Effects of pacing rate and timing of defibrillation shock on the relation between the defibrillation threshold and the upper limit of vulnerability in open chest dogs

Peng-Sheng Chen, Gregory K. Feld, Morton M. Mower, Barry B. Peters

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Abstract

To test the relation between the defibrillation threshold and the upper limit of vulnerability, the shock strength associated with 50% probability of successful defibrillalion (DFT50) and that associated with 50% probability of reaching the upper limit of vulnerability (ULV50) were determined in 20 open chest dogs with use of the delayed up-down method, with pacing drive cycle lengths of 150 to 500 ms and either single 6-ms shocks (10 dogs) or 12-ms biphasic shocks (10 dogs) given at the mid-upslope, peak and mid-downslope of the T wave of electrocardiographc lead II. The shocks were given by means of a patch-patch configuration on the anterior and posterior surfaces of the heart, which was paced from a stimulating electrode attached to the left ventricular apex. Analysis of variance showed no statistically significant differences in ULV50 as determined with different pacing cycle lengths. For monophasic shocks, DFT50 (331 ± 66 V or 5.8 ± 2.7 J) was not significantly different from ULV50 determined at the midupslope of the T wave (318 ± 64 V or 5 ± 2 J). The correlation coefficients between the two values were 0.74 (p = 0.014) for voltage and 0.67 (p = 0.034) for energy. In contrast, DFT50 was significantly higher than ULV50 as determined at the peak of the T wave (219 ± 43 V or 2.3 ± 1 J) and mid-downslope of the T wave (200 ± 38 V or 1.9 ± 0.9 J). In three dogs, ventricular fibrillation could not be induced at the mid-downslope of the T wave with any baseline pacing (S1) cycle length. For biphasic shocks, DFT50 (285 ± 53 V or 4 ± 1.5 J) was not significantly different from ULV50 as determined at the mid-upslope of the T wave (293 ± 54 V or 3.9 ± 1.2 J). The correlation coefficients between the two values were 0.90 (p <0.001) for voltage and 0.82 (p = 0.004) for energy. In contrast, DFT50 was significantly higher than ULV50 determined at the peak of the T wave (208 ± 31 V or 1.9 ± 0.5 J) and mid-downslope of the T wave (180 ± 16 V or 1.7 ± 0.8 J). In six dogs, ventricular fibrillation could not be induced at the mid-downslope of the T wave with any S1 cycle length. It is concluded that with either monophasic or biphasic shocks, DFT50 can be accurately estimated by ULV50 as determined at the mid-upslope of the T wave. Altering the baseline pacing cycle length does not affect this relation.

Original languageEnglish (US)
Pages (from-to)1555-1563
Number of pages9
JournalJournal of the American College of Cardiology
Volume18
Issue number6
DOIs
StatePublished - Nov 15 1991
Externally publishedYes

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Shock
Thorax
Dogs
Ventricular Fibrillation
Analysis of Variance
Electrodes

ASJC Scopus subject areas

  • Nursing(all)

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Effects of pacing rate and timing of defibrillation shock on the relation between the defibrillation threshold and the upper limit of vulnerability in open chest dogs. / Chen, Peng-Sheng; Feld, Gregory K.; Mower, Morton M.; Peters, Barry B.

In: Journal of the American College of Cardiology, Vol. 18, No. 6, 15.11.1991, p. 1555-1563.

Research output: Contribution to journalArticle

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title = "Effects of pacing rate and timing of defibrillation shock on the relation between the defibrillation threshold and the upper limit of vulnerability in open chest dogs",
abstract = "To test the relation between the defibrillation threshold and the upper limit of vulnerability, the shock strength associated with 50{\%} probability of successful defibrillalion (DFT50) and that associated with 50{\%} probability of reaching the upper limit of vulnerability (ULV50) were determined in 20 open chest dogs with use of the delayed up-down method, with pacing drive cycle lengths of 150 to 500 ms and either single 6-ms shocks (10 dogs) or 12-ms biphasic shocks (10 dogs) given at the mid-upslope, peak and mid-downslope of the T wave of electrocardiographc lead II. The shocks were given by means of a patch-patch configuration on the anterior and posterior surfaces of the heart, which was paced from a stimulating electrode attached to the left ventricular apex. Analysis of variance showed no statistically significant differences in ULV50 as determined with different pacing cycle lengths. For monophasic shocks, DFT50 (331 ± 66 V or 5.8 ± 2.7 J) was not significantly different from ULV50 determined at the midupslope of the T wave (318 ± 64 V or 5 ± 2 J). The correlation coefficients between the two values were 0.74 (p = 0.014) for voltage and 0.67 (p = 0.034) for energy. In contrast, DFT50 was significantly higher than ULV50 as determined at the peak of the T wave (219 ± 43 V or 2.3 ± 1 J) and mid-downslope of the T wave (200 ± 38 V or 1.9 ± 0.9 J). In three dogs, ventricular fibrillation could not be induced at the mid-downslope of the T wave with any baseline pacing (S1) cycle length. For biphasic shocks, DFT50 (285 ± 53 V or 4 ± 1.5 J) was not significantly different from ULV50 as determined at the mid-upslope of the T wave (293 ± 54 V or 3.9 ± 1.2 J). The correlation coefficients between the two values were 0.90 (p <0.001) for voltage and 0.82 (p = 0.004) for energy. In contrast, DFT50 was significantly higher than ULV50 determined at the peak of the T wave (208 ± 31 V or 1.9 ± 0.5 J) and mid-downslope of the T wave (180 ± 16 V or 1.7 ± 0.8 J). In six dogs, ventricular fibrillation could not be induced at the mid-downslope of the T wave with any S1 cycle length. It is concluded that with either monophasic or biphasic shocks, DFT50 can be accurately estimated by ULV50 as determined at the mid-upslope of the T wave. Altering the baseline pacing cycle length does not affect this relation.",
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T1 - Effects of pacing rate and timing of defibrillation shock on the relation between the defibrillation threshold and the upper limit of vulnerability in open chest dogs

AU - Chen, Peng-Sheng

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AU - Mower, Morton M.

