ECG lead, the Tpe interval is not systematically heart rate dependent, and no heart rate correction should be used in clinical Tpe investigations.

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Treatment of patients with myocardial infarction

Kazan medical journal ◽

10.17816/kazmj63558 ◽

1998 ◽

Vol 79 (1) ◽

pp. 57-69

Author(s):

I. A. Latfullin

Keyword(s):

Myocardial Infarction ◽

Heart Rate ◽

Pain Relief ◽

Patient Support ◽

Heart Rate Correction

A patient with suspected myocardial infarction (MI) or with a confirmed diagnosis should be admitted to a specialized (cardiological) hospital. Its treatment includes five main aspects: patient support, pain relief, reperfusion with thrombolytics and aspirin (all patients should receive 300 mg of aspirin tablets), heart rate correction, and respiratory resuscitation with defibrillation.

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The 2- and 6-Minute Walk Tests in Neuromuscular Diseases: Effect of Heart Rate Correction on the Learning Effect

International Journal of Physical Medicine & Rehabilitation ◽

10.4172/2329-9096.1000415 ◽

2017 ◽

Vol 05 (04) ◽

Cited By ~ 1

Author(s):

Kirsten Lykke Knak ◽

Linda Kahr Andersen ◽

Nanna Witting ◽

John Vissing

Keyword(s):

Heart Rate ◽

Learning Effect ◽

Neuromuscular Diseases ◽

Heart Rate Correction ◽

Minute Walk ◽

Walk Tests

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Heart Rate Correction of the J-to-Tpeak Interval

Scientific Reports ◽

10.1038/s41598-019-51491-4 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Katerina Hnatkova ◽

Jose Vicente ◽

Lars Johannesen ◽

Christine Garnett ◽

David G. Strauss ◽

...

Keyword(s):

Heart Rate ◽

Safety Evaluation ◽

Linear Regression Models ◽

Drug Induced ◽

Rr Intervals ◽

Channel Effects ◽

Linear Correction ◽

History Of ◽

Heart Rate Correction ◽

Log Linear

Abstract Drug-induced changes of the J to T peak (JTp) and J to the median of area under the T wave (JT50) were reported to differentiate QT prolonging drugs that are predominant blockers of the delayed potassium rectifier current from those with multiple ion channel effects. Studies of drug-induced JTp/JT50 interval changes might therefore facilitate cardiac safety evaluation of new pharmaceuticals. It is not known whether formulas for QT heart rate correction are applicable to JTp and JT50 intervals. QT/RR, JTp/RR, and JT50/RR profiles were studied in 523 healthy subjects aged 33.5 ± 8.4 years (254 females). In individual subjects, 1,256 ± 220 electrocardiographic measurements of QT, JTp, and JT50 intervals were available including a 5-minute history of RR intervals preceding each measurement. Curvilinear, linear and log-linear regression models were used to characterize individual QT/RR, JTp/RR, and JT50/RR profiles both without and with correction for heart rate hysteresis. JTp/RR and JT50/RR hysteresis correction needs to be included but the generic universal correction for QT/RR hysteresis is also applicable to JTp/RR and JT50/RR profiles. Once this is incorporated, median regression coefficients of the investigated population suggest linear correction formulas JTpc = JTp + 0.150(1-RR) and JT50c = JT50 + 0.117(1-RR) where RR intervals of the underlying heart rate are hysteresis-corrected, and all measurements expressed in seconds. The established correction formulas can be proposed for future clinical pharmacology studies that show drug-induced heart rate changes of up to approximately 10 beats per minute.

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Heart rate correction of the QT interval: A nonparametric individualized approach

Journal of Pharmacological and Toxicological Methods ◽

10.1016/j.vascn.2008.05.061 ◽

2008 ◽

Vol 58 (2) ◽

pp. 160

Author(s):

G. Greco ◽

A. Russu ◽

C. Arrigoni ◽

P. Magni ◽

G. De Nicolao ◽

...

Keyword(s):

Heart Rate ◽

Qt Interval ◽

Individualized Approach ◽

Heart Rate Correction

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Effects of hyperbaric oxygen exposure at 31.3 ATA on spontaneously beating cat hearts

Journal of Applied Physiology ◽

10.1152/jappl.1983.55.1.139 ◽

1983 ◽

Vol 55 (1) ◽

pp. 139-145 ◽

Cited By ~ 5

Author(s):

T. J. Doubt ◽

D. E. Evans

Keyword(s):

Heart Rate ◽

Hyperbaric Oxygen ◽

Ambient Pressure ◽

Cardiovascular Responses ◽

Time Dependent ◽

Ventricular Contractility ◽

Partial Pressure Of Oxygen ◽

Negative Effects ◽

Inotropic Effects ◽

Hyperbaric Oxygen Exposure

Cardiovascular responses to raised ambient pressure and acute hyperbaric oxygen (HBO) exposure [HBO, partial pressure of oxygen (PO2) = 2 ATA)] were examined in anesthetized cats. Relatively normoxic [PO2 = 0.35 ATA] helium compression to 31.3 ATA decreased spontaneous heart rate, prolonged the P-R and Q-T intervals of the ECG independently of changes in rate, and significantly increased ventricular contractility. HBO while at depth produced further decreases in heart rate, with no change in the P-R interval. The Q-T interval decreased significantly in the presence of bradycardia, particularly during the first 15 min of exposure. During the first 10-15 min of HBO exposure myocardial contractility and developed ventricular pressure were reduced, but contractility increased significantly at 30 min. These results indicate that HBO interacts with depth effects to produce hyperbaric bradycardia but reverses pressure actions on ventricular repolarization. The inotropic effects of HBO are time dependent, with slightly negative effects occurring initially, followed by positive inotropic actions at 30 min.

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