Heart rate variability is the normal beat-to-beat alterations of heart rate and reflects the ANS’s ability to respond to the environment (McMillan, 2002). Heart rate variability measurements were obtained from 24-hour Holter electrocardiogram recordings and derive from the analysis of consecutive R-R intervals (Gang & Malik, 2003). The predominant method for analysis of HRV is time and frequency domain analysis, and these measurements also provide information about ANS activity (Gang &
Malik, 2003). Time domain analyses are calculated using mathematical equations, with measures reflecting parasympathetic modulation and circadian rhythmicity. The time domain measure utilized within this study is the standard deviation of all RR intervals …show more content…
QT Interval The QT Interval represents ventricular depolarization, and repolarization and is the measurement from the onset of the QRS complex to the end deflection of the T wave
(Furukawa, Shimizu, Hiromoto, Kanemori, Masuyama, & Ohyanagi, 2006; Hunt, 2005).
The QT Interval normally ranges from 0.2-0.4 sec and is often corrected to be independent of heart rate. According to the Harriet Lane Handbook 14th edition (Barone,
1996), the QTc should not exceed 0.440 sec in children and 0.425 sec in adolescents and adults. The QT Interval adjusts to changes in heart rate (Barone, 1996; Moss & Allen,
2001), and for comparison at different heart rates, correction formulas were developed to determine the QTc Interval, and Bazett’s formula is used most often (Malik, Färbom,
Batchvarov, Hnatkova, & Camm, 2002). significance
The ANS regulates heart rate and blood pressure. Epinephrine and norepinephrine released by the sympathetic nervous system and acetylcholine released by the parasympathetic nervous system are major influences on heart rate and rhythm (Alter et al., 2006). Therefore, in light of cardiac automaticity, heart rate is largely controlled by
ANS function (Alter et al., 2006). Factors affecting cardiac autonomic
Malik, 2003). Time domain analyses are calculated using mathematical equations, with measures reflecting parasympathetic modulation and circadian rhythmicity. The time domain measure utilized within this study is the standard deviation of all RR intervals …show more content…
QT Interval The QT Interval represents ventricular depolarization, and repolarization and is the measurement from the onset of the QRS complex to the end deflection of the T wave
(Furukawa, Shimizu, Hiromoto, Kanemori, Masuyama, & Ohyanagi, 2006; Hunt, 2005).
The QT Interval normally ranges from 0.2-0.4 sec and is often corrected to be independent of heart rate. According to the Harriet Lane Handbook 14th edition (Barone,
1996), the QTc should not exceed 0.440 sec in children and 0.425 sec in adolescents and adults. The QT Interval adjusts to changes in heart rate (Barone, 1996; Moss & Allen,
2001), and for comparison at different heart rates, correction formulas were developed to determine the QTc Interval, and Bazett’s formula is used most often (Malik, Färbom,
Batchvarov, Hnatkova, & Camm, 2002). significance
The ANS regulates heart rate and blood pressure. Epinephrine and norepinephrine released by the sympathetic nervous system and acetylcholine released by the parasympathetic nervous system are major influences on heart rate and rhythm (Alter et al., 2006). Therefore, in light of cardiac automaticity, heart rate is largely controlled by
ANS function (Alter et al., 2006). Factors affecting cardiac autonomic