AU - Peters, Barry B.

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N2 - To test the relation between the defibrillation threshold and the upper limit of vulnerability, the shock strength associated with 50% probability of successful defibrillalion (DFT50) and that associated with 50% probability of reaching the upper limit of vulnerability (ULV50) were determined in 20 open chest dogs with use of the delayed up-down method, with pacing drive cycle lengths of 150 to 500 ms and either single 6-ms shocks (10 dogs) or 12-ms biphasic shocks (10 dogs) given at the mid-upslope, peak and mid-downslope of the T wave of electrocardiographc lead II. The shocks were given by means of a patch-patch configuration on the anterior and posterior surfaces of the heart, which was paced from a stimulating electrode attached to the left ventricular apex. Analysis of variance showed no statistically significant differences in ULV50 as determined with different pacing cycle lengths. For monophasic shocks, DFT50 (331 ± 66 V or 5.8 ± 2.7 J) was not significantly different from ULV50 determined at the midupslope of the T wave (318 ± 64 V or 5 ± 2 J). The correlation coefficients between the two values were 0.74 (p = 0.014) for voltage and 0.67 (p = 0.034) for energy. In contrast, DFT50 was significantly higher than ULV50 as determined at the peak of the T wave (219 ± 43 V or 2.3 ± 1 J) and mid-downslope of the T wave (200 ± 38 V or 1.9 ± 0.9 J). In three dogs, ventricular fibrillation could not be induced at the mid-downslope of the T wave with any baseline pacing (S1) cycle length. For biphasic shocks, DFT50 (285 ± 53 V or 4 ± 1.5 J) was not significantly different from ULV50 as determined at the mid-upslope of the T wave (293 ± 54 V or 3.9 ± 1.2 J). The correlation coefficients between the two values were 0.90 (p <0.001) for voltage and 0.82 (p = 0.004) for energy. In contrast, DFT50 was significantly higher than ULV50 determined at the peak of the T wave (208 ± 31 V or 1.9 ± 0.5 J) and mid-downslope of the T wave (180 ± 16 V or 1.7 ± 0.8 J). In six dogs, ventricular fibrillation could not be induced at the mid-downslope of the T wave with any S1 cycle length. It is concluded that with either monophasic or biphasic shocks, DFT50 can be accurately estimated by ULV50 as determined at the mid-upslope of the T wave. Altering the baseline pacing cycle length does not affect this relation.

AB - To test the relation between the defibrillation threshold and the upper limit of vulnerability, the shock strength associated with 50% probability of successful defibrillalion (DFT50) and that associated with 50% probability of reaching the upper limit of vulnerability (ULV50) were determined in 20 open chest dogs with use of the delayed up-down method, with pacing drive cycle lengths of 150 to 500 ms and either single 6-ms shocks (10 dogs) or 12-ms biphasic shocks (10 dogs) given at the mid-upslope, peak and mid-downslope of the T wave of electrocardiographc lead II. The shocks were given by means of a patch-patch configuration on the anterior and posterior surfaces of the heart, which was paced from a stimulating electrode attached to the left ventricular apex. Analysis of variance showed no statistically significant differences in ULV50 as determined with different pacing cycle lengths. For monophasic shocks, DFT50 (331 ± 66 V or 5.8 ± 2.7 J) was not significantly different from ULV50 determined at the midupslope of the T wave (318 ± 64 V or 5 ± 2 J). The correlation coefficients between the two values were 0.74 (p = 0.014) for voltage and 0.67 (p = 0.034) for energy. In contrast, DFT50 was significantly higher than ULV50 as determined at the peak of the T wave (219 ± 43 V or 2.3 ± 1 J) and mid-downslope of the T wave (200 ± 38 V or 1.9 ± 0.9 J). In three dogs, ventricular fibrillation could not be induced at the mid-downslope of the T wave with any baseline pacing (S1) cycle length. For biphasic shocks, DFT50 (285 ± 53 V or 4 ± 1.5 J) was not significantly different from ULV50 as determined at the mid-upslope of the T wave (293 ± 54 V or 3.9 ± 1.2 J). The correlation coefficients between the two values were 0.90 (p <0.001) for voltage and 0.82 (p = 0.004) for energy. In contrast, DFT50 was significantly higher than ULV50 determined at the peak of the T wave (208 ± 31 V or 1.9 ± 0.5 J) and mid-downslope of the T wave (180 ± 16 V or 1.7 ± 0.8 J). In six dogs, ventricular fibrillation could not be induced at the mid-downslope of the T wave with any S1 cycle length. It is concluded that with either monophasic or biphasic shocks, DFT50 can be accurately estimated by ULV50 as determined at the mid-upslope of the T wave. Altering the baseline pacing cycle length does not affect this relation.

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