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Description of the Strength‐Interval Relation with External Noninvasive Pacing
Author(s) -
LUCK JERRY C.,
GRUBB BLAIR P.,
MARKEL MICHAEL L.
Publication year - 1990
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1990.tb06937.x
Subject(s) - medicine , interval (graph theory) , relation (database) , cardiology , cardiac pacing , physical medicine and rehabilitation , combinatorics , data mining , mathematics , computer science
LUCK, J.C., ET AL.: Description of the Strength‐Interval Relation with External Noninvasive Pacing. The strength‐interval relationship obtained by external pacing (EXP) was compared to curves obtained by endocardial pacing from a right ventricular site. There were 17 patients, age 45 ± 17 years. Effective and functional ventricular refractory periods (ERP, FRP) were determined during a ventricular drive train of 8 stimuli at a cycle length 500 msec. Endocardial pacing threshold current averaged 0.5 ± 0.3 mA (range 0.2‐1.0 mA) and EXP threshold current averaged 64 ± 14 mA [range 40–80 mA]. At twice threshold, endocardial ventricular ERP was 235 ± 32 msec and FRP was 262 ± 29 msec. At 10 mA above threshold, EXP ventricular ERP was 276 ± 29 msec and was significantly longer than endocardial ERP at twice threshold (p < 0.001). EXP ventricular FRP shortened to 237 ± 39 msec at twice threshold and was similar to endocardial ERP (P = 0.55). EXP ventricular FRP was significantly longer than endocardial ERP (280 ± 29 vs 262 k 29 msec, p < 0.001) at twice threshold. EXP strength‐interval curves were similar to endocardial curves in 14 of 17 (82%) patients. We conclude, that at twice threshold, similar coupling intervals can be obtained with both endocardial and EXP. Therefore, EXP can provide critically coupled extrastimuli for programmed ventricular stimulation.