TY - JOUR
T1 - Subthreshold conditioning stimuli prolong human ventricular refractoriness
AU - Windle, John R.
AU - Miles, William M.
AU - Zipes, Douglas P.
AU - Prystowsky, Eric N.
N1 - Funding Information:
From the Krannert Institute of Cardiology, Department of Medicine, Indiana University School of Medicine, and the Richard L. Roudebush Veterans Administration Medical Center, Indianapolis, Indiana. This study was supported in part by the Herman C. Krannert Fund, Indianapolis, Indiana; by Grants HL-06308 and HL-07182 from the National Heart, Lung, and Blood Institute of the National Institutes of Health, Bethesda, Maryland; by the American Heart Association, Indiana Affiliate; and by the Veterans Administration, Washington, D.C. Manuscript received June 10,1985, accepted June 12,1985.
PY - 1986/2/15
Y1 - 1986/2/15
N2 - This study tested whether a subthreshold stimulus (Sc) inserted before a premature stimulus prolonged the right ventricular effective refractory period in humans, and whether the degree of effective refractory period lengthening was influenced by heart rate, Sc current intensity or Sc pulse duration. Sc at current intensity 10 mA and pulse width 2 ms prolonged mean effective refractory period from 255 ms to 277 ms (p < 0.001, n = 20). The increase in effective refractory period was similar in 6 patients studied at pacing cycle lengths 600 (259 to 289 ms) and 400 ms (236 to 258 ms). When Sc current intensities were varied at 2, 5 or 10 mA at a constant pulse duration of 100 ms the effective refractory period progressively prolonged by 6, 40 and 81 ms respectively (p < 0.02, n = 6). The pulse duration of Sc at a constant current of 10 mA significantly influenced effective refractory period prolongation. With Sc pulse durations of 2, 10, and 100 ms the effective refractory period prolonged by 16, 33 and 66 ms respectively (p < 0.01, n = 7). Thus, subthreshold impulses prolong the effective refractory period in human right ventricular myocardium. The prolongation of effective refractory period depended on Sc current intensity and pulse duration but was independent of heart rate at the cycle lengths tested. The use of subthreshold stimuli as antiarrhythmic therapy may be feasible in some patients.
AB - This study tested whether a subthreshold stimulus (Sc) inserted before a premature stimulus prolonged the right ventricular effective refractory period in humans, and whether the degree of effective refractory period lengthening was influenced by heart rate, Sc current intensity or Sc pulse duration. Sc at current intensity 10 mA and pulse width 2 ms prolonged mean effective refractory period from 255 ms to 277 ms (p < 0.001, n = 20). The increase in effective refractory period was similar in 6 patients studied at pacing cycle lengths 600 (259 to 289 ms) and 400 ms (236 to 258 ms). When Sc current intensities were varied at 2, 5 or 10 mA at a constant pulse duration of 100 ms the effective refractory period progressively prolonged by 6, 40 and 81 ms respectively (p < 0.02, n = 6). The pulse duration of Sc at a constant current of 10 mA significantly influenced effective refractory period prolongation. With Sc pulse durations of 2, 10, and 100 ms the effective refractory period prolonged by 16, 33 and 66 ms respectively (p < 0.01, n = 7). Thus, subthreshold impulses prolong the effective refractory period in human right ventricular myocardium. The prolongation of effective refractory period depended on Sc current intensity and pulse duration but was independent of heart rate at the cycle lengths tested. The use of subthreshold stimuli as antiarrhythmic therapy may be feasible in some patients.
UR - http://www.scopus.com/inward/record.url?scp=0022608483&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0022608483&partnerID=8YFLogxK
U2 - 10.1016/0002-9149(86)90757-5
DO - 10.1016/0002-9149(86)90757-5
M3 - Article
C2 - 3946251
AN - SCOPUS:0022608483
SN - 0002-9149
VL - 57
SP - 381
EP - 386
JO - The American Journal of Cardiology
JF - The American Journal of Cardiology
IS - 6
ER -