Avtor/Urednik		Starc, Vito; Zaletel, Marjan; Peterec, Daniel
Naslov		Approximately parabolic dependence of P-R interval length on heart rate during respiratory sinus arrhythmia
Tip		članek
Vir		J Cardiovasc Diagn P
Vol. in št.		Letnik 14, št. 3
Leto izdaje		1997
Obseg		str. 135-46
Jezik		eng
Abstrakt		To determine exactly how the length of the P-R interval varies with changes in heart rate during respiratory sinus arrhythmia, we used a modified high-resolution ECG to measure the high-fidelity P-R interval lenght. The P-R interval can lengthen in healthy people in response to increased heart rate or to the reduced heart rate accompanying increased vagal activity. This lengthening of the P-R interval may signal a tendency to develop atrioventricular (AV) block. In each of the 12 healthy young men, the P-R interval length was determined from each of five surface-averaged electrocardiograms, which were obtained by ECG signal averaging separately within each of five selected heart rate ranges. From these five P-R intervals and the corresponding heart rate data, we calculated a P-R interval lenght-heart rate curve (PR-HR curve). The heart range was further extended by tilting the subjects from the supine position to nearly upright (60 degrees), and P-R intervals were again determined. We found that when subjects were in the supine position, the PR-HR curve folowed an approximately parabolic pattern with heart rates 64.8 +- 6.4 beats/min (mean +- SD). Specifically, at slower heart rates, the P-R interval became shorter as heart rate increased, reaching the critical heart rate of67 beats/min where the P-R interval was the shortest and was independent of heart rate; at heart rates above that point, the P-R interval lengthened as heart rate increased. When subjects were upright, the pattern remained essentially parabolic with heart rates 92.0 +- 12.8 beats/min, although the P-R interval lenght was less dependent on heart rate, and the critical heart rate shifted to a higher value of 82.2 beats/min.(Abstact truncated at 2000 characters.)
Deskriptorji		ARRHYTHMIA, SINUS HEART RATE ELECTROCARDIOGRAPHY ADULT