What does this research mean for the field?

Transient myocardial ischemia during variant angina causes reversible QRS prolongation and increased terminal voltage, which result from conduction delay and delayed activation in the ischemic zone. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To characterize QRS complex waveform changes during transient myocardial ischemia in variant angina and determine the underlying electrophysiological mechanism.

May 1, 1985CirculationOpen Access

The QRS complex during transient myocardial ischemia: studies in patients with variant angina pectoris and in a canine preparation.

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Why the study?

What are the characteristics and mechanisms of QRS complex changes during transient myocardial ischemia?

Population

5 patients with variant angina pectoris and 7 dogs (canine preparation)

Comparison

Continuous electrocardiographic recordings… vs Baseline electrocardiograms (prior to ischemia)

Authors

JBJames E. BarnhillSaint Thomas West Hospital JWJohn P. WikswoElectrophysiology ADAlbert K. DawsonUnited States Department of Veterans Affairs

Discussion

Member takes

Implication

May support QRS metrics for detecting ischemia; leaves open human translation of canine conduction findings.

Key Points

To characterize QRS complex waveform changes during transient myocardial ischemia in variant angina and determine the underlying electrophysiological mechanism.
Continuous orthogonal lead electrocardiograms were recorded during 15 ischemic episodes in 5 patients with variant angina and evaluated via digital computer subtraction.
Experimental ischemia lasting 120 to 150 seconds was induced in 7 dogs to correlate three-dimensional myocardial conduction velocity with surface electrocardiographic recordings.
Ischemic episodes produced reversible QRS duration prolongation and increased terminal 40-millisecond voltage directed toward the ischemic zone across all 5 patients.
Canine experiments reproduced identical electrocardiographic alterations, which correlated directly with marked deceleration of myocardial conduction velocity in ischemic tissue.

Structured PICO

What are the characteristics and mechanisms of QRS complex changes during transient myocardial ischemia?

Population

5 patients with variant angina pectoris and 7 dogs (canine preparation)

Intervention

Continuous electrocardiographic recordings during transient myocardial ischemia (spontaneous in humans, induced for 120-150 sec in dogs)

Comparator

Baseline electrocardiograms (prior to ischemia)

Outcome

Characteristics of QRS changes (duration, voltage, vector) during ischemiasurrogate

Transient myocardial ischemia causes reversible QRS prolongation and increased terminal QRS voltage due to conduction delay in the ischemic zone.

Cite This Study

Barnhill et al. (1985) studied this question.

synapsesocial.com/papers/6a1a2bbe2da66836c8c7a04a https://doi.org/10.1161/01.cir.71.5.901

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The QRS complex during transient myocardial ischemia: studies in patients with variant angina pectoris and in a canine preparation.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

The QRS complex during transient myocardial ischemia: studies in patients with variant angina pectoris and in a canine preparation.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

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